Effect on injury on cells (W10)

Question 1

causes of cell injury

Answer 1

lack of O2
physical agents (temp, psi, electricity, radiation)
chemicals and drugs
infectious agents
immune reactions
genetic defects
nutrition

Question 2

reversible cell injury features?

Answer 2

rapid changes
swelling due to loss of ion/fluid homeostasis
fat accumulation (steatosis)

Question 3

when does reversible cell injury become irreversable

Answer 3

if experiences persistent injury - no defined ‘point of no return’

Question 4

fatty change histology?

Answer 4

large pale spaces - fat globules

Question 5

2 types of cell death

Answer 5

apoptosis and necrosis

Question 6

apoptosis overview?

Answer 6

membrane stays in tact
energy spent from own cell
apoptotic bodies spread off from cell
phagocytosis of cell and fragments

Question 7

apoptosis 2 stages

Answer 7

intrinsic
extrinsic (signal from outside cell - YOU MUST KILL YOURSELF!!!)

Question 8

apoptosis - extrinsic regulation

Answer 8

receptor ligand interactions
leads to series of intracellular protein-protein interactions
activates initiator caspase 8

Question 9

apoptosis - intrinsic pathway?

Answer 9

less BCL2 (anti-apoptotic proteins), more BAX and BAK (pro-apoptotic proteins)
this allows leakage of cytochrome C and SMAC out mitochondria
these lead to activation of caspase 9

Question 10

initiator caspase for intrinsic apoptosis pathway

Answer 10

caspase 9

Question 11

normal intrinsic pathway before apoptosis

Answer 11

growth factors cause transcription of more anti-apoptotic (BCL-2) proteins, outnumbering pro-apoptotic proteins therefore keeping cell alive

Question 12

initiator caspase for extrinsic apoptosis pathway

Answer 12

activates initiator caspase 8

Question 13

what do active initiator caspases act on in apoptosis? what does this cause?

Answer 13

activate executioner caspases (‘cut’ off inhibitory part) which then disassemble the cell

Question 14

what is autophagy

Answer 14

recycling and turnover of cytoplasmic cell constituents

Question 15

what regulates autophagy

Answer 15

autophagy-related genes (ATGs)

Question 16

what is autophagy a response to

Answer 16

extra/intracellular stress

Question 17

autophagy summary?

Answer 17

intracellular constituents get packages into autophagosomes which fuse with lysosomes containing enzymes that degrade the components, then the original building blocks are released back into the cytoplasm and are reused

Question 18

necrosis summary?

Answer 18

cell loses membrane integrity falls apart, contents outside cell cause inflammation. neutrophils are attracted to the area and cause more damage to other cells

Question 19

what does necrosis look like in histology

Answer 19

pink blobs, nuclei not in cells, no properly defined cells

Question 20

types of necrosis

Answer 20

coagulative
liquefactive
caseous
gangrenous (dry)
fat

Question 21

coagulative necrosis? histology?

Answer 21

cell proteins denature (due to lack of blood supply?)
cells lose nuclei and stain more deeply. ghost outlines of cells.

Question 22

liquefactive necrosis?

Answer 22

histology - tissue dissolves into mush, different causes:

inflammation (neutrophils destroy tissue)
bacteria into area of coagulative necrosis (pus, melted mushy tissue, smelly)
lipid rich tissue (eg in brain - cells don’t leave outlines, also go mushy)

Question 23

caseous necrosis?

Answer 23

histology - ragged mess, ‘cottage cheese’. cell death you see in the middle of a TB caused granuloma

Question 24

what is a granuloma

Answer 24

formed when immune cells clump together and create tiny nodules at the site of infection. the body’s way of containing an area of infection to stop it spreading

Question 25

what is caseous necrosis caused by

Answer 25

TB
mycobacterial infection

Question 26

dry gangrene?

Answer 26

extreme coagulative necrosis due to slowly developing vascular occlusion

Question 27

fat necrosis?

Answer 27

degradation of fatty tissue by lipases, forming chalky deposits

Question 28

necroptosis?

Answer 28

virus stops apoptosis, organism can cause organised necrosis to destroy cell as apoptosis cannot occur.

Question 29

earliest changes apoptosis vs necrosis?

Answer 29

apoptosis - cell shrinking
necrosis - cell swelling

Question 30

vesicles differences apoptosis vs necrosis?

Answer 30

apoptosis - formation of membrane enclosed vesicles
necrosis - no vesicle formation, lysis

Question 31

termination apoptosis vs necrosis?

Answer 31

apoptosis - continued fragmentation into smaller bodies
necrosis - complete lysis

Question 32

apoptosis vs necrosis regulation

Answer 32

apoptosis - tightly controlled
necrosis - loss of homeostatic regulation

Question 33

energy requirement apoptosis vs necrosis?

Answer 33

apoptosis - energy dependant
necrosis - passive

Question 34

DNA differences apoptosis vs necrosis?

Answer 34

apoptosis - non-random fragmentation prior to apoptotic body formation
necrosis - random fragmentation after cell lysis