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

Health Assessment Lecture: Respiratory System D

Good assessment skill is paramount in providing quality nursing care. There is the reason why Assessment is the first step in the nursing process and is incorporated in every phase. In assessment nurses can gather pertinent information from the patient's health status so as to have a good overview of the patient's condition to be able to formulate a nursing diagnosis and even help doctors to come up with their medical diagnosis- much more it help the whole health care team.

Thoracic Percussion

Percussion sets the chest wall and underlying structures in motion, producing audible and tactile vibrations. The nurse uses percussion to determine whether underlying tissues are filled with air, fluid, or solid material. Percussion also is used to estimate the size and location of certain structures within the thorax (eg, diaphragm, heart, liver).

Percussion usually begins with the posterior thorax. Ideally, the patient is in a sitting position with the head flexed forward and the arms crossed on the lap. This position separates the scapulae widely and exposes more lung area for assessment. The nurse percusses across each shoulder top, locating the 5-cm width

of resonance overlying the lung apices. Then the nurse proceeds down the posterior thorax, percussing symmetric areas at 5- to 6-cm (2- to 2.5-inch) intervals. The middle finger is positioned parallel to the ribs in the intercostal space; the finger is placed firmly against the chest wall before striking it with the middle finger of the opposite hand. Bony structures (scapulae or ribs) are not percussed.

Percussion over the anterior chest is performed with the patient in an upright position with shoulders arched backward and arms at the side. The nurse begins in the supraclavicular area and proceeds downward, from one intercostal space to the next. In the female patient, it may be necessary to displace the breasts for an adequate examination. Dullness noted to the left of the sternum between the third and fifth intercostal spaces is a normal finding because it is the location of the heart. Similarly, there is a normal span of liver dullness in the right thorax from the fifth intercostal space to the right costal margin at the midclavicular line. The anterior and lateral thorax is examined with the patient in a supine position. If the patient cannot sit up, percussion of the posterior thorax is performed with the patient positioned on the side. Dullness over the lung occurs when air-filled lung tissue is replaced by fluid or solid tissue. 

DIAPHRAGMATIC EXCURSION

The normal resonance of the lung stops at the diaphragm. The position of the diaphragm is different during inspiration than during expiration. To assess the position and motion of the diaphragm, the nurse instructs the patient to take a deep breath and hold it while the maximal descent of the diaphragm is percussed. The point at which the percussion note at the midscapular line changes from resonance to dullness is marked with a pen. The patient is then instructed to exhale fully and hold it while the nurse again percusses downward to the dullness of the diaphragm. This point is also marked. The distance between the two markings indicates

the range of motion of the diaphragm. Maximal excursion of the diaphragm may be as much as 8 to 10 cm (3 to 4 inches) in healthy, tall young men, but for most people it is usually 5 to 7 cm (2 to 2.75 inches). 

Normally, the diaphragm is about 2 cm (0.75 inches) higher on the right because of the position of the heart and the liver above and below the left and right segments of the diaphragm, respectively. Decreased diaphragmatic excursion may occur with pleural effusion and emphysema. An increase in intra-abdominal pressure, as in pregnancy or ascites, may account for a diaphragm that is positioned high in the thorax.

Health Assessment Lecture: Respiratory System C

Good assessment skill is paramount in providing quality nursing care. There is the reason why Assessment is the first step in the nursing process and is incorporated in every phase. In assessment nurses can gather pertinent information from the patient's health status so as to have a good overview of the patient's condition to be able to formulate a nursing diagnosis and even help doctors to come up with their medical diagnosis- much more it help the whole health care team.

Thoracic Palpation

The nurse palpates the thorax for tenderness, masses, lesions, respiratory excursion, and vocal fremitus. If the patient has reported an area of pain or if lesions are apparent, the nurse performs direct palpation with the fingertips (for skin lesions and subcutaneous masses) or with the ball of the hand (for deeper masses or

generalized flank or rib discomfort).

RESPIRATORY EXCURSION

Respiratory excursion is an estimation of thoracic expansion and may disclose significant information about thoracic movement during breathing. The nurse assesses the patient for range and symmetry of excursion. The patient is instructed to inhale deeply while the movement of the nurse’s thumbs (placed along the costal margin on the anterior chest wall) during inspiration and expiration is observed. This movement is normally symmetric. 

Posterior assessment is performed by placing the thumbs adjacent to the spinal column at the level of the tenth rib. The hands lightly grasp the lateral rib cage. Sliding the thumbs medially about 2.5 cm (1 inch) raises a small skinfold between the thumbs. The patient is instructed to take a full inspiration and to exhale fully. The nurse observes for normal flattening of the skinfold and feels the symmetric movement of the thorax.

Decreased chest excursion may be due to chronic fibrotic disease. Asymmetric excursion may be due to splinting secondary to pleurisy, fractured ribs, trauma, or unilateral bronchial obstruction.

TACTILE FREMITUS

Sound generated by the larynx travels distally along the bronchial tree to set the chest wall in resonant motion. This is especially true of consonant sounds. The detection of the resulting vibration on the chest wall by touch is called tactile fremitus.

Normal fremitus is widely varied. It is influenced by the thickness of the chest wall, especially if that thickness is muscular. However, the increase in subcutaneous tissue associated with obesity may also affect fremitus. Lower-pitched sounds travel better through the normal lung and produce greater vibration of the chest wall. Thus, fremitus is more pronounced in men than in women because of the deeper male voice. 

Normally, fremitus is most pronounced where the large bronchi are closest to the chest wall and least palpable over the distant lung fields. Therefore, it is most palpable in the upper thorax, anteriorly and posteriorly. The patient is asked to repeat “ninety-nine” or “one, two, three,” or “eee, eee, eee” as the nurse’s hands move down the patient’s thorax. The vibrations are detected with the palmar surfaces of the fingers and hands, or the ulnar aspect of the extended hands, on the thorax. The hand or hands are moved in sequence down the thorax. Corresponding areas of the thorax are compared . Bony areas are not tested.

Air does not conduct sound well but a solid substance such as tissue does, provided that it has elasticity and is not compressed. Thus, an increase in solid tissue per unit volume of lung will enhance fremitus; an increase in air per unit volume of lung will impede sound. Patients with emphysema, which results in the rupture of alveoli and trapping of air, exhibit almost no tactile fremitus. A patient with consolidation of a lobe of the lung from pneumonia will have increased tactile fremitus over that lobe. Air in the pleural space will not conduct sound.

Health Assessment Lecture: Respiratory System B

Good assessment skill is paramount in providing quality nursing care. There is the reason why Assessment is the first step in the nursing process and is incorporated in every phase. In assessment nurses can gather pertinent information from the patient's health status so as to have a good overview of the patient's condition to be able to formulate a nursing diagnosis and even help doctors to come up with their medical diagnosis- much more it help the whole health care team.

PHYSICAL ASSESSMENT OF THE LOWER RESPIRATORY STRUCTURES AND BREATHING

Thorax

Inspection of the thorax provides information about the musculoskeletal structure, the patient’s nutritional status, and the respiratory system. The nurse observes the skin over the thorax for color and turgor and for evidence of loss of subcutaneous tissue. It is important to note asymmetry, if present. When findings are

recorded or reported, anatomic landmarks are used as points of reference

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CHEST CONFIGURATION

Normally, the ratio of the anteroposterior diameter to the lateral diameter is 1 2. However, there are four main deformities of the chest associated with respiratory disease that alter this relationship: barrel chest, funnel chest (pectus excavatum), pigeon chest (pectus carinatum), and kyphoscoliosis.

Barrel Chest. Barrel chest occurs as a result of overinflation of the lungs. There is an increase in the anteroposterior diameter of the thorax. In a patient with emphysema, the ribs are more widely spaced and the intercostal spaces tend to bulge on expiration. The appearance of the patient with advanced emphysema is thus quite characteristic and often allows the observer to detect its presence easily, even from a distance.

Funnel Chest (Pectus Excavatum). Funnel chest occurs when there is a depression in the lower portion of the sternum. This may compress the heart and great vessels, resulting in murmurs. Funnel chest may occur with rickets or Marfan’s syndrome.

Pigeon Chest (Pectus Carinatum). A pigeon chest occurs as a result of displacement of the sternum. There is an increase in the anteroposterior diameter. This may occur with rickets, Marfan’s syndrome, or severe kyphoscoliosis.

Kyphoscoliosis. A kyphoscoliosis is characterized by elevation of the scapula and a corresponding S-shaped spine. This deformity limits lung expansion within the thorax. It may occur with osteoporosis and other skeletal disorders that affect the thorax.

BREATHING PATTERNS AND RESPIRATORY RATES

Observing the rate and depth of respiration is a simple but important aspect of assessment. The normal adult who is resting comfortably takes 12 to 18 breaths per minute. Except for occasional sighs, respirations are regular in depth and rhythm. This normal pattern is described as eupnea. 

Bradypnea, also called slow breathing, is associated with increased intracranial pressure, brain injury, and drug overdose. Tachypnea, or rapid breathing, is commonly seen in patients with pneumonia, pulmonary edema, metabolic acidosis, septicemia, severe pain, and rib fracture.  Shallow, irregular breathing is referred to as hypoventilation. An increase in depth of respirations is called hyperpnea. 

An increase in both rate and depth that results in a lowered arterial PCO2 level is referred to as hyperventilation. With rapid breathing, inspiration and expiration are nearly equal in duration. Hyperventilation that is marked by an increase in rate and depth, associated with severe acidosis of diabetic or renal origin, is called Kussmaul’s respiration.

Apnea describes varying periods of cessation of breathing. If sustained, apnea is life-threatening.

Cheyne-Stokes respiration is characterized by alternating episodes of apnea (cessation of breathing) and periods of deep breathing. Deep respirations become increasingly shallow, followed by apnea that may last approximately 20 seconds. The cycle repeats after each apneic period. The duration of the period of apnea may vary and may progressively lengthen; therefore, it is timed and reported. Cheyne-Stokes respiration is usually associated with heart failure and damage to the respiratory center (drug-induced, tumor, trauma).

Biot’s respirations, or cluster breathing, are cycles of breaths that vary in depth and have varying periods of apnea. Biot’s respirations are seen with some central nervous system disorders.

Certain patterns of respiration are characteristic of specific disease states. Respiratory rhythms and their deviation from normal are important observations that the nurse reports and documents. The rate and depth of different patterns of respiration are presented

In thin people, it is quite normal to note a slight retraction of the intercostal spaces during quiet breathing. Bulging during expiration implies obstruction of expiratory airflow, as in emphysema. Marked retraction on inspiration, particularly if asymmetric, implies blockage of a branch of the respiratory tree. Asymmetric bulging of the intercostal spaces, on one side or the other, is created by an increase in pressure within the hemithorax. This may be a result of air trapped under pressure within the pleural cavity where it does not normally appear (pneumothorax) or the pressure of fluid within the pleural space (pleural effusion).

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Health Assessment Lecture: Respiratory System A

Good assessment skill is paramount in providing quality nursing care. There is the reason why Assessment is the first step in the nursing process and is incorporated in every phase. In assessment nurses can gather pertinent information from the patient's health status so as to have a good overview of the patient's condition to be able to formulate a nursing diagnosis and even help doctors to come up with their medical diagnosis- much more it help the whole health care team.

The health history focuses on the physical and functional problems of the patient and the effect of these problems on his or her life. The reason the patient is seeking health care often is related to one of the following: dyspnea (shortness of breath), pain, accumulation of mucus, wheezing, hemoptysis (blood spit up from the respiratory tract), edema of the ankles and feet, cough, and general fatigue and weakness.

In addition to identifying the chief reason why the patient is seeking health care, the nurse tries to determine when the health problem or symptom started, how long it lasted, if it was relieved at any time, and how relief was obtained. The nurse collects information about precipitating factors, duration, severity, and associated

factors or symptoms and also assesses for risk factors and genetic factors that may contribute to the patient’s lung condition.

The nurse assesses the impact of signs and symptoms on the patient’s ability to perform activities of daily living and to participate in usual work and family activities. In addition, psychosocial factors that may affect the patient are explored. These factors include anxiety, role changes, family relationships, financial problems, employment status, and the strategies the patient uses to cope with them.

Many respiratory diseases are chronic and progressively debilitating. Therefore, ongoing assessment of the patient’s physical abilities, psychosocial supports, and quality of life is needed to plan appropriate interventions. It is important for the patient with a respiratory disorder to understand the condition and to be

familiar with necessary self-care interventions. The nurse evaluates these factors over time and provides education as needed.

Signs and Symptoms

The major signs and symptoms of respiratory disease are dyspnea, cough, sputum production, chest pain, wheezing, clubbing of the fingers, hemoptysis, and cyanosis. These clinical manifestations are related to the duration and severity of the disease.

DYSPNEA

Dyspnea (difficult or labored breathing, shortness of breath) is a symptom common to many pulmonary and cardiac disorders, particularly when there is decreased lung compliance or increased airway resistance. The right ventricle of the heart will be affected ultimately by lung disease because it must pump blood through

the lungs against greater resistance. It may also be associated with neurologic or neuromuscular disorders such as myasthenia gravis, Guillain-Barré syndrome, or muscular dystrophy.

Clinical Significance. In general, acute diseases of the lungs produce a more severe grade of dyspnea than do chronic diseases. Sudden dyspnea in a healthy person may indicate pneumothorax (air in the pleural cavity), acute respiratory obstruction, or ARDS. In immobilized patients, sudden dyspnea may denote pulmonary embolism. Orthopnea (inability to breathe easily except in an upright position) may be found in patients with heart disease and occasionally in patients with chronic obstructive pulmonary disease (COPD); dyspnea with an expiratory wheeze occurs with COPD. Noisy breathing may result from a narrowing of the airway or localized obstruction of a major bronchus by a tumor or foreign body. The presence of both inspiratory and expiratory wheezing usually signifies asthma if the patient does not have heart failure.

The circumstance that produces the dyspnea must be determined. Therefore, it is important to ask the patient the following questions:

• How much exertion triggers shortness of breath?

• Is there an associated cough?

• Is dyspnea related to other symptoms?

• Was the onset of shortness of breath sudden or gradual?

• At what time of day or night does the dyspnea occur?

• Is the shortness of breath worse when the patient is flat in bed?

• Does the shortness of breath occur at rest? With exercise? Running? Climbing stairs?

• Is the shortness of breath worse while walking? If so, when walking how far? How fast?

Relief Measures. The management of dyspnea is aimed at identifying and correcting its cause. Relief of the symptom sometimes is achieved by placing the patient at rest with the head elevated (high Fowler’s position) and, in severe cases, by administering oxygen.

COUGH

Cough results from irritation of the mucous membranes anywhere in the respiratory tract. The stimulus producing a cough may arise from an infectious process or from an airborne irritant, such as smoke, smog, dust, or a gas. The cough is the patient’s chief protection against the accumulation of secretions in the bronchi and bronchioles.

Clinical Significance. Cough may indicate serious pulmonary disease. The nurse needs to evaluate the character of the cough is it dry, hacking, brassy, wheezing, loose, or severe? A dry, irritative cough is characteristic of an upper respiratory tract infection of viral origin or may be a side effect of angiotensin-converting enzyme (ACE) inhibitor therapy. Laryngotracheitis causes an irritative, high-pitched cough. Tracheal lesions produce a brassy cough. A severe or changing cough may indicate bronchogenic carcinoma. Pleuritic chest pain accompanying coughing may indicate pleural or chest wall (musculoskeletal) involvement

The time of coughing is also noted. Coughing at night may herald the onset of left-sided heart failure or bronchial asthma. A cough in the morning with sputum production may indicate bronchitis. A cough that worsens when the patient is supine suggests postnasal drip (sinusitis). Coughing after food intake may

indicate aspiration of material into the tracheobronchial tree. A cough of recent onset is usually from an acute infection.

SPUTUM PRODUCTION

A patient who coughs long enough almost invariably produces sputum. Violent coughing causes bronchial spasm, obstruction, and further irritation of the bronchi and may result in syncope (fainting). A severe, repeated, or uncontrolled cough that is nonproductive is exhausting and potentially harmful. Sputum production is the reaction of the lungs to any constantly recurring irritant. It also may be associated with a nasal discharge.

Clinical Significance. A profuse amount of purulent sputum (thick and yellow, green, or rust-colored) or a change in color of the sputum probably indicates a bacterial infection. Thin, mucoid sputum frequently results from viral bronchitis. A gradual increase of sputum over time may indicate the presence of chronic bronchitis or bronchiectasis. Pink-tinged mucoid sputum suggests a lung tumor. Profuse, frothy, pink material, often welling up into the throat, may indicate pulmonary edema. Foul-smelling sputum and bad breath point to the presence of a lung abscess, bronchiectasis, or an infection caused by fusospirochetal or other anaerobic organisms.

Relief Measures. If the sputum is too thick for the patient to expectorate, it is necessary to decrease its viscosity by increasing its water content through adequate hydration (drinking water) and inhalation of aerosolized solutions, which may be delivered by any type of nebulizer. Strategies to assist the patient to cough productively are discussed later in this chapter.

Smoking is contraindicated with excessive sputum production because it interferes with ciliary action, increases bronchial secretions, causes inflammation and hyperplasia of the mucous membranes, and reduces production of surfactant. Thus, smoking impairs bronchial drainage. When the person stops smoking,

sputum volume decreases and resistance to bronchial infections increases.

The patient’s appetite may decrease because of the odor of the sputum or the taste it leaves in the mouth. The nurse encourages adequate oral hygiene and wise selection of food, measures that will stimulate appetite. In addition, the nurse encourages the patient and family to remove sputum cups, emesis basins, and soiled

tissues before mealtime. Encouraging the patient to drink citrus juices at the beginning of the meal may increase the palatability of the rest of the meal because these juices cleanse the palate of the sputum taste.

CHEST PAIN

Chest pain or discomfort may be associated with pulmonary or cardiac disease. Chest pain associated with pulmonary conditions may be sharp, stabbing, and intermittent, or it may be dull, aching, and persistent. The pain usually is felt on the side where the pathologic process is located, but it may be referred elsewhere—for example, to the neck, back, or abdomen.

Clinical Significance. Chest pain may occur with pneumonia, pulmonary embolism with lung infarction, and pleurisy. It also may be a late symptom of bronchogenic carcinoma. In carcinoma the pain may be dull and persistent because the cancer has invaded the chest wall, mediastinum, or spine.

Lung disease does not always produce thoracic pain because the lungs and the visceral pleura lack sensory nerves and are insensitive to pain stimuli. However, the parietal pleura has a rich supply of sensory nerves that are stimulated by inflammation and stretching of the membrane. Pleuritic pain from irritation of the parietal pleura is sharp and seems to “catch” on inspiration; patients often describe it as “like the stabbing of a knife.” Patients are more comfortable when they lie on the affected side as this splints the chest wall, limits expansion and contraction of the lung, and reduces the friction between the injured or diseased pleurae on that side. Pain associated with cough may be reduced manually by splinting the rib cage.

The nurse assesses the quality, intensity, and radiation of pain and identifies and explores precipitating factors, along with their relationship to the patient’s position. Also, it is important to assess the relationship of pain to the inspiratory and expiratory phases of respiration.

Relief Measures. Analgesic medications may be effective in relieving chest pain, but care must be taken not to depress the respiratory center or a productive cough, if present. Nonsteroidal anti-inflammatory drugs (NSAIDs) achieve this goal and thus are used for pleuritic pain. A regional anesthetic block may be performed to relieve extreme pain.

WHEEZING

Wheezing is often the major finding in a patient with bronchoconstriction or airway narrowing. It is heard with or without a stethoscope, depending on its location. Wheezing is a highpitched, musical sound heard mainly on expiration. 

Relief Measures. Oral or inhalant bronchodilator medications reverse wheezing in most instances.

CLUBBING OF THE FINGERS

Clubbing of the fingers is a sign of lung disease found in patients with chronic hypoxic conditions, chronic lung infections, and malignancies of the lung. This finding may be manifested initially as sponginess of the nailbed and loss of the nailbed angle.

HEMOPTYSIS

Hemoptysis (expectoration of blood from the respiratory tract) is a symptom of both pulmonary and cardiac disorders. The onset of hemoptysis is usually sudden, and it may be intermittent or continuous. Signs, which vary from blood-stained sputum to a large, sudden hemorrhage, always merit investigation. The most common causes are:

• Pulmonary infection

• Carcinoma of the lung

• Abnormalities of the heart or blood vessels

• Pulmonary artery or vein abnormalities

• Pulmonary emboli and infarction

Diagnostic evaluation to determine the cause includes several studies: chest x-ray, chest angiography, and bronchoscopy. A careful history and physical examination are necessary to diagnose the underlying disease, irrespective of whether the bleeding involved a very small amount of blood in the sputum or a massive hemorrhage.

The amount of blood produced is not always proportional to the seriousness of the cause.

First, it is important to determine the source of the bleeding— the gums, nasopharynx, lungs, or stomach. The nurse may be the only witness to the episode. When documenting the bleeding episode, the nurse considers the following points:

• Bloody sputum from the nose or the nasopharynx is usually preceded by considerable sniffing, with blood possibly appearing in the nose.

• Blood from the lung is usually bright red, frothy, and mixed with sputum. Initial symptoms include a tickling sensation in the throat, a salty taste, a burning or bubbling sensation in the chest, and perhaps chest pain, in which case the patient tends to splint the bleeding side. The term “hemoptysis” is reserved for the coughing up of blood arising from a pulmonary hemorrhage. This blood has an alkaline pH (greater than 7.0).

• If the hemorrhage is in the stomach, the blood is vomited (hematemesis) rather than coughed up. Blood that has been in contact with gastric juice is sometimes so dark that it is referred to as “coffee grounds.” This blood has an acid pH (less than 7.0).

CYANOSIS

Cyanosis, a bluish coloring of the skin, is a very late indicator of hypoxia. The presence or absence of cyanosis is determined by the amount of unoxygenated hemoglobin in the blood. Cyanosis appears when there is 5 g/dL of unoxygenated hemoglobin. A patient with a hemoglobin level of 15 g/dL will not demonstrate cyanosis until 5 g/dL of that hemoglobin becomes unoxygenated, reducing the effective circulating hemoglobin to two thirds of the normal level. An anemic patient rarely manifests cyanosis, and a

polycythemic patient may appear cyanotic even if adequately oxygenated. Therefore, cyanosis is not a reliable sign of hypoxia. Assessment of cyanosis is affected by room lighting, the patient’s skin color, and the distance of the blood vessels from the surface of the skin. In the presence of a pulmonary condition, central cyanosis is assessed by observing the color of the tongue and lips. This indicates a decrease in oxygen tension in the blood. Peripheral cyanosis results from decreased blood flow to a certain area of the body, as in vasoconstriction of the nailbeds or earlobes from exposure to cold, and does not necessarily indicate a central systemic problem.

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 4.2: Gas Exchange

ANATOMY AND PHYSIOLOGY LECTURE 4.2

GAS EXCHANGE

The air we breathe is a gaseous mixture consisting mainly of nitrogen (78.62%) and oxygen (20.84%), with traces of carbon dioxide (0.04%), water vapor (0.05%), helium, and argon. The atmospheric pressure at sea level is about 760 mm Hg. Partial pressure is the pressure exerted by each type of gas in a mixture of gases. The partial pressure of a gas is proportional to the concentration of that gas in the mixture. The total pressure exerted by the gaseous mixture is equal to the sum of the partial pressures.

PARTIAL PRESSURE OF GASES

Based on these facts, the partial pressures of nitrogen and oxygen can be calculated. The partial pressure of nitrogen is 79% of 760 (0.79 × 760), or 600 mm Hg; that of oxygen is 21% of 760 (0.21 × 760), or 160 mm Hg. Chart 21-3 spells out terms and abbreviations related to partial pressure of gases.

Once the air enters the trachea, it becomes fully saturated with water vapor, which displaces some of the gases so that the air pressure within the lung remains equal to the air pressure outside (760 mm Hg). Water vapor exerts a pressure of 47 mm Hg when it fully saturates a mixture of gases at the body temperature of

37°C (98.6°F). Nitrogen and oxygen are responsible for the remaining 713 mm Hg (760 − 47) pressure. Once this mixture enters the alveoli, it is further diluted by carbon dioxide. In the alveoli, the water vapor continues to exert a pressure of 47 mm Hg. The remaining 713 mm Hg pressure is now exerted as follows:

nitrogen, 569 mm Hg (74.9%); oxygen, 104 mm Hg (13.6%); and carbon dioxide, 40 mm Hg (5.3%).

PARTIAL PRESSURE IN GAS EXCHANGE

When a gas is exposed to a liquid, the gas dissolves in the liquid until an equilibrium is reached. The dissolved gas also exerts a partial pressure. At equilibrium, the partial pressure of the gas in the liquid is the same as the partial pressure of the gas in the gaseous mixture. Oxygenation of venous blood in the lung illustrates this point. In the lung, venous blood and alveolar oxygen are separated by a very thin alveolar membrane. Oxygen diffuses across this membrane to dissolve in the blood until the partial pressure of oxygen in the blood is the same as that in the alveoli (104 mm Hg). However, because carbon dioxide is a byproduct

of oxidation in the cells, venous blood contains carbon dioxide at a higher partial pressure than that in the alveolar gas. In the lung, carbon dioxide diffuses out of venous blood into the alveolar gas. At equilibrium, the partial pressure of carbon dioxide in the blood and in alveolar gas is the same.

EFFECTS OF PRESSURE ON OXYGEN TRANSPORT

Oxygen and carbon dioxide are transported simultaneously dissolved in blood or combined with some of the elements of blood. Oxygen is carried in the blood in two forms: first as physically dis-olved oxygen in the plasma, and second in combination with the hemoglobin of the red blood cells. Each 100 mL of normal arterial blood carries 0.3 mL of oxygen physically dissolved in the plasma and 20 mL of oxygen in combination with hemoglobin. Large amounts of oxygen can be transported in the blood because it combines easily with hemoglobin to form oxyhemoglobin: O2 + Hgb ↔ HgbO2

The volume of oxygen physically dissolved in the plasma varies directly with the partial pressure of oxygen in the arteries (PaO2). The higher the PaO2, the greater the amount of oxygen dissolved. For example, at a PaO2 of 10 mm Hg, 0.03 mL of oxygen is dissolved in 100 mL of plasma. At 20 mm Hg, twice this amount is dissolved in plasma, and at 100 mm Hg, 10 times this amount is dissolved. Therefore, the amount of dissolved oxygen is directly proportional to the partial pressure, regardless of how high the oxygen pressure rises.

The amount of oxygen that combines with hemoglobin also depends on PaO2, but only up to a PaO2 of about 150 mm Hg. When the PaO2 is 150 mm Hg, hemoglobin is 100% saturated and will not combine with any additional oxygen. When hemoglobin is 100% saturated, 1 g of hemoglobin will combine with 1.34 mL

of oxygen. Therefore, in a person with 14 g/dL of hemoglobin, each 100 mL of blood will contain about 19 mL of oxygen associated with hemoglobin. If the PaO2 is less than 150 mm Hg, the percentage of hemoglobin saturated with oxygen is lower. For example, at a PaO2 of 100 mm Hg (normal value), saturation is 97%; at a PaO2 of 40 mm Hg, saturation is 70%. 

OXYHEMOGLOBIN DISSOCIATION CURVE

The oxyhemoglobin dissociation curve  shows the relationship between the partial pressure of oxygen (PaO2) and the percentage of saturation of oxygen (SaO2). The percentage of saturation can be affected by the following factors: carbon dioxide, hydrogen ion concentration, temperature, and 2,3-diphosphoglycerate.

A rise in these factors shifts the curve to the right so that more oxygen is then released to the tissues at the same PaO2. A reduction in these factors causes the curve to shift to the left, making the bond between oxygen and hemoglobin stronger, so that less oxygen is given up to the tissues at the same PaO2. The unusual shape of the oxyhemoglobin dissociation curve is a distinct advantage to the patient for two reasons:

1. If the arterial PO2 decreases from 100 to 80 mm Hg as a result of lung disease or heart disease, the hemoglobin of the arterial blood remains almost maximally saturated (94%) and the tissues will not suffer from hypoxia.

2. When the arterial blood passes into tissue capillaries and is exposed to the tissue tension of oxygen (about 40 mm Hg), hemoglobin gives up large quantities of oxygen for use by the tissues.

Clinical Significance. 

The normal value of PaO2 is 80 to 100 mm Hg (95% to 98% saturation). With this level of oxygenation,

there is a 15% margin of excess oxygen available to the tissues. With a normal hemoglobin level of 15 mg/dL and a PaO2 level of 40 mm Hg (oxygen saturation 75%), there is adequate oxygen available for the tissues but no reserve for physiologic stresses that increase tissue oxygen demand. When a serious incident occurs

(eg, bronchospasm, aspiration, hypotension, or cardiac dysrhythmias) that reduces the intake of oxygen from the lungs, tissue hypoxia will result.

An important consideration in the transport of oxygen is cardiac output, which determines the amount of oxygen delivered to the body and which affects lung and tissue perfusion. If the cardiac output is normal (5 L/min), the amount of oxygen delivered to the body per minute is normal. If cardiac output falls, the amount ofoxygen delivered to the tissues also falls. Under normal conditions, most of the oxygen delivered to the body is not used. In fact, only 250 mL of oxygen is used per minute. Under normal conditions, this is approximately 25% of available oxygen. The rest of the oxygen returns to the right side of the heart, and the PaO2 of venous blood drops from 80 to 100 mm Hg to about 40 mm Hg.

Carbon Dioxide Transport
At the same time that oxygen diffuses from the blood into the tissues, carbon dioxide diffuses from tissue cells to blood and is transported to the lungs for excretion. The amount of carbon dioxide in transit is one of the major determinants of the acid–base balance of the body. Normally, only 6% of the venous carbon dioxide is removed in the lungs, and  nough remains in the arterial blood to exert a pressure of 40 mm Hg. Most of the carbon dioxide (90%) is carried by red blood cells; the small portion (5%) that remains dissolved in the plasma (partial pressure of carbon dioxide [PCO2]) is the critical factor that determines carbon dioxide movement in or out of the blood. Although the many processes involved in respiratory gas transport seem to occur in intermittent stages, the changes are rapid, simultaneous, and continuous.

 Neurologic Control of Ventilation
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 centers in the medulla oblongata and pons control the rate and depth of ventilation to meet the body’s metabolic demands.

The apneustic center in the lower pons stimulates the inspiratory medullary center to promote deep, prolonged inspirations. The pneumotaxic center in the upper pons is thought to control the pattern of respirations.

Several groups of receptor sites assist in the brain’s control of respiratory function. The central chemoreceptors, located in the medulla, respond to chemical changes in the cerebrospinal fluid, which result from chemical changes in the blood. These receptors respond to an increase or decrease in the pH and convey a message to the lungs to change the depth and then the rate of ventilation to correct the imbalance. The peripheral chemoreceptors are located in the aortic arch and the carotid arteries and respond first to changes in PaO2, then to partial pressure of carbon dioxide (PaCO2) and pH. The Hering-Breuer reflex is activated by stretch receptors in the alveoli. When the lungs are distended, inspiration is inhibited; as a result, the lungs do not become over distended. In addition, proprioceptors in the muscles and joints respond to body movements, such as exercise, causing an increase in ventilation. Thus, range-of motion exercises in an immobile patient stimulate breathing. Baroreceptors, also located in the aortic and carotid bodies, respond to an increase or decrease in arterial blood pressure and cause reflex hypoventilation or hyperventilation.

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.