endocrinology

Question 1

what is receptor ?

Answer 1

specific binding site in plasma membrane or interior of target cell with which a chemical messenger combines with it to exert effects

Question 2

what are messengers in endocrine system?

Answer 2

hormones

Question 3

where are receptors for steroid hormones (oestrogen) (lipid soluble)?

Answer 3

inside cell

Question 4

where are receptors for peptide hormones (FSH) and catecholamines (adrenaline)

Answer 4

on plasma membrane

Question 5

how can hormones inflence target cell?

Answer 5

can regulate own receptors, or receptors of other hormones.
up-regulation - increase receptors
down - regulation - decrease in receptors

Question 6

give examples where hormones affect other hormone receptors?

Answer 6

oestrogen in first part of menstrual cycle must be present to prime receptors for progesterone in second half of cycle.
thyroid hormones are needed to up-regulate adrenaline receptors and allow it to release fatty acid from adipose tissue

Question 7

what are agonists?

Answer 7

molecules that bind to receptors and induce post-receptor events - effect
(hormones)

Question 8

what are antagonists?

Answer 8

molecules that bind to receptor and block binding of agonist- fail to trigger intracellular events - no effect

Question 9

what can agonists of hormones be?

Answer 9

drugs

e.g.clomiphene citrate is antagonist of oestrogen

Question 10

what can activity or membrane receptors result in?

Answer 10

receptor-enzyme activity
activity of JAK kinases
G proteins coupled to ion channels and enzymes to generate 2nd messengers such as calcium and cAMP

Question 11

what is speed of responses to receptors?

Answer 11

membrane receptor activity can cause slow(gene transcription) and rapid (phosphorylation) responses on same target slaves.

Question 12

what can activity of intracellular receptors result in?

Answer 12

activation/inhibition of transcription of genes
change in synthesis of proteins coded by those genes
change in rate of protein synthesis or cellular activity

Question 13

what pathways can steroid use?

Answer 13

can bind intracellulary. AND some can also act on membrane receptors - non-genomic response

Question 14

howcan large doses of hormones be used in drugs?

Answer 14

e.g. progesterone in mornign after pill

cortisol to reduce inflammation

Question 15

what are endocrine glands coordinated by?

Answer 15

hypothalamic-hypophyseal axis (hypothalamus - pituitary gland)

linked by portel system and nerves

Question 16

what factors are released by hypothalamus?

Answer 16

thyrotrophin releasing factor
growth hormone releasing/inhibiting factor
corticotrophin releasing hormone (CRH)
GnRH (stimulates LH and FSH production from anterior pituitary cells)
oxytocin
ADH

hypothalamus releases factors that pass to pituitary gland

Question 17

what hormones are released from adenohypophysis?

Answer 17

growth hormone 
prolactin
thyrotrophin
adenocorticotrophin
MSH - melanocyte stimulating hormone)
FSH
LH