Chapter 16
Endocrine System
Composed of:
Glands
 Hormones
 Effector Organs

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Hormone Delivery
Secretion
Interstitial Fluid
Blood
Target Tissues
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Hormone Receptors
•Hormones only
affect target
cells with
specific
membrane
proteins called
receptors
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Endocrine vs Nervous System
Slow acting
 Long lasting

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Fast acting
Short duration
Endocrine vs Nervous System
Endocrine and nervous systems work together
 Endocrine system

» hormones released into the bloodstream travel
throughout the body
» results may take hours, but last longer

Nervous system
» certain parts release hormones into blood
» rest releases neurotransmitters excite or inhibit
nerve, muscle & gland cells
» results in milliseconds, brief duration of effects
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General Functions of
Hormones

Help regulate:
»
»
»
»
extracellular fluid
metabolism
biological clock
contraction of cardiac &
smooth muscle
» glandular secretion
» some immune functions


Growth & development
Reproduction
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Endocrine Glands Defined

Exocrine glands
» secrete products into ducts which empty into body cavities or
body surface
» sweat, oil, mucous, & digestive glands

Endocrine glands
» secrete products (hormones) into bloodstream
» pituitary, thyroid, parathyroid, adrenal, pineal
» other organs secrete hormones as a 2nd function
– hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach,
liver, small intestine, skin, heart & placenta
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Hormone Classifications:

1. Protein based (polypeptides).
example = human growth hormone

2. Lipid based (steroidal).
example = testosterone
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Regulation of Hormones:
Negative-feedback mechanism.
 Non-hormone substance (ex. blood
glucose and insulin)
 Stimulation by nervous system
 Stimulation by another hormone

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Major Glands and Hormones


Hyothalamus
Pituitary (p 613).
» Secretes 9 major hormones.
» Has two lobes (anterior and posterior)
» Human Growth Hormone (somatotropin, GH).
– Impacts all cells of the body.
– Major role in maturation, protein synthesis, use of fat, and
CHO sparing.
» Prolactin (PRL).
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Major Glands and Hormones

Pituitary
» Thyroid stimulating hormone (TSH).
» Adrenocorticotropic hormone (ACTH).
– (ACTH) - Impacts the adrenal cortex and
regulates adrenal cortex hormone secretion.
» Follicle stimulating hormone (FSH).
» Luteinizing hormone (LH).
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Major Glands and Hormones

Thyroid (p. 620).
» Has two lobes.
» Thyroxine (T4).
» Triiodothyronine (T3).
Impact all cells in the body.
 Increases rate of cellular metabolism,
increases heart rate and force of
contraction.

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Major Glands and Hormones

Parathyroid glands
» Parathyroid Hormone (PTH).
– Calcium balance in the blood.
– Stimulates osteoclasts.
– Enhances reabsorption of calcium by the
kidneys.
– Increases absorption of calcium in the intestine.
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Major Glands and Hormones
Adrenal (cortex and medulla: p. 626).
 Cortex produces:

» corticosteroids,
– Impacts most cells of the body.
– Controls metabolism of all fuels and has an antiinflammatory action.
» mineralocorticoids
– Impacts kidneys causing Na retention and K
excretion. Aldosterone - sodium ion balance.
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Major Glands and Hormones
» Glucocorticoids.
– Impacts most cells of the body.
– Controls metabolism of all fuels and has an antiinflammatory action.
– Cortisol
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Major Glands and Hormones

Androgens
» Impact sex organs.
» Responsible for development of secondary
sexual characteristics.
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Adrenal Medulla

Catecholamines
» Epinephrine
– Impacts most cells of the body.
– Mobilizes glycogen, increases skeletal muscle blood flow,
increases heart rate and contractility, increases oxygen
consumption.
» Norepinephrine
– Impacts most cells of the body through vasoconstriction
which increases blood flow, increases heart rate and
contractility, increases VO2.
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Pancreatic Hormones

Pancreas
» Insulin
– Impacts all cells of the body.
– Regulates blood glucose levels.
– Increases the utilization of glucose and the synthesis of
fat.
» Glucagon
– Impacts all cells of the body.
– Increases blood glucose levels and stimulates the
breakdown of protein and fat.
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Major Glands and Hormones

Ovaries
» Estrogen
– Affects sex organs and adipose tissue.
– Responsible for the development of female secondary
sexual characteristics.
» Progesterone

Testes
» Testosterone
– Affects sex organs and muscles.
– Responsible for the development of male secondary
sexual characteristics.
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Endocrine System and
Exercise

The body’s response and adaptation to
exercise is influenced by the endocrine
system.

The body’s response and adaptation to
exercise also influences endocrine
function.
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Ergogenic Aids

Work or performance enhancing
substances

Includes nutritional supplements, drugs,
etc.
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DSHEA Act of 1994

With passage of DSHEA (Dietary Supplement and
Health Education Act), Congress amended the
FD&C Act to include several provisions that apply
only to dietary supplements and dietary ingredients
of dietary supplements.
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DSHEA Act of 1994


As a result of these provisions, dietary ingredients
used in dietary supplements are no longer subject
to the pre-market safety evaluations required of
other new food ingredients or for new uses of old
food ingredients.
They must, however, meet the requirements of
other safety provisions.
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Bottom Line on DSHEA?





―Health Freedom‖ is for sellers—not buyers!
What’s in a product is dubious
Safety of products is dubious
Claims and marketing often misleading or
fraudulent
Pay-to-be-a-Guinea Pig is the reality!
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“All Natural” = Good???
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“All Natural” substances always good?





Botulism
Aflatoxin
Salmonella
E. coli
Rattlesnake venom
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Poison Ivy
 Nicotine
 Cocaine
 ―Boogers‖
 ...and Bovine
Excrement!!!
 Etc.

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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