apoptosis v necrosis

Question 1

describe apoptosis

Answer 1

programmed cell death
takes place in SINGLE cells
an important process in normal cell turnover in the body
prevents accumulated genetic damage from dividing and producing cells- that might develop into cancer cells

Question 2

what are the two processes that result in death of cells?

Answer 2

Apoptosis
Necrosis

Question 3

how does a cell decide to apoptose?

Answer 3

One of the mechanisms is detecting the amount of DNA damage within the cell.
p53 is a protein in cells which can detect DNA damage and can then trigger apoptosis

Question 4

how des a cell apoptose?

Answer 4

The cell triggers a series of proteins which lead to the release of enzymes ( caspases) within the cell which eventually auto digest the cell

Question 5

what is apoptosis important for in the healthy functioning of the body?

Answer 5

-Development
- Cell turnover

Question 6

describe apoptosis in development

Answer 6

removal of cells during development e.g. interdigital webs

Question 7

describe apoptosis in cell turnover

Answer 7

removal of cells during normal turnover e.g. cells in the intestinal villi at the tips, to be replaced by cells from below

Question 8

describe apoptosis in cancer

Answer 8

• cells in tumours often don’t apoptose when they would have been expected to which results in increase in the tumour size and accumulation of genetic mutations.
• Often this is due to mutations in the P53 gene so the p53 protein can no longer detect DNA damage and instigate apoptosis.

Question 9

describe apoptosis in HIV

Answer 9

-the HIV virus can induce apoptosis.
- It can induce apoptosis in CD4 helper cells which reduces their numbers enormously to produce an immunodeficient state.

Question 10

Describe Necrosis

Answer 10

It is the wholesale destruction of large numbers of cells by some external factor.

Question 11

Give four clinical examples of necrosis

Answer 11

• Infarction due to loss of blood supply e.g. myocardial infarction, cerebral infarction
• Frostbite
• Toxic venom from reptiles and insects
• Pancreatitis

Question 12

What does the body do after necrosis

Answer 12

Tries to clean the mess by- macrophages phagocytosing dead cells and usually by replacing the necrotic tissue by fibrous scar tissue.

Question 13

caseous necrosis

Answer 13

can be due to tuberculosis so a pathologist would always order stains for mycobacteria