Cell Injury

Question 1

what is pathophysiology

Answer 1

how physiology is affected by disease

Question 2

what is pathogenesis

Answer 2

the sequence of events at the organ, cellular, ultra structual, and molecular levels, by which the disease develops

Question 3

how long can the following survive without oxygen:
* neurons
* heart cells
* liver cells
* a leg

Answer 3

• neurons: 3-5 mins
• heart cells: 30-60 mins
• liver cells: 102 hours
• a leg: many hours

Question 4

lack of ATP due to hypoxia causes 4 things to happen

Answer 4

1. cannot power the NaK+ pump
2. compensation with lactic fermentation
3. calcium pump stops functioning
4. leads to a build up of adenosine monophosphate AMP

Question 5

accumulation of intra-cellular sodium causes (3):

Answer 5

1. causes the cell to swell
2. decreased ATP increase AMP (adenosine monophosphate)
3. AMP stimulate the enzyme phosphofructokinase, causing an increased rate of anaerobic respiration

Question 6

what are the consequences of anaerobic respiration (6)

Answer 6

1. glycogen is used to generate energy
2. lactic acid and inorganic phosphates accumulate
3. this lowers cell pH
4. ribosomes detatch from RER = reduced protein synthesis
5. membrane becomes more permeable
6. formation of surface blebbs

Question 7

what happens to cause irreversible cell injury

Answer 7

1. mitochondria develop amorphous densities from severe vacuolization
2. Ca++ rapidly accumulates in the cell (NaK+ pump not removing it)

Question 8

what happens when mitochondria absorb large amounts of calcium

Answer 8

1. it combines with inorganic phosphate to form hydroxyapatite granules
2. it activate phopholipase, which hydrolizes membranes - leading to destruction
3. uncontrolled calcium influx causes lysosomal membrane leakage, releasing their components which degrade the cell

Question 9

what is a free radical

Answer 9

a type of ion, that is highly reactive, with low chemical specificity - i.e., they can react with most molecules

Question 10

what is a free radical

Answer 10

a type of ion, that is highly reactive, with low chemical specificity - i.e., they can react with most molecules

Question 11

what are the 5 types of damage caused by free radicals

Answer 11

1. lipid peroxidation
2. membrane damage
3. cross-linking
4. lysosome damage
5. accumulation of the age pigment

Question 12

what are the 2 principle pathways for cell death

Answer 12

1. necrosis
2. apoptosis

Question 13

what is the most common form of necrosis

Answer 13

coagulation necrosis

Question 14

what is liquifactive necrosis

Answer 14

is usual following total loss of blood to the brain eg stroke
or when neutrophils digest tissue via hydrolytic enzymes as in most bacterial infections

Question 15

what is caseous necrosis

Answer 15

crumbling of tissue, common in tuberculosis

Question 16

where is fat necrosis seen

Answer 16

mainly affect breast tissue, where adipocytes rupture and release their contents, which is broken fown into fatty acids and glycerol (soap)

Question 17

where does fibrin necrosis ocurr

Answer 17

affects small arteries and arterioles

Question 18

what are the stages of apoptosis (9)

Answer 18

1. separate from adjacent cells
2. shrink
3. mitochondra breakdown and release cytochrome c
4. blebbing
5. chromatin degrades
6. break into small fragments
7. phospholipid exposed on surface
8. signals to phagocytic cells
9. phagocytic cells secrete cytokines that inhibit inflammation

Question 19

what are the pathological reasons for apoptosis

Answer 19

1. infected with virus
2. CTL’s induce apoptosis in each other
3. damage to DNA
4. cancerous
5. mutations in p53 gene (tumour suppressor cell)

Question 20

how does radiation and chemicals affect cancerous cells

Answer 20

can induce apoptosis in some types of cancer cells

Question 21

mechanisms for cell suicide

Answer 21

1. signals within the cell
2. death activator
   TNF-alpha
   lymphotoxin (TNF-beta)
   fas ligand
3. triggered by UV light, x-rays