Cell Adaptations

Question 0

What are the final outcomes of signalling biochemistry?

Answer 0

Survival - resist apoptosis
Division - enter cell cycle
Differentiation - take on specialised form and function
Death - undergo apoptosis

Question 1

What does the size of cell population depend on?

Answer 1

Rate of proliferation, cell differentiation and cell death by apoptosis

Question 2

What are the different means of cell to cell signalling?

Answer 2

Hormones, local mediators and direct contact of cell-cell or cell-stroma

Question 3

Define paracrine

Answer 3

Cell produces signalling molecules which act on adjacent cells

Question 4

Define autocrine

Answer 4

Cells respond to signalling molecules that they produce themselves

Question 5

Define endocrine

Answer 5

Hormones are synthesised by cells in an endocrine organ

Question 6

What are growth factors?

Answer 6

Local mediators in proliferation. Polypeptides that act on surface receptors - modulation of gene expression.

Question 7

What do growth factors affect?

Answer 7

Cell proliferation and inhibition, locomotion,contractility, differentiation, viability, activation, angiogenesis

Question 8

Give some examples of growth factors.

Answer 8

Epidermal GF, vascular endothelial GF, platelet derived GF, granulocyte colony stimulating factor.

Question 9

What increases growth rate?

Answer 9

Shortened cell cycle, conversion of quiescent cells to proliferating cells by making them enter the cell cycle

Question 10

What is the restriction point?

Answer 10

It’s a checkpoint between G1 & S and is the most important checkpoint. Checkpoint activation delays cell cycles and triggers DNA repair mechanisms or apoptosis via p53

Question 11

What are cyclins and CDKs needed for?

Answer 11

Cyclin-CDK activated complex phosphorylates multiple proteins and these proteins are critical for passage onto the next stage. This is regulated by CDK inhibitors.

Question 12

What type of differentiation do stem cells show?

Answer 12

Asymmetric

Question 13

What are labile stem cells like?

Answer 13

They divide persistently to replenish losses

Question 14

What are stable stem cells like?

Answer 14

They are normally quiescent or proliferate slowly, but persistently when required

Question 15

What are permanent stem cells like?

Answer 15

Stem cells are present, but cannot mount an effective proliferative response to significant cell loss

Question 16

What are the five types of cell adaptation?

Answer 16

Regeneration, hypertension, hypertrophy, atrophy and metaplasia

Question 17

Which cell types undergo regeneration?

Answer 17

Tendons –> weak healing, secondary ruptures tend to occur at site of primary injury
Liver –> adjusts to size of recipient
Skin –> keratinocytes

Question 18

When does hypertrophy usually occur?

Answer 18

Mainly occurs in permanent cells. Caused by an increase in functional demand or hormonal stimulation. Workload is shared by a greater mass of cellular components e.g. body builders, pregnancy etc

Question 19

When does atrophy occur?

Answer 19

Decreased functional demand/workload, loss of innervation, inadequate blood supply, inadequate nutrition, loss of endocrine stimuli, ageing, persistent injury and pressure

Question 20

Why does metaplasia occur?

Answer 20

Due to altered stem cell differentiation and may represent an adaptive substitution of cells that are sensitive to stress by cell types better able to withstand the environment. Sometimes is a prelude to dysplasia and cancer

Question 21

Define hypoplasia

Answer 21

Underdevelopment or incomplete development of a tissue or organ at embryonic stages e.g. kidney, breasts etc

Question 22

Define aplasia

Answer 22

Complete failure of a specific tissue or organ to develop. Embryonic developmental disorder e.g. thymic aplasia. Also used to describe an organ whose cells have ceased to proliferate.

Question 23

What effects does spinal muscular atrophy have?

Answer 23

This condition causes disruption in the innervation of muscles due to deterioration of the neurones connecting the brain and spinal cord to muscles.

Question 24

What causes spinal muscular dystrophy?

Answer 24

Can be genetic - SMN1 gene produces SMN protein which are needed by the neurones to connect the brain and spinal cord with the muscles. If this gene is damaged then less protein is formed, therefore less neurones are able to connect the spinal cord with the body.

A type of SMA called spinal muscular atrophy with respiratory distress (SMARD) is inherited in the same way as types I, II and III, but there’s a problem with a gene called IGHMBP2.
SMA that develops in adults (type IV) is linked to the SMN1 gene in some cases, although not all cases are thought to be inherited. In cases where adult SMA is passed on, the way it’s inherited can be different from the types I, II and III. For example, it’s sometimes possible for someone to develop adult-onset SMA if only one parent has the defective gene.

Question 25

What treatments are there for prostrate cancer?

Answer 25

Luteinising hormone (LH) blockers – e.g. goserelin (also called Zoladex)
Gonadotrophin releasing hormone (GnRH) blockers – e.g.degarelix (Firmagon)
Anti androgens – e.g. flutamide (also called Drogenil)
Cytochrome p17 blockers – abiraterone (Zytiga)

Question 26

What changes occur to uterus in response to hormones?

Answer 26

Oestrogen stimulates the growth of milk ducts in the breasts. The increasing level of oestrogen leads to ovulation halfway through the cycle, and then the hormone progesterone takes over in the second half of the cycle, stimulating the formation of the milk glands. These hormones are believed to be responsible for the cyclical changes such as the swelling, pain, and tenderness that many women experience in their breasts just before menstruation.

Question 27

In psoriasis what alterations occur and what are the mechanisms behind these alterations?

Answer 27

Squamous cells proliferate at a much greater rate than normal. T-cells attack healthy skin cells by mistake. This causes the deepest layer of skin to produce new skin cells more quickly than usual, which in turn triggers the immune system to produce more T-cells.

Question 28

What are the treatments for psoriasis?

Answer 28

Topical - creams and ointments that are applied to your skin e.g. vitamin D analogues
Phototherapy - your skin is exposed to certain types of ultraviolet light
Systemic - oral and injected medications that work throughout the entire body e.g. prednizone

Question 29

How do creams work in treating psoriasis?

What are the potential issues?

Answer 29

Vitamin D - by slowing the rate at which skin cells divide.
Steroid - These are other commonly used treatments. They work by reducing inflammation. They are easy to use and may be a good treatment for difficult areas such as the scalp and face. However, one problem with steroids is that in some cases, once you stop using the cream or ointment, the psoriasis may rebound back worse than it was in the first place. Also, side-effects may occur with long-term use, especially with the more potent (stronger) preparations.

Question 30

How does phototherapy help psoriasis sufferers?

Answer 30

UV light (usually B) slows down cell growth. Can make mild psoriasis go away after 25 sessions

Question 31

What happens to your muscles when you exercise regularly for a long period?

Answer 31

Muscles will hypertrophy in response to exercise because there will be a greater need for them. They will initially rip/break down and then grow back thicker. There is an increase in blood flow received by the muscles, allowing for more perfusion.

Question 32

What happens when you suddenly stop exercising (e.g. broken limb in a cast)

Answer 32

Atrophy - decrease in size and number because the muscle is not being used as much and therefore it’s metabolic demands decrease. Muscle tissue is replaced more slowly and lost muscle tissue is replaced with a tough, fibrous tissue. Changes in the nervous system cause muscles to have reduced tone and ability to contract.

Question 33

How do steroid hormones work?

Answer 33

Steroid hormones work by stimulation of receptor molecules in muscle cells, which activate specific genes to produce proteins. They also affect the activation rate of enzyme systems involved in protein metabolism, thus enhancing protein synthesis and inhibiting protein degradation (called an anti-catabolic effect).

Question 34

What are diverticula?

Answer 34

Small bulges that stick out of the side of the large intestine (colon).

Question 35

How can you differentiate between diverticular disease and diverticulitis?

Answer 35

Symptoms of diverticular disease include: lower abdominal pain and feeling bloated
Symptoms of diverticulitis include: more severe abdominal pain and high temperature (38ºC or above)