L13 - cellular adaptations

Question 1

The cell enters the cell cycle which goes __ -> ___ -> ___ -> ___. After cell cycle competion the cell either restarts or exits via G0 until further growth signals occur.

Answer 1

G1/S/G2/M

Question 2

Which is the only phase visibe under the conventional microscope. What does this consist of?

Answer 2

M phase - Mitosis (nuclear division) and cytokinesis.

Question 3

Briefly explain what happens in G1, S and G2

Answer 3

G1 - cell and organelle growth
S - DNA synthesis
G2 - cell prepares to divide.

Question 4

What is the restriction point? What phase is this in?

Answer 4

Towards the end of G1, it is the most important cell checkpoint. The majority of cells that pass this point will go on to divide

NOTE - this is the most commonly altered checkpoint in cancers

Question 5

What are the other two checkpoints?

Answer 5

G1/S - checks for DNA damage before DNA replication

G2/M - checks for DNA damage after DNA replication

Question 6

If any of the cell checkpoints are activated, the tumour suppressor gene protein ___ comes into action.

Answer 6

P53

Question 7

P53 has many effecs including inhibition of angiogenesis/stimulation of DNA repair etc. but mainly ___ ___ ___. If the promblems aren’t fixed it will trigger apoptosis

Answer 7

cell cycle arrest

Question 8

Progression through the cell cycle and particularly the G1/S transition is regulated by proteins called ___ and their associated enzymes ___ ____ ____.

Answer 8

Cyclins

Cyclin-dependent kinases (Cdk’s)

Question 9

Activated Cdk’s drive the cell cycle by phosphorylating proteins - an important one is the _______ ___, theey are critical for the cell cycle to move to the next phase

Answer 9

Retinoblastoma protein (RB protein)

Question 10

Cdk’s are tightly regulated by Cdk ______

Answer 10

inhibitors

Question 11

Complete 
G1/S phase = Cyclin _/Cdk 2
S/G2 phase = Cyclin _/Cdk2
G2/M phase = cyclin _/Cdk 1
M/G1 phase = Cyclin D/Cdk _

Answer 11

E
A
B
4

(EABD 2214)

Question 12

What is the normal function of the Rb protein. Which cyclin/Cdk complex inactivates it thus permeating progression through the cell cycle?

Answer 12

Prevents DNA replication

Cyclin D/Cdk4

Question 13

Name three factor determining the size of a cell population

Answer 13

Balance of cell proliferation versus cell death/physiological conditions/proto-oncogene activation/growth factors/pathological conditions

Question 14

Definre hyperplasia

Answer 14

An increase in tissue or organ size by increasing cell NUMBER

Question 15

What categories of tissues does hyperplasia take place in?

Answer 15

Labile/stable

Question 16

Hyperplasia is a reversible normal response but can happen secondary to a pathological cause. Why can repeated cell divisions be bad?

Answer 16

Increases the risk of mutations and neoplasia

Question 17

Give a physiological and pathological example of hyperplasia

Answer 17

Physiological - prolierfation of endometrium in response to oestrogen in the menstrual cycle/Bone marrow produces more erythrocytes in response to hypoxia

Pathological - Eczema/thyroid goitre in iodine deficiency

Question 18

Define hypertrophy

Answer 18

An increase in tissue or organ size due to increase in cell SIZE

Question 19

All types of tissue undergo hypertrophy but what tissue category in particular?

Answer 19

Permanent

Question 20

Give a physiological cause of hypertrophy and a pathological one.

Answer 20

Physiological - Skeletal muscle growth/pregnant uterus/cardiac muscle in athletes
Pathologial - RV hypertrohpy (secondary to pulmonary issues)/inflammatory bowel conditions

Question 21

Give an example of a ‘compensatory hypertrophy’’

Answer 21

If a kidney is removed the other will hypertrophy to compensate for this

Question 22

What is atrophy?

Answer 22

A shrinkage of a tissue or organ due to an acquired decrease in size and/or number of cells

Question 23

Give an example of physiological and 3 of pathological atrophy

Answer 23

Physiological - Ovarian atrophy in post-menopausal women

Pathological - Muscle atrophy after disuse/denervation atrophy (e.g. wasted hand muscles after median nerve damage)
/inadequate blood supply (e.g. thinning of the legs in peripheral vascular disease)/inadequate nutrition (e.g. wasting of muscles with malnutrition)/senile atrophy (brain/heart)/pressure on tissues secondary to tumours/cerebral atrophy in alzheimers

Question 24

Define metaplasia

Answer 24

A reversible change of one differentiated cell type to another

Question 25

What tissue categories can metaplasia occur in?

Answer 25

Labile or stable

NOTE - cannot occur across germ layers.

Question 26

Metaplasia is the result of genetic reprogramming of stem cells in response to stress, it is sometimes a preulde to dysplasia and cancer. Give an example of metaplasia

Answer 26

Bronchial pseudostratified ciliated epithelium becoming stratified squamous epithelium in response to cigarette smok/
Stratified squamous epithelium becoming glandular in the oesophagus (Barrett’s oesophagus) - in response to chronic acid reflux

Question 27

Give an example of when metaplasia can be a preulde to cancer

Answer 27

Barret’s oesophagus and oesophageal adenocarcinoma/squamous metaplasia in the bronchus and bronchial cancer/intestinal metaplasia of the stomch and gastric adenocarcinoma

Question 28

Define aplasia and give an example

Answer 28

Complete failure of a specific organ or itssue to develop

Examples - Kidney aplasia/aplastic anaemia/thymic aplasia in autoimmunity

Question 29

Define hypoplasia and give an example

Answer 29

Underdevelopment of a tissue or organ due to an inadequate NUMBER of cells. It is congenital

Examples - testicular in Klinefelter’s syndrome/renal/breast/heart chambers

Question 30

What is involution

Answer 30

It is normal programed shrinkage of an organ e.g. the uterus after childbirth (overlaps with atrophy)

Question 31

Define reconstitution and give an example

Answer 31

Replaement of the lost part of the body. Different to regenerating as it requires several different cell types.

Example - normal angiogenesis in adults

Question 32

Define atresia and give an example

Answer 32

The congenital imperforation of an opening (fails to open). It is congential

Examples - Anus/vagina/small bowel

Question 33

What is dysplasia

Answer 33

The abnormal maturation of cells within a tissue - potentially reversible. Often a preulde to cancer

Question 34

What should be given to a patient who has taken a suspected opioid overdose?

Answer 34

Naloxone (opiate antagonist)

Question 35

Which cellular afaptation does NOT generally predispose to neoplasia?

Answer 35

hypertrophy