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Immunology > Necrosis & apoptosis > Flashcards

Necrosis & apoptosis Flashcards

1
Q

What is apoptosis?

A

Programmed cell death

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2
Q

Describe the process of apoptosis (when the actual cell dies).

A

Nucleus condenses
Cell shrinks
Blebs form
Phagocyte digests

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3
Q

What are blebs?!

A

When the cell’s cytoskeleton breaks up it causes the membrane to bulge outwards.

These bulges are called blebs

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4
Q

What are apoptotic bodies?

A

When blebs detach from the cell taking some cytoplasm with them

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5
Q

Why does apoptosis occur?

A

If cell is too old

If cell has DNA damage

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6
Q

What regulates apoptosis? How does it do it?

A

p53 protein

It senses DNA damage in cells and triggers apoptosis

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7
Q

In what instances can apoptosis be good?

A

In development: apoptosis is needed for healthy development, for example it separates the fingers

In parts of the body with high cell turnover: gut epithelia

Prevents many cancers + viral infections

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8
Q

What happens when you have a lack of apoptosis?

A

Cancer

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9
Q

In terms of apoptosis what is cancer?

A

A lack of apoptosis

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10
Q

In terms of apoptosis what is HIV?

A

Too much apoptosis

HIV induces apoptosis of T helper cells, causing a weakened immune system

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11
Q

What is necrosis?

A

Traumatic cell death. The cells are not expecting to die

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12
Q

Causes of necrosis?

A

Infarction
Frostbite
Avascular necrosis of bone
Pancreatitis

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13
Q

List the types of necrosis!

A

L G F F C C

Leadmill
Go + see
Fickle
Friends
Clean
Cut (kid)
Liquefactive
Gangrenous
Fat necrosis
Fibrinoid
Coagulative
Caseous
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14
Q

What causes coagulative necrosis?

A

Blood loss

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15
Q

Where can coagulative necrosis occur?

A

Any tissue except brain

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16
Q

Macroscopic appearance of coagulative necrosis?

A

Tissue is firm

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17
Q

Microscopic appearance of coagulative necrosis?

A

Cell outlines are preserved

Everything looks red

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18
Q

What causes liquefactive necrosis?

A

Neutrophils releasing their toxic contents, liquefying the tissue

Also blood loss in the brain

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19
Q

When is liquefactive necrosis seen?

A

In brain infarcts

In infections

20
Q

Macroscopic appearance of liquefactive necrosis?

A

Tissue is liquidy, creamy yellow (pus)

21
Q

Microscopic appearance of liquefactive necrosis?

A

Lots of neutrophils & cell debris

22
Q

When is caseous necrosis seen?

Why?

A

In tuberculosis

Occurs because the body is trying to fight off and kill the infection with macrophages.

The lung itself gets damaged

23
Q

Macroscopic appearance of caseous necrosis?

A

White, soft, cheesy looking

24
Q

Microscopic appearance of caseous necrosis?

A

Fragmented cells and debris, surrounded by a collar of lymphocytes and macrophages
(a granuloma!)

25
Q

What causes fat necrosis?

A

Damaged cells release lipases, which split triglyceride esters within fat cells

26
Q

When is fat necrosis seen?

A

In acute pancreatitis

27
Q

Macroscopic appearance of fat necrosis?

A

Chalky, white areas

Caused by the combination of newly formed free fatty acids and calcium (saponification)

28
Q

What is saponification? What does it look like?

A

When free fatty acids mix with calcium

Looks chalky white

29
Q

Microscopic appearance of fat necrosis?

A

Shadowy outlines of dead fat cells

Bluish cast from the calcium deposits, because they are basophilic

30
Q

When is fibrinoid necrosis seen?

A

In immune reactions in vessels

31
Q

What causes fibrinoid necrosis?

A

When antigen-antibody complexes combine with fibrin

32
Q

Macroscopic appearance of fibrinoid necrosis?

A

None, the changes are too small

33
Q

Microscopic appearance of fibrinoid necrosis?

A

Vessel walls are thickened and look pink-ish red

34
Q

When is gangrenous necrosis seen?

A

When an entire limb loses blood supply and dies

35
Q

Macroscopic appearance of gangrenous necrosis?

A

Skin looks black and dead

Underlying tissues are in varying stages of decomposition

36
Q

Microscopic appearance of gangrenous necrosis?

A

Initially there is coagulative necrosis from the loss of blood supply - dry gangrene

If bacterial infection is present you’ll see liquefactive necrosis - wet gangrene

37
Q

What is the difference between wet and dry gangrene?

A

Dry: coagulative necrosis due to loss of blood supply

Wet: Liquefactive necrosis due to bacterial infection

38
Q

What type of necrosis is this?

A patient’s finger feels firm to touch

A sample is taken and when viewed under a microscope you see everything looks red with ghostly outlines of dead cells

A

Coagulative necrosis

Caused by loss of blood supply

39
Q

What type of necrosis is this?

A patient has had a fatal stroke.

In the autopsy you see the brain tissue looks liquidy and yellow.

A

Liquefactive necrosis

40
Q

What type of necrosis is this?

A patient’s leg ulcer is seeping white/yellow fluid.

A sample of skin viewed under a microscope shows many neutrophils and debris of dead cells.

A

Liquefactive necrosis

Caused by infection

41
Q

What type of necrosis is this?

A patient presents with breathlessness and is coughing up blood.

A lung biopsy shows the tissue is white and soft.

When viewed under a microscope you see circular structures; surrounded by lymphocytes & macrophages, with fragmented dead cells in the centres.

A

Caseous necrosis

Caused by TB

The circular structures are granulomas

42
Q

What type of necrosis is this?

A patient dies of acute pancreatitis.

The autopsy shows the tissue around the pancreas is chalky .

Under the microscope you see a bluish tinge and outlines of dead cells.

A

Fat necrosis

Chalky because of saponification

Bluish because the calcium deposits are basophilic

43
Q

What type of necrosis is this?

A sample of tissue is viewed under the microscope looks pink-ish red and you can see that the vessel walls are thickened.

The sample looks healthy to the naked eye

A

Fibrinoid necrosis

Caused by immune reactions in vessels

44
Q

What type of necrosis is this?

A patient presents because their left leg has turned black with green tinges and they no longer have the use of it.

Under the microscope you see everywhere looks red with outlines of dead cells

A

Gangrenous necrosis

Dry gangrene: signs of coagulative necrosis

This will have been caused by a lack of blood supply

45
Q

What type of necrosis is this?

A patient is in ITU with sepsis. You notice their fingers and toes begin looking black.

A sample under a microscope shows many neutrophils mixed with cell debris

A

Gangrenous necrosis

Wet gangrene: signs of liquefactive necrosis

This will have been caused by infection

Immunology (16 decks)

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