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PATHOPHYSIOLOGY
CHAPTER 1
CELLULAR DYNAMICS CELLS: STRUCTURE, FUNCTIONS AND ORGANIZATION
Key Concepts
1. Cellular organdies - inner organs of the cell. Highly organized physical structures suspended in
protoplasm.
a) Plasma membrane. Semi-permeable barrier that separates intracellular from extra cellular
fluids.

Composed of lipid bilayer embedded with protein.

Small pres permit passage. Proteins function as channels and carriers across the membrane.

Also act as receptors and enzymes. Individual organelles are bounded by membrane.
b) Mitochondria. Cigar shaped organelles that synthesize ATP is produced.

Oxidative phosophorylation. Glucose is transformed to ATP. Power plant.

Christae. Folded inner membrane where ATP is produced.
Oxidative phosphorylation. Glucose is transformed to ATP and water by way of the Krebs' cycle
in the presence of oxygen.Glycolysis. Anaerobic reduction of glucose to ATP and lactic acid.
c) Endoplasmic reticulum (ER). Netlike system of membranes.

Granular (rough ER). Covered with RNA particles called ribosomes. Produces proteins
for extracellular transport.

Agranular (smooth ER). Produces triglycerides, fatty acids, steroids, and phospholipids.
May store calcium.

Cisternae - fluid-filled spaces between folded membranes of ER.
d) Polyribosomes - free in cytoplasm. Produce proteins for intracellular use.
e) Golgi complex - receives proteins from rough ER and processed them for extracellular secretion.
f) Lysosomes. Contain hydrolytic enzymes that digest foreign proteins and cellular debris.
g)
Microtubules. Non membranous hollow filaments.

Maintain shape of cell.

Act as internal conduit within cell.

Provide cellular movement by way of cilia and flagella.
h)
Cilia and flagella.

Cilia. Hair like extensions that line upper respiratory tree and uterine tubes. Achieve coordinate movement utilizing ATP.

Flagellum. .Extension of sperm cell enabling it to move.
j)
Centrioles - direct formation chromosomes into the spindle apparatus during mitosis.j
k)
Nucleus - central organelle surrounded by the nuclear envelope.

Responsible for transmission of genetic information.

Nucleolus. Granular mass of RNA and protein that produces ribosome's.

Chromatin. Fibres of DNA and protein that condense to from 46 chromosomes in the
human cell.

Gene. Linear sequence of nucleotides that codes an amino acid. Located on DNA
master strand.

Protein synthesis * Transcription. DNA unwinds and genetic message is transcribed onto messenger RNA unwinds
and genetic message is transcribed onto messenger RNA (mRNA), which leaves nucleus through
pores and joins ribosome's. 4 Translation. Genetic message is deciphered within ribosomes.
Transfer RNA (RNA) carries amino acid to ribosomes for binding with mRNA into peptide chains.
A. Regeneration II. REPRODUCTIVE ABILITY OF CELLS

Labile cells have life span of hours or days (e.g.., white blood cells and epithelial
cells).

Stable cells span several years (e.g. osteocytes, parenchyma cells of liver and glandular
cells).

Permanent cells last the life of the organism (e.g. nerve cells and muscle cells).
B.Reproduction
1. Stages of the cell cycle

Gl - time from formation to prereplication.

S - NA replication occurs

G2 - time interval posteplication topremitosis.

M - Cell division occurs
2. Replication. DNA strands separate and chromosomes duplicate themselves.
3. Mitosis. Cell divides into two identical daughter cells by four ordered phases.

Prophase chromosomes that doubled during the s. phase become distinct. Centrioles
duplicate and migrate to opposite poles of the nucleus. The nuclear membrane disappears.

Metaphase. The mitotic spindle is formed and chromosomes line up in preparation for
migration to opposite poles of the dividing cell.

Anaphase. the chromosomes split with movement to opposite poles of the spindle.
The spindle elongates.

Telophase. The separated daughter chromosomes uncoil. Segments of the nuclear envelope
reform. Constriction of the cytoplasm occurs, which gives way to pull the daughter cells apart.
III. Cellular exchange. Passage of substances through the plasma membrane.
A. Passive movement - no expenditures of cellular energy.
> Diffusion. Net movement of a substance down a concentration gradient to equilibrium. Either
dissolves in membrane or passes gradient to equilibrium. Either dissolves in membrane or passes
though protein channels. Lipid soluble and uncharged particles diffuse readily.
Temperature and surface area also affect diffusion rate.
Osmosis. Net diffusion of water through as electively permeable membrane from an area of low
solute concentration (highosmotic pressure) to an area of greater solute concentration. (Low
osmotic
> pressure).
> Facilitated diffusion. Movement of a substance down a concentration gradient utilizing a
carrier molecule to facilitate passage through the cell membrane. Glucose, for example, is transport
edbyinsulin.
B. Active movement. Requires expenditure of ATP.
1. Active transport. Carrier-mediated transport against a gradient utilizing energy. 'Pump/'
> Sodium-potassium pump. Transports sodium out of the cell and potassium into the cell.
Prevents cellular swelling with water.
> Characteristics.
* Specificity. Transport a particular solute.
* Saturation. Have a maximum rte for transport, that is, transport maximum TM&
Competition. Two solutes will compete for transport. <5* Energy dependent.
Requires ATP.
2. Endocystosis. Bringing a substance into the cell through ji imagination of cell membrane.
> Pinocytosis. Protein and electrolyte solutions enter cytoplasm encased in vesicle. Lysosomes
release material for intracellular use.
> Phagocytosis. Microorganisms are brought into cell enclosed in vesicle for lysosomes to digest.
3. Exocytosis. Out pouching of membrane for release of secretary products into the ECF.
IV. CELL MOVEMENT
A. Amoeboid locomotion. Forward projection of the pseudopodium utilizing ATP and calcium
ions.
Leukocytes, for example, move from the blood into tissues to destroy foreign proteins.
B. Muscular contraction (see fig. 1-1 below. See also text fig. 1-24 on p.25 for more detail)
1.
Skeletal (multinucleated, striated). The nerve terminal responds to stimulation and releases
ACH, which changes ion permeability of muscle.
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