Cell Adaptation Flashcards by Jade Montgomery

Define cellular adaptation

In response to physiological or pathological stimuli, cells adapt by modifying metabolism (show new steady state) or growth pattern (show structural changes) to better equip them for survival

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What are the three classes of cells once maturity is attained?

Labile cells
Stable cells
Permanent cells

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Define labile cells

Constantly divide to replenish those that are constantly lost
Short lifespan
High mitotic rate

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Examples of labile cells

skin, mucous membranes, bone marrow, lymph nodes

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Define stable cells

Able to divide, but will only do so occasionally
Long Lifespan
Low mitotic rate
These cells need to be specially stimulated to divide

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Examples of stable cells

liver, kidney, glands, smooth muscle

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Define permanent cells

Have lost the ability to divide
Cells need to be maintained for life
Cells are lost progressively
Not replaced by regeneration
No/Little mitotic activity

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Examples of permanent cells

Neurones, cardiac muscle, skeletal muscle

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Striated muscle in an adult is an example of which cell type?

Permanent cells

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What does increased cellular activity mean in terms of cellular adaptations?

Increase in size or number of cells

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What does decreased cellular activity mean in terms of cellular adaptations?

Decrease in size or number of cells

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What does alteration of cell morphology mean in terms of cellular adaptations?

Change in cell differentiation

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What are the 11 types of growth variation?

Hyperplasia
Hypertrophy
Atrophy
Agenesis
Aplasia
Hypoplasia
Metaplasia
Dysplasia
Hamartoma
Choristoma
Neoplasia

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Define Hyperplasia

Hyperplasia is the increase in mass of an organ due to an increase in the number of its specialised constituent cells

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Define physiological hyperplasia

Physiological: endometrium; pubertal/lactating breast

Hormonal: Growth factor dependent enlargement of striated muscle
Compensatory: remaining kidney after nephrectomy

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Define pathological hyperplasia

Mainly due to altered hormones or growth factors

e. g. fibroadenosis of breast; prostate hyperplasia; thyroid hyperplasia
- Reactive: skin callous, lymph nodes/spleen after infection

Define Hypertrophy

Hypertrophy is the increase in mass of an organ due to an increase in the size of its specialised cells

Skeletal muscle of athletes (physiological)
Heart muscle of hypertensive patients (pathological)

Does smooth muscle undergo hyperplasia or hypertrophy?

It undergoes a mixture of both

Define atrophy

Atrophy is the decrease in mass of an organ due to a decrease in the size and/or number of its specialised constituent cells

What is the mechanism of atrophy?

APOPTOSIS

Increase in catabolism of cytoplasmic structural proteins (proteins link with ubiquitin and then degraded by a protease complex)
Removal of organelles by autophagy

Define physiological atrophy and give some examples

INVOLUTION

Uterus after menopause/childbirth
Testes in old age
Thymus gland after childhood

What are the 4 generalised pathological atrophy means and some examples?

MALNUTRITION/STARVATION
- Kwashiorkor - protein deficiency
- Anorexia nervosa
MALIGNANT CACHEXIA
- Malignancy - tumours spread all over body
HYPOPITUITARISM
- Decreased growth hormone secretion
PROGERIA
- Increased ageing rate

Define agenesis

Agenesis is the failure of an organ to develop at all from its primordia
- Complete failure to produce the embryonic cell mass destined to form an organ

3 examples of agenesis

ANENCEPHALY
- Lack of a cerebrum - fatal defect
AGENESIS OF KIDNEY
- unilateral or bilateral
AMELIA
- no limbs - thalidomide

Define aplasia

Aplasia is a sudden cessation of growth leading to decreased mass of tissue and defective development of an organ - Correctly formed embryonic mass fails to differentiate into a well developed organ

Causes of aplasia

- Drug therapy (chemotherapy) - Radiotherapy - Nuclear accidents - Nuclear bomb blasts

What is thymus gland aplasia?

Occurs during childhood, depleted T-cells leading to immunodeficiency

What is bone marrow aplasia?

Depleted blood cells, leading to aplastic anaemia

Define hypoplasia

Hypoplasia is where tissues fail to attain full size (deficient growth) leading to decreased mass of tissue and incomplete development of an organ - Organ-specific structures develop correctly, but are abnormally small and not fully functional

What are 2 examples of hypoplasia

CRYPTOCHIDISM - Maldescended testes causing sterility MICROCEPHALY - Hypoplasia of the brain - neurological deficit

Define metaplasia

Metaplasia is where a fully differentiated adult cell changes into another more resilient, but less specialised, fully differentiated adult cell type in response to chronic injury

What are 3 examples of metaplasia

SMOKERS AIRWAY - CIGARETTES - Normal respiratory epithelium changes to stratified squamous epithelium GALL BLADDER - GALL STONES - Normal columnar epithelium changes to stratified squamous epithelium URINARY BLADDER - URINARY CALCULI - Normal transitional epithelium changes to stratified squamous epithelium

Define dysplasia

Dysplasia is abnormal growth and differentiation with loss of regularity of cells, loss of normal orientation and relationship to one another, i.e. abnormal tissue organisation - Dysplasia leads to a disordered, atypical, defective growth with a compromised function

What are 3 causes of dysplasia

``` ORAL CAVITY - Smoking, ill-fitting dentures, diet SMOKERS AIRWAY - cigarettes CERVIS OF UTERUS - HPV and HSV II infection ```

Define hamartoma

A hamartoma is a focal overgrowth of normal cells in a tissue in which these cells are usually present

Define choristoma (ectopia)

A choristoma is a focal overgrowth of normal cells found in a tissue in which these cells are NOT usually present

What is Meckel's diverticulum?

It is a choristoma It occurs in 2-3% of the population 2-3 cm blind pouch in the ileum; 20-30 cm from the ileocaecal valve A persistence of the omphalomesenteric duct Wall has gastric and pancreatic choristoma

Define neoplasia

Neoplasia is the process which leads to the formation of an abnormal, uncontrolled new growth of tissue, which has no coordinated useful function in the body - The abnormal mass is called a neoplasm (tumour) - The study of neoplasia is termed oncology