Download 6. Hormonal Regulation of Exercise.

Hormonal Regulation of
Exercise
Chapter 21 and 22
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The Endocrine System
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
Gland
Hormone
Target organ or
tissue.
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Hormones
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Hormones can be classified as either
steroidal or nonsteroidal.
» Steroid hormones are lipid soluble, and
most are formed from cholesterol.
» Nonsteroid hormones are proteins,
peptides, or amino acids.
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Hormones
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Hormones are generally secreted into
the blood and then circulate through the
body to exert an effect only on their
target cells.
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Hormones
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Steroid hormones pass through cell
membranes and bind to receptors inside
the cell.
» They use a mechanism called direct gene
activation to cause protein synthesis.
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Hormones
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Non-steroidal hormones cannot enter
cells easily, so they bind to receptors on
the cell membrane.
» This activates a second messenger within
the cell which in turn can trigger numerous
cellular processes.
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Hormones
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Secretion of most hormones is regulated
by a negative feedback system.
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Hormones
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The number of receptors for a specific
hormone can be altered to meet the
body’s demands.
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Hormones
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Key point - the
pituitary gland was
once thought to be
the master
endocrine gland
solely in control of
many other glands
and organs.
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Control
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It is now recognized that the pituitary
gland is largely controlled by the
hypothalamus.
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Hormones
See Table 21.3 (p. 629) for
listing of glands, hormones,
and major function.
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Pituitary Hormones
Anterior Lobe
 Somatotropin (hgH) - Impacts all cells of
the body.
» Major role in maturation, protein synthesis,
use of fat, and CHO sparing.
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Pituitary Hormones
Anterior Lobe
 Andrenocorticotropin (ACTH) - Impacts
the adrenal cortex and regulates adrenal
cortex hormone secretion.
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Pituitary Hormones
Posterior Lobe
 Antidiruretic Hormone (ADH or
vasopressin) - impacts the kidneys.
» Regulates water excretion and blood
pressure by vasoconstriction.
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Thyroid Hormone

Thyroxine and triiodothyronine - Impact
all cells in the body.
» Increases rate of cellular metabolism,
increases heart rate and force of
contraction.
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Adrenal Hormones
Medulla
 Epinephrine - Impacts most cells of the
body.
» Mobilizes glycogen, increases skeletal
muscle blood flow, increases heart rate and
contractility, increases oxygen
consumption.
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Adrenal Hormones
Medulla
 Norepinephrine - impacts most cells of
the body through vasoconstriction which
increases blood flow, increases heart
rate and contractility, increases VO2.
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Adrenal Hormones
Cortex
 Mineralcorticoids (aldosterone) - impacts
kidneys causing Na retention and K
excretion.
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Adrenal Hormones
Cortex
 Glucocorticoids (cortisol) - impacts most
cells of the body.
» Controls metabolism of all fuels and has an
anti-inflammatory action.
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Adrenal Hormones
Cortex
 Androgens and estrogens - impacts sex
organs.
» Responsible for development of secondary
sexual characteristics.
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Pancreatic Hormones
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Insulin - impacts all cells of the body.
» Regulates blood glucose levels.
» Increases the utilization of glucose and the
synthesis of fat.
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Pancreatic Hormones
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Glucagon - impacts all cells of the body.
» Increases blood glucose levels and
stimulates the breakdown of protein and fat.
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Gonadal Hormones
Testes
 Testosterone - affects sex organs and
muscles.
» Responsible for the development of male
secondary sexual characteristics.
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Gonadal Hormones
Ovaries
 Estrogen - affects sex organs and
adipose tissue.
» Responsible for the development of female
secondary sexual characteristics.
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Hormones and Exercise
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Catecholamines - secretion increases.
» Greater increase with intense exercise.
» Secrete more norepinephrine than
epinephrine.
» Secretion increases less after training.
» Significance - increased blood glucose.
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Hormones and Exercise
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Somatotropin - increases with exercise.
» Increases more in unfit person.
» Declines faster in fit person.
» Significance - unknown?
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Hormones and Exercise
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ACTH-cortisol - increases with exercise.
» Greater increase with intense exercise.
» Increases less after submaximal exercise
training.
» Significance - increased gluconeogenesis
in liver.
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Hormones and Exercise
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Testosterone - Increases with exercise.
» Effect - none.
» Significance - unknown?
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Hormones and Exercise
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Insulin - decreases during exercise.
» Decreases less after training.
» Significance - increased stimulus to utilize
blood glucose.
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Hormones and Exercise
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Glucagon - Increases with exercise.
» Increases less after training.
» Significance - increased blood glucose via
glycogenolysis and gluconeogenesis.
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Hormones and Exercise
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Renin-angiotensis-aldosterone Increase with exercise.
» Same after training in rats.
» Significance - Na retention to maintain
plasma volume.
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Hormones and Exercise
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ADH - Increases with exercise.
» Effect - none
» Significance - Causes water retention to
maintain plasma volume.
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Hormones and Metabolism
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Plasma glucose is increased by the
combined actions of glucagon,
epinephrine, norepinephrine, and
cortisol.
» These hormones promote glycogenolysis
and gluconeogenesis, thus increasing the
amount of glucose available for use as a
fuel source.
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Hormones and Metabolism
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Insulin helps the released glucose enter
the cells where it can be used for energy
production.
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Insulin
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But insulin levels decline during
prolonged exercise, indicating that
exercise facilitates the action of insulin
so that less of the hormone is required
during exercise than when at rest.
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Hormones and Metabolism
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When CHO reserves are low, the body
turns more to fat oxidation for energy,
and this process is facilitated by cortisol,
epinephrine, norepinephrine, and growth
hormone.
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Hormones and Metabolism
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Cortisol accelerates lipolysis, releasing
free fatty acids into the blood so they
can be taken up by the cells and used
for energy production.
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Cortisol
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But cortisol levels peak and then return
to near normal levels during prolonged
exercise.
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Hormones and Metabolism:
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When this happens, the catecholamines
and growth hormone take over cortisol’s
role.
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Hormones and Metabolism:
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Key point - Loss of fluid (plasma) from
the blood results in a concentration of
the constituents of the blood, a
phenomenon referred to as
hemoconcentration.
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Hormones and Metabolism:
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Conversely, a gain of fluid into the blood
results in a dilution of the constituents of
the blood, which is referred to as
hemodilution.
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Fluid Balance and Hormones
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The 2 primary hormones involved in the
regulation of fluid balance are
aldosterone and antidiuretic hormone
(ADH).
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Fluid Balance and Hormones:
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When plasma volume or blood pressure
decreases, Angiotensinogen II increases
peripheral resistance, raising the blood
pressure.
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Fluid Balance and Hormones
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Angiotensinogen II also triggers the
release of aldosterone from the adrenal
cortex.
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Aldosterone
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Aldosterone promotes sodium
reabsorption in the kidneys, which in
turn causes water retention, thus
increasing plasma volume.
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Fluid Balance and Hormones
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ADH acts on the kidneys, promoting
water conservation.
» Through this mechanism, the plasma
volume is increased, which results in
dilution of the plasma solutes.
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Anabolic Androgenic Steroids
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Anabolic Androgenic Steroids
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Anabolic Androgenic Steroids
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Anabolic Androgenic Steroids
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Anabolic Androgenic Steroids
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Anabolic Androgenic Steroids
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Anabolic Androgenic Steroids
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