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Pathological Processes * > S7 Cellular Adaptation > Flashcards

S7 Cellular Adaptation Flashcards

1
Q

What is cell population dependent on?

A
  • rate of cell proliferation
  • rate of cell differentiation
  • rate of cell death by apoptosis
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2
Q

Can cell proliferation be physiological, pathological or both?

A

Both

Excessive physiological stimulation becomes pathological e.g. benign prostatic hypertrophy

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3
Q

What controls cell proliferation?

A
  • proto-oncogenes and tumour suppressor genes regulate normal cell proliferation
  • chemical mediators/signal from the micro environment -simulate or inhibit
  • signalling molecules bind to receptors (cell membrane, cytoplasm, nucleus) leading to modulation of gene expression
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4
Q

What are the check points in mitosis?

A

Control mechanisms in the cell cycle

  • G1 checkpoint - as enter S stage
  • G2 checkpoint - as enter M stage
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5
Q

What is the restriction point?

A

The most critical checkpoint and most of the cells that pass the R point will complete the cell cycle (point of no return)

This is the most commonly altered checkpoint in cancer cells

Activation of this checkpoint delays cell cycle and triggers DNA repair mechanisms or apoptosis via p53

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6
Q

What is p53 activated by?

A

Stresses

  • oxidative stress
  • nutrient deprivation
  • hypoxia
  • DNA damage
  • oncogene expression
  • ribosomal dysfunction
  • telomere attrition (reduction)
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7
Q

What does p53 cause?

A
  • metabolism
  • DNA repair
  • apoptosis
  • migration
  • cell cycle arrest
  • autophagy
  • angiogenesis
  • senescence

All of which suppress a tumour

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8
Q

How are cyclins and cycling dependent kinases (CDKs) related?

A

CDKs are activated by binding to cyclins

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9
Q

What is retinoblastoma protein?

A

A protein that usually prevents DNA replication, it is inactivated by phosphorylation by cyclin D/CDK4 complex

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10
Q

What are cyclins/CDK complexes? What are CDK inhibitors?

A

Oncogenes

Tumour suppressor genes

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11
Q

What are the 4 ways cells can adapt?

A
  • hyperplasia
  • hypertrophy
  • atrophy
  • metaplasia
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12
Q

What is hyperplasia? When does it occur?

A

An increase in tissue or organ size due to increased cell numbers
Occurs in labile or stable tissues

When there’s increased functional demand or hormonal stimulation

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13
Q

Is hyperplasia under physiological or pathological control?

A

Physiological and it is reversible

But can occur secondary to a pathological cause but the proliferation itself is normal

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14
Q

What do repeated cell divisions expose the cell to?

A

The risk of mutations and neoplasia

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15
Q

What are two examples of physiological hyperplasia?

A
  • proliferation endometrium under influence of oestrogen e.g. menstrual period
  • bone marrow producing erythrocytes in response to hypoxia
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16
Q

What are two examples of pathological hyperplasia?

A
  • eczema/psoriasis

* thyroid goitre in iodine deficiency

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17
Q

What is hypertrophy? When does it occur?

A

An increase in tissue or organ size due to increased cell size
Occurs in labile, stable and PERMANENT tissues

If there’s increased functional demand or hormonal stimulation

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18
Q

What happens to the structural components of a cell during hypertrophy? What is the advantage of this?

A

Amount of structural components increase - it means the workload is shared by a greater mass of cellular components

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19
Q

When does hypertrophy usually occur alongside hyperplasia?

A

When the tissues are labile or stable

20
Q

What are two physiological examples of hypertrophy?

A
  • skeletal muscle mass increase from exercising

* pregnancy - uterus increases due to hypertrophy and hyperplasia

21
Q

What are two pathological examples of hypertrophy?

A
  • right/left ventricular hypertrophy due to e.g. stenosis of vessels/damage to valves
  • if there is obstruction of the urethra, the bladder has to expand to allow for the build up of urine
22
Q

What organ undergoes hypertrophy in athletes?

A

The heart

23
Q

What is compensatory hypertrophy?

A

For example, if a kidney is removed/isn’t functioning, the other kidney takes on an increased workload and undergoes hypertrophy

24
Q

What is atrophy?

A

Shrinkage of a tissue/organ due to an acquired decrease in size and/or number of cells - can lead to death - theres a reduced number of structural components in the cells

25
Q

Is tissue atrophy only a result of cell atrophy?

A

No - also due to apoptosis

Tissue atrophy is reversible up to a point

26
Q

What is an example of physiological atrophy?

A

After pregnancy, the womb shrinks again

27
Q

What can cause pathological atrophy?

A
  • reduced functional demand/workload - disuse
  • loss of innervation
  • ischaemia
  • inadequate nutrition
  • loss of endocrine stimuli
  • persistent injury
  • ageing- senile atrophy
  • pressure
  • toxic agents and drugs
  • xrays
  • immunological mechanisms -
28
Q

What can undergo atrophy due to disuse?

A

Muscles - this is reversible

29
Q

What can undergo atrophy due to denervation?

A

muscles e.g. hand muscle wastage after median nerve damage

30
Q

When can atrophy occur due to inadequate blood supply?

A

Thinning of skin on legs due to peripheral vascular disease

31
Q

When can atrophy occur due to inadequate nutrition?

A

Wasting of muscles due to malnutrition

32
Q

What can undergo atrophy due to loss of endocrine stimuli?

A

Breast tissue

Reproductive organs

33
Q

When can atrophy occur due to persistent injury?

A

When there’s inflammation of the muscle - polymyositis

34
Q

What can undergo atrophy due to ageing?

A

Brain

Heart

35
Q

What can undergo atrophy due to pressure?

A

Tissues around an enlarging benign tumour (can be secondary to ischaemia)

36
Q

What is a disease that can occur due to cerebral atrophy?

A

Alzheimer’s disease

37
Q

As well as cells, what also can undergo atrophy?

A

Extracellular matrix

38
Q

What is an immunological mechanism that causes atrophy?

A

Atrophy of gastric mucosa due to pernicious anaemia in which autoantibodies are produced that attack parietal cells

39
Q

What is metaplasia? When does this occur? What can is lead to?

A

Reversible change of one differentiated cell type to another type
Occurs in labile or stable tissues

An adaptive substitution of cells that are sensitive to stress by cell types better able to withstand the adverse environment

Dysplasia and cancer

40
Q

What are two examples of metaplasia?

A
  • bronchial psuedostratified ciliated epithelium are converted to stratified squamous epithelium due to the effects of smoking
  • stratified squamous epithelium are converted to gastric glandular epithelium due persistent acid reflux (Barrett’s oesophagus)
41
Q

What is aplasia? What are examples?

A

The complete failure of a specific tissue/organ to develop - embryonic developmental disorder
Can also be used to describe an organ whose cells have ceased to proliferate

  • thymic aplasia - results in infections and autoimmune problems
  • aplasia of a kidney
  • aplasia or bone marrow in aplastic anaemia
42
Q

What is hypoplasia?

A

Underdevelopment or incomplete development of a tissue/organ at embryonic stage results in an inadequate number of cells

It isn’t the opposite of hyperplasia, as hypoplasia is congenital

43
Q

What are some examples of hypoplasia?

A
  • renal
  • breast
  • testicular (Klinefelter’s syndrome)
  • chambers of the heart
44
Q

What is involution? Give two examples.

A

It is the normal programmed shrinkage of an organ

  • uterus after childbirth
  • thymus in early life
45
Q

What is reconstitution? Give examples of this is humans.

A

Replacement of a lost part of the body

  • finger nails
  • hair
  • angiogenesis
46
Q

What is atresia? What are some examples?

A

A congenital disorder where there is absence or abnormal narrowing of an opening/passage in the body

  • pulmonary valves
  • anus
  • vagina
  • small bowel
47
Q

What is dysplasia?

A

The abnormal maturation of cells within a tissue, it is potentially reversible and is often a pre-cancerous condition

Pathological Processes * (10 decks)

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