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Objectives
By studying this chapter, you should be able to do the following:
Describe the concept of hormone–receptor interaction.
Identify the factors influencing the concentration of a hormone in the blood.
Describe the mechanisms by which hormones act on cells.
Describe the role of the hypothalamus in the control of hormone secretion from the anterior and posterior pituitary glands.
Identify the site of release, stimulus for release, and the predominant action of the following hormones: epinephrine, norepinephrine, glucagon, insulin, cortisol, aldosterone, thyroxine, growth hormone, estrogen, and testosterone.
Discuss the use of testosterone (and its synthetic analogs) and growth hormone on muscle growth and their potential side effects.
Contrast the role of plasma catecholamines with intracellular factors in the mobilization of muscle glycogen during exercise.
Discuss the four hormonal mechanisms by which blood glucose homeostasis is maintained.
Graphically describe the changes in the following hormones during graded and prolonged exercise: insulin, glucagon, cortisol, growth hormone, epinephrine, and norepinephrine.
Describe the effect of changing hormone and substrate levels in the blood on the mobilization of free fatty acids from adipose tissue.
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Outline
Neuroendocrinology
Hormones: Regulation and Action
Hormonal Control of Substrate Mobilization during Exercise
Muscle-Glycogen Utilization
Blood Glucose Homeostasis during Exercise
Hormone–Substrate Interaction
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Key Terms
acromegaly
adenylate cyclase
adiponectin
adrenal cortex
adrenocorticotrophic hormone (ACTH)
aldosterone
alpha receptors
anabolic steroids
androgenic steroid
androgens
angiotensin I and II
anterior pituitary
antidiuretic hormone (ADH)
beta receptors
calcitonin
calmodulin
catecholamines
cortisol
counter-regulatory
cyclic AMP
diabetes mellitus
diacylglycerol
endocrine glands
endocrinology
epinephrine (E)
estrogens
follicle-stimulating hormone (FSH)
G protein
glucagon
glucocorticoids
growth hormone (GH)
hormones
hypothalamic somatostatin
hypothalamus
incretins
inositol triphosphate (IP3)
insulin
insulin-like growth factors (IGFs)
leptin
luteinizing hormone (LH)
melanocyte-stimulating hormone (MSH)
mineralocorticoids
myokine
neuroendocrinology
norepinephrine (NE)
pancreas
phosphodiesterase
phospholipase C
pituitary gland
posterior pituitary gland
prolactin
protein kinase C
receptors
redundancy
releasing hormones
renin
second messengers
sex steroids
somatostatin
steroids
testosterone
thyroid gland
thyroid-stimulating hormone (TSH)
thyroxine (T4)
triiodothyronine (T3)
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Exercise imposes a variety of biological stresses on the body. A vigorous bout of exercise provides numerous challenges including the homeostatic regulation of blood glucose, body temperature, blood pressure, and blood volume. These responses to exercise are the physiologic culmination of localized regulatory factors that impact the major organs in addition to individual tissues and cells within the body. In a healthy individual, the physiologic stresses imposed by exercise are regulated simultaneously through a systemic communication process involving hormones.
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In general terms, hormones are chemical messengers produced in one tissue that signal changes in other organs and tissues throughout the body. Hormones are transported throughout the body via blood where they interact with cellular receptors. The study of hormones, and their effects on the body, is called endocrinology. The endocrine system represents the various body ...