A&P Lecture 1: The Cell

"You need to know the normal before you can determine the abnormal." 

Knowledge in Anatomy and Physiology is paramount before tackling advance Nursing Courses. It is the reason why Anatomy and Physiology class is taken first before professional courses like Pathophysiology, Medical Surgical Nursing, Maternal and Child Nursing and Psychiatric Nursing.Anatomy and Physiology is a good foundation when you already try to study illnesses. This A&P Lecture Series is designed to help students develop a solid understanding of the concepts of anatomy and physiology and to use this knowledge to solve problems.

ANATOMY AND PHYSIOLOGY LECTURE 1

THE CELL

The Cell is the basic unit of life. Cells are the smallest parts of an organism, such as a human, that have the characteristics of life. Although cells may have quite different structures and functions, they share several characteristics which includes:

• Cell metabolism and energy use
• Synthesis of molecules
• Communication
• Reproduction and inheritance

Plasma Membrane

Structure: Lipid bilayer composed of phospholipids and cholesterol with proteins that extend across or are embedded in either surface of the lipid bilayer

Function: Outer boundary of cells that controls entry and exit of substances; receptor molecules function in intercellular communication; marker molecules enable cells to recognize one another.

***Read more about the Plasma Membrane here

Cytoplasm

Fluid Part

Structure: Water with dissolved ions and molecules; colloid with suspended proteins

Function:Contains enzymes that catalyze decomposition and synthesis reactions; ATP is produced in glycolysis reactions

Cytoskeleton/ Microtubules

Structure: Hollow cylinders composed of the protein tubulin; 25 nm in diameter

Function: Support the cytoplasm and form centrioles, spindle fibers, cilia, and flagella; responsible for movement of structures in the cell

Actin Filaments

Structure: Small fibrils of the protein actin; 8 nm in diameter

Function: Provide structural support to cells, support microvilli, responsible for cell movements

Intermediate Filaments

Structure:Protein fibers; 10 nm in diameter

Function: Provide structural support to cells

Cytoplasmic Inclusions

Structure:Aggregates of molecules manufactured or ingested by the cell; may be membrane-bound

Function: Function depends on the molecules: energy storage (lipids, glycogen), oxygen transport (hemoglobin), skin color (melanin), and others

*** Read More about the Cytosol and its components here

Organelles, Nucleus

Nuclear envelope

Structure:Double membrane enclosing the nucleus; the outer membrane is continuous with the endoplasmic reticulum; nuclear pores extend through the nuclear envelope

Function: Separates nucleus from cytoplasm and regulates movement

of materials into and out of the nucleus

Chromatin

Structure:Dispersed, thin strands of DNA, histones, and other proteins; condenses to form chromosomes during cell division

Function: DNA regulates protein (e.g., enzyme) synthesis and therefore the chemical reactions of the cell; DNA is the genetic, or hereditary, material

Nucleolus

Structure: One or more dense bodies consisting of ribosomal RNA and proteins

Function: Assembly site of large and small ribosomal subunits

***Read more about the Nucleus and it's components here

Cytoplasmic Organelles

Ribosome

Structure:Ribosomal RNA and proteins form large and small subunits; attached to endoplasmic reticulum or free ribosomes are distributed throughout the cytoplasm

Function: Site of protein synthesis
 ***Read more about Ribosome here

Rough endoplasmic reticulum

Structure: Membranous tubules and flattened sacs with attached ribosomes

Function: Protein synthesis and transport to Golgi apparatus

*** Read more about the Endoplasmic Reticulum here

Smooth endoplasmic reticulum

Structure: Membranous tubules and flattened sacs with no attached ribosomes

Function: Manufactures lipids and carbohydrates; detoxifies harmful chemicals; stores calcium
*** Read more about the Endoplasmic Reticulum here

Golgi apparatus

Structure: Flattened membrane sacs stacked on each other

Function: Modifies, packages, and distributes proteins and lipids for secretion or internal use

***Read more about the Golgi apparatus here

Secretory vesicle

Structure: Membrane-bound sac pinched off Golgi apparatus

Function: Carries proteins and lipids to cell surface for secretion

***Read more about the Secretory vesicle here

Lysosome

Structure: Membrane-bound vesicle pinched off Golgi apparatus

Function: Contains digestive enzymes
***Read more about the Lysosomes  here

Peroxisome

Structure: Membrane-bound vesicle

Function: One site of lipid and amino acid degradation; breaks down hydrogen peroxide

***Read more about Peroxisome here

Proteasomes

Structure: Tubelike protein complexes in the cytoplasm

Function: Break down proteins in the cytoplasm
***Read more about Proteasomes here

Mitochondria

Structure: Spherical, rod-shaped, or threadlike structures; enclosed by double membrane; inner membrane forms projections called cristae

Function: Major site of ATP synthesis when oxygen is available
***Read more about the Mitochondria here

Centrioles

Structure: Pair of cylindrical organelles in the centrosome, consisting of triplets of parallel microtubules 

Function: Centers for microtubule formation; determine cell polarity during cell division; form the basal bodies of cilia and flagella

***Read more about the Centriole here

Spindle fibers

Structure:Microtubules extending from the centrosome to chromosomes and other parts of the cell (i.e., aster fibers)

Function: Assist in the separation of chromosomes during cell division

***Read more about the Spindle fiber here

Cilia

Structure: Extensions of the plasma membrane containing doublets of parallel microtubules; 10 μm in length

Function: Move materials over the surface of cells
***Read more about the Cilia here

Flagellum

Structure: Extension of the plasma membrane containing doublets of parallel microtubules; 55 μm in length

Function: In humans, responsible for movement of spermatozoa

***Read more about the Flagellum here

Microvilli

Structure: Extension of the plasma membrane containing microfilaments

Function: Increase surface area of the plasma membrane for absorption and secretion; modified to form sensory receptors

***Read more about the Microvillli here