B2.004 Acute MI Deep Dive

Question 1

What is the universal definition of MI?

Answer 1

evidence of myocardial necrosis in a clinical setting consistent with acute myocardial ischemia

Question 2

What is necrosis?

Answer 2

a type of cell death

Question 3

What is hypertrophy?

Answer 3

increase in size of cells resulting in increase in size of organ; due to synthesis of more cellular components and more structural/functional proteins

Question 4

What is hyperplasia?

Answer 4

increase in number of cells in response to stimulus

Question 5

Why can hyperplasia be dangerous?

Answer 5

more proliferation can lead to more chance of DNA mutations during mutations; this can potentially lead to cancer

Question 6

Is hyperplasia always pathologic?

Answer 6

NO, can be a part of a physiologic process

Question 7

What is atrophy?

Answer 7

decrease in size and number of cells resulting in a decrease in organ size

Question 8

Why does atrophy occur?

Answer 8

autophagocytosis causes cell to cannibalize its own internal proteins for fuel

Question 9

What is metaplasia?

Answer 9

replacement of one differentiated cell type by another differentiated cell time; usually accompanied by increased cell division

Question 10

What are the main features of necrosis?

Answer 10

accidental death due to ATP depletion, loss of membrane integrity and leakage of cytoplasmic contents, always pathogenic

Question 11

What are the main features of apoptosis?

Answer 11

programmed death that is energy dependent, membrane integrity preserved to avoid inflammation, can be physiologic or pathologic

Question 12

What are 5 causes for necrosis?

Answer 12

hypoxia, physical agents, chemical agents, infectious agents, immunologic reactions, genetic derangements, nutritional imbalances

Question 13

What are 5 causes of physiologic apoptosis?

Answer 13

embryogenesis, hormonal involution, cell loss in proliferating cell pops, elimination of potentially harmful self reactive lymphocytes, immunologically mediated cell death

Question 14

What are 4 causes of pathogenic apoptosis?

Answer 14

DNA damage, accumulation of misfolded proteins, infections/ immunologic reactions, cell loss in organs after duct obstruction

Question 15

What are some mechanisms that facilitate necrosis?

Answer 15

depletion of ATP, mitochondrial damage, loss of Ca homeostasis, accumulation of ROS, defects in membrane permeability, damage to DNA/proteins

Question 16

How does an influx of Ca damage a cell?

Answer 16

activates cellular enzymes that cause damage and increase mitochondrial permeability which decreases ATP production

Question 17

How do ROS’s damage a cell?

Answer 17

can damage DNA, modify proteins, or cause lipid peroxidation

Question 18

How are ROS’s typically removed in a healthy cell?

Answer 18

O2 radical converted to H2O2 which is decomposed along with OH radicals to H2O by enzymes

Question 19

What are the two pathways for apoptosis?

Answer 19

intrinsic (mitochondrial)

extrinsic (death receptor initiated)

Question 20

Which protein family mediates the intrinsic apoptosis pathway?

Answer 20

BCL2 sensors and effectors cause mitochondria to release cytochrome c

Question 21

Which receptors mediate the extrinsic apoptosis pathway?

Answer 21

Fas and TNF

Question 22

Which proteins initiate and execute final apoptosis pathways?

Answer 22

capases

Question 23

What are 3 types of necrosis and how do they differ?

Answer 23

coagulative: seen in MI, substructure still exists
liquefactive: underlying substructure collapses leaving a cavity of dead cells and neutrophils (pus)
caseous: due to infectious agents, long acting response which results in granulous (hard) imflammation

Question 24

What is the biochemical effect of hypoxia?

Answer 24

no aerobic metabolism

Question 25

What is the biochemical effect of ischemia?

Answer 25

no aerobic metabolism or anaerobic glycolysis once substrates are exhaused

Question 26

What are some causes of arterial compromise?

Answer 26

thrombosis, embolism, vasospasm, hemorrhange into plaque, extrinsic compression, torsion, rupture, entrapment

Question 27

What are some causes of venous compromise?

Answer 27

thrombosis, common in tissue/organs w single drainage

Question 28

Where does liquefactive necrosis mostly occur?

Answer 28

CNS due to lack of collagen based infrastructure

Question 29

What is the source of reperfusion injury?

Answer 29

oxidative stress after prolonged oxygen depletion, intracellular calcium overload, imflammation