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Ellie's Path Processes > Sesh 7.1- Cellular Adaptations > Flashcards

Sesh 7.1- Cellular Adaptations Flashcards

1
Q

What determines the size of a cell population?

A

Rate of cell proliferation, differentiation and apoptosis

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2
Q

____________ regulate normal cell proliferation.

A

Proto-oncogenes

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3
Q

Name 2 ways in which cell populations can increase in size.

A
  1. Shortening cell cycle

2. Converting quiescent cells in G0 to proliferating cells

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4
Q

Which phases of the cell cycle are visible by light microscopy?

A

mitosis and cytokinesis

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5
Q

Where are the 2 cell cycle checkpoints and what are their functions?

A

Checkpoint after G1- is DNA damaged?
Checkpoint after G2- is all DNA replicated
-Prevent cells in normal state with damaged DNA from replicating

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6
Q

What is the restriction point (R)?

A

Most critical checkpoint in cell cycle near end of G1. Once cells pass point, will continue to replicate regardless. Most commonly altered checkpoint in cancer cells

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7
Q

What are cyclins and CDKs?

A

Cyclins bind CDKs (and CDKs substrate) to activate them, allowing them to phosphorylate target proteins, to allow the cell to go round the cell cycle.

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8
Q

What is the Hayflick limit?

A

The limited number of times a normal cell can divide due to telomere shortening.
61.3 times in humans

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9
Q

List the 4 ways in which cells can adapt.

A
  1. Hyperplasia
  2. Hypertrophy
  3. Atrophy
  4. Metaplasia
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10
Q

What is metaplasia?

A

Cells are replaced by cells of a different type.

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11
Q

Which cellular adaptation is not reversible?

A

Atrophy.

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12
Q

In which types of tissue does hyperplasia occur?

A

Labile or stable tissues.

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13
Q

Why does hyperplasia increase risk of neoplasia?

A

Increased no of cell divisions, means increased risk of mutation in nuclear division.

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14
Q

Why does hyperplasia occur?

A

Due to increased functional demand or hormonal stimulation.

Can also be secondary to pathological cause.

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15
Q

Give examples of physiological hyperplasia.

A
  • Proliferative endometrium w/ oestrogen stim

- Hypoxia causes bone marrow to produce erythrocytes

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16
Q

Give 2 examples of pathological hyperplasia.

A
  • Eczema- hyperplasia of epidermis

- Thyroid goitre in Iodine deficiency

17
Q

Which types of tissue does hypertrophy occur in?

A 
Permanent especially (can only undergo hypertrophy, not hyperplasia)
Also labile and stable tissues- often alongside hyperplasia.
18
Q

Why does tissue hypertrophy occur?

A

Increased functional demand or hormonal stimulation….

Cells contain more structural components- workload is shared between greater no of these

19
Q

Give 2 examples of physiological hypertrophy.

A
  1. Skeletal muscle

2. Pregnant uterus (hypertrophy & hyperplasia)

20
Q

Give 3 examples of pathological hypertrophy.

A
  1. Ventricular hypertrophy due to hypertension…can’t grow enough capillaries to compensate so heart is always hypoxic
  2. Hypertrophy of smooth muscle in bladder wall in response to enlarged prostate
  3. Hypertrophied bowel proximal to stricture
21
Q

What is compensatory hypertrophy?

A

Hypertrophy of organ in response to damage to part of that organ or to 1 of a paired organ e.g. If have 1 kidney removed, remaining kidney will hypertrophy.

22
Q

Define atrophy.

A

Shrinkage of a tissue or organ due an acquired decrease in number and/or size of cells.

23
Q

What happens within the cell during atrophy?

A
  • Shrinks to a size at which survival is still possible
  • Reduced structural components e.g. Muscle fibres (gets rid of things it no longer needs into residual bodies)
  • May result in cell death
24
Q

Is tissue atrophy only due to cellular atrophy?

A

No, is a combination of cellular atrophy AND apoptosis.

25
Q

Is tissue atrophy reversible?

A

Yes but only up to a point…if get fibrotic tissue, not reversible.

26
Q

Give 2 examples of physiological atrophy.

A
  1. Ovarian atrophy in post-menopausal women

2. Uterine atrophy after childbirth

27
Q

Give reasons why pathological atrophy can occur.

A
  1. Disuse- reduced functional demand or workload e.g. Skel muscle w/ cast on
  2. Denervation atrophy
  3. Inadequate blood supply
  4. Inadequate nutrition (brain is last organ that would atrophy)
  5. Loss of endocrine stimuli
  6. Persistent injury
  7. Senile atrophy (cells reach Hayflick limit)
  8. Pressure e.g. From tumour
28
Q

What is atrophy of extracellular matrix?

A

Loss of bone matrix rather than Ca2+ etc.
get if inactive or in space and not putting weight on bones.
Increased fracture risk.

29
Q

Define metaplasia.

A

Reversible change of 1 differentiated cell type to another.

30
Q

Do you get metaplasia across germ layers?

A

No..e.g. Usually epithelium changes to diff type of epithelium.

31
Q

Which cell types can metaplasia occur in?

A

Labile or stable.

32
Q

Give examples of metaplasia.

A
  1. Cigarette smoke causes bronchial pseudostratified ciliated epithelium–>stratified squamous
  2. Persistent acid reflux causes stratified squamous epithelium–> gastric glandular epithelium (Barrett’s oesophagus)
  3. Bone marrow damage can cause spleen to diff to be able to produce blood cells
  4. If start to exercise sooner than should after skel muscle exercise, get metaplasia of fibroblasts to osteoblasts
33
Q

Can metaplasia predispose to cancer?

A

Yes, but not known why.
E.g. Barrett’s epithelium and oesophageal cancer
Intestinal metaplasia of stomach and gastric adenocarcinoma

34
Q

What is aplasia?

A

Complete failure of tissue or organ to develop (an embryonic developmental disorder), or whose cells have ceased to proliferate (e.g. Bone marrow in aplastic anaemia or post-chemo).

35
Q

What is hypoplasia?

A

Under/incomplete development of tissue/organ at EMBRYONIC STAGE due to inadequate no of cells.
Congenital condition.
E.g. Hypoplastic left heart syndrome

36
Q

What is involution?

A

Normal programmed shrinkage of organ.
Some overlap with atrophy.
E.g. Uterus after childbirth

37
Q

What is reconstitution and can it happen in humans?

A
  • Replacement of a lost part of the body

- Generally doesn’t but can if cut 1/2 finger off before 4 yrs old, will grow back.

38
Q

What is atresia?

A

Means ‘no orifice’.

It is congenital imperforation of an opening e.g. Anus

39
Q

What is dysplasia?

A

An abnormal maturation of cells within a tissue.

Often pre-cancerous.

Ellie's Path Processes (6 decks)

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