Illinois State University Hormonal Regulation of Exercise Chapter 21 and 22.
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Transcript of Illinois State University Hormonal Regulation of Exercise Chapter 21 and 22.
Illinois State University
Hormones
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.
Illinois State University
Hormones
Hormones are generally secreted into the blood and then circulate through the body to exert an effect only on their target cells.
Illinois State University
Hormones
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.
Illinois State University
Hormones
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.
Illinois State University
Hormones
Secretion of most hormones is regulated by a negative feedback system.
Illinois State University
Hormones
The number of receptors for a specific hormone can be altered to meet the body’s demands.
Illinois State University
Hormones
Key point - the pituitary gland was once thought to be the master endocrine gland solely in control of many other glands and organs.
Illinois State University
Control
It is now recognized that the pituitary gland is largely controlled by the hypothalamus.
Illinois State University
Hormones
See Table 21.3 (p. 629) for listing of glands,
hormones, and major function.
Illinois State University
Pituitary Hormones
Anterior Lobe Somatotropin (hgH) - Impacts all cells of
the body. » Major role in maturation, protein synthesis,
use of fat, and CHO sparing.
Illinois State University
Pituitary Hormones
Anterior Lobe Andrenocorticotropin (ACTH) - Impacts
the adrenal cortex and regulates adrenal cortex hormone secretion.
Illinois State University
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.
Illinois State University
Adrenal Hormones
Medulla Norepinephrine - impacts most cells of
the body through vasoconstriction which increases blood flow, increases heart rate and contractility, increases VO2.
Illinois State University
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
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
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
Catecholamines - secretion increases. » Greater increase with intense exercise.» Secrete more norepinephrine than
epinephrine.» Secretion increases less after training.» Significance - increased blood glucose.
Illinois State University
Hormones and Exercise
Somatotropin - increases with exercise.» Increases more in unfit person.» Declines faster in fit person.» Significance - unknown?
Illinois State University
Hormones and Exercise
ACTH-cortisol - increases with exercise.» Greater increase with intense exercise.» Increases less after submaximal exercise
training.» Significance - increased gluconeogenesis
in liver.
Illinois State University
Hormones and Exercise
Testosterone - Increases with exercise.» Effect - none.» Significance - unknown?
Illinois State University
Hormones and Exercise
Insulin - decreases during exercise.» Decreases less after training.» Significance - increased stimulus to utilize
blood glucose.
Illinois State University
Hormones and Exercise
Glucagon - Increases with exercise.» Increases less after training.» Significance - increased blood glucose via
glycogenolysis and gluconeogenesis.
Illinois State University
Hormones and Exercise
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
ADH - Increases with exercise. » Effect - none» Significance - Causes water retention to
maintain plasma volume.
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Hormones and Metabolism
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
Insulin helps the released glucose enter the cells where it can be used for energy production.
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Insulin
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
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.
Illinois State University
Hormones and Metabolism
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
But cortisol levels peak and then return to near normal levels during prolonged exercise.
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Hormones and Metabolism:
When this happens, the catecholamines and growth hormone take over cortisol’s role.
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Hormones and Metabolism:
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:
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
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:
When plasma volume or blood pressure decreases, Angiotensinogen II increases peripheral resistance, raising the blood pressure.
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Fluid Balance and Hormones
Angiotensinogen II also triggers the release of aldosterone from the adrenal cortex.
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Aldosterone
Aldosterone promotes sodium reabsorption in the kidneys, which in turn causes water retention, thus increasing plasma volume.
Illinois State University
Fluid Balance and Hormones
ADH acts on the kidneys, promoting water conservation.» Through this mechanism, the plasma
volume is increased, which results in dilution of the plasma solutes.