Cellular Adaptations

Question 1

what is adaptation?

Answer 1

the physiological ability to respond to prolonged exposure to stress agents

Question 2

what is hyperplasia?

Answer 2

• increase in number of cells by mitosis
• leads to increase in size of organ

Question 3

hyperplasia can only take place if cell population is …

Answer 3

capable of replication

Question 4

physiological causes of hyperplasia

Answer 4

• muscle growth due to exercise
• hyperplasia of breat tissue at puberty, lactation & pregnancy - due to hormones like progesterone, oestrogen
• thyroid hyperplasia - due to increased mmetabolic demands during puberty & pregnancy
• growth of some organs after surgical resection e.g. liver transplant

Question 5

pathological causes of hyperplasia - hormone stimulation

Answer 5

• acromegaly due to an increase in growth hormone
• gynaecomastia due to increased oestrogen
• polycythaemia due to increased erythropoietin

Question 6

pathological causes of hyperplasia - chronic irritation

Answer 6

• thickened epidermis due to constant scratching
• bronchial mucous gland hyperplasia in smokers & asthmatics
• cirrhosis of liver in alcoholics

Question 7

pathological causes of hyperplasia - chemical imbalance

Answer 7

• parathyroid gland hyperplasia from long term hypocalcaemia
• thyroid enlargement due to iodine deficiency

Question 8

what is hypertrophy?

Answer 8

• increase in size of current cells
• leads to an increase in size of organ
• no new cells; just bigger cells

Question 9

in hypertrophy tissues are … of dividing

Answer 9

incapable

Question 10

what cells involved in hypertrophy?

Answer 10

• secretory cells
• contractile cells

Question 11

causes of hypertrophy - physiological

Answer 11

any muscle that has an increased functional demand due to workload, not extent of time

Question 12

causes of hypertrophy - pathological

Answer 12

• left ventricular hypertrophy due to increased preload & afterload
• smooth muscle hypertrophy in urinary bladder in response to urethal obstruction
• compensatory hypertrophy of healthy kidney after removal of other kidney

Question 13

what is atrophy?

Answer 13

• decrease in size of abnormally formed tissue/organ
• causing diminished metabolism

Question 14

atrophy - how is metabolism diminished?

Answer 14

• reduction in cell size
• reduction in cell numbers

Question 15

mechanisms of atrophy

Answer 15

• decreased protein synthesis
• increased protein degradation
• loss of cells by apoptosis

Question 16

causes of atrophy - physiological

Answer 16

general underuse of skeletal muscle

Question 17

causes of atrophy - pathological

Answer 17

• tissue hypoxia due to atherosclerosis in carotid arteries
• trissue compression due to pressure from tumours
• cancer
• lack of nutrition with muscle as a source of energy
• skin thinning after prolonged use of steroids

Question 17

what is metaplasia?

Answer 17

• one type of mature cell is replaced by a different type of mature cell
• because new cell is more resistant to a particular stress, better able to withstand adverse environment
• sometimes reversible if irritant is removed

Question 18

causes of metaplasia

Answer 18

• intestinal metaplasia - caused by H.pylori ( increase in goblet & paneth cells )
• squamous metaplasia - induced by toxins ( tobacco )

Question 19

what is dysplasia?

Answer 19

• presence of neoplastic epithelia confined within the basement membrane of the gland

Question 20

most reliable method for dysplasia

Answer 20

microscopic examination

Question 21

likely to be …. rate of cell multiplication and disordered maturation

Answer 21

increased