Lecture 9 - Hormonal Control During Exercise

Question 1

nervous system vs endocrine system communication

Answer 1

NS

• > electrical communication

ES

• > chemical communication

Question 2

role of endocrine system

Answer 2

• > maintain homeostasis via hormones, that act on target cells
• > maintains homeostasis during exercise

*controls substrate metabolism, regulates fluid and electrolyte balance

Question 3

how are glands stimulated to release hormones

Answer 3

Humeral Stimuli

• > control of hormone release in response to changes in extracellular fluid (i.e. iron blood conc.)

Hormonal stimuli

• > release of hormone in response to another hormone (2ns messenger)

Neural stimuli

• > the NS directly stimulates some glands (fight/flight)

Question 4

what are Steroid hormones and which organs/structures secrete them

Answer 4

• > derived from choloesterol
• > lipid/fat soluble; can diffuse through the membrane

secreted by…

• > adrenal cortex
• > placenta
• > ovaries
• > testes

Question 5

types of hormones

Answer 5

steroid and non-steroid hormones

Question 6

non-steroid hormones

Answer 6

• > not fat soluble; cannot pass through the membrane
• > secreted in bursts
• > secretion is regulated by negative feedback

2 groups

• > protein/peptide hormones
• > amino acid hormones

Question 7

is blood plasma conc. of hormones a good indicator or hormone action?

Answer 7

no

• > cells change sensitivity to hormones and the number of receptors on the cell

Question 8

down/upregulation

Answer 8

Down-regulation

• > decease in the number of receptors during high plasma concentrations (desensitization)

Up-Regulation

• > increase in the number of receptors during high plasma concentrations (sensitization)

Question 9

how are the effects of hormones limited

Answer 9

hormone-specific receptors limit the scope of their effects

• > no receptor on surface = no hormonal effect

Question 10

where do hormones bind to receptors

Answer 10

hormone-receptor complex

Question 11

where are the steroid hormone receptors found?

Answer 11

in the cytoplasm or nucleus of the cell, steroid hormones can cross the membrane

• > hormone-receptor complex will enter nucleus once activated

Question 12

how do non-steroid hormones initiate a response in the cell if then cant cross the membrane

Answer 12

there’s a receptor on the cell membrane that, once activated, will activate a second messenger

• > the 2nd messenger will carryout hormonal effects and increase the hormones effect by activating other messenger

Question 13

prostaglandins

Answer 13

• > 3rd class of (pseudo) hormones
• > derived from arachidonic acid
• > acts as a local hormone, immediate area

* inflammatory response

Question 14

which systems/ glands contribute to the hormonal regulation of metabolism during exercise

Answer 14

endocrine glands are responsible for metabolic regulation during exercise

• > anterior pituitary gland
• > thyroid gland
• > adrenal gland
• > pancreas

*hormones release by these glands affect the metabolism of carbs and fats

Question 15

anterior pituitary gland

Answer 15

• > attached to the inferior hypothalamus
• > 3 lobes (ant, intermediate, post)

- > releases growth hormone (GH)

*GH release is proportional to exercise intensity

Question 16

Thyroid gland

Answer 16

- > secretes T3 and T4

*leads to increase in metabolic rate of al tissues, protein synthesis, # and size of mitochondria, glucose uptake in cell

• > ant. pituitary releases thyrotropin/thyroid stimulating hormone (TSH) which travels to thyroid to stimulate the secretion of T3 and T4

*exercise increases TSH release

Question 17

Adrenal Medula

Answer 17

releases catecholamines (fight/flight)

• > nor/epinephrine (20%/80%)
• > catecholamines release influences BP, HR, BF, respiration, ect.

Question 18

Adrenal Cortex

Answer 18

releases corticosteroids

• > glucocorticoids, mineralcorticoids, and gonadocorticoids

*major glucocorticoid is cortisol

• > which increases gluconeogenesis, FFA mobilization, protein catabolism

Question 19

pancrease

Answer 19

releases insulin and glucagon

Question 20

insulin

Answer 20

decreases blood glucose levels by…

• > increases glucose transport into cell
• > increasing the synthesis of glycogen
• > it counters hyperglycaemia and opposes glucagon

Question 21

glucagon

Answer 21

raises blood glucose by…

• > increasing glyconeogenesis and glycogenolysis
• > counters hyperglycemia

Question 22

adequate glucose during exercise requires…

Answer 22

• > glucose release by the liver and glucose uptake in muscles

Question 23

hormones that increase circulating glucose

Answer 23

• > glucagon
• > epi/norepinephrine
• > cortisol

*also affected by GH and T3 and T4

Question 24

as exercise intensity increases…

Answer 24

• > catecolamine release increases
• > glycogenolysis rate increase
• > muscle glycogen used up before liver glycogen

Question 25

as exercise duration increases…

Answer 25

• > more liver glycogen is utilized

*increased muscle glucose uptake leads to increase liver glucose released

Question 26

triglyceride

Answer 26

FFA + glycerol

Question 27

lipolysis (fat breakdown) is caused by…

Answer 27

lipolysis is stimulated by lipase

• > decreased insulin
• > nor/epinephrine
• > cortisol
• > GH

Question 28

regulation of fat metabolism during exercise

Answer 28

when glycogen is depleted, we need fat energy substrates

• > in response, hormones accelerate fat breakdown (lipolysis)