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Pathology I: Test 1 > Lecture 2: Cellular Adaptations > Flashcards

Lecture 2: Cellular Adaptations Flashcards

1
Q

what two changes trigger cells to adapt?

A
  1. Changes due to normal physiological processes and

2. Changes in the environment

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2
Q

Explain why cells are described as ‘adaptable units’

A

Because they have the physiological ability to constantly adapt to changes in it’s environment both internally and external of the body

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3
Q

What is the general term for the mechanism that allows cells to adapt back to ‘normal’ when there is a change in its environment?

A

Homeostatic mechanisms

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4
Q

List the two types of physiological adaptations cells can go through

A
  1. Physiological METABOLIC adaptations

2. Physiological STRUCTURAL adaptations

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5
Q

Describe what a physiological metabolic adaptation of the cell is and give an example.

A

Physiological metabolic adaptations are subtle changes of metabolic function that are finely regulated at biochemical level.
EXAMPLE: If the body goes through a period of fasting, the cellular change that occurs is fatty acids are mobilised from adipose tissue to supply energy.

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6
Q

List the THREE types of physiological structural adaptations the cell can go through

A
  1. Increase in cellular activity
  2. Decrease in cellular activity
  3. Change in cell morphology
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7
Q

What increase/decrease triggers the cell to go through structural adaptations and why?

A
  • There is an increase or decrease of functional demand on tissues
  • There is an increase or decrease of hormonal stimulation of tissue
    Why? So that the cell can withstand changes in its environment better
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8
Q

Define the term pathological stimuli

A

Pathological stimuli are those that trigger severe changes in cellular environment and are often the result of disease

EXAMPLE UV Rays

    • pathological response = blistering and loss of epidermis
  • -physiological response = tanning, melanin production induced
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9
Q

List THREE types of pathological stimuli and their examples:

A
  1. Genetic: gene defects chromosomal defects
  2. Physical agents: mechanical trauma, thermal damage, irradiation
  3. Chemical agents: heavy metal toxicity, solvents, drugs
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10
Q

How does the cell respond to injury caused by exposure to pathological stimuli (metabolic changes)?

A

It goes through a series of metabolic changes:

it decreases expression of unnecessary housekeeping genes and increases expression of cell stress genes.

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11
Q

What are housekeeping genes?

A

They are genes that code for normal structural proteins

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12
Q

What are cell stress genes?

A

They are genes that code for cell-stress proteins which are a set of proteins with cell-organising and protective functions

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13
Q

Why are cell stress proteins produced?

A

They are a rapid response system to pathological stimuli exposure, that are produced to minimise cell damage and ensure cell viability.

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14
Q

What is another name for cell stress proteins and why the name?

A

Heat-shock proteins HSPs

They were initially described in response to a heat shock experiment

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15
Q

Name two heat shock/cell stress proteins

A
  1. Small heat shock proteins

2. Ubiquitin

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16
Q

What is the role of small heat shock proteins and ubiquitin in cell stress response?

A

sHSP: role is to act as a molecular chaperone, and to protect normal or damaged proteins from further damage

Ubiquitin: role is to remove old or damaged proteins; acts as a co-factor for proteolysis

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17
Q

What other protein is formed in response to pathological stimuli

A

Inclusion bodies (it is a protein aggregate made up of abnormal cell constituents and ubiquitin)

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18
Q

Describe inclusion bodies

A

They are visible, permanent masses that appear within the cytoplasm of certain cells that undergo chronic stress.

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19
Q

If cells cannot adapt to changing environment/damaging stimulus what happens?

A

It can lead to failure of cellular function, sublethal cellular damage and eventually cell death

20
Q

Why would cell death occur to a cell during stress response

A

it occurs when pathological stimulus so severe, it overwhelms cell stress response or when the cell is particularly susceptible to pathological stimulus (different cells have varying degrees of susceptibility to diff stimuli)

21
Q

When cellular activity increases due to increase in functional demand, what two specific physiological structural adaptations will the cell go through?

A

It will increase in cell mass, which is by:

  1. Increasing number of cells in tissue and
  2. Increasing size of existing cells in tissue
22
Q

Increasing number of cells in tissue is defined by what word?

A

Hyperplasia

23
Q

Increasing size of the existing cells in tissue is defined by what word?

A

Hypertrophy

24
Q

Compare and contrast hypertrophy and hyperplasia

A

HYPERPLASIA is caused by increase in cell division.
HYPERTROPHY is caused by increase in size of existing cells and at the same time functional capacity.

HYPERPLASIA occurs only in tissues that have the capacity to divide.
HYPERTROPHY occurs in tissues composed of non-dividing cell populations such as skeletal and cardiac muscle and nerve cells.

HYPERPLASIA and HYPERTROPHY may occur independently of each other or together.
The increase in cell mass through these two processes describes both physiological and pathological process.

25
Q

Give a physiological example of organs/tissues increasing their cellular mass due to

  • Hyperplasia and
  • Hypertrophy
A

HYPERPLASIA
Endometrial gland cells increase in number in response to oestrogen (normal menstrual cycle)

HYPERTROPHY
Skeletal muscle fibres increase in size due to exercise

26
Q

Give a pathological example of organs/tissues increasing their cellular mass due to

  • Hyperplasia and
  • Hypertrophy
A

HYPERPLASIA
Increase in number of parathyroid hormone-secreting cells by parathyroid gland (gland controls calcium levels) if serum Calcium abnormally low.

HYPERTROPHY
Cardiac muscle cells of left ventricle (the ventricle that pumps blood to entire body periphery) increases in size to overcome resistance of blood from severe narrowing of aortic valve (which may be due to atheroma formation) thereby increasing blood pressure.
To do this the muscle walls must become stronger bigger to contract harder and to pump adequate blood through to the rest of the body.

27
Q

Compare and contrast UNIFORM and NODULAR hyperplasia

A

Uniform hyperplasia: cell growth in number occurs uniformly throughout all cells of the tissue/organ.

Nodular hyperplasia: uneven cell growth throughout tissue or organ - nodules of excessive cell growth occur between areas of normal tissue - hyperplastic nodules.
Occurs in tissues in which cells are trophic hormone dependent (hormones that have a growth effect onthe tissue it is stimulating).

28
Q

Why does NODULAR hyperplasia occur and give an example of known nodular hyperplasia

A

Occurs due to disturbance in hormone responsiveness of target tissue.
EXAMPLE
Nodular hyperplasia of prostate gland in old age - because urine from the bladder passes through the urethra and the urethra passes through the prostate gland, hyperplastic nodules on the prostate gland may push against the urethra, which leads to problems in frequency of passing urine.

29
Q

What feature of HYPERPLASIA (increased cell number and growth) distinguishes it from NEOPLASIA (formation of new, often abnormal, growth)?

A

In hyperplasia, once the causative (pathological/physiological) stimulus stops, the tissue returns back to a normal pattern of growth, and the pattern of growth is usually quite stable when stimulus still exists.

In neoplasia, excessive cell growth does not decrease once the causative stimulus is removed.

30
Q

To decrease cellular activity due to a decrease in functional demand, what two specific physiological structural adaptation will the cell go through?

A

decrease in cell mass by:

  1. Decreasing number of cells in tissue
  2. Decreasing size of existing cells in tissue
  3. Done by initiating death to already established cells which is called apoptosis.
31
Q

Decreasing number of the existing cells in tissue is defined by what word?

A

Involution.

32
Q

Decreasing size of the existing cells in tissue is defined by what word?

A

Atrophy

33
Q

In regards to cellular metabolism, how does the size/volume of individual cells decrease, and what happens to the cytosolic structural proteins and organelles of those cells?

A

Cellular metabolism is decreased:
The synthesis of structural proteins is decreased by ubiquitin-proteosome system, which increases catabolism of cytosolic structural proteins and removal of organelles by autophagy.

34
Q

Define autophagy

A

It is the digestion of cellular components that are no longer useful such as unwanted cell organelles and other cellular structures.

35
Q

What are the four steps in the autophagy process (the formation of autophagic bodies)

A
  1. Formation of early autophagic body
  2. Formation of autophagic body
  3. late autophagic body: tubulovesicular body formation
  4. Formation of residual body
36
Q

Explain fully the process of eliminating unwanted cell organelles: autophagy

A

FORMATION OF EARLY AUTOPHAGIC BODY
Unwanted cell organelles: enwrapped by membrane derived from endoplasmic reticulum

FORMATION OF AUTOPHAGIC BODY
Early autophagic bodies fuse with vesicles containing lysosomal acid hydrolases - hydrolases cause degradation of organelles

LATE AUTOPHAGIC BODY: TUBULOVESICULAR BODY FORMATION
Shrinking and condensing of autophagic body and becomes electron dense with internal tubular or vesicular profiles

FORMATION OF RESIDUAL BODY
Late autophagic body becomes more electron dense and contains lipofuscin

37
Q

What is lipofuscin?

A

Lipofuscin is named the wear and tear pigment as it is mainly seen in ageing tissues going through cellular atrophy.
It is lamellar undigested lipid-rich cell material found in residual body (late stage autophagic body).
Under light microscopy it is seen as yellow-brown granules.

38
Q

What type of tissue can replace cell mass lost through cellular atrophy and/or involution?

A
  • Adipose tissue

- Fibrous tissue

39
Q

what is the appearance of replacement tissue under the microscope that is found in cellular atrophy?

A

brightly eosinophilic and hyaline

40
Q

Give two PHYSIOLOGICAL and PATHOLOGICAL examples of decreasing cell mass via atrophy/involution

A

PHYSIOLOGICAL

  • myometrium involutes after giving birth (post-partum)
  • skeletal muscle fibres decrease in size due to decrease activity in old age

PATHOLOGICAL

  • ischaemic atrophy: gradual decrease in blood supply to tissue results in loss of functioning cells through involution and cellular atrophy
  • skeletal muscle fibres in leg undergo cellular atrophy when immobilised due to fracture (splint usage)
41
Q

Define metaplasia

A

acquired, reversible transformation from one mature differentiated cell type into another - it usually affects epithelial or mesenchymal cells

42
Q

Why does a cell go through metaplasia?

A

The new type of cell is stable and better equipped to withstand the environmental stress

43
Q

Give two examples of metaplasia - state the name of the original tissue, the metaplastic tissue it transforms to and the stimulus that caused it.

A

OT: Ciliated columnar epithelium of bronchial tree
S: Cigarette smoke
MT: Squamous epithelium

OT: Oesophageal squamous epithelium
S: Gastric acid (heartburn)
MT: Columnar epithelium

44
Q

What regulates structural adaptations of the cell?

A

Growth factors which are various peptides

45
Q

How do growth factors regulate structural cellular adaptations?

A

They act upon specific cell-surface receptors (growth factor receptors)
These receptors then trigger intracellular (secondary) messenger systems with tyrosine kinase activity.
This modulates transcription regulation which directly affects processes of gene regulation/alteration of gene expression in cells

46
Q

What changes do growth factors go through to induce hyperplasia?

A

Growth factors (which are various peptides):

  • Local increase in it’s concentration,
  • Increased expression of growth factor receptors on cells
  • Upregulation of cell signalling system
47
Q

Give three examples of common growth factors

A
  • Epidermal growth factor
  • colony stimulating factors
  • platelet derived growth factor

Pathology I: Test 1 (11 decks)

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