Adaptations Of Cell Growth: Cell Injury Flashcards

1
Q

The cell’s response may be a change in 4 things

A

number
size
phenotype
metabolism
Etc

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2
Q

● Adaptations are a cell’s response to?

A

changes in its environment.

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3
Q

4 types of adaptation and slight explanation

A

• Hyperplasia : increase in cell number
● Hypertrophy : increase in cell size
● Metaplasia : change in cell phenotype
● Atrophy : reduction in cell size/number

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4
Q

Hypertrophy
● Increase in cell size which leads to?
● Seen in cells which?

A
  1. increase in the size of the organ.
  2. cannot multiply by division

May also be seen in cells which undergo division (hyperplasia/hypertrophy)

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5
Q

Hypertrophy Occurs as a result of

A

synthesis of increased structural elements in the affected cells

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6
Q

Can be physiologic or pathologic

● Physiologic hypertrophy results from ______ or ______

A

increased stimulation of the cell by hormones or increased functional demand.

E.g.
skeletal muscle in weightlifters

growth of the uterus in pregnancy.

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7
Q

● Pathologic hypertrophy is a response to _____

Examples include?

A

Disease

In aortic stenosis,
hypertension,
also in hypertrophic cardiomyopathy

when the heart muscle pumps against resistance in certain disease conditions

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8
Q

What is the mechanism of Hypertrophy

A

Increased synthesis of intracellular proteins

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9
Q

The combined actions of _____, ______and g_____ lead to generation of signals which are transmitted into the cell through signal transduction pathways. These signals activate transcription factors which increase?

A

Mechanical sensors
Vasoactive agents
Growth factors

the synthesis of muscle proteins.

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10
Q

Other adaptive changes can occur in hypertrophy. For example?

A

change from alpha to beta isoform of myosin heavy chain, increases expression of atrial natriuretic factor gene in states of cardiac hypertrophy.

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11
Q

Hypertrophy has its limits beyond which the enlargement of muscle mass cannot cope with the stimuli. This may lead to ____ &____

A

fibrosis and myocyte death.

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12
Q

Hyperplasia is?

It may occur together with hypertrophy if the cell is capable of?

A

Increase in the number of cells in a particular organ/tissue

Dividing

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13
Q

Physiologic hyperplasia there’s 2 types
Give examples

A

● Functional: when there is a need to increase functional capacity e.g. breast in puberty/pregnancy.

● Compensatory: need to replace function of damaged cells e.g. liver post-resection and bone marrow after blood loss.

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14
Q

Pathological hyperplasia results from excessive or inappropriate actions of _____ or _____.

Pathologic hyperplasia may be _____

A

hormones or growth factors

Pre cancerous

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15
Q

3 examples of pathologic hyperplasia

A

Endometrial hyperplasia due to increase in estrogen

○ Benign prostatic hyperplasia due to androgen effects

Skin changes in response to viral infections (warts in Human Papillomavirus infections)

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16
Q

Mechanism of hyperplasia

A

Growth factor driven proliferation of existing cells

Increased output of new cells from stem cells

17
Q

Atrophy is ?

● Maybe physiologic or pathologic.

A

Reduction in the size of a tissue or organ due to a reduction in cell size and number

18
Q

Example of physiologic atrophy

A

in regression of uterus to normal size post pregnancy.

19
Q

6 types of pathologic atrophy and explanation

DDINEP

A
  1. Decreased workload (disuse atrophy): e.g. muscle atrophy following fracture/ prolonged bed rest
  2. Denervation atrophy: muscles need nerve stimulation to metabolism and function
  3. Ischaemia : due to atherosclerosis. E.g. senile atrophy in the brain & heart
  4. Inadequate nutrition: skeletal muscle proteins may be used as energy source.
  5. Loss of endocrine stimulation: e.g. breast, uterus
  6. Pressure effects: tissue compression for long periods of time.
    E.g. by a tumour or POP cast (fracture)
20
Q

The purpose of atrophy is to?

A

create a new balance between the cell’s demands and its supply of nutrients/oxygen.

21
Q

3 mechanisms of atrophy

A
  1. Increased degradation and reduced synthesis of proteins.
  2. Protein synthesis is reduced due to the reduction in metabolism
  3. Degradation of protein occurs through the
    ubiquitin-proteasome pathway and through autophagy.
22
Q

Metaplasia is a reversible cell change in which?

But it really is ?

A

one differentiated cell type is replaced by another cell type.

The reprogramming of stem cells to differentiate along a new pathway

23
Q

It is an adaptive change to stress such that_____ replaces _____

● However, the functional effects of the original cell may be lost and these changes may be ______

A

the cell better able to withstand the stress

the cell sensitive to the stress.

Pre cancerous

24
Q

Give the 3 metaplasmic changes and their examples

A
  1. Columnar to squamous epithelial changes:
    - Respiratory tract e.g smokers, Vit A deficiency/excess
    - Excretory ducts e.g. salivary glands, bile duct
  2. Squamous to columnar changes:
    - Oesophagus (Barett’s oesophagus)
  3. Connective tissue metaplasia
    - Myositis ossificans
25
Mechanism of metaplasia is
Reprogramming of stem cells found in that tissue or of undifferentiated mesenchymal cells in surrounding tissues. The environmental stimulants program these cells towards a differentiation pathway These precursor cells differentiate along a new pathway due to the expression of genes induced by external stimuli and transcription factors
26
Effects of metaplasia
Fertile ground for development of malignancy. E.g. is Barrett’s oesophagus leading to sq