Lecture 12 - Cellular Adaptations Flashcards

1
Q

What determines the size of a cell population in an a adult?

A

Rate of cell:
-Proliferation
-Differentiation
-Death by apoptosis

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2
Q

When do cell numbers in a population increase?

A

Increased cell proliferation
Decreased cell death

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3
Q

Where can receptors be that regulate gene expression stimulating or inhibiting cellular proliferation?

A

Inside cell
On cell membrane

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4
Q

What genes regulate normal cell proliferation?

A

Proto-oncogenes
Tumour suppressor genes

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5
Q

What happens to a cell once it has completed a full cell cycle?

A

Renters G1
Leaves at G0

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6
Q

What is the type of differentiation which makes a cell permanently leave the cell cycle?

A

Terminal differentiation

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7
Q

What are the 3 parts to Interphase?

A

G1
S (DNA Synthesis)
G2

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8
Q

What is the protein which suppresses the cell cycle?

A

P53 protein

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9
Q

What is the point of checkpoints in the cell cycle?

A

Sense damage to DNA

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10
Q

What are the checkpoints in the interphase stage of the cell cycle?

A

G1 Checkpoint
G2 Checkpoint

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11
Q

What is the function of the G1 checkpoint?

A

Checks for DNA damage before replication

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12
Q

What is the function of the G2 checkpoint?

A

Checks DNA after replication
Checks cell size

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13
Q

What is the name of the proteins which drive cell cycle by phosphorylation of proteins?

A

Cyclin Dependant Kinases (CDK)

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14
Q

What is the Cyclin Dependant Kinase which allows for DNA replication to take place?

A

CDK4

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15
Q

How does CDK4 allow for DNA replication to take place?

A

CDK4 inactivates Rb
Rb inactivates/prevents DNA replication

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16
Q

What is the effect of CDK inhibitors on the cell cycle?

A

CDK always activated, meaning Rb always inactivated so cell cycle is driven .
Rb not able to inhibit cycle

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17
Q

What is cell adaptation?

A

The state between a normal unstressed cell and an overstressed injured cell

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18
Q

What are the 4 important types of cell adaptation?

A
  • Hyperplasia
    -Hypertrophy
    -Atrophy
    -Metaplasia
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19
Q

What is Hyperplasia?

A

Increase in number of cells

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20
Q

What is Hypertrophy?

A

Increase in cell size WITHOUT increase in cell number

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21
Q

What is Atrophy?

A

Decrease in cell size and or cell number

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22
Q

What is metaplasia?

A

Cells are replaced by cells of a different cell type

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23
Q

In hyperplasia, what are the reasons that hyperplasia may take place?

A

Increased functional demand
External stimuli

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24
Q

What type of tissues can hyperplasia take place?

A

Labile tissues
Stable tissues

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25
Q

What is neoplasia?

A

Irreversible hyperplasia that is irreversible

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26
Q

What triggers hyperplasia to take place?

A

Hormones (hormones that inc functional capacity)

Compensatory (inc in tissue mass after tissue damage)

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27
Q

What 2 hormones lead to the physiological hyperplasia of breast tissue?

A

Prolcatin
Oxytocin

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28
Q

What excess hormone is linked to psoriasis?

A

Growth factor hormone

29
Q

What type of tissue does hypertrophy happen in?

A

Permanent tissue

30
Q

When does hypertrophy take place?

A

When theres on increase in functional demand
Increased hormonal stimulation

31
Q

What changes happen in the cell in Hypertrophy?

A

More cytoplasm
More proteins

32
Q

What are 3 examples of physiological hypertrophy?

A

Skeletal muscle hypertrophy (gym)

Smooth muscle hypertrophy in pregnancy

Cardiac muscle hypertrophy in athletes

33
Q

What may be a cause of pathological cardiac hypertrophy?

A

Hypertension

Heart under constant level of strain

34
Q

What is Benign Prostatic Hyperplasia?

A

Prostate under goes hyperplasia.
The smooth muscle of the bladder undergoes hyperplasia due to the urethra narrowing, this means the smooth muscles has to contract harder

35
Q

What is likely to happen to the remaining kidney following a unilateral nephrectomy?

A

Compensatory hypertrophy

36
Q

What levels can atrophy happen at?

A

Level of cell
Level of organ

37
Q

Why is atrophy bad for a cell?

A

Cell contains fewer components so has a reduced function

38
Q

What type of tissue do atrophic organs have an increased amount of?

A

Connective tissue

39
Q

Atrophy is REVERSIBLE, however the longer it goes on for the harder it is for it to be reversed.

Why is this the case?

A

More and more of the parenchyma cells get replaced by the connective tissue

40
Q

What are parenchymal cells?

A

The functional cells that do the specific functions of the tissue

41
Q

What are 2 examples of physiological atrophy??

A

Uterine atrophy following birth

Thymic (Thymus) atrophy

42
Q

What can lead to muscular atrophy?

A

Atrophy of dissuse
Denervation atrophy (muscle loses innervation and dies)

43
Q

What is senile atrophy?

A

Atrophy that happens with age in permanent tissues

44
Q

How can a brain tumour cause atrophy?

A

The brain tumour puts pressure on surrounding healthy brain cells causing PRESSURE ATROPHY

45
Q

How can peripheral vascular disease lead to atrophy?

A

Inadequate blood supply leads to cells shrinking

46
Q

What is Metaplasia?

A

A reversible change where one differentiated cell type is replaced by another cell type

47
Q

Where does Metaplasia not occur in adults?

A

Striated muscle cells
Neurones

48
Q

What is the aim of metaplasia?

A

An adaptive response where stem cells are programmed to switch to a different cell type more adapted to its environment

49
Q

What type of tissues does Metaplasia most commonly happen in?

A

epithelial tissues

50
Q

In epithelial tissues what epithelial cell type is normally changed from and to in Metaplasia?

A

Columnar epithelium (fragile) ———> Squamous epithelium (more resilient)

51
Q

What is the problem with meta plastic epithelium?

A

My lose functions that the original epithelium performed

52
Q

What is Dysplasia?

A

Cells abnormally differentiate into different cell types
Disorganised

53
Q

Is Dysplasia reversible?

A

YES (REVERSIBLE)

54
Q

Is neoplasia reversible?

A

NO (IRREVERSIBLE)

55
Q

How is myeloid Metaplasia of the spleen adaptive and useful?

A

If bone marrow is compromised the spleen can take over as a site of Haematopoiesis

56
Q

In smokers, what is an example of Metaplasia that takes place?

A

Squamous metaplasia in bronchiole epithelium

57
Q

What is the Metaplasia of Barrett’s oesophagus?

A

Persistent acid reflux causes normal epithelium to replaced by glandular cells

58
Q

What metaplastic changes happen in Traumatic myositis ossificans?

A

Fibroblasts change to osteoblasts

Connective tissue changes to bone

New bone forms in soft tissue of leg due to premature return to exercise following trauma

59
Q

What is Aplasia?

A

Complete failure of a specific organ or tissue to develop

Also used to describe organs that have stopped proliferating

60
Q

What is Hypoplasia (NOT opposite of Hyperplasia)?

A

Congenital underdevelopment or incomplete development of a tissue or organ

61
Q

Why is hypoplasia NOT the opposite of hyperplasia?

A

Hypoplasia is congenital

Hyperplasia is not congenital

62
Q

What is Atresia?

A

Congenital imperforation of an opening

NO HOLE?ORIFICE

63
Q

What is Reconstitution?

A

The replacement of a lost part of the body
(Think of a lizard)

64
Q

What part of the human body undergoes Reconstitution?

A

Small blood vessels following injury

65
Q

What is Involution?

A

The normal programmed shrinkage of an organ

66
Q

What is an example of involution in humans?

A

Shrinkage of the temporary Fetal organs

67
Q

What are the 3 levels of dysplasia?

A

Mild
Moderate
Severe

68
Q

What happens to the level of organisation in the grading of dysplasia?

A

Becomes more and more disorganised

69
Q

Why may dysplasia be a cause of concern?

A

Potentially cancerous