Interactions and pathologies

Question 1

what is synergism

Answer 1

different hormones that have the same effect on the body via different cellular mechanisms have a greater effect than the sum of their separate effects on the body

Question 2

what is thought to be the reason for synergism

Answer 2

overlapping effects on second messenger systems

Question 3

what is permissiveness

Answer 3

a hormone that cannot fully exert its effects unless a second hormone is present

Question 4

what is an example of permissiveness

Answer 4

for sexual maturation to occur thyroid hormone must be present, thyroid hormone is also responsible for epinephrine efficacy

Question 5

what is antagonism

Answer 5

action of one hormone opposes the effect of another hormone

Question 6

what may hormones with antagonistic actions do

Answer 6

compete for same receptor
act through different metabolic pathway (insulin and glucagon)
decrease number of receptors for opposing hormone (insulin and growth hormone)

Question 7

what are causes of endocrine pathologies

Answer 7

hormone excess
hormone deficiency
abnormal responsiveness of target tissue to hormone

Question 8

what is hypersecretion

Answer 8

hormonal effects are exaggerated, excess is due to hypersecretion

Question 9

what are the causes of hypersecretion

Answer 9

benign tumours
cancerous tumours
non-endocrine tumours
iatrogenic

Question 10

what causes iatrogenic hypersecretion

Answer 10

exogenous medication replaces and exceeds normal hormone levels, which causes atrophy of gland, cells then shrink and lose their ability to produce ACTH and cortisol

Question 11

what is hyposecretion

Answer 11

too little hormone is secreted
can occur in the hypothalamus, pituitary or endocrine glands

Question 12

what are the causes of hyposecretion

Answer 12

atrophy of the gland (most common)
insufficient dietary iodine

Question 13

what pathways are affected in hyposecretion

Answer 13

negative feedback pathways
trophic hormone levels increase in an attempt to raise levels of hypo-secreted hormones

Question 14

what can downregulation cause

Answer 14

hyperinsulinemia

Question 15

what is an example of transduction abnormalities

Answer 15

testicular feminisation syndrome
androgen receptors are non-functional due to a genetic mutation, androgens produced by developing foetus are unable to influence genitalia development
results in a child who appears female but lacks a uterus and ovaries

Question 16

what is pseudohypoparathyroidism

Answer 16

patient displays signs of low parathyroid hormone, even though blood hormone levels are fine
due to an inherited defect of G-protein where there is no linking of receptor to adenylyl cyclase

Question 17

what are the features of secondary hypersecretion due to a hypothalamic problem

Answer 17

excess amounts of all hormones in pathway (at hypothalamus, pituitary and adrenal cortex)

Question 18

what are the features of secondary hypersecretion due to pituitary problem

Answer 18

normal levels of hypothalamic hormone but excess of all other hormones (at pituitary gland and adrenal cortex)

Question 19

what are the features of primary hypersecretion

Answer 19

due to a problem with adrenal cortex
only excess hormones at end of pathway (adrenal cortex)