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CHAPTER
1
3
ENDOCRINE SYSTEM
OVERVIEW
The endocrine system, like the nervous system, controls body activities to maintain a relatively constant environment. The
methods used by these two systems are different. The nervous system responds quickly to a perceived change; and the endocrine
system, using chemical messengers, responds more slowly but its effects are longer lasting. After studying this chapter, you will
be able to describe the difference between endocrine and exocrine glands and locate the various glands and the hormones they
secrete (Leaming Outcomes 1, 8-10). You will have mastered information about how hormones function and be able to list the
important functions ofvarious hormones, how hormones are classified, how steroid and nonsteroid honnones affect target cells,
and how hormone secretion is controlled so that homeostasis is maintained (Learning Outcomes 2-7). Finally, you will
understand stress and its effects, the general stress response, and the impact of aging on the endocrine system (Leaming
Outcomes 11-13).
A knowledge ofthe function ofthe endocrine
system is basic to the understanding
ofhow metabolic
processes are regulated to
meet the changing needs ofthe body.
LEARNING OUTCOMES
Atter you have studied this chapter, you should be able to:
13.1
13.2
13.3
13.4
Introduction (p. a83)
1.
Distinguish between endocrine and exocrine glands.
General Characteristics of the Endocrine System @. a83)
2.
Explain what makes a cell a target for a hormone.
3.
List some important functions of hormones.
Hormone Action (p. 484)
Describe how hormones can be classified according to their chemical composition.
4.
5.
Explain how steroid and nonsteroid hormones affect their target cells.
Control of Hormonal Secretions (p.491)
Discuss how negative feedback mechanisms regulate hormone secretion.
6.
7.
Explain how the nervous system controls hormone secretion.
13.5-13.i0 PituitaryGland-OtherEndocrineGlands
Name and describe the locations of the major endocrine glands and list the hormones
8.
9.
Describe the actions of the various hormones and their contributions to homeostasis.
10.
Explain how the secretion of each hormone is regulated.
13.11 StressandltsEffects(p. 513)
Distinguish between physical and psychological stress.
1 1.
12.
Describe the general stress response.
13.12 Life-Span Changes (p. 515)
13.
that they secrete.
Describe some ofthe changes ofthe endocrine system that are associated with aging.
FOCUS QUESTION
How do the functions ofthe nervous system and the endocrine system differ, and how do they complement one another?
MASTERY TEST
Now take the mastery test. Do not guess. Some questions may have more than one coffect answer. As soon as you complete the
test, corect it. Note your successes and faiiures so that you can read the chapter to meet your learning needs.
L
A biochemical secreted by
a cell into
interstitial fluid that eventually reaches the bloodstream and acts on target ceils is
alan
2.
Glands that secrete substances into interstitial fluid and affect only neighboring ceils are
glands.
those that affect oniy the secretory cells are
3.
Glands that release their secretions into ducts that lead to the outside
-.
t26
-
ofthe body
are
glands;
glands.
4.
Glands that controi the rate ofchemical reactions, help transport substances through cell membranes, and help reguiate
fluid and electrolye balance
glands.
5.
6.
List the functions ofendocrine gland hormones.
are
Hormones belong to all of the following chemical families except
a. amines.
b. polysaccharides.
7.
glycoproteins.
c.
d.
peptide hormones.
c.
d.
adrenal gland.
carbohydrates.
a
gland.
gland.
pituitary
th1'roid
protein hormones.
protein hormone is that secreted by the
parathl'roid gland.
Prostaglandins are potent substances that act (locally/systemically).
Steroid hormones influence cells by
a.
b.
12.
hormones.
amine hormones.
steroid
An example of
a.
b.
10.
11.
c.
d.
steroids.
Norepinephrine and epinephrine are examples of
a.
b.
9.
proteins.
Steroid hormones are
a. lipids.
b. proteins.
8.
c.
d.
processes.
reproduction.
c.
d.
altering the cell's metabolic
influencing the rate ofcell
A combination with
a cell membrane binding site that activates an
changing the nature ofcellular protein.
causing special proteins to be synthesized.
activity site is characteristic of
hormones.
13.
Which of the following substances is
a.
b.
14.
c.
d.
adenosinediphosphate
adenosinetriphosphate
c.
d.
the conditions under which it is secreted.
its chemical composition.
Athletes may abuse
cyclic adenosine monophosphate
G protein
type ofmembrane receptors present.
protein substrate molecules in the cell
to increase muscle size and improve athletic performance.
Prostaglandins have hormonelike effects and are thought to act by regulating
a.
b.
17.
common second messenger mediating the action of nonsteroid hormones?
The physiologic action of a hormone is determined by
a.
b.
15.
16.
a
the rate of
mitosis.
the production of cyclic
c.
d.
AMP.
cellular oxidation
the utilization of glucose.
The characteristics ofthe negative feedback systems that regulate hormone secretion include
a.
b.
activation by nerve
impulses.
exertion ofan inhibitory effect on the
c.
d.
giand.
exertion ofa stimulating effect on the gland.
a tendency
for levels ofhormone to
fluctuate.
18.
19.
The part of the brain most closely related to endocrine function is the
The hormones secreted by the anterior lobe ofthe pituitary giand include
a.
b.
20.
21.
c.
d.
th1'roid-stimulatinghormones.
luteinizinghormone.
Nerve impulses from the hypothalamus stimulate the
antidiuretichormone.
ox1-tocin.
lobe of the pituitary gland.
Which of the following are actions of pituitary growth hormone?
a.
enhance the movement of amino acids
through the cell membrane
b.
increase the utilization ofglucose by cells
c.
d.
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increase the utilization offats by cells
enhance the movement of potassium across
the cell membrane
22.
Which of the followine conditions is/are likely to occur when the secretion of growth hormone is low during
childhood?
a.
b.
c.
d.
mental retardation
short stature; weli-proportioned appearance
small, short body; large head
failure to develop secondary sex
characteristics
23.
24.
25.
An adult who suffers from the oversecretion of growth hormone is said to have
The pituitary hormone that stimulates and maintains milk production following childbirth is
Thyrotropin secretion is regulated by
a.
b.
26.
follicles
ofestrogen
growth ofegg
the osmolarity of blood.
c.
d.
production ofprogesterone
TRH secreted by the hypothalamus.
production
production ofsperm cells
Which of the following pituitary hormones helps maintain fluid balance?
c.
d.
a. oxytocin
b. ACTH
28.
c.
d.
Which of the following does follicle-stimulating hormone produce?
a.
b.
27.
homones.
blood sugar levels.
circulating thyroid
antidiuretic hormone
vasopressin
Antidiuretic hormone increases blood pressure by stimulating the contraction of the smooth muscle in blood vessels by
increasing calcium ion concentration.
a.
b.
29.
30.
True
False
The thyroid hormones that affect the metabolic rate are
and
Which of the following are functions of thyroid hormones?
a.
b.
c.
d.
control sodium levels
decrease rate
ofenergy reiease from
carbohydrates
31.
32.
33.
A thyroid dysfunction characterized by exophthalmos, weight loss, excessive perspiration, and emotional instability is
b.
Parathormone enhances the absorption
intestine.
Parathormone stimulates the bone to
ionized
calcium.
of
release
c.
Parathormone stimulates the kidney to
conser,/e calcium.
d.
Parathormone secretion is stimulated by the
thyroiditis.
hlpothalamus.
c.
d.
activity.
disease.
reduced osteociastic
Cushing's
The hormones of the adrenal medulla
are
kidney stones.
hypocalcemia.
and
The adrenal hormone aldosterone belongs to a category ofcorlical hormones called
a. mineralocorticoids.
b. glucocorticoids.
39.
hyperthyroidism.
Injury to or removal ofparathyroid glands is likely to result in
a.
b.
38.
c.
d.
Which of the following statements about parathomone is/are true'?
calcium from the
36.
37.
of
The thy'roid hormone that tends to keep calcium in the bone is
a.
35.
enhance the breakdown and mobilization
fats
The element necessary for normal function of the thyroid gland is
a. simple goiter.
b. m1o<edema.
34.
increase protein synthesrs
c.
sex hormones.
The most important action(s) of corlisol in helping the body overcome stress is/are
a.
inhibition ofprotein synthesis to increase
levels of circulating amino acids.
b.
increasing the release offatty acids and
decreasing the use ofglucose.
the
c.
d.
Adrenal sex hormones are primarily (male/female).
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stimulation ofgluconeogenesis.
conservation of water.
40.
Masculinization ofwomen, elevated blood glucose, decreases in tissue protein, and sodium retention are associated
with
a.
b.
c.
d.
Addison's disease.
hypersecretion of adrenal cortical hormone.
Cushing's disease.
hlposecretion ofadrenal cortical hormone.
41.
The endocrine portion ofthe pancreas is made up ofcells called
42.
The hormone that responds to a low blood sugar by stimulating the liver to convert glycogen to glucose is
43.
The actions of insulin include
44.
45.
a.
enhancing glucose absorption from the small
intestine.
c.
promoting the transport of amino acids out
of the cell.
b.
facilitating the transport ofglucose across
the cell membrane.
d.
increasing the synthesis offats.
Hlpoinsulinism results in a disease called
The endocrine gland(s) that seem(s) to influence circadian rhythms is/are the
a. thymus.
b. pineal gland.
46.
.
48.
c.
d.
seizure disorders.
sudden infant death syndrome.
Thymosin, the secretion of the th)'rnus gland, affects the production of certain white blood ceils known as
Stressors stimulate which of the following endocrine glands?
a.
b.
49.
gonads.
The only valid claim for the use of melatonin supplements is
a. insomnia.
b. autism.
47
c.
c.
d.
islets ofLangerhans
parathyroid glands
adrenal cortex
adrenal medulla
A person experiencing emotional stress is (more/less) likely to develop an infection than an individual with a lower
stress leve1.
50.
The hormone secreted by the kidney is
51.
The most obvious change in endocrine function involves
a.
b.
c.
d.
thyroid function.
declines in an athlete to handle stress.
blood glucose regulation.
sexual function.
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STUDY ACTIVITIES
Definition of Word Parts (p. 482)
Define the following word parts used in this chapter.
cort-
-crin
diuretendo-
exohorm-
hlperhypolactmedparatoc-tropic
vas-
13.1 Introduction (p. a83)
A.
The two systems that regulate body functions to maintain homeostasis are the
svstem.
B.
C.
D.
E.
The two systems involved in maintaining homeostasis (do/do not) coordinate with each other.
The endocrine svstem secretes
Hormones are secreted into the bloodstream and carried to specific cells called
List the glands that are not endocrine glands that also secrete substances that affect body function
13.2 General Characteristics of the Endocrine System fu. a83)
A.
Compare the endocrine and nervous systems in terms of their similarities and differences.
B.
What are the functions of the endocrine system?
130
system and the
13.3 Hormone Action (p.484)
A.
Describe the chemical composition of steroid and nonsteroid hormones
B.
Compare the mechanism of action of steroid and nonsteroid hormones.
C.
List the hormones that require cAMP to function.
D.
Compare hormones and prostaglandins.
What is the role of prostaglandins in the response of target tissue to hormonal stimulation?
F.
How is the knowledge of prostaglandins used in current medical practice?
13.4 Control of Hormonal Secretions (p.491)
A.
Describe a negative feedback system and explain its use in the endocrine system,
B.
What is the role of tropic hormones in regulation of certain hormone levels?
C
What endocrine glands are directly stimulated by the nervous system?
D.
What endocrine glands respond to changes in the composition of the intemal environment?
13.5 Pituitary Gland @. a92)
A.
On the following illustration, identify the numbered parts of the pituitary gland
15
14
131
B.
Fill in the following chart.
Hormones of the Pituitary Gland
Hormone
Source of Control
Actions (Be Specific)
Anterior lobe
Growth hormone
Prolactin
Thy'roid-stimulating hormone
Adrenocorticotropic hormone
Follicle-stimulating hormone
Luteinizing hormone
Posterior lobe
Antidiuretic hormone
Oxytocin
C.
Describe the "pulse secretion" of growth hormone.
D.
Answer the following questions on pituitary dysfunction.
1.
2.
An insufficient amount of growth hormone in childhood is called
3.
4.
5.
An oversecretion ofgrowth hormone during childhood leads to a condition called
How is the condition in question
1 treated?
An oversecretion of growth hormone in an adult leads to
a
condition calied
A disorder of ADH regulation that is manifested by increased urine production is
t32
13.6 Thyroid Gland
A.
On the following illustration of the thyroid gland, label the numbered structures,
B.
Answer the following questions conceming thyroid hormones and their functions.
1.
What element is needed to sl,nthesize th1'roxine and triiodothynonine?
What is the function of thyroglobulin?
C.
3.
What are the functions of thyroxine and triiodothyronine?
4.
What is the function of calcitonin?
Fill in
the lollowing chart.
Disorders of the Thyroid
Disorder
Problems Encountered
Hyperthyroid
Graves' disease
Hypefthyroidism
Hlpothyroid
Hashimoto's disease
Hypothyroidism (infantile)
Hypothlroidism (adult)
Simple goiter
133
13.7 Parathyroid Glands
A.
Where are the parathyroid glands located?
B.
Answer the following concerning parathyroid honnones.
L
Describe how parathormone affects blood levels ofcalcium and phosphorus. Include its effect on bone, the
intestine, and the kidneys.
2.
How does parathormone interact with calcitonin to maintain blood calcium levels?
3.
Why is it important to maintain normal levels of calcium?
13.8 Adrenal Glands
A.
Where are the adrenal glands located?
B.
Answer the following conceming hormones of the adrenal medulla.
C.
1.
List the hormones secreted by the adrenal medulla.
2.
What are the effects of these hormones?
Fill in the following chart.
Adrenocortical Hormones
Zone of the
Cortex
Stimulus for
Secretion
Effects of Hormone
Mineralocorticoids
(e.g., aldosterone)
Glucocorticoids
(e.g., cortisol)
Sex hormones
D.
How do ACE inhibitors lower blood pressure?
E.
What are the symptoms and heatment of Addison's disease? Of Cushing's disease?
134
13.9 Pancreas
A.
B.
L
Where is the pancreas located?
2.
What secretory tissues are found in the pancreas?
3.
Describe the endocrine portion ofthe pancreas.
Fill
in the following charl.
Hormones of the Pancreas
Hormone
Source of Control
Effects of Hormone
Glucagon
Insulin
Somatostatin
C.
Compareinsulin-dependentandnoninsulin-dependentdiabetesmellitus.
13.10 Other Endocrine
Glands
A.
Where is the pineal gland located, and what is its function?
B.
Where is the thymus gland located, and what is its function?
13.11 Stress and Its Effects (p. 51a)
A.
Defrne slress and list the factors that lead to stress.
B.
Describe the body's response to stress. Be sure to include changes in hormone secretion and the positive aspects of the
stress response.
13.12 Life-Span Changes (p. 515)
Describe the effect oflife-span changes on each ofthe endocrine glands.
135
Clinical Focus Question
Based on your knowledge of the endocrine system, what symptoms might an individual who had a tumor of the pituitary gland
experience?
When you have completed the study activities to your satisfaction, retake the mastery test and compare yow performance with
your initial attempt. Ifthere are still areas you do not understand, repeat the appropriate study activities.
136