MoD Session 7- Cellular Adaptations Flashcards Preview

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Flashcards in MoD Session 7- Cellular Adaptations Deck (62)
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0
Q

What regulates normal cell proliferation?

A

Proto oncogenes

1
Q

What is the size of cell populations dependent on?

A

The rate of:

  • cell differentiation
  • cell proliferation
  • apoptosis
2
Q

What are the 4 outcomes for cells?

A
  • differentiate (become specialised)
  • divide (enter cell cycle)
  • survive (resist apoptosis)
  • die (apoptosis)
3
Q

What are the three types of cell signalling?

A
  • autocrine
  • paracrine
  • endocrine
4
Q

What is autocrine signalling?

A

Where the cells respond to the signalling molecules that they themselves produce.

5
Q

What is intracrine signalling?

A

Where the cell is affected by the signalling molecule that it produces, but this signal binds intracellularly and is never secreted.

6
Q

What is paracrine signalling?

A

Where the signalling molecule produced by a cell acts on neighbouring cells.

7
Q

What is endocrine signalling?

A

The cell secretes a hormone which travels in the blood stream to a distant target cell/ organ.

8
Q

Cell to cell signalling can be via… (3)

A
  • hormones
  • local mediators
  • direct cell-cell or cell-stroma contact
9
Q

What codes for growth factors?

A

Proto Oncogenes

10
Q

What distance do growth hormones act over?

A

Short distance

11
Q

Apart from cell proliferation and inactivation, what else do growth hormones affect? (6)

A
  • locomotion
  • differentiation
  • angiogenesis
  • contractility
  • activation
  • viability
12
Q

With respect to the cell cycle, how does increased tissue growth occur? (2)

A
  • shortening the cell cycle

- conversion of quiescent cells to proliferating cells by causing them to enter the cell cycle.

13
Q

Which phase of the cell cycle is distinctive under the light microscope?

A

M

14
Q

What does phase M include?

A
  • mitosis (nuclear division)

- cytokinesis (cell division)

15
Q

What is the rest of the cell cycle called?

A

Interphase

16
Q

What is cell progression controlled by and what do they do?

A

Checkpoints. They sense damage to DNA and ensure that damaged DNA does not replicate.

17
Q

Wait is the most critical checkpoint and where is it found?

A
The restriction (R) checkpoint. 
It is found at the end of G1.
18
Q

What happens if checkpoint activation occurs?

A

The protein P53 comes into play and suspends the cell cycle and triggers DNA repair (if poss) or apoptosis.

19
Q

Which protein and its associated enzyme control the cell cycle progression?

A

Cyclins

Cyclin-dependent kinases (CDKs)

20
Q

What do activated CDKs do

A

Phosphorylate proteins so that they can move to the next stage of the cell cycle.

21
Q

What is the activity of cyclin-CDK complexes regulated by?

A

CDK inhibitors

22
Q

What are labile cells and give 2 examples.

A

Ones that continue to multiply throughout life.

Bone marrow and epithelium.

23
Q

What are stable cells and give 2 examples.

A

Stable cells are ones that both mature and stem cells can proliferate if needed, in regenerative bursts. They are usually quiescent.
Examples liver and kidney cells.

24
Q

Define quiescent.

A

Dormant

25
Q

What are permanent cells and give 3 examples.

A

They are cells that are permanently differentiated and therefore cannot proliferate.
Examples are cardiac muscle, skeletal muscle and neural tissue

26
Q

What are stem cells?

A

Cells with prolonged proliferation activity that show asymmetric replication.

27
Q

What is asymmetric replication?

A

Where one daughter cell remains as a stem cell and the other goes on to differentiate into another cell type.

28
Q

Are stem cells present in permanent cell populations?

A

Yes but they cannot amount an effective proliferative response to significant cell loss.

29
Q

What is cell adaptation?

A

It is the state between a normal, unstressed cell and an over stressed injured cell. It is reversible.

30
Q

What is regeneration?

A

The replacement of cells by identical ones to maintain organ/tissue size.

31
Q

What is the hayflick number?

A

The number of cell divisions possible.

32
Q

What is the human hayflick number?

A

61.3

33
Q

What is reconstitution?

A

The replacement of a lost part of the body.

34
Q

What is hyperplasia?

A

An increase in organ/tissue size due to increased cell numbers.

35
Q

What does hormonal hyperplasia lead to?

A

Increase in functional capacity

36
Q

What does compensatory hyperplasia lead to?

A

Increased tissue mass after injury.

37
Q

What 2 cell populations can hyperplasia occur in?

A

Labile and stable.

38
Q

Give an example of physiological hyperplasia

A

Increased bone marrow production of erythrocytes in response to hypoxia conditions.m

39
Q

Give an example of a pathological hyperplasia

A

Epidermal thickening in chronic eczema and psoriasis.

40
Q

What is hypertrophy?

A

An increase in organ/tissue size due to increased cell size.

41
Q

Why are cells bigger in hypertrophy?

A

They have more structural components

42
Q

What cell population is hypertrophy seen in?

A

Permanent

43
Q

Give 2 physiological examples of hypertrophy

A
  • skeletal muscle hypertrophy of a bodybuilder

- smooth muscle hypertrophy of a pregnant uterus

44
Q

Give a pathological example of hypertrophy

A

Ventricular cardiac muscle hypertrophy in response to hypertension.

45
Q

What is the disadvantage of cardiac hypertrophy?

A

Anoxia occur because although the number of capillaries increases, this is insufficient to satisfy the increased muscle mass.

46
Q

What is compensatory hypertrophy and when does it happen?

A

It happens when you remove one of a pair of organs- the other organ increases in size to compensate for the loss of its partner.

47
Q

What is atrophy?

A

A shrinkage of a tissue/organ due to reduced cell size and/or number.

48
Q

What is cellular atrophy?

A

A decrease in cell size.

49
Q

What is organ or tissue atrophy due to?

A

A decrease in cell size and apoptosis.

50
Q

How does cells shrinkage occur?

A

By self-digestion. (Autophagosomes)

51
Q

Give 2 physiological examples of atrophy.

A
  • decrease in size of the uterus following parturition

- ovarian atrophy in post menopausal women.

52
Q

Give 3 of the 7 listed examples of pathological atrophy. (See workbook for more)

A
  • muscle atrophy due to disuse
  • denervation atrophy. E.g in the hand due to median nerve damage
  • peripheral vascular disease due to inadequate blood supply
  • wasting of muscles due to malnutrition
  • loss of endocrine stimulation
  • persistent injury
  • senile atrophy
53
Q

What is metaplasia?

A

The replacement of one cell type with another cell type with a different phenotype.

54
Q

Wha is the difference between metaplasic and dysplasic epithelium?

A

Metaplasic is fully differentiated

Dysplasic is disorganised and has an abnormal differentiation.

55
Q

Give an example when metaplasia useful.

A

When bone marrow is destroyed by disease, splenic tissue undergoes metaplasia to bone marrow.

56
Q

Give an example when metaplasia is not useful.

A

When cigarette smoke causes pseudostratified columnar epithelia in the oesophagus to change into stratified squamous epithelia.

57
Q

What Is Aplasia?

A

The complete failure of a tissue or organ to develop, or an organ whose cells have ceased to proliferate.
It is an embryonic developmental disorder.

58
Q

What is involution?

A

It is the normal, planned shrinkage of an organ.

E.g the uterus after childbirth.

59
Q

What is hypoplasia?

A

The congenital underdevelopment or incomplete development of an organ or tissue. There are therefore an inadequate number of cells.
It is an embryonic developmental disorder.

60
Q

What is atresia?

A

When there is no orifice produced. E.g the anus or vagina.

61
Q

What is dysplasia?

A

The abnormal maturation of cells within a tissue.

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