519
CHAPTER THIRTEEN
Endocrine System
13.11
STRESS AND ITS EFFECTS (PAGE 513)
Stress occurs when the body responds to stressors
that threaten the maintenance of homeostasis. Stress
responses include increased activity of the sympathetic
nervous system and increased secretion of adrenal
hormones.
1. Types of stress
a. Physical stress results from environmental factors
that are harmful or potentially harmful to tissues.
b. Psychological stress results from thoughts about
real or imagined dangers.
c. Factors that produce psychological stress vary with
the individual and the situation.
2. Responses to stress
a. Responses to stress maintain homeostasis.
b. The hypothalamus controls a general stress
syndrome.
13.12
LIFE-SPAN CHANGES (PAGE 515)
With age, endocrine glands shrink and accumulate ±
brous
connective tissue, fat, and lipofuscin, but hormonal
activities usually remain within the normal range.
1. GH levels even out, as muscular strength declines.
2. ADH levels increase due to slowed breakdown.
3. The thyroid shrinks but control of metabolism
continues.
4. Decreasing levels of calcitonin and increasing levels of
parathyroid hormone increase osteoporosis risk.
5. The adrenal glands show aging-related changes, but
negative feedback maintains functions.
6. Muscle, liver, and fat cells may develop insulin
resistance.
7. Changes in melatonin secretion affect the body clock.
8. Thymosin production declines, hampering infectious
disease resistance.
b. The endocrine portion, called the pancreatic islets
(islets of Langerhans), secretes glucagon, insulin,
and somatostatin.
2. Hormones of the pancreatic islets
a. Glucagon stimulates the liver to produce glucose,
increasing concentration of blood glucose. It also
breaks down fat.
b. Insulin activates facilitated diffusion of glucose
through cell membranes, stimulates its storage,
promotes protein synthesis, and stimulates fat
storage.
c. Facilitated diffusion of glucose into nerve cells
does not depend on insulin.
d. Somatostatin inhibits insulin and glucagon release.
13.10
OTHER ENDOCRINE GLANDS (PAGE 511)
1. Pineal gland
a. The pineal gland is attached to the thalamus near
the roof of the third ventricle.
b. Postganglionic sympathetic nerve ± bers innervate it.
c. It secretes melatonin, part of the regulation of
circadian rhythms.
2. Thymus gland
a. The thymus gland lies posterior to the sternum and
between the lungs.
b. It shrinks with age.
c. It secretes thymosin, which affects the production of
certain lymphocytes that, in turn, provide immunity.
3. Reproductive glands
a. The testes secrete testosterone.
b. The ovaries secrete estrogens and progesterone.
c. The placenta secretes estrogens, progesterone, and
a gonadotropin.
4. The digestive glands include certain glands of the
stomach and small intestine that secrete hormones.
5. Other hormone-producing organs include the heart
and kidneys.
13.1 Introduction
1
Contrast the def
nitions oF
endocrine gland
and
exocrine
gland.
(p. 483)
13.2 General Characteristics of the Endocrine System
2
Explain the specif
city oF a hormone For its target cell
.
(p. 483)
3
List six general Functions oF hormones. (p. 484)
13.3 Hormone Action
4
Explain how hormones can be grouped on the basis oF
their chemical composition. (p. 484)
5
List the steps oF steroid hormone action. (p. 485)
6
List the steps oF the action oF most nonsteroid hormones.
(p. 486)
7
Explain how prostaglandins are similar to hormones and
how they are di±
erent. (p. 491)
CHAPTER ASSESSMENTS
13.4 Control of Hormonal Secretions
8
Diagram the three mechanisms that control hormone
secretion, including negative Feedback. (p. 492)
13.5 Pituitary Gland
9
Describe the location and structure oF the pituitary gland.
(p. 492)
10
List the hormones that the anterior pituitary secretes.
(p. 492)
11
Explain two ways that the brain controls pituitary gland
activity. (p. 494)
12
Releasing hormones come From which one oF the
Following? (p. 494)
a. thyroid gland
b. anterior pituitary gland
c. posterior pituitary gland
d. hypothalamus
previous page 549 David Shier Hole's Human Anatomy and Physiology 2010 read online next page 551 David Shier Hole's Human Anatomy and Physiology 2010 read online Home Toggle text on/off