Card Set Information
Mechanisms of cellular injury
A decrease or shrinkage in size
Can effect skeletal muschle, heart, secondary sex organs, and the brain
Causes - decreased workload, use, pressure, blood supply, nutrition, hormonal stimulation, or nervous stimulation
Increase in the size of cells
Can effect heart, kidneys
Caused by increased stimulation and demand
Abnormal changes in the size, shape, and organization of mature cells
Effect smooth muscle, frequently epithelial tissue of cervix and respiratory tract.
Reversible replacement of one mature cell by another, sometimes less differentiated cell type.
Can be caused by chronic injury or irritation
Example is cells of bronchial lining by stratisfied squamous epithelial cells. These cells do not secrete mucous or have cilia, causing loss of bital protective mechanism.
An increase in the number of cells resulting from an increased rate of celluar division.
Compensatory hyperplasia - allows organs to regenerate
Hormonal hyperplasia - allows endometrium of uterus to grow and thicken for reception of fertilized ovum. (pregnancy).
Review the steps of hypoxic injury to the myocardium
1) Within 1 minute, heart becomes pale and has difficulty contracting
2) 3-5 minutes, ceases to contract
3) Abrupt lack of contraction is cuased by a rapid decrease in mitochondrial phosphorylation
4) Insufficient ATP production
5) Lack of ATP leads to increase in anearobic metabolism
6) ATP then generated from glycogen (stored energy)
7) When glycogen depleted, even anaerobic metabolsim stops.
Explain the NA-K+ action with hypoxia
See. page 53.
Reduction of ATP levels causes plasma membrane's NA+-K+ pump and Na+-Ca++ exchange to fail
Intracellular accumuilation of Na+ and Ca++ and diffusion K+ out of the cell.
Na+ and H20 then can enter the cell freely
Cellular swelling results.
An electrically uncharged atom or group of atoms having an unpaired electron is what?
What is the concern with free radicals?
Having one unpaired electron makes the molecule unstable
To stabilize, it gives up an electron to another molecule, or steals one
Therefore it is capable of injurious chemical bond formation with protiens, lipids, carbohydrates - keey molecules in membranes and nucleic acids.
What is the primary site of damage from a free radical in a cell
How can free radicals be reduced with antioxidants?
1) Spontaneous decay of superoxide to H20 and H202 (hydrogen peroxide)
2) Antioxidants - vitamins A, C, E Sellenium
Describe the cellular response to injury
1) Loss of ATP retards sodium-potassium pump
2) Disruption of transport mechanisms across cell memberane
3) Reduction or cessation of cellular metabolism
4) Water collects in vacoules of the ER
5) Damage to lysosomal membrane
6) Cellular death
7) Phagocytosis of WBC
Describe injury by carbon monoxide
Carbon has 300 times binding capactiy to hemoglobin which prevents oxygen binding to hgb