Pathology - Cellular Adaptations Flashcards

1
Q

How is cell proliferation controlled?

A
  • chemical signals from the microenvironment can simulate/inhibit cell proliferation
  • signalling molecules bind to a receptor, causing modulation of gene expression
  • receptors usually in cell membrane, but can be in cytoplasm/nucleus
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2
Q

How can a cell population be increased?

A
  • shorten the cell cycle

- convert quiescent cells to proliferating cells by making them enter the cell cycle

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3
Q

How does the body determine whether a cell is able to replicate?

A

It has checkpoints in mitosis, where it checks that the DNA has replicated successfully and the cell is big enough

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4
Q

What is the restriction point?

A

Most critical checkpoint - the majority of cells which pass this will complete the cell cycle. Checkpoint activation delays cell cycle and triggers DNA repair mechanisms/apoptosis via p53

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5
Q

What are cyclins?

A

Cyclins and cyclin dependent kinases (CDKs) are active during different phases of the cell cycle. Cyclin activates CDK, which phosphorylates the target protein (which is bound to cyclin)

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6
Q

What is hyperplasia?

A

Increase in tissue or organ size due to increased cell numbers

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7
Q

What is hypertrophy?

A

Increase in tissue or organ size due to increased cell size

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8
Q

What is atrophy?

A

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

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9
Q

What is metaplasia?

A

Reversible change of one differentiated cell type to another

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10
Q

What types of tissue does hyperplasia occur in?

A

Labile/stable tissues

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11
Q

What causes hyperplasia?

A
  • increased functional demand/hormonal stimulation

- can occur secondary to a pathological cause but proliferation is normal response

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12
Q

Is hyperplasia reversible?

A

Yah

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13
Q

In which types of tissue does hypertrophy occur?

A

Labile, stable but especially permanent

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14
Q

Does hypertrophy usually occur alone in tissue?

A

No, it usually occurs along with hyperplasia

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15
Q

Why don’t athletes get cardiac muscle hypertrophy despite their muscle being under more strain?

A

They have a rest between exercises, so the strain on their heart goes back to normal. Obese people cannot ‘rest’ their heart, so they always have stress on it

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16
Q

What is compensatory hypertrophy?

A

If one of a pair of organs is damaged/removed, the other will enlarge, eg kidneys

17
Q

What happens to a cell in atrophy?

A

The cell shrinks to a size at which survival is still possible. There are reduced structural components, which may eventually result in cell death.

18
Q

What is the relationship between cell atrophy and tissue atrophy?

A

Organ/tissue atrophy is typically due to combination of cellular atrophy and apoptosis, which is reversible up to a point

19
Q

What are ‘residual bodies’?

A

These break off from cells undergoing atrophy, and contain unnecessary organelles

20
Q

Give an example of atrophy due to reduced functional demand/workload

A

Muscle atrophy after disuse - this is reversible with activity

21
Q

Why may the hand muscles become wasted in just one part of the hand?

A

Median nerve damage leads to atrophy

22
Q

Give an example of atrophy due to inadequate blood supply

A

Thinning of skin on legs with peripheral vascular disease

23
Q

What is atrophy of the extracellular matrix called in older people?

A

Osteoporosis

24
Q

Which cell types have metaplasia?

A

Labile or stable tissues

25
Q

Is there a link between metaplasia and cancer?

A

Epithelial metaplasia can be a prelude to to dysplasia and cancer

26
Q

What is aplasia?

A

Complete failure of a specific tissue/organ to develop - this is an embryonic developmental disorder eg. Aplasia of a kidney

27
Q

What is hypoplasia?

A

Underdevelopment or incomplete development of a tissue or organ at embryonic stage due to an inadequate number of cells

28
Q

What is involution?

A

Normal programmed shrinkage of an organ which overlaps with atrophy. Eg. Occurs in uterus after childbirth

29
Q

What is reconstitution?

A

Replacement of a lost part of the body. Angiogenesis is the only mechanism for this in humans

30
Q

What is atresia?

A

Congenital imperforation of an opening, eg lack of an anus, vagina or small bowel

31
Q

What is dysplasia?

A

Abnormal maturation of cells within a tissue. This is potential reversible and an often pre-cancerous condition