Chapter 5: Cell Signaling and the Hormonal Responses to Exercise

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 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 93

  • Blood Hormone Concentration 94

  • Hormone–Receptor Interaction 95

• Hormones: Regulation and Action 98

  • Hypothalamus and the Pituitary Gland 98

  • Thyroid Gland 101

  • Parathyroid Gland 102

  • Adrenal Gland 102

  • Pancreas 106

  • Testes and Ovaries 106

• Hormonal Control of Substrate Mobilization during Exercise 111

  • Muscle-Glycogen Utilization 111

  • Blood Glucose Homeostasis during Exercise 114

  • Hormone–Substrate Interaction 120

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

cyclic AMP

diabetes mellitus

diacylglycerol

endocrine glands

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

neuroendocrinology

norepinephrine (NE)

pancreas

phosphodiesterase

phospholipase C

pituitary gland

posterior pituitary gland

prolactin

protein kinase C