Types of hormones (endocrine system)

Question 1

What are the different anterior pituitary hormones?

Answer 1

• adrenocorticotropic hormone (ACTH/corticotropin)
• TSH
• gonadotropins: LH and FSH
• prolactin
• GH

Question 2

Function of ACTH

Answer 2

target cells: zona fascilulata and zone reticularis of adrenal cortex

stimulate adrenal cortex to secrete cortisol

Question 3

Function of TSH

Answer 3

target cells: thyroid follicular cells

stimulate T3 and T4 secretion

Question 4

Function of LH

Answer 4

stimulate ovulation, corpus luteum development, oestrogen and progesterone secretion for female

stimulate testosterone secretion for male

Question 5

Function of FSH

Answer 5

promote follicular growth and development; stimulates oestrogen secretion for female

stimulates sperm production for male

Question 6

Function of prolactin (PRL)

Answer 6

target cells: female mammary glands

promotes breast development and stimulate milk secretion

Question 7

Function of GH

Answer 7

stimulate growth of muscle, cartilage and bones

regulates metabolism by:
- increasing protein synthesis
- maintaining blood glucose level by decreasing uptake of glucose in peripheral tissues and enhance glucose synthesis in the liver
- mobilising fat store as energy by stimulating triglyceride breakdown and oxidation in adipocytes

GH mechanism mediated by:
- direct effect via GH receptor
- indirect effect via IGF-I from liver and other tissues

Question 8

Function of vasopressin

Answer 8

stimulate insertion of water channels into membranes of kidney tubules > promote H2O reabsorption

high concentration > vasoconstriction

Question 9

Function of oxytocin

Answer 9

stimulate contractions of uterus during labour

stimulate contraction of mammary alveoli > milk ejection

hormone of love and trust

Question 10

Function of aldosterone

Answer 10

stimulate kidneys to reabsorb Na+ and secrete K+

secondary effect: osmotic retention of water and expansion of ECF volume to maintain blood pressure

Question 11

Function of cortisol

Answer 11

adaptation to stress

metabolic effect:
-glucose: stimulate hepatic gluconeogenesis; inhibit glucose uptake and consumption by many tissues but not the brain tissue
- protein: reduces protein stores in all tissues except liver via promoting degradation and inhibiting synthesis
-lipid: increase lipolysis in the limbs and promote fatty acid oxidation

immunosuppressive effects: suppress all aspects of inflammatory response

Question 12

Function of parathyroid hormone (PTH)

Answer 12

stimulated by decrease in blood Ca2+

target cells: bone, kidneys and intestines

increase plasma Ca2+ and decreases plasma PO43- concentration; stimulate vitamin D activation

Question 13

Function of melanopsin

Answer 13

detects light > triggers action potential that is transmitted as nerve impulse to SCN > suppresses melatonin secretion

Question 14

Function of melatonin

Answer 14

hormone that brain produces in response to darkness

helps with timing of circadian rhythms and with sleep

Question 15

Function of thyroid hormones

Answer 15

increase overall basal metabolic rate
- stimulate consumption of glucose and fatty acids and increase metabolic heat
- convert glycogen into glucose and stimulate protein degradation

sympathetic-mimicking effect: increase target cell responsiveness to Epi and NE > increase heart rate and stroke volume

essential for normal growth and promotes maturation of nervous system

Question 16

Function of vitamin D

Answer 16

promote Ca2+ and PO43- absorption from intestine

increase responsiveness of bone to PTH

Question 17

Function of calcitonin

Answer 17

secretion stimulated by high blood Ca2+

acts as physiologic antagonist to PTH:
- inhibits osteoclast activity
- delays calcium absorption form intestine
- increases calcium urinary excretion

used to treat osteoporosis

Question 18

Function of epinephrine

Answer 18

flight or fight response:
- increase rate and strength of cardiac contraction
- dilates blood vessels supplying heart and skeletal muscles exclusively through beta-2 receptor

metabolic response:
- promotes hepatic gluconeogenesis and glycogenolysis and lipolysis
- stimulates glucagon secretion and inhibits insulin secretion

Question 19

Function of insulin

Answer 19

acts on insulin receptors mainly in skeletal muscles, liver and adipose tissues

promotes entry of glucose, amino acids and fatty acids into cells and increase anabolic process

inhibits glycogenolysis, lipolysis and protein degradation