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Flashcards in Cellular Adaptations Deck (65)
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1
Q

What three factors affect cell populations in adults?

A

Cell proliferation, cell differentiation and cell death (apoptosis)

2
Q

What is responsible for normal cell proliferation?

A

Proto oncogenes.

3
Q

What four processes can cells undergo?

A

Proliferation, differentiation, death and survival

4
Q

Where on cells do growth factors act?

A

They act on cell surface receptors.

5
Q

How do growth factors affect rate of cell proliferation?

A

They bind to receptors, stimulating transcription of genes which regulate entry into the cell cycle.

6
Q

What cell types are affected by epidermal growth factor?

A

Epithelial cells, hepatocytes and fibroblasts.

7
Q

What cells produce epidermal growth factor?

A

keratinocytes, macrophages and inflammatory cells.

8
Q

What is the role of vascular endothelial growth factor?

A

It induces blood vessel development.

9
Q

In what circumstances does VEGF have a function?

A

Angiogenesis in tumours, chronic inflammation and wound healing.

10
Q

What cells are stimulated by platelet derived growth factor?

A

Fibroblasts, smooth muscle cells and monocytes.

11
Q

When is platelet derived growth factor released?

A

It is released from a granules of platelets upon their activation.

12
Q

What growth factor stimulates neutrophil and granulocyte production?

A

Granulocyte colony stimulating factor.

13
Q

What two factors can increase tissue growth?

A

Shortening of the cell cycle, or conversion of quiescent cells into proliferating cells.

14
Q

What protein suspends the cell cycle?

A

P53 suspends the cell cycle at the restriction point.

15
Q

What causes the genetic instability of cancer cells?

A

Defective cell cycle checkpoints.

16
Q

Name the molecules which regulate cell cycle progression

A

Cycling and their associated enzymes (cyclindependant kinases)

17
Q

How is the cell cycle driven?

A

Cyclins bind to the cyclin dependant kinase and this forms an active complex which phosphorylates proteins (e.g. Retinoblastoma susceptibility protein) which is critical for the next stage of the cell cycle.

18
Q

State two ways in which growth factors act on cyclin and cyclin dependant kinases

A

They can stimulate cyclin production or they can inhibit cyclin inhibitor production.

19
Q

What is a Labile cell population?

A

This is a population of cells which continue to proliferate throughout their lifetime so as epithelial cells.

20
Q

Give two examples of permenant cells.

A

Neurones in CNS and cardiac myocytes.

21
Q

What are stable cells?

A

These are cells which usually proliferate at low rates, however this can increase if tissue damage etc. occurs.

22
Q

What is a stem cell?

A

This is a cell in an adult which has a prolonged proliferating ability and divides asymmetrically, giving rise to a stem cell and a mature cell.

23
Q

If neurones are destroyed or damaged, what fills the space?

A

Glial cells.

24
Q

What type of cell population is bone marrow?

A

It is Labile as it has an ability to replicate.

25
Q

What is cell adaptation?

A

This is where changes to the cell occur so that it sits between the normal unstressed cell and the injured stressed cell and is more susceptible to disease.

26
Q

What is regeneration?

A

This is replacement of cell losses to maintain organ/ tissue size.

27
Q

What happens when there is excessive tissue damage?

A

Generally resolution or regeneration are not possible and so it heals with a fibrous scar.

28
Q

Why are cells generally restricted on the number of times they can replicate?

A

Telomere shortening.

29
Q

Name three things which can stimulate cells to regenerate.

A

Growth factors, cell to cell communication and electric currents and nervous stimuli in the limbs.

30
Q

What is reconstitution?

A

This is regeneration of a body type and therefore requires coordinated growth of multiple tissue types.

31
Q

What example of reconstitution can we see in adults?

A

Small blood vessels can reconstitute and this is vital for wound healing.

32
Q

What can cause hyperplasia of an organ?

A

Increased external stimulation or increased functional demand.

33
Q

What is hyperplasia?

A

Increase in the size of an organ due to increased cell numbers.

34
Q

In what cases is hyperplasia a normal response?

A

It is a normal response to excessive hormone or growth factor production.

35
Q

What can be said about the neoplasticism risk of hyper plastic tissue?

A

The tissue is undergoing more replications and so there is increased risk of mutation and neoplasia.

36
Q

What type of condition Is increased erythrocyte production in the bone marrow due to low oxygen?

A

Physiological

37
Q

State an example of a pathological hyperplasia

A

Thickening of the skin in eczema/ psoriasis.

38
Q

In what cell populations is hypertrophy common?

A

Permenant cell populations.

39
Q

What is hypertrophy?

A

This is an increase in tissue/ organ size due to an increase in cell size due to an increased number of structural components.

40
Q

When a tissue has endocrine stimulus to get bigger, what usually happens?

A

Both hyperplasia and hypertrophy.

41
Q

Why is cardiac hypertrophy associated with fibrosis?

A

As the heart gets bigger, there is no new growth of blood vessels and so there are areas of the heart tissue which do not have a blood supply leading to anoxia and then fibrosis.

42
Q

How do hyperplasia and hypertrophy resolve?

A

When there is removal of the stimulus, the organ/ tissue will return to its normal size.

43
Q

What is atrophy?

A

Decrease in size of an organ due to an decrease in number of cells as well as cellular size.

44
Q

What are the common causes of atrophy?

A

Reduction in growth factors or nutrient supply to the tissue

45
Q

What happens in cellular atrophy?

A

The cell shrinks and there is a reduction of internal components and leads to reduced function.

46
Q

What type of response is cellular atrophy?

A

It is an adaptive response but can lead to cell death.

47
Q

How are cells which undergo apoptosis removed?

A

On an external surface they are lost into the lumen, but otherwise they are removed by phagocytosis.

48
Q

In cell deletion, what type of cells are lost first?

A

Parenchymal cells which leads to atrophied organs containing large amounts of connective tissue.

49
Q

What are autophagosomes?

A

These contain lipofuscin and remnants of organelles which cannot further be digested.

50
Q

What is seen in cells during cell shrinkage?

A

Self-digestion leads to residual bodies being seen within the cells.

51
Q

What is ubiquitin?

A

This binds to proteins which are to be removed.

52
Q

What two things is atrophy usually linked with?

A

It is usually pathological or linked with senescence.

53
Q

State some pathological causes of atrophy.

A

Reduced functional demand, reduced nutrient supply, loss of innervation, persistent injury, blockage of a duct, X-Rays, toxic damaged immunological mechanisms, aging, loss of endocrine stimulation, inadequate blood supply.

54
Q

What is metaplasia?

A

Replacement of one differentiated tissue with another.

55
Q

In what cell types is metaplasia common?

A

Epithelia and connective tissue.

56
Q

What causes signals for metaplasia?

A

Cytokines and growth factors.

57
Q

What is dysplastic epithelium?

A

This is disorganised epithelium with abnormal differentiation.

58
Q

What is lost in metaplasia?

A

The original function of the tissue (e.g. Possessing cilia or secreting mucus)

59
Q

What is Barrett’s oesophagus?

A

This is where repeated acid reflux causes a change in epithelium from stratified squamous to gastric.

60
Q

What type of metaplasia can occur in young people who return to sports too quickly?

A

Connective tissue becomes bone.

61
Q

What is Aplasia?

A

Is an embryonic disorder in which a tissue/organ has failed to develop.

62
Q

What is Involution?

A

This is when atrophy is a physiological process such as the uterus after childbirth shrinks back towards its original size.

63
Q

What is the term used to describe when there is underdevelopment or incomplete development of a tissue or organ in an embryo?

A

Hypoplasia

64
Q

What is atresia?

A

This is where there is congenital imperfection of an opening such as the anus or vagina.

65
Q

What is dysplasia?

A

Abnormal maturation of cells within a tissue - this is potentially reversible but often a pre-cancerous condition.