Intro - hypertrophy, hyperplasia, metaplasia, dysplasia

Question 1

Hypertrophy

Answer 1

Increase in size of a tissue due to increase in size constituent cells

Question 2

Physiological example of hypertrophy

Answer 2

exercise
- muscle and LV hypertrophy
Uterine smooth muscle hypertrophy at puberty and pregnancy (triggered by oestrogens)

Question 3

Pathological example of hypertrophy

Answer 3

Hypertension

Cells that can’t divide can only get bigger by hypertrophy e.g. heart

Question 4

For muscles, which is stronger: myofibril hypertrophy or sarcoplasmic hypertrophy?

Answer 4

Myofibril hypertrophy makes the muscles stronger.

Sarcoplasmic hypertrophy makes the muscles look bigger but they aren’t really stronger.

Question 5

What happens in hypertrophy?

Answer 5

Increase in intracellular protein.

No division

Question 6

Hyperplasia

Answer 6

Increase in size of tissue caused by increase in number of constituent cells by mitosis

Atypical hyperplasia can = pre cancerous

Question 7

Examples of hyperplasia

Answer 7

Benign or malignant hyperplasia of the smooth muscle in the prostate
Too much oestrogen in comparison to progesterone -> endometriosis
Hyperplasia of bone marrow cells that produce RBCs in people living at high altitudes (stimulated by EPO and is compensatory)
Mix of hypertrophy and hyperplasia in pregnancy at the smooth muscle of the uterus
Hyperplasia is important in repair e.g. of vascular endothelial cells or regeneration of specialise cells

Question 8

Atrophy

Answer 8

Decrease in size of tissue or cell caused by decrease in number of constituent cells or decrease in their size or both
Often by mechanisms involving apoptosis

Question 9

Causes of atrophy

Answer 9

• Reduction in requirement of that function (e.g. in development the Wollfian or Mullerian ducts atrophy or thymus atrophies with age)(e.g. immobilised limbs - body perceives reduced function)
• Hormones
• Loss of endocrine stimulation
• Lack of nutrition (atrophy of adipose tissue)
• Pressure
• Loss of innervation or blood supply

Question 10

Metaplasia

Answer 10

Change in differentiation of a cell from one fully-differentiated type to a different fully-differentiated type.

Occurs in response to alterations in the cellular environment e.g. Barrett’s oesophagus (squamous to columnar due to presence of acid)

Question 11

Dysplasia

Answer 11

Imprecise term for morphological changes seen in cells in the progression to becoming cancer
(abnormal size, shape and organisation)
Can also mean lack of development e.g. dysplasia in bones where the bones don’t develop properly

Question 12

Plasia

Answer 12

= Growth

Question 13

Hypoplasia

Answer 13

Can be used interchangeably with atrophy
BUT better used for failure in attainment of normal size/shape of an organ due to a developmental failure therefore, it is a failure in morphogenesis

Question 14

Morphogenesis

Answer 14

complex process of development of structural shape and form of organs/limbs etc from primitive masses