Causes of cell injury

Question 1

Compare hypoxia and schema and give examples

Answer 1

-hypoxia is when there is a lack of O2 concentration supplied to the cells. There is a lack of oxidative respiration but glycolotic respiration can continue to make ATP
ex/ cardiovascular failure or anemia
-ischemia is a complete lack of blood flow to an area so there is a lack of O2 and nutrients. This tissue is unable to undergo oxidative or glycolotic respiration. Tissues are damaged faster and more severe.
ex/ infarction, heart failure, shock

Question 2

List some other reasons for cell injury

Answer 2

• physical agents - mechanical trauma, extreme temps
• infective agents - fungi, bacteria, viruses
• immunological reactions - congenital or acquired defects or diseases
• genetic derangements - clotting factors
• nutritional imbalance - vitamin and mineral imbalance
• workload imbalance - overworked or underworked cells

Question 3

How does the depletion of ATP cause cell injury?

Answer 3

-ATP is important to keep Na/K and Ca pumps working properly and it can be made through the oxidative phosphorylation pathway or through glycolytic pathway.
-if there is a lack of ATP the Na/K pump won’t work properly so there will be excess Na inside the cell compared to K so water will try and balance this out, causing the cell to swell.
Also, the Ca pump will not work properly so there will be an influx of Ca into the cell, which activated enzymes that destroy cell structures, including the mitochondria
When the mitochondria is damaged, then cytochrome C is released and it activates apoptosis
-the increased amount of Ca also activates phospholipase A which degrades phospholipids in mitochondrial membrane. Also Ca activates proteases which degrades cell membranes

Question 4

describe the challenge with repercussion injury

Answer 4

reperfusion injury is when the blood source is returned to the tissue. If there is reversible damage to the tissue this can be a good thing but if the tissue has irreversible damage then returning blood supply make cause more damage then good.
-this is because the blood flow will mobilize free radicals that have been accumulating, it will mobilize the WBC which will enhance the inflammatory reaction, it will mobilize a build up of Ca that is in the blood causing more damage to cells

Question 5

What is pathological calcification and what are the two types?

Answer 5

• when there is an abnormal amount of Ca, Mg and other minerals in the tissue
  1. dystrophic calcification - local calcification in necrotic or damaged tissue without high serum levels of Ca (ex/ white muscle disease)
  2. Metastatic calcification - hypercalemia in normal tissues

Question 6

What are some reasons for hypercalemia in tissues?

Answer 6

1. Vit D toxicity so there is an increased amount of Ca resorption from the gut
2. increased secretion of parathyroid hormone causing more Ca in blood
3. destruction of bone tissue from bone tumor, which mobilizes Ca that was previously in bone
4. renal failure causing retention of phosphate which further causes increased amount of PTH secretion and bone resorption

Question 7

How will hypercalcemia appear?

Answer 7

grossly: salt deposits, white granules or clumps with a gritty appearance
micro: Ca is basophilic and will appear clumpy

Question 8

Name and describe intracellular occlusions

Answer 8

• anything that can be seen within the cell that is abnormal
  1. storage disease: defect in lysosomal enzymes that causes the accumulation of lysosomes
  2. viral inclusions: viruses that are within the cytoplasm or in the nucleus
  3. prion disease: has intraneuronal vacuoles