Cell turnover and tissue death

Question 1

Cell cycle phases

Answer 1

G phase, S phase and M phase.

Question 2

G1 phase

Answer 2

gap phase, preceding DNA synthesis, cell grows

Question 3

S phase

Answer 3

synthesis phase; DNA replication

Question 4

M phase

Answer 4

Mitosis phase: chromosomal replication, cell duplicates its own full DNA

Question 5

Interphase

Answer 5

G and S phases

Question 6

Mitosis stages

Answer 6

Prophase, Metaphase, Anaphase, Telophase

Question 7

Prophase

Answer 7

chromosomes condense and become visible. centrioles migrate to opposite poles.

Question 8

Metaphase

Answer 8

chromatids line up along cell equator

Question 9

Anaphase

Answer 9

daughter chromatids are pulled apart - cleavage lines formed

Question 10

Telophase

Answer 10

new membrane forms around daughter nuclei - chromosomes decondense

Question 11

cytokinesis

Answer 11

final division of cytoplasm

Question 12

labial cells

Answer 12

have got a high turnover and high cell division (stratified squamos)

Question 13

stable cells

Answer 13

– cells that have temporarily exited the cell cycle – G0. Example – hepatocytes in the liver

Question 14

Permanent cells

Answer 14

cells that have terminally differentiated, so when they die, they are not going to be replaced. E.g. Glial cells of the brain

Question 15

ischemia

Answer 15

restriction of blood supply to tissues - cells die off

Question 16

hyperplasia

Answer 16

an increase in the number of cells without the increase in the size of the cell. Eg pregnancy and increase in breast volume. Benign prostatic hyperplasia – in men.

Question 17

hypertrophy

Answer 17

increase in size but not number

Question 18

hyperplasia vs neoplasia

Answer 18

hyperplasia is controlled and reversible. neoplasia (cancer) is not.

Question 19

atrophy

Answer 19

decrease in cell size. e.g. - Thickening of epithelium – atrophic buccal mucosa

Question 20

metaplasia

Answer 20

change from one differentiated cell type to another differentiated cell type. As part of a change in function. Bronchial lining – epithelium in normal people is got ciliated pseudostratified columnar epithelium. Smokers have stratified epithelium as a protection. urinary - transitional to stratified squamous

Question 21

dysplasia

Answer 21

premalignant change

Question 22

autophagy

Answer 22

response to starvation and nutrient deprivation where the cell recycles its organelles. it forms an envelope around organelles that require recycling and it fuses with lysosomes

Question 23

necrosis

Answer 23

• Pathological response distinct from apoptosis, taking place in response to overwhelming tissue damage. Involves disruption of cell membranes and leakage of cell contents, causing an inflammatory response

Question 24

features of necrosis

Answer 24

as a general rule of thumb it goes about in an uncontrolled manner. Phenotypically recognised as cell swelling. How to recognise necrotic cell – in its later stages undergo swelling
Contents of cell leaches out due to loss on integrity of cell membrane – inflammation
Early stages include initial shrinkage which manifests for eosinophils
Nucleus condenses
Cytoplasm becomes more granular
And loss of nuclear definition

Question 25

stages of necrosis

Answer 25

- Pyknosis: initial shrinkage characterised by condensation of cytoplasm and nucleus - Karyorrhexis when nucleus stats to break down – nucleus fragments - Karyolysis – complete loss of the nucleus itself – nuclear lysis

Question 26

coagulative necrosis

Answer 26

most common. Result of ischaemia and loss of oxygen. Recognise it by seeing the outline of the normal cell structure. Protein coagulation occurs and faint cell outlines remain after cell death. Feature of hypoxic environments – e.g. seen in myocardial infarction

Question 27

liquefactive necrosis

Answer 27

less common, where u can’t really see the outline. More of a gross macroscopic appearance. Not microscopic. The brain undergoes this. – it is associated with cellular destruction and pus formation, like in pneumonia or when Undergone a stroke etc

Question 28

caseous necrosis

Answer 28

TB. mix of coagulative and liquefactive necrosis.

Question 29

fibrinoid necrosis

Answer 29

related to blood vessels

Question 30

fat necrosis

Answer 30

– trauma to adipocytes can lead to release of their lipid content, provoking an intense inflammatory reaction – acute pancreatitis.

Question 31

apoptosis

Answer 31

- Regulated and targeted programmed cell death. Highly regulated and controlled. - Can occur due to cytotoxic drugs, heat shock and ionising radiation

Question 32

features of apoptosis

Answer 32

- cell shrinkage - loss of surface contact, detachment from adjacent cells and tissues - organelles conserved - nucleus condenses and fragments - phagocytosis - without inflammation

Question 33

extrinsic pathway of apoptosis

Answer 33

death ligand binds to death receptor on surface of cell. caspase 8 activated which in turn activates caspase 3, causing cell destruction.

Question 34

intrinsic pathway of apoptosis

Answer 34

dan damage due to radiation. triggers sensing through mitochondria. cytochrome c. activated further apoptotic pathways. caspase 9 activation. leads to caspase 3 activation causing cell destruction.

Question 35

caspase 8

Answer 35

extrinsic

Question 36

caspase 9

Answer 36

intrinsic

Question 37

caspase 3

Answer 37

common in both