hormonal control exercise

(1)

(2)

(3)

Endocrine Glands

and Their Hormones

•

Several endocrine glands in body; each may

produce more than one hormone

(4)

Hormonal Regulation

of Metabolism During Exercise

•

Major endocrine glands responsible for

metabolic regulation

– Anterior pituitary gland – Thyroid gland

– Adrenal gland – Pancreas

•

Hormones released by these glands affect

(5)

Endocrine Regulation of Metabolism:

Anterior Pituitary Gland

•

Pituitary gland attached to inferior

hypothalamus

•

Three lobes: anterior, intermediate, posterior

•

Secretes hormones in response to

hypothalamic hormone factors

– Releasing factors, inhibiting factors

– Exercise  secretion of all anterior pituitary

(6)

Anterior Pituitary Gland

•

Releases growth hormone (GH)

– Potent anabolic hormone – Builds tissues, organs

– Promotes muscle growth (hypertrophy) – Stimulates fat metabolism

(7)

Endocrine Regulation of Metabolism:

Thyroid Gland

•

Secretes triiodothyronine (T

3

), thyroxine (T

4

)

•

T

3

and T

4

lead to increases in

– Metabolic rate of all tissues – Protein synthesis

– Number and size of mitochondria – Glucose uptake by cells

(8)

Thyroid Gland

•

Anterior pituitary releases thyrotropin

– Also called thyroid-stimulating hormone (TSH) – Travels to thyroid, stimulates T3 and T4

•

Exercise increases TSH release

(9)

Adrenal Medulla

•

Releases catecholamines (fight or flight)

– Epinephrine 80%, norepinephrine 20%

–  Exercise   sympathetic nervous system   epinephrine and norepinephrine

•

Catecholamine release increases

– Heart rate, contractile force, blood pressure – Glycogenolysis, FFA

(10)

Adrenal Cortex

•

Releases corticosteroids

– Glucocorticoids

– Also, mineralocorticoids, gonadocorticoids

•

Major glucocorticoid: cortisol

–  Gluconeogenesis

–  FFA mobilization, protein catabolism

(11)

Endocrine Regulation of Metabolism:

Pancreas

•

Insulin: lowers blood glucose

– Counters hyperglycemia, opposes glucagon –  Glucose transport into cells

–  Synthesis of glycogen, protein, fat

– Inhibits gluconeogenesis

•

Glucagon: raises blood glucose

(12)

Regulation of Carbohydrate

Metabolism During Exercise

•

Glucose must be available to tissues

•

Glycogenolysis (glycogen 

glucose)

(13)

•

Adequate glucose during exercise requires

– Glucose release by liver

– Glucose uptake by muscles

•

Hormones that  circulating glucose

– Glucagon – Epinephrine

(14)

•

Circulating glucose during exercise also

affected by

– GH:  FFA mobilization,  cellular glucose uptake

– T3, T4:  glucose catabolism and fat metabolism

(15)

Metabolism During Exercise

•

As exercise intensity increases

– Catecholamine release 

– Glycogenolysis rate  (liver, muscles)

– Muscle glycogen used before liver glycogen

•

As exercise duration increases

– More liver glycogen utilized

–  Muscle glucose uptake   liver glucose release

(16)

[image:16.720.45.679.86.510.2]

Figure 4.4

(17)

Metabolism During Exercise

•

Glucose

mobilization

only half the story

•

Insulin: enables glucose

uptake

in muscle

•

During exercise

– Insulin concentrations 

– Cellular insulin sensitivity 

(18)

[image:18.720.95.619.81.502.2]

Figure 4.5

(19)

Regulation of Fat Metabolism During

Exercise

•

FFA mobilization and fat metabolism critical

to endurance exercise performance

– Glycogen depleted, need fat energy substrates – In response, hormones accelerate fat breakdown

(lipolysis)

•

Triglycerides 

FFAs + glycerol

– Fat stored as triglycerides in adipose tissue – Broken down into FFAs, transported to muscle – Rate of triglyceride breakdown into FFAs may

(20)

Regulation of Fat Metabolism During

Exercise

•

Lipolysis stimulated by

– (Decreased) insulin – Epinephrine

– Norepinephrine – Cortisol

– GH

(21)

Hormonal Regulation of Fluid and

Electrolytes During Exercise

•

During exercise, plasma volume 

, causing

–  Hydrostatic pressure, tissue osmotic pressure

–  Plasma water content via sweating

–  Heart strain,  blood pressure

•

Hormones correct fluid imbalances

– Posterior pituitary gland – Adrenal cortex

(22)

Electrolytes: Posterior Pituitary

•

Posterior pituitary

– Secretes antidiuretic hormone (ADH), oxytocin – Produced in hypothalamus, travels to posterior

pituitary

– Secreted upon neural signal from hypothalamus

•

Only ADH involved with exercise

–  Water reabsorption at kidneys

(23)

Electrolytes: Posterior Pituitary

•

Stimuli for ADH release

–  Plasma volume = hemoconcentration = 

osmolality

–  Osmolality stimulates osmoreceptors in

hypothalamus

•

ADH released, increasing water retention

by kidneys

(24)

Electrolytes: Adrenal Cortex

•

Adrenal cortex

– Secretes mineralocorticoids

– Major mineralocorticoid: aldosterone

•

Aldosterone effects

–  Na+ retention by kidneys

(25)

Electrolytes: Adrenal Cortex

•

Stimuli for aldosterone release

–  Plasma Na+

–  Blood volume, blood pressure

–  Plasma K+

(26)

Electrolytes: Kidneys

•

Kidneys

– Target tissue for ADH, aldosterone – Secrete erythropoietin (EPO), renin

•

EPO

– Low blood O2 in kidneys  EPO release – Stimulates red blood cell production

(27)

Hormonal Regulation of Fluid and

Electrolytes: Kidneys

•

Stimulus for renin (enzyme) release

–  Blood volume,  blood pressure

– Sympathetic nervous system impulses

•

Renin-angiotensin-aldosterone mechanism

– Renin: converts angiotensinogen  angiotensin I

– ACE: converts angiotensin I  angiotensin II

(28)

[image:28.720.92.617.74.511.2]

Figure 4.8

(29)

[image:29.720.191.544.107.504.2]

Figure 4.9

(30)

Electrolytes: Osmolality

•

Osmolality

– Measure of concentration of dissolved particles (proteins, ions, etc.) in body fluid compartments – Normal value: ~300 mOsm/kg

•

Osmolality and osmosis

– If compartment osmolality , water drawn in

(31)

Hormonal Regulation of Fluid and

•

Aldosterone and osmosis

– Na+ retention   osmolality

–  Osmolality   water retention

– Where Na+ moves, water follows

(32)

•

ADH, aldosterone effects persist for 12 to 48

h after exercise

•

Prolonged Na

+

retention  abnormally high

[Na

+

] after exercise

– Water follows Na+