MoD Session 1- Cell Injury Flashcards Preview

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Flashcards in MoD Session 1- Cell Injury Deck (56)
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What is disease a failure of?

Homeostasis

1

What 4 factors does the degree of cell injury depend on?

-type of tissue
-type of injury
-duration of injury
-severity of injury

2

What is hypoxia and how does it cause cell injury?

It is oxygen deprivation.
It can cause decreased aerobic respiration and therefore cell injury.

3

What is Ischaemia and why is it more dangerous than hypoxia?

It is a reduction blood supply, therefore causing a reduced supply of oxygen and metabolic substrates.

4

What are the four causes of hypoxia?

-hypoxaemic hypoxia- less arterial oxygen
-histiocytic hypoxia- disabled oxidative phosphorylation enzymes
-anaemia hypoxia- inability of haemoglobin to carry oxygen
-ischaemic hypoxia- reduced blood supply.

5

What are some of the physical agents that cause cell injury? (5 max)

Temperature extremes
Radiation
Direct trauma
Electric currents
Atmospheric pressure changes

6

What are toxins that cause cell injury? (4 max)

-insecticides, herbicides
-pollutants, poisons, asbestos
-alcohol and drugs
-high oxygen conc.

7

What are micro-organisms that cause cell injury? (3)

-fungi
-bacteria
-viruses

8

What two immune mechanisms can cause cell injury?

-hypersensitivity reactions
-autoimmune reactions

9

What are the 7 causes of cell injury?

-hypoxia
-immune mechanisms
-dietary imbalance
-genetic abnormalities
-toxins
-micro-organisms
-physical agents

10

What are 4 target sites for cell injury?

-nucleus
-mitochondria
-cell membranes
-proteins

11

What are the three main consequences of reversible hypoxia injury?

-ribosomes detach from the ER as there is less ATP therefore less protein synthesis and increased lipid deposition.
-NA+/K+ pump activity is reduced therefore high intracellular sodium and water follows= swelling.
-more glycolysis- more lactic acid production. Low pH affects enzyme activity.

12

Why does irreversible injury eventually occur as a result of hypoxia?

Membrane integrity is disturbed and it becomes increasingly permeable.
Entry of calcium activates enzymes which destroy the cell.

13

What is ischaemic reperfusion injury?

When a tissue injury is worsened by the return of blood flow to a damaged, but not yet necrotic tissue.

14

What are free radicals and give the three most important examples.

They are reactive oxygen species with a single unpaired electron in their outer orbit that can react with other molecules to produce more free radicals.
H2O2, OH. , O2-

15

What are the body's defence against free radicals? (2)

-heat shock proteins - increased production when the body is in oxidative stress. They repair misfolded proteins to maintain cellular viability.
-anti-oxidants- SOD, catalase and peroxidases remove free radicals, scavengers such as Vit A,C and E, and glutathione neutralise them.

16

What are the reversible and irreversible cytoplasmic changes under the L microscope?

-reversible- reduced pink staining due to increased water accumulation
-irreversible- dark oink staining due to detached ribosomes and protein denaturation.

17

What acre the reversible and irreversible nuclear changes seem under the L microscope?

-reversible- chromatin clumping
-irreversible- pyknosis, karryolysis, karryohexis

18

What are some of the reversible features seen under the electron microscope?

-blebbing
-swelling- sodium potassium pump failure
-chromatin clumping
-ribosome separation

19

What are some of the irreversible features seen under the electron microscope?

-myelin figures
-membrane defects
-ER lysis
-cell swelling
-pyknosis, karryohexis, karryolysis

20

Define oncosis

Cell death with swelling.
It is a change that occurs in cells prior to death.

21

Define apoptosis

Cell death with shrinkage.
Cell suicide

22

Define necrosis

It is not a process, but an appearance of cell death. Morphological changes that occur 4-24 hours after cell death.
Also sees swelling.

23

Which the of necrosis appears white, is denatured proteins and therefore is firm and has a ghost outline?

Coagulative

24

Which type of necrosis occurs due to neutrophil death and is digestion of tissues?

Liquefactive

25

Where is Liquefactive necrosis typically found?

The brain

26

What type of necrosis has amorphous debris and a cottage cheese like appearance?

Caseous

27

What is caseous necrosis associated with?

Infection. E.g TB

28

When does fat necrosis occur? (2)

-as a result of direct trauma to adipose
-following acute pancreatitis as lipases are released which act on adipose.

29

What is a characteristic feature of fat necrosis?

Chalky deposits due to the release of fatty acids reacting with calcium.

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