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INTRODUCTION

Objectives

By studying this chapter, you should be able to do the following:

  1. Describe the concept of hormone–receptor interaction.

  2. Identify the factors influencing the concentration of a hormone in the blood.

  3. Describe the mechanisms by which hormones act on cells.

  4. Describe the role of the hypothalamus in the control of hormone secretion from the anterior and posterior pituitary glands.

  5. 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.

  6. Discuss the use of testosterone (and its synthetic analogs) and growth hormone on muscle growth and their potential side effects.

  7. Contrast the role of plasma catecholamines with intracellular factors in the mobilization of muscle glycogen during exercise.

  8. Discuss the four hormonal mechanisms by which blood glucose homeostasis is maintained.

  9. Graphically describe the changes in the following hormones during graded and prolonged exercise: insulin, glucagon, cortisol, growth hormone, epinephrine, and norepinephrine.

  10. Describe the effect of changing hormone and substrate levels in the blood on the mobilization of free fatty acids from adipose tissue.

Outline

Neuroendocrinology

  • Blood Hormone Concentration

  • Hormone–Receptor Interaction

Hormones: Regulation and Action

  • Hypothalamus and the Pituitary Gland

  • Thyroid Gland

  • Parathyroid Gland

  • Adrenal Gland

  • Pancreas

  • Testes and Ovaries

Hormonal Control of Substrate Mobilization during Exercise

  • Muscle-Glycogen Utilization

  • Blood Glucose Homeostasis during Exercise

  • Hormone–Substrate Interaction

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)

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.

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 ...

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