hormonal control of metabolism

Question 1

which parameters can change to allow adaptation to energy demands?

Answer 1

HR, substrate levels, respiratory rate, ventilatory rate, temperature regulation, fluid homeostasis

Question 2

how does the endocrine system respond to exercise?

Answer 2

slower onset but longer lasting response, can be global

Question 3

what can the targets of hormone release be?

Answer 3

a organ or specific cells in tissues

Question 4

what determines the cellular mechanism of action for a hormone?

Answer 4

chemical structure

Question 5

how is secretion and plasma control of hormones dynamic?

Answer 5

responds to requirements, not constant secretion. may be time limited, over different periods of time or in cycles. often uses a negative feedback loop

Question 6

why do plasma hormone levels not always reflect the activity?

Answer 6

receptor desensitisation

Question 7

what do steroidal hormones do?

Answer 7

alter protein synthesis in the long-term via alteration of gene transcription

Question 8

which glands secrete steroidal hormones?

Answer 8

adrenal cortex - cortisol, aldosterone
ovaries - oestrogen, progesterone
testes - testosterone
placenta - oestrogen, progesterone

Question 9

what are non-steroidal hormones?

Answer 9

large, non-lipid soluble, polar

Question 10

what can non-steroidal hormones be?

Answer 10

peptide or protein hormones - insulin or glucagon

amino acid derived hormones - thyroxine, noradrenaline

Question 11

what are prostaglandins?

Answer 11

a type of hormone/pseudohormone derived from arachidonic acid

Question 12

give an example of a prostaglandin hormone?

Answer 12

thromoxane, which is released from platelets and causes vasoconstriction

Question 13

what is the role of endocrine glands during exercise?

Answer 13

metabolic regulation and metabolism of carbohydrates and fat

Question 14

what hormones increase circulating glucose?

Answer 14

glucagon, adrenaline, noradrenaline, cortisol

Question 15

what occurs as exercise intensity increases?

Answer 15

catecholamine release increases, glyconeogenolysis rate increases in the liver and muscles. muscle glycogen is used before liver glycogen

Question 16

what occurs as exercise duration increases?

Answer 16

more liver glycogen is utilised, there is increased muscle glucose uptake, which causes increased liver glucose release. as glycogen stores decrease, glucagon levels increase

Question 17

how do pancreatic beta cells control release of insulin?

Answer 17

when glucose is high, ATP synthesis is stimulated, this blocks the ATP-sensitive potassium channel, leading to depolarisation and activation of calcium channels. insulin is released via calcium dependent vesicular release

Question 18

how does insulin promote influx of glucose in exercise?

Answer 18

insulin receptor activity stimulates Akt, which causes translocation of vesicles containing GLUT4 to the membrane. greater cell surface expression permits greater influx of glucose.

Question 19

why is GLUT4 preferred in exercise?

Answer 19

GLUT1 is always present at the cell surface, but is not efficient

Question 20

what is the role of pancreatic a-cells?

Answer 20

modulate glucagon release

Question 21

how do pancreatic a-cells respond to low glucose?

Answer 21

Na+ and Ca2+ channels contribute to depolarisation, action potentials stimulate release of glucagon

Question 22

how do pancreatic a-cells respond high glucose?

Answer 22

the Katp is blocked by the presence of increased ATP, Na channels cannot recover from inactivation. there is reduced Ca2+ entry and reduced glucagon release.

Question 23

what process does glucagon stimulate?

Answer 23

glycogenolysis via the Gs/cAMP/PKA mediated pathway

Question 24

what is the functional effect of sympathetic drive in exercise?

Answer 24

adrenaline release -> decreased blood flow to the gut, increased flow to vascular smooth muscle in skeletal muscle. via increase in b-adrenoceptor stimulation, and decrease in a-adrenoceptor stimulation cause vasodilation in skeletal muscle and vasoconstriction in the gut

Question 25

how is the difference in response to the same ligand potentiated between the mesenteric vascular smooth muscle and the skeletal vascular smooth muscle?

Answer 25

in the mesentery, a-adrenoceptors predominate, whereas in the skeletal muscle, B-adrenoceptors predominate.

Question 26

what is the effect of exercise on fat metabolism?

Answer 26

lipolysis, stimulated by decreased insulin, and increased adrenaline, noradrenaline, cortisol and growth hormone

Question 27

where are antidiuretic hormone and aldosterone secreted from?

Answer 27

adh- posterior pituitary gland

aldosterone - adrenal cortex

Question 28

how are ADH and aldosterone utilised to regulate fluid and electrolyte balance?

Answer 28

aldosterone increases water re-absorption

Question 29

what part of the brain is responsible for satiety control?

Answer 29

ventromedial nucleus

Question 30

what part of the brain is responsible for appetite control?

Answer 30

lateral hypothalamus

Question 31

what does cholecystokinin do?

Answer 31

decrease appetite in response to secretion when the stomach is full

Question 32

what does leptin do?

Answer 32

decrease appetite, secreted by the adipose tissue

Question 33

what do Glucagon-like peptide 1 and peptide YY do?

Answer 33

decrease appetite in response to exercise

Question 34

what does ghrelin do?

Answer 34

increase appetite, secreted by intestine