Causes of Cell injury

Question 1

Causes of cell injury

Answer 1

-hypoxia
-ischemia
-physical agents
-Infectious agents
-immunologic reactions
-genetic derangements
-nutritional imbalances
-chemical agents

Question 2

Hypoxia

Answer 2

-decrease below normal levels of oxygen in inspired gases, arterial blood, or tissue

Question 3

Ischemia

Answer 3

-local absence of blood due to obstruction of the blood supply or local stagnation/congestion of blood

Question 4

Why is ischemia worse for tissue than hypoxia?

Answer 4

-waste accumulates
-blood supplies nutrients/O2 (ischemia occurs, then so does hypoxia)

Question 5

Mechanisms of cell injury

Answer 5

-hypoxia/ischemia
>will result in an increase in mitochondrial work load
-ROS (anaerobic metabolism byproduct)
-Radiation mutations

Question 6

Ischemia affect on mitochondria

Answer 6

-decreases oxidative phosphorylation in the mitochondria, resulting in decrease in ATP (necrosis) and cytochrome c release (apoptosis)
>ATP needed for Na-K ATPase, affecting ion distribution in cells, resulting in cell swelling
-Also increases anaerobic glycolysis, which decreases pH and can result in further damage to cell

Question 7

Oxygen free radicals

Answer 7

-antioxidants are supposed to remove the ROS, but if they are not removed that cell will swell and die

Question 8

Defences against free radicals

Answer 8

-antioxidants (vitamin E, A, C)
-metal binding proteins (iron and copper binders)
-enzymatic free radical scavengers

Question 9

Reperfusion injury

Answer 9

-injury that occurs as a result of restoration of blood flow
>brings with it an increase in O2, resulting in increase in free radical production
**this sudden influx may not be able to be handled due to a decrease in the free radical scavengers
>influx of more calcium
>recruitment of neutrophils
>complement activation
>systemic effects- damage is localized but when blood flow restored, it takes the waste and flushes it through the body