MOD Cellular Adaptations

Question 1

Define paracrine signalling

Answer 1

A cell synthesises and secretes signalling molecules that act on adjacent cells

Question 2

Define intracrine signalling

Answer 2

Cell does not secrete synthesised signalling molecules, they act intracellularly.
Form of autocrine.

Question 3

What are growth factors?
What are they coded for by?
What do they do?

Answer 3

Local chemical mediators at act over a short distance.
Coded for by proto-oncogenes.
Stimulate cell proliferation, migration

Question 4

How do growth factors affect cells?

Answer 4

Stimulate transcription and translation of genes that control path of cell through cell cycle.
Affect proliferation, migration, locomotion, contractility and differentiation

Question 5

Give 4 growth factors

Answer 5

Epidermal growth factor
Vascular endothelial growth factor
Platelet derived growth factor
Granule yet colony stimulating factor

Question 6

What does EGF do?

Produced by?

Answer 6

Nitrogen if for epithelia, fibroblasts, hepatocytes.

Produced by keratinocytes

Question 7

What does VEGF do?

Answer 7

Angiogenesis in tumours, chronic inflammation and healing

Question 8

Where is PDGF stored?
What is it produced by?
What does it do?

Answer 8

Stored in alpha granules of platelets
Produced by macrophages, endothelium, SMCs
Proliferation and migration of fibroblasts, SMC, hepatocytes.

Question 9

What does granulocyte colony stimulating factor do?

Answer 9

Srimulates bone marrow to produce granulocytes, neutrophils

Question 10

Give 5 stages of the cell cycle

Answer 10

G1 - cellular content is replicated. DNA checked.
S - DNA replication
G2 - cell checks everything and repairs errors
Mitosis/cytokinesis
G0 - cell cycle arrest, terminally differentiated cells

Question 11

What occurs at checkpoints?

Answer 11

Monitor damage to DNA. Damaged DNA is not replicated

Question 12

What is the most critical checkpoint

Answer 12

Restriction point at end of G1

Question 13

What happens if a checkpoint is activated?

Answer 13

p53 suspends the cell cycle and triggers DNA repair or apoptosis.

Question 14

When are the checkpoints?

Answer 14

Restriction checkpoint at the end of G1
G1/S
G2/M

Question 15

How is the cell cycle controlled? (Protein?)

Answer 15

Cyclins and cycklin dependent kinases drive th cell cycle by phosphorylation of proteins that are required for progress.
CDK inhibitors regulate cyclin-CDK complexes

Question 16

What is regeneration?

Answer 16

The replacement of lost cells in tissues in order to maintain size of tissue.

Question 17

What is reconstitution

Answer 17

The replacement of a lost body part.

Requires coordinated regeneration.

Question 18

give tissues good at regeneration

Answer 18

Bone
Epithelia
Liver
Mesothelia
SMC

Question 19

Tissues poor at regeneration

Answer 19

Cartilage
tendons
Striated muscle

Question 20

Tissues that do not regenerate

Answer 20

CNS

Adipose

Question 21

Define hyperplasia. What tissues does it occur in?

Answer 21

An increase in tissue size by increasing number of cells.

Occurs in labile and stable tissues.

Question 22

What causes hyperplasia

Answer 22

Response to increased functional demand or stimulation

Question 23

Describe and give example of physiological hyperplasia

Answer 23

Hormonal, compensatory
Increased production of erythrocytes in low oxygen.
Increased endometrial cells with oestrogen

Question 24

Describe and give example of pathological hyperplasia

Answer 24

Overstimulation by hormone or grow factor.

Iodine deficiency leads to goitre

Question 25

Describe hypertrophy. What tissue? Response to?

Answer 25

Increase in tissue size due to increase in cell size by increasing structural components. Permanent tissue Response to increased functional demand.

Question 26

Examples of physiological hypertrophy

Answer 26

Muscles in bodybuilder | SMC in pregnant uterus

Question 27

Examples of pathological hypertrophy

Answer 27

Ventricular hypertrophy due to hypertension, valvular disease SMC hypertrophy above intestinal stenosis Bladder smooth muscle hypertrophy with bladder obstruction.

Question 28

Describe cardiac hypertrophy

Answer 28

Exercise Hypertension Valvular disease Loss of compliance and elasticity so loss of intropy.

Question 29

Describe compensatory hypertrophy.

Answer 29

Missing one of pair of organs leads to hypertrophy of the remaining. Reversible

Question 30

Define atrophy

Answer 30

Shrinkage of tissue due to reduction in number of cells or cell size.

Question 31

Define cellular atrophy

Answer 31

Reduced cell size

Question 32

Define organ atrophy

Answer 32

Reduced cell size and number

Question 33

How does cell deletion occur?

Answer 33

Cell induced into apoptosis.If on surface, lost. If within, cleared by phagocytosis. Parenchyma lost before strong.

Question 34

Describe cell shrinkage

Answer 34

Self digestion. Limited due to organelle requirement Ulbiquitin targets proteins for deletion.

Question 35

Describe physiological atrophy examples

Answer 35

Post menopause ovarian atrophy | Uterine atrophy post party's

Question 36

Give some causes of pathological atrophy

Answer 36

``` Disuse trophy Denervation atrophy Senile atrophy inadequate blood supply Reduced hormonal stimulation Inadequate nutrition ```

Question 37

Define metaplasia

Answer 37

Reversible replacement of one adult differentiated cell type with another. Abnormal regeneration.

Question 38

How does Metaplasia occur

Answer 38

Stem cells reprogrammed to produce. Different progeny. | Only occurs in tissues at can replicate.

Question 39

Why does metaplasia occur

Answer 39

Expression of new genetic programme which results in cells assuming different structure and function Secondary to signal molecules.

Question 40

Give some examples of useful metaplasia

Answer 40

Bone marrow damaged... Spleen to marrow | Abrasion in ducts leads to columnar epithelial lining turning to stratified squamous.

Question 41

Give some examples of detrimental metaplasia.

Answer 41

Smoking... Bronchial pseudo stratified Ciliated epithelia to stratified squamous Barrett's oesophagus... Stratified squamous to secretory intestinal epithelium due to acid reflux. Myosotis ossificans... Trauma to skeletal muscle leads to bone formation due to fibroblasts becoming osteoblasts.

Question 42

Define aplasia

Answer 42

Complete failure of tissue to develop. | Organs that have ceased to proliferate

Question 43

Define involution

Answer 43

Normal programmed shrinkage | Uterus after childbirth

Question 44

Define Hypoplasia

Answer 44

Congenital underdevelopment of tissue Not opposite of hyperplasia Inadequate number of cells

Question 45

Define atresia

Answer 45

Congenital imperforation of an opening

Question 46

Define dysplasia

Answer 46

Ordered disorganisation of tissue in. Reversible pre neoplastic change.

Question 47

Define autocrine signalling

Answer 47

Cell synthesises signal molecules that act on the cell itself.