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Mechanisms Of Disease > Cellular Adaptations > Flashcards

Cellular Adaptations Flashcards

0
Q

What are the four outcomes of cellular signalling?

A

Survive - i.e. resists apoptosis
Divide - i.e. enters cell cycle
Differentiate - i.e. takes on specialised form and function
Die - i.e. undergoes apoptosis

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1
Q

What factors affect cell population size?

A

Rate of cell proliferation
Rate of cell differentiation
Rate of apoptosis

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2
Q

How does cellular signalling work?

A

Signalling occurs through binding of a signalling molecule to a receptor either on the cell surface or within the cell
This binding causes a change to gene expression

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3
Q

Through what methods can cell signalling occur?

A

Hormones
Local mediators
Direct cell-cell contact

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4
Q

What are the three types of cellular signalling?

A

Autocrine - cell produces a signal that it itself responds to
Paracrine - cell produces a signal that acts on a neighbouring cell
Endocrine - cell produces a hormone that travel through circulation to target cell

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5
Q

What are growth hormones?

A

Local mediators involved in cell proliferation
The stimulate the transcription of genes that regulate entry of cells into the cell cycle
Act on specific cell surface receptors
Coded for by proto-oncogenes

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6
Q

What do growth hormones affect?

A 
Cell proliferation and inhibiton
Locomotion
Contractility
Differentiation
Viability
Activation
Angiogenesis
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7
Q

Name some growth hormones/factors

A

Epidermal growth factor
Vascular derived growth factor
Platelet derived growth factor
Granulocyte-colony stimulating factor

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8
Q

What are the stages of the cell cycle?

A

G1-S-G2-M

From G1 can go to G0 and then to terminal differentiation

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9
Q

How can you increase proliferation?

A

Shortening the cell cycle

Conversion of quiescent cells to proliferating cells

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10
Q

What are the two checkpoints in the cell cycle?

A

At the end of G1
At the end of G2
Checkpoints are activated by the p53 protein

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12
Q

What is the restriction point?

A

The checkpoint after G1

It very critical and the most commonly altered in cancerous cells

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13
Q

How is the cell cycle controlled?

A

By cyclins and cyclin-dependent kinases

They form a complex which phosphorylate proteins that are needed for progression to the next stage of the cell cycle

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14
Q

Define Labile cell populations and give examples

A

Divide persistently

e.g. Surface epithelia and bone marrow

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15
Q

Define Stable cell populations and give examples

A

Normally quiescent but proliferate persistently when required
e.g. liver hepatocytes and bone osteoclasts

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16
Q

Define permanent cell populations and give examples

A

Can’t proliferate

e.g. brain neurones and cardiac and skeletal muscle

17
Q

Describe asymmetric replication

A

When a stem cell replicates one daughter cell remains a stem cell while the other differentiates into a mature, non-dividing cell

18
Q

Define regeneration

A

Replacement of cell loses by identical cells to maintain tissue or organ size
Different tissues have different regeneration capacities

19
Q

Give examples of when regeneration occurs

A

In the liver after a partial hepatectomy

Replacement of the epidermis of the skin after a burn

20
Q

How do neurones regenerate?

A

They don’t, instead they undergo plasticity in which the brain develops alternative pathways

21
Q

What is the Hayflick number?

A

It is the average number of times a cell can regenerate, in humans this number is 61.3

22
Q

What is reconstitution?

A

The replacement of a lost part of the body through regeneration of several cell types

23
Q

Define hyperplasia

A

Increase in tissue or organ size due to increase cell numbers
Only occurs in liable or stable cell populations

24
Q

Give some physiological examples of hyperplasia

A

Proliferation of endometrium under influence of oestrogen

Bone marrow produces erythrocytes in hypoxia

25
Q

Give some pathological examples of hyperplasia

A

Epidermal thickening in chronic eczema or psoriasis

Thyroid goitre in iodine deficiency

26
Q

Define Hypertrophy

A

Increase in tissue or organ size due to increased cell size

Mostly occurs in permanent cell populations

27
Q

Give some physiological examples of hypertrophy

A

Skeletal muscle hypertrophy of body builders

Smooth muscle hypertrophy of a pregnant uterus

28
Q

Give some pathological examples of hypertrophy

A

Ventricular smooth muscle hypertrophy in response to systemic hypertension or valvular disease
Bladder smooth muscle hypertrophy with bladder constriction due to an enlarged prostrate

29
Q

What is compensatory hypertrophy?

A

e.g. when you remove one kidney the other enlarges by hypertrophy and hyperplasia to compensate

30
Q

Define atrophy

A

The shrinkage of a tissue or an organ due to an acquired decrease in size and/or number of cells
The cell can survive but it has fewer cellular components and reduced function

31
Q

Give some physiological examples of atrophy

A

Ovarian atrophy in post menopausal women

Decrease in the size of the uterus after parturition

32
Q

Give some pathological examples of atrophy

A

Atrophy of disuse - reduced functional demand/workload
Denervation atrophy - loss of innervation
Inadequate blood supply
Inadequate nutrition
Aging
Loss of endocrine stimuli

33
Q

Define metaplasia

A

Reversible change of one differentiated cell to another

Most commonly happens in epithelial tissue

34
Q

Give examples of when metaplasia happens

A

Cigarrete smoke - pseudostratified epithelium of the bronchi become stratified squamous epithelium
Persistent acid reflux - stratifies squamous epithelium of gut becomes gastric-type epithelium
Chronic irritation by stones - columnar epithelium lining ducts becomes stratified squamous epithelium

35
Q

Define hypoplasia

A

Underdevelopment or incomplete development of a tissue or organ at the embryonic stage

36
Q

Define aplasia

A

Complete failure of a specific tissue or organ to develop

37
Q

Define dysplasia

A

Abnormal maturation of cells within a tissue

38
Q

Define atresia

A

Absence or abnormal narrowing of an opening or passage in the body

39
Q

Define involution

A

Normal programmed shrinkage of an organ

Mechanisms Of Disease (4 decks)

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