Anatomy and Physiology Notes: Conduction System of the Heart

   Key Concepts

1. The electrical activity of cardiac cells is caused by the selective opening and closing of plasma membrane channels for sodium, potassium, and calcium ions.

2. Depolarization is achieved by the opening of sodium and calcium channels and the closing of potassium channels.

3. Repolarization is achieved by the opening of potassium channels and the closing of sodium and calcium

channels.

4. Pacemaker potentials are achieved by the opening of channels for sodium and calcium ions and the closing of channels for potassium ions.

5. Electrical activity is normally initiated in the sinoatrial (SA) node where pacemaker cells reach threshold first.

6. Electrical activity spreads across the atria, through the atrioventricular (AV) node, through the Purkinje system, and to ventricular muscle.

7. Norepinephrine increases pacemaker activity and the speed of action potential conduction.

8. Acetylcholine decreases pacemaker activity and the speed of action potential conduction.

9. Voltage differences between repolarized and depolarized regions of the heart are recorded by an electrocardiogram (ECG).

10. The ECG provides clinically useful information about rate, rhythm, pattern of depolarization, and mass of electrically active cardiac muscle.

Pathway

SA Node

|

Walls of the Atrium (Atrial Contraction)

|

AV Node

|

Delay in transmission

(To provide ample time for ventricular filling)

|

Bundle of His

|

Left and Right Bundle Branch

|

Purkinje Fibers

|

Ventricular Contraction

Notes on Fluid and Electrolytes 4 FLUID VOLUME DEFICIT

FLUID VOLUME DEFICIT

A. Description
1. Dehydration occurs when the fluid intake of the body is not sufficient to meet the fluid needs of the body.
2. The goal of treatment is to restore fluid volume, replace electrolytes as needed, and eliminate the cause of the fluid volume deficit.

B. Types of fluid volume deficits
1. Isotonic dehydration
a. Water and dissolved electrolytes are lost in equal proportions.
b. Known as hypovolemia, isotonic dehydration is the most common type of dehydration.
c. Isotonic dehydration results in decreased circulating blood volume and inadequate tissue perfusion.

2. Hypertonic dehydration
a. Water loss exceeds electrolyte loss.
b. The clinical problems that occur result from alterations in the concentrations of specific plasma electrolytes.
c. Fluid moves from the intracellular compartment into the plasma and interstitial fluid spaces, causing cellular dehydration and shrinkage.

3. Hypotonic dehydration
a. Electrolyte loss exceeds water loss.
b. The clinical problems that occur result from fluid shifts between compartments, causing a decrease in
plasma volume.
c. Fluid moves from the plasma and interstitial fluid spaces into the cells, causing a plasma volume deficit and causing the cells to swell.

C. Causes of fluid volume deficits
1. Isotonic dehydration
a. Inadequate intake of fluids and solutes
b. Fluid shifts between compartments
c. Excessive losses of isotonic body fluids

2. Hypertonic dehydration—conditions that increase fluid
loss, such as excessive perspiration, hyperventilation,
ketoacidosis, prolonged fevers, diarrhea, early-stage
renal failure, and diabetes insipidus

3. Hypotonic dehydration
a. Chronic illness
b. Excessive fluid replacement (hypotonic)
c. Renal failure
d. Chronic malnutrition

D. Assessment
1. Cardiovascular
a. Thready, increased pulse rate
b. Decreased blood pressure and orthostatic (postural) hypotension
c. Flat neck and hand veins in dependent positions
d. Diminished peripheral pulses

2. Respiratory: Increased rate and depth of respirations

3. Neuromuscular
a. Decreased central nervous system activity, from lethargy to coma
b. Fever

4. Renal
a. Decreased urinary output
b. Increased urinary specific gravity

5. Integumentary
a. Dry skin
b. Poor turgor, tenting present
c. Dry mouth

6. Gastrointestinal
a. Decreased motility and diminished bowel sounds
b. Constipation
c. Thirst
d. Decreased body weight

7. Hypotonic dehydration: skeletal muscle weakness

8. Hypertonic dehydration
a. Hyperactive deep tendon reflexes
b. Pitting edema

9. Laboratory findings
a. Increased serum osmolality
b. Increased hematocrit
c. Increased blood urea nitrogen (BUN) level
d. Increased serum sodium level

E. Interventions
1. Monitor cardiovascular, respiratory, neuromuscular, renal, integumentary, and gastrointestinal status.
2. Prevent further fluid losses and increase fluid compartment volumes to normal ranges.
3. Provide oral rehydration therapy if possible and intravenous (IV) fluid replacement if the dehydration is
severe; monitor intake and output.
4. Generally, isotonic dehydration is treated with isotonic fluid solutions, hypertonic dehydration with hypotonic fluid solutions, and hypotonic dehydration with hypertonic fluid solutions.
5. Administer medications as prescribed such as antidiarrheal, antimicrobial, antiemetic, and antipyretic
medications, to correct the cause and treat any symptoms.
6. Administer oxygen as prescribed.
7. Monitor electrolyte values and prepare to administer medication to treat an imbalance, if present.

Anatomy and Physiology Notes: Gastrointestinal-Hepatobillary System

This is an outlined lecture note on the Anatomy and Physiology of theGastrointestinal-Hepatobillary System. Some information are so compressed that some concepts are not explained in detail. If it is your first time to meet such information please refer to your textbook for further explanation of the concept. This review material requires a student to have a prior knowledge and good foundation of the subject matter for this only emphasizes important/ key information deemed important in understanding advanced concept in Pathophysiology and Medical Surgical Nursing.

Functions of the gastrointestinal system
- Process food substances.
- Absorb the products of digestion into the blood.
- Excrete unabsorbed materials.
- Provide an environment for microorganisms to synthesize nutrients, such as vitamin K.

 Mouth
- Contains the lips, cheeks, palate, tongue, teeth, salivary glands, muscles, and maxillary bones
- Saliva contains the amylase enzyme (ptyalin) that aids in digestion.

Esophagus
- Collapsible muscular tube about 10 inches long
- Carries food from the pharynx to the stomach


The stomach
- Contains the cardia, fundus, the body, and the pylorus
- Mucous glands are located in the mucosa and prevent autodigestion by providing an alkaline protective covering.
- The lower esophageal (cardiac) sphincter prevents reflux of gastric contents into the esophagus.
- The pyloric sphincter regulates the rate of stomach emptying into the small intestine.
- Hydrochloric acid kills microorganisms, breaks food into small particles, and provides a chemical environment that facilitates gastric enzyme activation.
- Pepsin is the chief coenzyme of gastric juice, which converts proteins into proteases and peptones.
- Intrinsic factor is necessary for the absorption of vitamin B12.
- Gastrin controls gastric acidity.

Small intestine
- The duodenum contains the openings of the bile and pancreatic ducts.
- The jejunum is about 8 feet long.
- The ileum is about 12 feet long.
- The small intestine terminates in the cecum.

Pancreatic intestinal juice enzymes
- Amylase digests starch to maltose.
- Maltase reduces maltose to monosaccharide glucose.
-  Lactase splits lactose into galactose and glucose.
- Sucrase reduces sucrose to fructose and glucose.
- Nucleases split nucleic acids to nucleotides.
-. Enterokinase activates trypsinogen to trypsin.


Large intestine
- About 5 feet long
- Absorbs water and eliminates wastes
- Intestinal bacteria play a vital role in the synthesis of some B vitamins and vitamin K.
- Colon: Includes the ascending, transverse, descending, and sigmoid colons and rectum
- The ileocecal valve prevents contents of the large intestine from entering the ileum.
- The anal sphincters control the anal canal.

Peritoneum: Lines the abdominal cavity and forms the mesentery that supports
the intestines and blood supply

Liver
-The largest gland in the body, weighing 3 to 4 lb.
-Contains Kupffer's cells, which remove bacteria in the portal venous blood
- Removes excess glucose and amino acids from the portal blood
- Synthesizes glucose, amino acids, and fats
- Aids in the digestion of fats, carbohydrates, and proteins
- Stores and filters blood (200 to 400 mL of blood stored)
- Stores vitamins A, D, and B and iron
- The liver secretes bile to emulsify fats (500 to 1000 mL of bile/day).
 Hepatic ducts
a. Deliver bile to the gallbladder via the cystic duct and to the
duodenum via the common bile duct.
b. The common bile duct opens into the duodenum, with the pancreatic duct at the ampulla of Vater.
c. The sphincter prevents the reflux of intestinal contents into the
common bile duct and pancreatic duct.

Gallbladder
-Stores and concentrates bile and contracts to force bile into the duodenum during the digestion of fats
- The cystic duct joins the hepatic duct to form the common bile duct.
- The sphincter of Oddi is located at the entrance to the duodenum.
- The presence of fatty materials in the duodenum stimulates the liberation of cholecystokinin, which causes contraction of the gallbladder and relaxation of the sphincter of Oddi.

Pancreas
Exocrine gland
- Secretes sodium bicarbonate to neutralize the acidity of the stomach contents that enter the duodenum
-. Pancreatic juices contain enzymes for digesting carbohydrates, fats, and proteins.
Endocrine gland
- Secretes glucagon to raise blood glucose levels and secretes somatostatin to exert a hypoglycemic effect
- The islets of Langerhans secrete insulin.
- Insulin is secreted into the bloodstream and is important for carbohydrate metabolism.

“If at first you don't succeed, try, try again. Then quit. No use being a damn fool about it.”  -WC Fields

Anatomy and Physiology Notes: Endocrine System

This is an outlined lecture note on the Anatomy and Physiology of the Endocrine System. Some information are so compressed that some concepts are not explained in detail. If it is your first time to meet such information please refer to your textbook for further explanation of the concept. This review material requires a student to have a prior knowledge and good foundation of the subject matter for this only emphasizes important/ key information deemed important in understanding advanced concept in Pathophysiology and Medical Surgical Nursing.


Functions of Endocrine Glands
- Maintenance and regulation of vital functions
- Response to stress and injury
- Growth and development
- Energy metabolism
- Reproduction
- Fluid, electrolyte, and acid-base balance

Hypothalamus 
- Portion of the diencephalon of the brain, forming the floor and part of the lateral wall of the third ventricle
- Activates, controls, and integrates the peripheral autonomic nervous system, endocrine processes, and many somatic functions, such as body temperature, sleep, and appetite

Pituitary gland 
- The master gland; located at the base of the brain 2. Influenced by the hypothalamus; directly affects the function of the other endocrine glands
- Promotes growth of body tissue, influences water absorption by the kidney, and controls sexual development and function

Adrenal gland
- One adrenal gland is on top of each kidney.
- Regulates sodium and electrolyte balance; affects carbohydrate, fat, and protein metabolism; influences the development of sexual characteristics; and sustains the fight-or-flight response
 Adrenal cortex
- The cortex is the outer shell of the adrenal gland.
-. The cortex synthesizes glucocorticoids and mineralocorticoids and secretes small amounts of sex hormones
Adrenal medulla
- The medulla is the inner core of the adrenal gland.
- The medulla works as part of the sympathetic nervous system and produces epinephrine and norepinephrine.

Thyroid gland
- Located in the anterior part of the neck
- Controls the rate of body metabolism and growth and produces thyroxine (T4), triiodothyronine (T3), and thyrocalcitonin

Parathyroid glands
- Located on the thyroid gland
- Control calcium and phosphorus metabolism; produce parathyroid hormone

Pancreas
- Located posteriorly to the stomach
- Influences carbohydrate metabolism, indirectly influences fat and protein metabolism, and produces insulin and glucagon

Ovaries and testes
-The ovaries are located in the pelvic cavity and produce estrogen and progesterone.
-The testes are located in the scrotum, control the development of the secondary sex characteristics, and produce testosterone.

Negative feedback loop
-Regulates hormone secretion by the hypothalamus and pituitary gland
-Increased amounts of target gland hormones in the bloodstream decrease secretion of the same hormone and other hormones that stimulate its release.

“Success is getting what you want, happiness is wanting what you get” -Kinsela

Anatomy and Physiology Notes: The Heart

Heart and heart wall layers
1. The heart is located in the left side of the mediastinum.
2. The heart consists of three layers.
a. The epicardium is the outermost layer of the heart.
b. The myocardium is the middle layer and is the
actual contracting muscle of the heart.
c. The endocardium is the innermost layer and lines
the inner chambers and heart valves.


Pericardial sac
1. Encases and protects the heart from trauma and infection
2. Has two layers
a. The parietal pericardium is the tough, fibrous outer membrane that attaches anteriorly to the lower half
of the sternum, posteriorly to the thoracic vertebrae, and inferiorly to the diaphragm.
b. The visceral pericardium is the thin, inner layer that closely adheres to the heart.
3. The pericardial space is between the parietal and visceral layers; it holds 5 to 20 mL of pericardial fluid, lubricates the pericardial surfaces, and cushions the heart.


There are four heart chambers
1. The right atrium receives deoxygenated blood from the body via the superior and inferior vena cava.
2. The right ventricle receives blood from the right atrium and pumps it to the lungs via the pulmonary artery.
3. The left atrium receives oxygenated blood from the lungs via four pulmonary veins.
4. The left ventricle is the largest and most muscular chamber; it receives oxygenated blood from the lungs via the left atrium and pumps blood into the systemic circulation via the aorta.

There are four valves in the heart.
1. There are two atrioventricular valves, the tricuspid and the mitral, which lie between the atria and ventricles.
a. The tricuspid valve is located on the right side of the heart.
b. The bicuspid (mitral) valve is located on the left side of the heart.
c. The atrioventricular valves close at the beginning of ventricular contraction and prevent blood from flowing
back into the atria from the ventricles; these valves open when the ventricle relaxes.

2. There are two semilunar valves, the pulmonic and the aortic.
a. The pulmonic semilunar valve lies between the right ventricle and the pulmonary artery.
b. The aortic semilunar valve lies between the left ventricle and the aorta.
c. The semilunar valves prevent blood from flowing back into the ventricles during relaxation; they open during
ventricular contraction and close when the ventricles begin to relax.

Sinoatrial (SA) node

1. The main pacemaker that initiates each heartbeat
2. It is located at the junction of the superior vena cava and the right atrium.
3. The sinoatrial node generates electrical impulses at 60 to 100 times per minute and is controlled by the sympathetic and parasympathetic nervous systems.

Atrioventricular (AV) node
1. Located in the lower aspect of the atrial septum
2. Receives electrical impulses from the sinoatrial node
3. If the sinoatrial node fails, the atrioventricular node can initiate
and sustain a heart rate of 40 to 60 beats/min.

The bundle of His
1. A continuation of the AV node; located at the interventricular septum
2. It branches into the right bundle branch, which extends down the right side of the interventricular septum, and the left bundle branch, which extends into the left ventricle.
3. The right and left bundle branches terminate into Purkinje fibers.

Purkinje fibers
1. Purkinje fibers are a diffuse network of conducting strands located beneath the ventricular endocardium.
2. These fibers spread the wave of depolarization through the ventricles.
3. Purkinje fibers can act as the pacemaker with a rate between 20 and 40 beats/min when higher pacemakers fail


Coronary arteries 
1. The coronary arteries supply the capillaries of the myocardium with blood.
2. The right coronary artery supplies the right atrium and ventricle, the inferior portion of the left ventricle, the posterior septal wall, and the sinoatrial and atrioventricular nodes.
3. The left main coronary artery consists of two major branches, the left anterior descending and the circumflex arteries.
4. The left anterior descending artery supplies blood to the anterior wall of the left ventricle, the anterior ventricular septum, and the apex of the left ventricle.
5. The circumflex artery supplies blood to the left atrium and the
lateral and posterior surfaces of the left ventricle.

Anatomy and Physiology Quiz

I. Fluid and Electrolyte and Acid – Base Balance

1. Approximately 60% of the weight of a typical adult consists of fluid. Body fluid is located in two fluid compartments namely what?
a. Intracellular and intravascular
b. Extracellular and intracellular
c. Intracellular and interstitial
d. Extravascular and intracellular

2. When two different solutions are separated by a membrane that is impermeable to the dissolved substances, fluid shifts through the membrane from the region of low solute concentration to the region of high solute concentration until the solutions are of equal concentration. This diffusion of water caused by a fluid concentration gradient is known as what?
a. Diffusion
b. Filtration
c. Osmosis
d. Active Transportation

3. Hydrostatic pressure in the capillaries tends to filter fluid out of the intravascular compartment into the interstitial fluid. Movement of water and solutes occurs from an area of high hydrostatic pressure to an area of low hydrostatic pressure is known as what?
a. Diffusion
b. Filtration
c. Osmosis
d. Active Transport

4. A patient presented the following signs and symptoms: confusion, muscle cramps and weakness,  dry skin, ↑pulse,  ↓ BP. The patient’s lab result shows ↓ serum and urine sodium and  ↓ urine specific gravity. The doctor told you that the patient is exhibiting hyponatremia. Hyponatremia is having a serum sodium below what? (Smeltzer 2012)
a. 145 mEq/L
b. 108 mEq/L
c. 96.5 mEq/L
d. 135 mEq/L

5. A patient with congestive heart failure is given oral potassium supplements to avoid digoxin toxicity. As a nurse you are aware that the normal serum level for potassium is what? (Smeltzer 2012)
a. 135-145 mEq/L
b. 3.5-5.0 mEq/L
c. 8.5-10.5 mg/dL
d. 1.8-2.7 mg/dL

Evaluate the following arterial blood gas values

6. pH: 7.5   PaCO2: 31   HCO3 : 26

7. pH: 7.38  PaCO2: 32  HCO3: 19

8. pH: 7.24  PaCO2: 60  HCO3: 32

9. pH: 7.41  PaCO2: 30  HCO3 18

10. pH: 7.5  PaCO2: 42  HCO3: 33

II. Respiratory System

11. Resting respiration is the result of cyclic excitation of the respiratory muscles by the phrenic nerve. The rhythm of breathing is controlled by respiratory centers in the brain. The inspiratory and expiratory center is located in the?
a. Medulla Oblongata
b. Hypothalamus
c. Pons
d. Cerebellum

12. The _____ center in the lower pons stimulates the inspiratory medullary center to promote deep, prolonged inspirations.
a. Pneumotaxic
b. Apneustic
c. Chemotaxic
d. Physiotaxic

13. A term that correspond the amount of air inhaled and exhaled with each breath.
a. Residual Volume
b. Inspiratory Reserve Volume
c. Expiratory Reserve Volume
d. Tidal Volume
14. It is the volume of air in the lungs after maximum inhalation
a. Vital Capacity
b. Inspiratory Capacity
c. Functional Residual Capacity
d. Total Lung Capacity

15. The volume of air remaining in the lungs after a normal expiration .
a. Vital Capacity
b. Inspiratory Capacity
c. Functional Residual Capacity
d. Total Lung Capacity

III.  Cardiovascular System

16. It is the ability of the heart to initiate electrical impulse.
a. Excitability
b. Automaticity
c. Conductivity
d. Permeability

17. It is called as the primary pace maker of the heart which fires 60 to 100 impulse per minute
a. SA Node
b. AV Node
c. Bundle of His
d. Purkinje Fibers

18. The ___  coordinates the incoming electrical impulses from the atria and after a slight delay, allowing the atria time to contract and complete ventricular filling then relays the impulse to the ventricles.
a. SA Node
b. AV Node
c. Bundle of His
d. Purkinje Fibers

19. This heart sound is created by the closure of the tricuspid and bicuspid valve
a. S1
b. S2
c. S3
d. S4

20. This heart sound is created b the closure of the pulmonic and aortic valves
a. S1
b. S2
c. S3
d. S4

Anatomy and Physiology Notes: Respiratory System

Primary functions of the respiratory system
1. Provides oxygen for metabolism in the tissues
2. Removes carbon dioxide, the waste product of metabolism

Secondary functions of the respiratory system
1. Facilitates sense of smell
2. Produces speech
3. Maintains acid-base balance
4. Maintains body water levels
5. Maintains heat balance

Upper respiratory tract
1. Nose: Humidifies, warms, and filters inspired air

2. Sinuses: Air-filled cavities within the hollow bones that surround the nasal passages and provide resonance during speech

3. Pharynx
a. Passageway for the respiratory and digestive tracts located behind
the oral and nasal cavities
b. Divided into the nasopharynx, oropharynx, and laryngopharynx

4. Larynx
a. Located above the trachea, just below the pharynx at the root of
the tongue; commonly called the voice box
b. Contains two pairs of vocal cords, the false and true cords
c. The opening between the true vocal cords is the glottis.
d. The glottis plays an important role in coughing, which is the most
fundamental defense mechanism of the lungs.

5. Epiglottis
a. Leaf-shaped elastic structure attached along one end to the top of
the larynx
b. Prevents food from entering the tracheobronchial tree by closing
over the glottis during swallowing

Lower respiratory tract
1. Trachea: Located in front of the esophagus; branches into the right
and left main stem bronchi at the carina

2. Main stem bronchi
a. Begin at the carina
b. The right bronchus is slightly wider, shorter, and more vertical than the left bronchus.
c. The mainstem bronchi divide into secondary or lobar bronchi that enter each of the five lobes of the lung.
d. The bronchi are lined with cilia, which propel mucus up and away from the lower airway to the trachea, where it can be expectorated or swallowed.

3. Bronchioles
a. Branch from the secondary bronchi and subdivide into the small terminal and respiratory bronchioles

b. The bronchioles contain no cartilage and depend on the elastic recoil of the lung for patency.
c. The terminal bronchioles contain no cilia and do not participate in gas exchange.

4. Alveolar ducts and alveoli
a. Acinus (plural acini) is a term used to indicate all structures distal to the terminal bronchiole.
b. Alveolar ducts branch from the respiratory bronchioles.
c. Alveolar sacs, which arise from the ducts, contain clusters of alveoli, which are the basic units of gas exchange.
d. Type II alveolar cells in the walls of the alveoli secrete surfactant, a phospholipid protein that reduces the surface tension in the alveoli; without surfactant, the alveoli would collapse.

5. Lungs
a. Located in the pleural cavity in the thorax
b. Extend from just above the clavicles to the diaphragm, the major muscle of inspiration
c. The right lung, which is larger than the left, is divided into three lobes, the upper, middle, and lower lobes.
d. The left lung, which is narrower than the right lung to accommodate the heart, is divided into two lobes.
e. The respiratory structures are innervated by the phrenic nerve, the vagus nerve, and the thoracic nerves.
f. The parietal pleura lines the inside of the thoracic cavity, including the upper surface of the diaphragm.

g. The visceral pleura covers the pulmonary surfaces.
h. A thin fluid layer, which is produced by the cells lining the pleura, lubricates the visceral pleura and the parietal pleura, allowing them to glide smoothly and painlessly during respiration.
i. Blood flows through the lungs via the pulmonary system and
the bronchial system.

6. Accessory muscles of respiration include the scalene muscles, which elevate the first two ribs, the sternocleidomastoid muscles, which raise the sternum, and the trapezius and pectoralis muscles, which fix
the shoulders.


Respiratpry Process
a. The diaphragm descends into the abdominal cavity during inspiration, causing negative pressure in the lungs.
b. The negative pressure draws air from the area of greater pressure, the atmosphere, into the area of lesser pressure, the lungs.
c. In the lungs, air passes through the terminal bronchioles into the alveoli to oxygenate the body tissues.
d. At the end of inspiration, the diaphragm and intercostal muscles relax and the lungs recoil.
e. As the lungs recoil, pressure within the lungs becomes higher than atmospheric pressure, causing the air, which now contains the cellular waste products carbon dioxide and water, to move from the alveoli in the lungs to the atmosphere.
f. Effective gas exchange depends on distribution of gas (ventilation) and blood (perfusion) in all portions of the lungs

Notes on Fluid and Electrolyte 2: CONCEPTS OF FLUID AND ELECTROLYTE BALANCE

CONCEPTS OF FLUID AND ELECTROLYTE BALANCE

Ebook Version here

A. Electrolytes
1. Description: A substance that is dissolved in solution and ome of its molecules split or dissociate into electrically charged atoms or ions.
2. Measurement
a. The metric system is used to measure volumes of fluids—liters (L) or milliliters (mL).
b. The unit of measure that expresses the combining activity of an electrolyte is the milliequivalent (mEq).
c. One milliequivalent (1 mEq) of any cation will always react chemically with 1 mEq of an anion.
d. Milliequivalents provide information about the number of anions or cations available to combine with other anions or cations.

B. Body fluid compartments

1. Description
a. Fluid in each of the body compartments contains electrolytes.
b. Each compartment has a particular composition of electrolytes, which differs from that of other compartments.
c. To function normally, body cells must have fluids and electrolytes in the right compartments and in the right amounts.
d. Whenever an electrolyte moves out of a cell, another electrolyte moves in to take its place.
e. The numbers of cations and anions must be the same for homeostasis to exist.
f. Compartments are separated by semipermeable membranes.

2. Intravascular compartment: Refers to fluid inside a blood vessel

3. Intracellular compartment
a. The intracellular compartment refers to all fluid inside the cell.
b. Most bodily fluids are inside the cell.

4. The extracellular compartment is the fluid outside the cell.
a. The extracellular compartment includes the interstitial fluid, which is fluid between cells (sometimes called the third space), blood, lymph, bone, connective tissue, water, and transcellular fluid.
b. Transcellular fluid is the fluid in various parts of the body, such as peritoneal fluid, pleural fluid, cerebrospinal fluid, and synovial fluid.

C. Third-spacing
1. Third-spacing is the accumulation and sequestration of trapped extracellular fluid in an actual or potential body space as a result of disease or injury.
2. The trapped fluid represents a volume loss and is unavailable for normal physiological processes.
3. Fluid may be trapped in body spaces such as the pericardial, pleural, peritoneal, or joint cavities, the bowel, or the aabdomen, or within soft tissues after trauma or burns.
4. Assessing the intravascular fluid loss caused by third-spacing is difficult. The loss may not be reflected
in weight changes or intake and output records and may not become apparent until after organ malfunction occurs.

D. Edema
1. Edema is an excess accumulation of fluid in the interstitial space.
2. Localized edema occurs as a result of traumatic injury from accidents or surgery, local inflammatory processes, or burns.
3. Generalized edema, also called anasarca, is an excessive accumulation of fluid in the interstitial space throughout the body and occurs as a result of conditions such as cardiac, renal, or liver failure.

E. Body fluid
1. Description
a. Body fluids transport nutrients to the cells and carry waste products from the cells.
b. Total body fluid (intracellular and extracellular) amounts to about 60% of body weight in the adult,
55% in the older adult, and 80% in the infant.
c. Thus, infants and the older adult are at ahigher risk for fluid-related problems than younger adults; children have a greater proportion of body water than adults and the older adult has the least proportion of body water.
2. Constituents of body fluids
a. Body fluids consist of water and dissolved substances.
b. The largest single fluid constituent of the body is water.
c. Some substances, such as glucose, urea, and creatinine, do not dissociate in solution; that is, they do not separate from their complex forms into simpler substances when they are in solution.
d. Other substances do dissociate; for example, when sodium chloride is in a solution, it dissociates or
separates into two parts or elements.

F. Body fluid transport
1. Diffusion
a. Diffusion is the process whereby a solute (substance that is dissolved) may spread through a solution or solvent (solution in which the solute is dissolved).
b. Diffusion of a solute will spread the molecules from an area of higher concentration to an area of lower concentration.
c. A permeable membrane will allow substances to pass through it without restriction.
d. A selectively permeable membrane will allow some solutes to pass through without restriction but will prevent other solutes from passing freely.
e. Diffusion occurs within fluid compartments and from one compartment to another if the barrier
between the compartments is permeable to the diffusing substances.

2. Osmosis
a. Osmotic pressure is the force that draws the solvent from a less concentrated solute through a selectively permeable membrane into a more concentrated solute, thus tending to equalize the concentration of the solvent.
b. If a membrane is permeable to water but not to all the solutes present, the membrane is a selective or semipermeable membrane.
c. Osmosis is the movement of solvent molecules across a membrane in response to a concentration gradient, usually from a solution of lower to one of higher solute concentration.
d. When a more concentrated solution is on one side of a selectively permeable membrane and a less concentrated solution is on the other side, a pull called osmotic pressure draws the water through
the membrane to the more concentrated side or the side with more solute.

3. Filtration
a. Filtration is the movement of solutes and solvents by hydrostatic pressure.
b. The movement is from an area of higher pressure to an area of lower pressure.

4. Hydrostatic pressure
a. Hydrostatic pressure is the force exerted by the weight of a solution.
b. When a difference exists in the hydrostatic pressure on two sides of a membrane, water and diffusible solutes move out of the solution that has the higher hydrostatic pressure by the process of filtration.
c. At the arterial end of the capillary, the hydrostatic pressure is higher than the osmotic pressure; therefore, fluids and diffusible solutes move out of the capillary.
d. At the venous end, the osmotic pressure or pull is higher than the hydrostatic pressure, and fluids and some solutes move into the capillary.
e. The excess fluid and solutes remaining in the interstitial spaces are returned to the intravascular compartment by the lymph channels.

5. Osmolality
a. Osmolality refers to the number of osmotically active particles/kilogram of water; it is the concentration of a solution.
b. In the body, osmotic pressure is measured in milliosmoles (mOsm).
c. The normal osmolality of plasma is 270 to 300 milliosmoles/kilogram (mOsm/kg) water.

G. Movement of body fluid
1. Description
a. Cell membranes separate the interstitial fluid from the intravascular fluid.
b. Cell membranes are selectively permeable; that is, the cell membrane and the capillary wall will allow water and some solutes free passage through them.
c. Several forces affect the movement of water and solutes through the walls of cells and capillaries.
d. The greater the number of particles within the cell, the more pressure exists to force the water through
the cell membrane.
e. If the body loses more electrolytes than fluids, as can happen in diarrhea, then the extracellular fluid will contain fewer electrolytes or less solute than the intracellular fluid.
f. Fluids and electrolytes must be kept in balance for health; when they remain out of balance, death can
occur.

2. Isotonic solutions
a. When the solutions on both sides of a selectively permeable membrane have established equilibrium or are equal in concentration, they are isotonic.
b. An example of an isotonic solution is 0.9% sodium chloride, which is referred to as isotonic saline solution or normal saline solution.
c. Isotonic solutions are isotonic to human cells, and thus very little osmosis occurs; isotonic solutions have the same osmolality as body fluids.
d. Other solutions that are isotonic are 5% dextrose in water, 5% dextrose in 0.225% saline, and Ringer's
lactate solution.

3. Hypotonic solutions
a. When a solution contains a lower concentration of salt or solute than another more concentrated solution, it is considered hypotonic.
b. A hypotonic solution has less salt or more water than an isotonic solution; these solutions have lower osmolality than body fluids.
c. 0.45% sodium chloride, 0.225% sodium chloride, and 0.33% sodium chloride are examples of hypotonic solutions.
d. Hypotonic solutions are hypotonic to the cells; therefore, osmosis would continue in an attempt to bring about balance or equality.

4. Hypertonic solutions
a. A solution that has a higher concentration of solutes than another less concentrated solution is hypertonic; these solutions have a higher osmolality than body fluids.
b. Hypertonic solutions include 3% sodium chloride, 5% sodium chloride, 10% dextrose in water, 5% dextrose in 0.9% sodium chloride, 5% dextrose in 0.45% sodium chloride, and 5% dextrose in Ringer's lactate solution.
c. Refer to Table 14-1 (Chap. 14) for a list of isotonic, hypotonic, and hypertonic solutions.

5. Osmotic pressure
a. The amount of osmotic pressure is determined by the concentration of solutes in solution.
b. When the solutions on each side of a selectively permeable membrane are equal in concentration, they are isotonic.
c. A hypotonic solution has less solute than an isotonic solution, whereas a hypertonic solution contains more solute.
d. A solvent will move from the less concentrated solute side to the more concentrated solute side to equalize concentration.

6. Active transport
a. If an ion is to move through a membrane from an area of lower concentration to an area of higher concentration, an active transport system is necessary.
b. An active transport system moves molecules or ions against concentration and osmotic pressure.
c. Metabolic processes in the cell supply the energy for active transport.
d. Substances that are transported actively through the cell membrane include ions of sodium, potassium, calcium, iron, and hydrogen, some of the sugars, and the amino acids.

H. Body fluid excretion
1. Description
a. Fluids leave the body by several routes, including the skin, lungs, gastrointestinal tract, and kidneys.
b. The kidneys excrete the largest quantity of fluid.
c. As long as all organs are functioning normally, the body is able to maintain balance in its fluid content.

2. Skin
a. Water is lost through the skin in the amount of about 400 mL/day.
b. The amount of water lost by perspiration varies according to the temperature of the environment and of the body, but the average amount of loss by perspiration alone is 100 mL/day.
c. Water lost through the skin is called insensible loss (the individual is unaware of losing that water).

3. Lungs
a. Water is lost from the lungs through expired air that is saturated with water vapor.
b. The amount of water lost from the lungs varies with the rate and the depth of respiration.
c. The average amount of water lost from the lungs is about 350 mL/day.
d. Water lost from the lungs is called insensible loss.

4. Gastrointestinal tract
a. Large quantities of water are secreted into the gastrointestinal tract, but almost all this fluid is reabsorbed.
b. A large volume of electrolyte-containing liquids moves into the gastrointestinal tract and then returns again into the extracellular fluid.
c. The average amount of water lost in the feces is 150 mL/day, equal to the amount of water gained through the oxidation of foods.
d. Severe diarrhea results in the loss of large quantities of fluids and electrolytes.

5. Kidneys
a. The kidneys play a major role in regulating fluid and electrolyte balance.
b. Normal kidneys can adjust the amount of water and electrolytes leaving the body.
c. The quantity of fluid excreted by the kidneys is determined by the amount of water ingested and the amount of waste and solutes excreted.
d. The usual urine output is about 1500 mL/day; however, this varies greatly depending on fluid intake, amount of perspiration, and other factors.

I. Body fluid replacement
1. Description: Water enters the body through three sources—orally ingested liquids, water in foods, and water formed by oxidation of foods.
2. Amounts
a. The average total amount of water taken into the body by all three sources is 2500 mL/day.
b. About 10 mL of water is released by the metabolism of each 100 calories of fat, carbohydrates, or proteins.
3. Electrolytes
a. Electrolytes are present in foods and liquids.
b. With a normal diet, an excess of essential electrolytes is
taken in and the unused electrolytes are excreted.

J. Maintaining fluid and electrolyte balance
1. Description
a. Homeostasis is a term that indicates the relative stability of the internal environment.
b. Concentration and composition of body fluids must be nearly constant.
c. In a client, when one of the substances is deficient, either fluids or electrolytes, the substance must be replaced normally by the intake of food and water or by therapy such as intravenous solutions and medications.
d. When the client has an excess of fluid or electrolytes, therapy is directed toward assisting the body to eliminate the excess.
2. The kidneys play a major role in controlling all types of balance in fluid and electrolytes.
3. The adrenal glands, through the secretion of aldosterone, also aid in controlling extracellular fluid volume by regulating the amount of sodium reabsorbed by the kidneys.
4. Antidiuretic hormone from the pituitary gland regulates the osmotic pressure of extracellular fluid by regulating the amount of water reabsorbed by the kidney.


To get this for free please follow the instruction bellow:

1. Follow this site by clicking "Follow" button on the side bar
2. Click the Like button bellow
3. Comment on the post ---> why you need it?
4. Write the email address the ebook will be sent.
5. A confirmation message will be sent for valid requests.
6. Wait for the ebook in your inbox

Notes on Fluids and Electrolytes Part 1

This Notes on Fluids and Electrolytes (1) focus primarily on the assessment of a fluid and electrolyte imbalance, interventions, and evaluating the expected outcomes. Fluids and electrolytes constitute a content area that is sometimes complex and difficult to understand. The nurse must understand cell functions and properties and the concepts related to body fluids as outlined in this chapter. It focuses on the common fluid and electrolyte disturbances. As you review this content, focus on the Pyramid Points related to the causes, assessment findings, and related treatments. In any fluid or electrolyte imbalance, nursing interventions include monitoring significant laboratory results and monitoring the client's cardiovascular, respiratory, gastrointestinal, neuromuscular, renal, and central nervous system status. Integrated Processes addressed in this chapter are Caring, Communication and Documentation, Nursing Process, and Teaching/Learning.

Important Terms

calcium
A mineral element needed for the process of bone formation, coagulation of blood, excitation of cardiac and skeletal muscle, maintenance of muscle tone, conduction of neuromuscular impulses, and the synthesis and regulation of the endocrine and exocrine glands. The normal adult level is 8.6 to 10.0 mg/dL.

fluid volume deficit
Dehydration in which the fluid intake of the body is not sufficient to meet the fluid needs of the body.

fluid volume excess
Fluid intake or fluid retention that exceeds the fluid needs of the body. Also called overhydration or fluid overload.

homeostasis
The tendency of biological systems to maintain relatively constant conditions in the internal environment while continuously interacting with and adjusting to changes originating within or outside the system.

hypercalcemia
A serum calcium level that exceeds 10.0 mg/dL.

hyperkalemia
A serum potassium level that exceeds 5.1 mEq/L.

hypermagnesemia
A serum magnesium level that exceeds 2.6 mg/dL.

hypernatremia
A serum sodium level that exceeds 145 mEq/L.

hyperphosphatemia
A serum phosphorus level that exceeds 4.5 mg/dL.

hypocalcemia
A serum calcium level less than 8.6 mg/dL.

hypokalemia
A serum potassium level less than 3.5 mEq/L.

hypomagnesemia
A serum magnesium level less than 1.6 mg/dL.

hyponatremia
A serum sodium level less than 135 mEq/L.

hypophosphatemia
A serum phosphorus level less than 2.7 mg/dL.

magnesium
Concentrated in the bone, cartilage, and within the cell itself; required for the use of adenosine triphosphate (ATP) as a source of energy. It is necessary for the action of numerous enzyme systems such as carbohydrate metabolism, protein synthesis, nucleic acid synthesis, and contraction of muscular tissue. It
also regulates neuromuscular activity and the clotting mechanism. The normal adult level is 1.6 to 2.6 mg/dL.

potassium
A principle electrolyte of intracellular fluid and the primary buffer within the cell itself. It is needed for nerve conduction, muscle function, acid-base balance, and osmotic pressure. Along with calcium and magnesium, it controls

sodium
An abundant electrolyte that maintains osmotic pressure and acid-base balance and transmits nerve impulses. The normal adult level is 135 to 145 mEq/L.

A&P Lecture 4.3: Ventilation Perfusion Ratio

The following picture shows the Ventilation Perfusion Ratio. Please click the picture to be enlarged

Normal Ratio (A)

In the healthy lung, a given amount of blood passes an alveolus and is matched with an equal amount of gas (A). The ratio is 1:1 (ventilation matches perfusion).

Low Ventilation–Perfusion Ratio: Shunts (B)

Low ventilation–perfusion states may be called shuntproducing disorders. When perfusion exceeds ventilation, a shunt exists (B). Blood bypasses the alveoli without gas exchange occurring. This is seen with obstruction of the distal airways, such as with pneumonia, atelectasis, tumor, or a mucus plug.

High Ventilation–Perfusion Ratio: Dead Space (C)

When ventilation exceeds perfusion, dead space results (C). The alveoli do not have an adequate blood supply for gas exchange to occur. This is characteristic of a variety of disorders, including pulmonary emboli, pulmonary infarction, and cardiogenic shock.

Silent Unit (D)

In the absence of both ventilation and perfusion or with limited ventilation and perfusion, a condition known as a silent unit occurs (D). This is seen with pneumothorax and severe acute respiratory distress syndrome.

A&P Lecture 4.1: Function of the Respiratory System

The cells of the body derive the energy they need from the oxidation of carbohydrates, fats, and proteins. As with any type of combustion, this process requires oxygen. Certain vital tissues, such as those of the brain and the heart, cannot survive for long without a continuous supply of oxygen. However, as a result of oxidation in the body tissues, carbon dioxide is produced and must be removed from the cells to prevent the buildup of acid waste products. The respiratory system performs this function by facilitating life-sustaining processes such as oxygen transport, respiration and ventilation, and gas exchange.

Oxygen Transport

Oxygen is supplied to, and carbon dioxide is removed from, cells by way of the circulating blood. Cells are in close contact with capillaries, the thin walls of which permit easy passage or exchange of oxygen and carbon dioxide. Oxygen diffuses from the capillary through the capillary wall to the interstitial fluid. At this point, it diffuses through the membrane of tissue cells, where it is used by mitochondria for cellular respiration. The movement of carbon dioxide occurs by diffusion in the opposite direction—from cell to blood.

Respiration

After these tissue capillary exchanges, blood enters the systemic veins (where it is called venous blood) and travels to the pulmonary circulation. The oxygen concentration in blood within the capillaries of the lungs is lower than in the lungs’ air sacs (alveoli). Because of this concentration gradient, oxygen diffuses from the alveoli to the blood. Carbon dioxide, which has a higher concentration in the blood than in the alveoli, diffuses from the blood into the alveoli. Movement of air in and out of the airways (ventilation) continually replenishes the oxygen and removes the carbon dioxide from the airways and lungs. This whole process of

gas exchange between the atmospheric air and the blood and between the blood and cells of the body is called respiration.

Ventilation

During inspiration, air flows from the environment into the trachea, bronchi, bronchioles, and alveoli. During expiration, alveolar gas travels the same route in reverse. Physical factors that govern air flow in and out of the lungs are collectively referred to as the mechanics of ventilation and include air pressure variances, resistance to air flow, and lung compliance.

Air Pressure Variances

Air flows from a region of higher pressure to a region of lower pressure. During inspiration, movement of the diaphragm and other muscles of respiration enlarges the thoracic cavity and thereby lowers the pressure inside the thorax to a level below that of atmospheric pressure. As a result, air is drawn through the trachea and bronchi into the alveoli. During expiration, the diaphragm relaxes and the lungs recoil, resulting in a decrease in the size of the thoracic cavity. The alveolar pressure then exceeds atmospheric pressure, and air

flows from the lungs into the atmosphere.

Airway Resistance

Resistance is determined chiefly by the radius or size of the airway through which the air is flowing. Any process that changes the bronchial diameter or width affects airway resistance and alters the rate of air flow for a given pressure gradient during respiration. With increased resistance, greater-than-normal respiratory effort is required to achieve normal levels of ventilation.

Compliance

Compliance, or distensibility, is the elasticity and expandability of the lungs and thoracic structures. Compliance allows the lung volume to increase when the difference in pressure between the atmosphere and thoracic cavity (pressure gradient) causes air to flow in. Factors that determine lung compliance are the surface tension of the alveoli (normally low with the presence of surfactant) and the connective tissue (ie, collagen and elastin) of the lungs. Compliance is determined by examining the volume pressure relationship in the lungs and the thorax. Compliance is normal (1.0 L/cm H2O) if the lungs and thorax easily stretch and distend when pressure is applied. High or increased compliance occurs if the lungs have lost their

elasticity and the thorax is overdistended (eg, in emphysema).

Low or decreased compliance occurs if the lungs and thorax are “stiff.” Conditions associated with decreased compliance include morbid obesity, pneumothorax, hemothorax, pleural effusion, pulmonary edema, atelectasis, pulmonary fibrosis, and acute respiratory distress syndrome (ARDS), which are discussed in later chapters in this unit. Measurement of compliance is one method used to assess the progression and improvement in patients with ARDS. Lungs with decreased compliance require greater-thannormal energy expenditure by the patient to achieve normal levels of ventilation. Compliance is usually measured under static conditions.

Lung Volumes and Capacities

Lung function, which reflects the mechanics of ventilation, is viewed in terms of lung volumes and lung capacities. Lung volumes are categorized as tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume. Lung capacity is evaluated in terms of vital capacity, inspiratory capacity, functional residual capacity, and total lung capacity.

A&P Lecture 4: Sturcture Respiratory System

NOTE: The following organ lecture on Anatomy and Physiology will be structured closely to concepts by which nurses must know to be able to have a good foundation in the normal Anatomy and Physiology to know the normal from abnormal findings for Health Assessment and to have a good grasp regarding deviations in the normal functions and structures of the the body in contrast to that during an illness state for advance subjects such as Medical-Surgical Nursing, Maternal and Child Nursing and Psychiatric Nursing.

ANATOMY AND PHYSIOLOGY LECTURE 4

RESPIRATORY SYSTEM

Nurses often encounter disorders of the respiratory system from the community to the intensive care unit. The diversity of respiratory ailments from simple colds to an evolving pulmonary edema necessitates an the development of expert assessment  skills to provide accurate problem identification and prompt treatment to be able to return patients in their optimal level of functioning. In order to differentiate between normal and abnormal assessment findings, an understanding of respiratory function and the significance of abnormal diagnostic test results is essential.

Overview

The respiratory system is composed of the upper and lower respiratory tracts. Together, the two tracts are responsible for ventilation. The upper respiratory tract warms and filters inspired air so that the lower respiratory tract can accomplish gas exchange. Gas exchange involves delivering oxygen to the tissues through the bloodstream and expelling waste gases, such as carbon dioxide, during expiration. The respiratory system works with the cardiovascular system; the respiratory system is responsible for ventilation and diffusion, and the cardiovascular system is responsible for oxygen delivery. 

Upper Respiratory Tract

Nose

Our nose serves as a passageway for air to pass to and from the lungs. It filters impurities and humidifies and warms the air as it is inhaled. The nose is composed of an external and an internal portion. The external portion protrudes from the face and is supported by the nasal bones and cartilage. The anterior nares (nostrils) are the external openings of the nasal cavities.

The internal portion of the nose is a hollow cavity separated into the right and left nasal cavities by a narrow vertical divider, the septum. Each nasal cavity is divided into three passageways by the projection of the turbinates from the lateral walls. The turbinate bones are also called conchae for the name suggested by their shell-like appearance. Because of their curves, these bones increase the mucous membrane surface

of the nasal passages and slightly obstruct the air flowing

through them.

Air entering the nostrils is deflected upward to the roof of the nose, and it follows a circuitous route before it

reaches the nasopharynx. It comes into contact with a large surface of moist, warm, highly vascular, ciliated mucous membrane (called nasal mucosa) that traps practically all the dust and organisms in the inhaled air. The air is moistened, warmed to body temperature, and brought into contact with sensitive nerves. Some of these nerves detect odors; others provoke sneezing to expel irritating dust. Mucus, secreted continuously by goblet cells, covers the surface of the nasal mucosa and is moved back to the nasopharynx by the action of the cilia which are fine hairs.

Paranasal Sinuses

The paranasal sinuses include four pairs of bony cavities that are lined with nasal mucosa and ciliated pseudostratified columnar epithelium. These air spaces are connected by a series of ducts that drain into the nasal cavity. The sinuses are named by their location: frontal, ethmoidal, sphenoidal, and maxillary . A prominent function of the sinuses is to serve as a resonating chamber in speech. The sinuses are a common site of infection.

Pharynx, Tonsils, and Adenoids

The pharynx, or throat, is a tubelike structure that connects the nasal and oral cavities to the larynx. It is divided into three regions: nasal, oral, and laryngeal. The nasopharynx is located posterior to the nose and above the soft palate. The oropharynx houses the faucial, or palatine, tonsils. The laryngopharynx extends from the hyoid bone to the cricoid cartilage. The epiglottis forms the entrance to the larynx. The adenoids, or pharyngeal tonsils, are located in the roof of the nasopharynx. The tonsils, the adenoids, and other lymphoid tissue encircle the throat. These structures are important links in the chain of lymph nodes guarding the body from invasion by organisms entering the nose and the throat. The pharynx functions as a passageway for the respiratory and digestive tracts.

Larynx

The larynx, or voice organ, is a cartilaginous epitheliumlined structure that connects the pharynx and the trachea. The major function of the larynx is vocalization. It also protects the lower airway from foreign substances and facilitates coughing. It is frequently referred to as the voice box and consists of the following:

• Epiglottis: a valve flap of cartilage that covers the opening to the larynx during swallowing

• Glottis: the opening between the vocal cords in the larynx

• Thyroid cartilage: the largest of the cartilage structures; part of it forms the Adam’s apple

• Cricoid cartilage: the only complete cartilaginous ring in the larynx (located below the thyroid cartilage)

• Arytenoid cartilages: used in vocal cord movement with the thyroid cartilage

• Vocal cords: ligaments controlled by muscular movements that produce sounds; located in the lumen of

the larynx. 

Trachea

The trachea, or windpipe, is composed of smooth muscle with C-shaped rings of cartilage at regular intervals. The cartilaginous rings are incomplete on the posterior surface and give firmness to the wall of the trachea, preventing it from collapsing. The trachea serves as the passage between the larynx and the bronchi

Lower Respiratory Tract

The lower respiratory tract consists of the lungs, which contain the bronchial and alveolar structures needed for gas exchange.

Lungs

The lungs are paired elastic structures enclosed in the thoracic cage, which is an airtight chamber with distensible walls. Ventilation requires movement of the walls of the thoracic cage and of its floor, the diaphragm. The effect of these movements is alternately to increase and decrease the capacity of the chest. When the capacity of the chest is increased, air enters through the trachea (inspiration) because of the lowered pressure within and inflates the lungs. When the chest wall and diaphragm return to their previous positions (expiration), the lungs recoil and force the air out through the bronchi and trachea. Inspiration occurs during the first third of the respiratory cycle, expiration during the later two thirds. The inspiratory phase of respiration normally requires energy; the expiratory phase is normally passive, requiring very little energy. In respiratory diseases, such as chronic obstructive pulmonary disease (COPD), expiration requires energy.

Pleura

The lungs and wall of the thorax are lined with a serous membrane called the pleura. The visceral pleura covers the lungs; the parietal pleura lines the thorax. The visceral and parietal pleura and the small amount of pleural fluid between these two membranes serve to lubricate the thorax and lungs and permit smooth motion of the lungs within the thoracic cavity with each breath.

Mediastinum

The mediastinum is in the middle of the thorax, between the pleural sacs that contain the two lungs. It extends from the sternum to the vertebral column and contains all the thoracic tissue outside the lungs (heart, thymus,

certain large blood vessels [ie, aorta, vena cava], and esophagus).

Lobes

Each lung is divided into lobes. The right lung has upper, middle, and lower lobes, whereas the left lung consists of upper and lower lobes. Each lobe is further subdivided into two to five segments separated by fissures, which are extensions of the pleura.

Bronchi and Bronchioles

There are several divisions of the bronchi within each lobe of the lung. First are the lobar bronchi (three in the right lung and two in the left lung). Lobar bronchi divide into segmental bronchi (10 on the right and 8 on the left), which are the structures identified when choosing the most effective postural drainage position for a given patient. Segmental bronchi then divide into subsegmental bronchi. These bronchi are surrounded by connective tissue that contains arteries, lymphatics, and nerves.

The subsegmental bronchi then branch into bronchioles, which have no cartilage in their walls. Their patency depends entirely on the elastic recoil of the surrounding smooth muscle and on the alveolar pressure. The bronchioles contain submucosal glands, which produce mucus that covers the inside lining of the airways. The bronchi and bronchioles are also lined with cells that have surfaces covered with cilia. These cilia create a constant whipping motion that propels mucus and foreign substances away from the lungs toward the larynx.

The bronchioles then branch into terminal bronchioles, which do not have mucus glands or cilia. Terminal bronchioles then become respiratory bronchioles, which are considered to be the transitional passageways between the conducting airways and the gas exchange airways. Up to this point, the conducting airways contain about 150 mL of air in the tracheobronchial tree that does not participate in gas exchange; this is known as physiologic dead space. The respiratory bronchioles then lead into alveolar ducts and alveolar sacs and then alveoli. Oxygen and carbon dioxide exchange takes place in the alveoli.

Alveoli

The lung is made up of about 300 million alveoli, which are arranged in clusters of 15 to 20. These alveoli are

so numerous that if their surfaces were united to form one sheet, it would cover 70 square meters—the size of a tennis court.

There are three types of alveolar cells. Type I alveolar cells are epithelial cells that form the alveolar walls. Type II alveolar cells are metabolically active. These cells secrete surfactant, a phospholipid that lines the inner surface and prevents alveolar collapse. Type III alveolar cell macrophages are large phagocytic cells that ingest foreign matter (eg, mucus, bacteria) and act as an important defense mechanism.

A&P Lecture 2: Cell Cycle and Cell Division

ANATOMY AND PHYSIOLOGY LECTURE 2

CELL CYCLE AND CELL DIVISION

The life of a cell is called the cell cycle. It is usually divided into five phases or gaps: G0, G1, S, G2, and M. Some cells may not have a G1 phase, and others may not have a G2 stage. However, all cells must grow, replicate their genetic material if they are to divide, and undergo the process of mitosis if they are to replicate. G0 is the stage during which the cell may leave the cell cycle and either remain in a state of inactivity or reenter the cell cycle at another time. G1 is the stage during which the cell is starting to prepare for mitosis through DNA and protein synthesis and an increase in organelle and cytoskeletal elements. The S phase is the synthesis phase, during which DNA replication occurs and the centrioles are beginning to replicate. G2 is the premitotic phase and is similar to G1 as for RNA and protein synthesis. The M phase is the phase during which cell mitosis occurs. Nondividing cells, such as mature nerve cells and cells not preparing for mitosis, are said to be in the G0 phase of the cell cycle .

Cell Division

Cell division, or mitosis, which was first described in 1875, is the process during which a parent cell divides and each daughter cell receives a chromosomal karyotype identical to the parent cell. Cell division gives the body a means of replacing cells that have a limited life span, such as skin and blood cells; increasing tissue mass during periods of growth; and providing for tissue repair and wound healing. Despite the early cytologic description of the four stages of mitosis, it was not until the early 1950s that the importance of the cell cycle was realized. 

Mitosis, which is a dynamic and continuous process, usually lasts from 1 to 11⁄2 hours. It is divided into four stages: prophase, metaphase, anaphase, and telophase (Fig. 4-13). The phase during which the cell is not undergoing division is called interphase. During prophase, the chromosomes become visible because of increased coiling of the DNA, the two centrioles replicate, and a pair moves to each side of the cell. Simultaneously, the microtubules of the mitotic spindle appear between the two pairs of centrioles. Later in prophase, the nuclear envelope and nucleolus disappear. Metaphase involves the organization of the chromosome pairs in the midline of the cell and the formation of a mitotic spindle composed of the microtubules. Anaphase is the period during which separation of the chromosome pairs occurs, with the microtubules pulling one member of each pair of 46 chromosomes toward the opposite cell pole. Cell division, or cytokinesis, is completed after telophase, the stage during which the mitotic spindle vanishes and a new nuclear membrane develops and encloses each complete set of chromosomes.

Cell division is controlled by changes in the intracellular concentrations and activity of three major groups of

intracellular proteins: (1) cyclins, (2) cyclin-dependent kinases, and (3) the anaphase-promoting complex. The central components of the cell cycle control system are the cyclin-dependent kinases, whose activity depends on association with the regulatory units called cyclins. Oscillations in the activity of the various cyclin-dependent kinases lead to initiation of the different phases of the cell cycle. For example, activation of the S-phase cyclin-dependent kinases initiates the S phase of the cell cycle, whereas activation of the M-phase cyclin-dependent kinases triggers mitosis. The anaphase-promoting complex is responsible for the breakdown of the M cyclins and other regulators of mitosis.

Cell division is also controlled by several external factors, including the presence of cytokines, various growth

factors, or even adhesion factors when the cell is associated with other cells in a tissue. In addition, the cell cycle is regulated by several checkpoints that determine whether DNA replication has occurred with a high degree of fidelity. Two of the better understood are the DNA damage and the spindle formation checkpoints. If these biochemical checkpoints are not faithfully met, the cell may default to programmed

cell death or apoptosis.

Anatomy and Physiology Compiled Lecture Notes: The Cell

THE CELL

• Introduction

• The Cell Membrane

• The Nucleus

• The Cytoplasm

• The Ribosomes

• The Endoplasmic Reticulum

• The Golgi Complex

• The Secretory Vesicles

• The Lysosomes

• The Peroxisomes

• The Proteasomes

• The Mitochondria

• The Accessory Parts

• Cillia
• Flagella
• Microvilli
• Centrioles
• Spindle Fibers

A&P Lecture 1.11: Centrioles and Spindle Fibers

This is an in depth  explanation of Centriloes and Spindle fiber as a part of the cell. This lecture note is linked to A&P Lecture 1: The Cell

ANATOMY AND PHYSIOLOGY LECTURE 1.11

CENTRIOLES AND SPINDLE FIBERS

Centrioles and Spindle Fibers

The centrosome, a specialized zone of cytoplasm close to the nucleus, is the center of microtubule formation. It contains two centrioles . Each centriole is a small, cylindrical organelle about 0.3–0.5 μm in length and 0.15 μm in diameter, and the two centrioles are normally oriented perpendicular to each other within the centrosome. The wall of the centriole is composed of nine evenly spaced, longitudinally oriented, parallel units, or triplets. Each unit consists of three parallel microtubules joined together.

Microtubules appear to influence the distribution of actin and intermediate filaments. Through its control of microtubule formation, the centrosome is closely involved in determining cell shape and movement. The microtubules extending from the centrosomes are very dynamic—constantly growing and shrinking. Before cell division, the two centrioles double in number, the centrosome divides into two, and one centrosome, containing two centrioles, moves to each end of the cell.

Microtubules called
spindle fibers extend out in all directions from the centrosome. These microtubules grow and shrink even more rapidly than those of nondividing cells. If the extended end of a spindle fiber comes in contact with a kinetochore, a specialized region in the centromere of each chromosome, the spindle fiber attaches to the kinetochore and stops growing or shrinking. Eventually, spindle fibers from each centrosome bind to the kinetochores of all the chromosomes. During cell division, the microtubules facilitate the movement of chromosomes toward the two centrosomes

A&P Lecture 1.12: Cilia Flagella and Microvilli

This is an in depth  explanation of Lysosomes as a part of the cell. This lecture note is linked to A&P Lecture 1: The Cell

ANATOMY AND PHYSIOLOGY LECTURE 1.12

CILLIA, FLAGELLA AND MICROVILLI

Cilia and Flagella

Cilia  are structures that project from the surface of cells and are capable of movement. They vary in number from one to thousands per cell. Cilia are cylindrical in shape, about 10 μm in length and 0.2 μm in diameter, and the shaft of each cilium is enclosed by the plasma membrane. Two centrally located microtubules and nine peripheral pairs of fused microtubules, the so-called 9 2 arrangement, extend from the base to the tip of each cilium. Movement of the microtubules past each other, a process that requires energy from ATP, is responsible for movement of the cilia. Dynein arms, proteins connecting adjacent pairs of microtubules, push the microtubules past each other. A basal body (a modified centriole) is located in the cytoplasm at the base of the cilium. Cilia are numerous on surface cells that line the respiratory tract and the female reproductive tract. In these regions, cilia move in a coordinated fashion, with a power stroke in one direction and a recovery stroke in the opposite direction. Their motion moves materials over the surface of the cells. For example, cilia in the trachea move mucus embedded with dust particles upward and away from the lungs. This action helps keep the lungs clear of debris.

Flagella  have a structure similar to cilia but are longer (45 μm). Sperm cells are the only human cells to possess flagella and usually only one flagellum exists per cell. Furthermore, whereas cilia move small particles across the cell surface, flagella move the entire cell. For example, each sperm cell is propelled by a single flagellum. In contrast to cilia, which have a power stroke and a recovery stroke, flagella move in a

wavelike fashion.

Microvilli

Microvilli ) are cylindrically shaped

extensions of the plasma membrane about 0.5–1.0 μm in length and 90 nm in diameter. Normally, many microvilli are on each cell, and they function to increase the cell surface area. A student looking at photographs may confuse microvilli with cilia. Microvilli, however, are only one-tenth to one-twentieth the size of cilia. Individual microvilli can usually be seen only with an electron microscope, whereas cilia can be seen with a light microscope. Microvilli do not move, and they are supported with actin filaments, not microtubules. Microvilli are found in the intestine, kidney, and other areas in which absorption is an important

function. In certain locations of the body, microvilli are highly modified to function as sensory receptors. For example, elongated microvilli in hair cells of the inner ear respond to sound.

A&P Lecture 1.10: Mitochondria

This is an in depth  explanation of Mitochondria as a part of the cell. This lecture note is linked to A&P Lecture 1: The Cell

ANATOMY AND PHYSIOLOGY LECTURE 1.10

MITOCHONDRIA

All cells in the body, with the exception of mature red blood cells, have from a hundred to a few thousand organelles called mitochondria (singular, mitochondrion ). Mitochondria serve as sites for the production of most of the energy of cells

Mitochondria vary in size and shape, but all have the same basic structure.. Each mitochondrion is surrounded by an inner and outer membrane, separated by a narrow intermembranous space. The outer mitochondrial membrane is smooth, but the inner membrane is characterized by many folds, called cristae, which project like shelves into the central area (or matrix ) of the mitochondrion. The cristae and the matrix compartmentalize the space within the mitochondrion and have different roles in the generation of cellular energy.

Mitochondria can migrate through the cytoplasm of a cell and are able to reproduce themselves. Indeed, mitochondria contain their own DNA. All of the mitochondria in a person’s body are derived from those inherited from the mother’s fertilized egg cell. Thus, all of a person’s mitochondrial genes are inherited from the mother. Mitochondrial DNA is more primitive (consisting of a circular, relatively small, doublestranded

molecule) than that found within the cell nucleus. For this and other reasons, many scientists believe that mitochondria evolved from separate organisms, related to bacteria, that invaded the ancestors of animal cells and remained in a state of symbiosis. This symbiosis might not always benefit the host; for example, mitochondria produce superoxide radicals that can provoke an oxidative stress and some scientists believe that accumulations of mutations in mitochondrial DNA may contribute to aging. Mutations in mitochondrial DNA occur at a rate at least ten times faster than in nuclear DNA (probably due to the superoxide radicals),

and there are more than 150 mutations of mitochondrial DNA presently known to contribute to different human diseases. However, genes in nuclear DNA code for 99% of mitochondrial proteins (mitochondrial DNA contains only 37 genes), and so many mitochondrial diseases are produced by mutations in nuclear DNA.

Neurons obtain energy solely from aerobic cell respiration, which occurs in mitochondria. Thus, mitochondrial fission (division) and transport over long distances is particularly important in neurons, where axons can be up to l meter in length. Mitochondria can also fuse together, which may help to repair those damaged by “reactive oxygen species” generated within mitochondria.