Chapter 5-Cell Signaling and the Hormonal Responses to Exercise

classes of hormones

1. amino acid derivatives

2. peptides/protein

3. steroids

what is the ultimate goal of hormones?

to maintain blood glucose levels

hormones released from the anterior pituitary gland

1. Andrenocorticotropic hormone (ACTH)

2. growth hormone (GH)

hormones released from the posterior pituitary gland

1. antidiuretic hormone (ADH)

what is released from the hypothalamus that inhibits the anterior pituitary from releasing GH?

somatostatin

beta 1 receptor (E or NE?)

E = NE

beta 1 receptor (membrane-bound enzyme)

adenylate cyclase

beta 1 receptor (intracellular mediator)

increase cyclic AMP

beta 1 receptor (effects on various tissues)

increase heart rate

increase glyconeogenesis

increase lipolysis

beta 2 receptor (E or NE?)

E >>>> NE

beta 2 receptor (membrane-bound enzyme)

adenylate cyclase

beta 2 receptor (intracellular mediator)

increase cyclic AMP

beta 2 receptor (effects on various tissues)

increase bronchodilation

increase vasodilation

beta 3 receptor (E or NE?)

NE > E

beta 3 receptor (membrane-bound enzyme)

adenylate cyclase

beta 3 receptor (intracellular mediator)

increase cyclic AMP

beta 3 receptor (effects on various tissues)

increase lipolysis

alpha 1 receptor (E or NE?)

E >/= NE

alpha 1 receptor (membrane-bound enzyme)

phospholipase C

alpha 1 receptor (intracellular mediator)

increase Ca++

alpha 1 receptor (effects on various tissues)

increase phosphodiesterase

increase vasoconstriction

alpha 2 receptor (E or NE?)

E >/= NE

alpha 2 receptor (membrane-bound enzyme)

adenylate cyclase

alpha 2 receptor (intracellular mediator)

decrease cyclic AMP

alpha 2 receptor (effects on various tissues)

-decreases insulin secretion

-opposes actions of B 1/2 receptors

-decrease HR, glyconeogenesis, lypolysis, bronchodilation, vasodilation

what are beta blockers (meds) used for?

meds for heart failure

-don't want the heart ot work harder

which receptor is good for exercise?

beta

which hormones are released from the adrenal cortex?

aldosterone and cortisol

functions of aldosterone

1. controls Na+ reabsorption and K+ secretion

2. regulation of blood volume and blood pressure

how does aldosterone regulate blood volume and pressure?

through the renin-angiotensin-aldosterone system

what is aldosterone stimulated by?

1. increased K+ concentration

2. decreased plasma volume (55% --> 48%)

does aldosterone increase or decrease during exercise?

increase

renin-angiotensis system

1. dehydration, Na+ deficiency, or hemmorrhage

2. decrease in blood volume

3. decrease in blood pressure

4. juxtaglomerular cells of kidneys recognize drop

5. kidneys release renin

6. liver releases angiotensin

7. converted to angiotensin 1

8. angiotensin 1 travels to lungs, acted on my ACE

9. increased angiotensin 2

-acts on adrenal cortex and arterioles

10. angiotensin 2 acts on adrenal cortex

11. increased aldosterone

12. kidneys: increase Na+/water reabsorption, increased secretion of K+/H+ into urine

13. increase blood volume

14. angiotensin also vasoconstricts the arterioles

15. blood pressure increases until returned to normal

besides angiotensin 2, what else can act on the adrenal cortex?

increased K+ in extracellular fluid

what is the main function of cortisol?

to maintain plasma glucose

functions of cortisol

1. promotes protein breakdown for gluconeogenesis

2. simtulates FFA mobilization

3 stimulates glucose synthesis

4. blocks uptake of glucose into cells

by blocking the uptake of glucose into cells, it promotes the use of

FFAs as fuel

cortisol is stimulated by

stress

exercise

bone break

burns

via ACTH

short-term stress response cause

nerve impulses to the adrenal medulla to release E and NE

what are the short-term stress responses?

1. increase HR

2. increase BP

3. liver converts glycogen to glucose and releases into blood

4. bronchodilation

5. vasoconstriction for digestive tract and urine output

6. increase metabolic rate

long-term stress response causes

hypothalamus to release CRH, ACTH to be released from anterior pituitary, adrenal cortex to release mineralocorticoids and glucocoriticoids

mineralocorticoids

aldosterone

glucocorticoids

cortisol

mineralocorticoids cause what type of long-term stress response?

1. retention of Na+/water by kidneys

2. increase BV and BP

glucocorticoids cause what type of long-term stress response?

1. proteins/fats converted to glucose or broken down for energy

2. increase blood glucose

3. suppression of immune system

the pancrease has 2 types of functions

1. exocrine

-secretes in own tubes

2. endocrine

-secretes into blood

the pancreas secretes 2 hormones

1. insulin

-from beta cells

2. glucagon

-from alpha cells

insulin promotes

storage of glucose, amino acids, and fats

lack of insulin causes

DM

glucagon promotes

mobilization of fatty acids and glucose

does insulin or glucagon increase during exercise?

glucagon

are insulin and glucagon fast or slow acting hormones?

fast

insulin and glucagon secretion is influenced by

catecholamines

insulin acts on

1. adipose tissue

2. muscle

3. liver

glucagon acts on

1. adipose tissue

2. liver

characteristics of insulin

1. uptake/storage of glucose and FFA

2. plasma concentration decreases during exercise

3. decrease insulin response post training

characteristics of glucagon

1. mobilization of glucose and FFA fuels

2. plasma concentration increases during exercise

3. decrease response post training

an increase in E/NE causes

decrease in insulin

increase in glucagon

increase plasma FFA

maintain blood glucose (increase)

change in insulin in trained vs untrained individuals

insulin doesn't change as much in trained individuals

trained athletes don't produce as much insulin to have same effect (better insulin sensitivity)

change in glucagon in trained vs untrained individuals

no change in plasma glucagon in trained athletes

-increased glucagon sensitivity

-decreased glucose uptake by muscles

-increase us of fat by muscles

what hormones increase response due to exercise?

E

NE

GH

cortisol

glucagon

what hormone decreases response due to exercise?

insulin

plasma glucose is maintaiend through 4 processess

1. mobilization of glucose from liver glycogen stores**

2. mobilization of FFA from adipose tissue

3. gluconeogenesis from amino acids, lactic acid, and glycerol

4. blocking entry of glucose into cells

2. mobilization of FFA from adipose tissue

spares blood glucose

4. blocking entry of glucose into cells

forces use of FFA as a fuel

slow acting hormones

cortisol and GH

fast acting hormones

E, NE, insulin, and glucagon

out of the fast acting hormones, which ones are released sooner and why?

E and NE because they are neural hormones

DM 1

beta cells don't produce insulin

DM 2

lack of insulin sensitivity