18
The Endocrine System
ANSWERS TO PRE-LAB ASSIGNMENTS
Pre-Lab Activity 1:
1. a. pineal gland
b. hypothalamus
c. anterior pituitary gland
d. posterior pituitary gland
e. thyroid gland
f. parathyroid glands
g. thymus
h. adrenal cortex
i. adrenal medulla
j. pancreas
k. ovaries
l. testes
2. Pineal gland, hypothalamus, and posterior pituitary
gland should be circled.
3. Endocrine glands are ductless glands that release
hormones into the blood. Exocrine glands are glands
with ducts that release products onto external and
internal body surfaces. Endocrine secretions interact
with target cells. Exocrine secretions do not necessarily interact with target cells.
Pre-Lab Activity 2:
1. a.
b.
c.
2. a.
b.
c.
d.
2
3
1
2
4
3
1
Pre-Lab Activity 3:
1. too little; too much
2. feedback
ANSWERS TO ACTIVITY QUESTIONS
Activity 1
A. Hypothalamus
1. Answers will vary.
2. The hypothalamus regulates blood pressure, hunger, thirst, body temperature, and some reproductive functions.
Additionally, the hypothalamus produces a variety of releasing and inhibiting hormones that regulate the release of
hormones from the anterior pituitary gland.
3. The hypothalamus synthesizes two neurohormones, antidiuretic hormone (ADH) and oxytocin (OXY), which are
stored in the posterior pituitary gland. These are called neurohormones because they are delivered to the posterior
pituitary by the neurons rather than through the bloodstream.
4. Anterior pituitary gland
B. Pituitary Gland
1. Answers will vary.
2. The hypothalamus via the infundibulum
3. Answers will vary, but should include the following: During development, the anterior pituitary gland arises as an
outpocketing of the roof of the mouth and is composed of epithelial tissue; as a result, its cells resemble glandular
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CHAPTER 18 The Endocrine System
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epithelial tissue. The posterior pituitary gland, by contrast, is derived embryologically from an outgrowth of the
diencephalon and consists of nervous tissue.
4. By releasing and inhibiting hormones (tropic hormones) from the hypothalamus (hormonal control)
5. By nerve impulses from the hypothalamus (neural control)
C. Pineal Gland
1. Answers will vary.
2. The epithalamus, which is a portion of the thalamus
3. Melatonin
D. Thymus
1. Answers will vary.
2. Thymosin and Thymopoietin
3. They stimulate the production of T lymphocytes.
E. Thyroid Gland
1. Answers will vary.
2. The isthmus is a narrow piece of tissue that connects the two lobes of the thyroid gland.
3. T3, T4, and calcitonin
F. Parathyroid Gland
1. Answers will vary.
2. Parathyroid hormone
3. Falling calcium ion levels in the blood (humoral control)
G. Adrenal Gland
1. Answers will vary.
2. The adrenal cortex makes up the external portion of the adrenal gland; the adrenal medulla makes up the
internal portion of the adrenal gland.
3. Regulatory hormones from the hypothalamus (corticotropin-releasing hormone) and the pituitary gland (adrenocorticotropic hormone) stimulate release of the hormones.
4. The sympathetic nervous system regulates secretion of hormones from the adrenal medulla.
H. Pancreas
1. Answers will vary.
2. The pancreas contains exocrine acinar cells that secrete digestive enzymes and endocrine islet cells that secrete
hormones.
3. Insulin and glucagon; insulin decreases blood glucose levels, and glucagon increases blood
glucose levels.
4. Insulin and glucagon release is controlled humorally.
I. Testes
1. Answers will vary.
2. Endocrine and reproductive
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3. Testosterone
J. Ovaries
1. Answers will vary.
2. Endocrine and reproductive
3. Estrogens and progesterone
K. Making Connections
Making Connections: Hormones
Connections to
Things I Have Already
Learned
Hormone
Source
Target(s)
Biological Action(s)
Gonadotropinreleasing hormone
(GnRH)
Hypothalamus
Anterior
pituitary (AP)
Stimulates release of FSH
and LH from gonadotropes
FSH and LH are
gonadotropins; they
target the gonads (testes
and ovaries)
Oxytocin
Hypothalamus
Uterus and
mammary
glands
Stimulates uterine smooth
muscle contractions;
stimulates myoepithelial
cells in mammary glands
Produced by the
hypothalamus but stored
in the posterior pituitary
gland
Luteinizing
hormone
Pituitary
gland
Ovary, testis
Stimulates ovary to
produce estrogen and
progesterone; stimulates
testis to produce
testosterone
A gonadotropin
Growth hormone
Pituitary
gland
Bone, muscle,
adipose tissue,
liver, cartilage
Stimulates growth
Acts on the epiphyseal
plate to stimulate bone
growth
T3/T4
Thyroid gland
Bone, muscle,
adipose cells,
liver, etc.
Regulates metabolic rate
and thermoregulation;
promotes growth and
development
Iodine critical for
production of thyroid
hormones
Calcitonin
Thyroid gland
Bone
Decreases blood calcium
levels
Antagonistic to
parathyroid hormone
Parathyroid
hormone
Parathyroid
gland
Bone, kidneys,
small intestine
Increases blood calcium
levels
Antagonistic to calcitonin
Aldosterone
Adrenal cortex
Kidneys
Stimulates cells of the
kidneys to reabsorb sodium
ions
Steroid hormone
Cortisol
Adrenal cortex
Liver, muscle,
Regulates glucose
Synthetic cortisol =
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CHAPTER 18 The Endocrine System
199
adipose cells
metabolism
cortizone
Epinephrine and
norepinephrine
Adrenal
medulla
Heart, lungs,
skeletal muscles,
etc.
Contribute to the
fight-or-flight response
Used to be called
adrenaline and
noradrenaline
Insulin
Pancreas
Liver, muscle,
adipose cells
Stimulate cells to take up
glucose and store it as
glycogen in the liver
Type I diabetics produce
no or insufficient insulin
Glucagon
Pancreas
Liver
Releases glucose from
stored glycogen
Glucagon is released
when “glucose is gone”
Testosterone
Testis
Testis, muscles,
larynx, etc.
Spermatogenesis and
development of male sex
characteristics
Anabolic steroids are
synthetic testosterone
Estrogen
Ovary
Ovaries,
breasts,
adipose cells,
etc.
Female reproductive cycle
and development of female
sex characteristics
Lowers blood cholesterol
Progesterone
Ovary
Ovaries,
breasts,
adipose cells,
etc.
Female reproductive cycle
and development of female
sex characteristics
The pregnancy hormone
Activity 2
1. b. How do the cells of the anterior pituitary and the posterior pituitary differ in appearance?
Cells of the anterior pituitary are more densely packed and stain darker than cells of the poster pituitary that are
more loosely packed.
Suggest a reason for this difference. The anterior pituitary gland is an endocrine gland, whereas the posterior
pituitary is a neuroendocrine gland and contains mostly nervous tissue.
2. What is the function of follicular cells? They secrete thyroglobulin, which enables them to produce T3 and T4
What is the function of colloid? It stores a gelatinous material that is rich in iodine.
What are the cells surrounding the follicles called? Parafollicular cells
Which hormone do these cells secrete? Calcitonin
3. Describe the appearance of the chief cells. Small cells with darkly stained nucleus that takes up most of cell
Which hormone is produced by the chief cells? Parathyroid hormone
4. b. Describe the appearance of the cells in each layer and name the major hormone secreted by each layer.
Zona glomerulosa: round clusters of cells – aldosterone (main mineralocorticoid)
Zona fasciculata: cord-like rows of cells – cortisol (main glucocorticoid)
Zona reticularis: net-like arrangement of cells – androgens
Describe the appearance of the cells in the adrenal medulla. Answers will vary.
Name the hormones produced in the adrenal medulla. Epinephrine and norepinephrine
5. b. Describe the appearance of the acinar cells. Abundant, darkly staining cells
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Describe the appearance of the pancreatic islets.
cells
Which hormone is produced by alpha cells?
Which hormone is produced by beta cells?
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Lightly staining cells clustered among darkly staining acinar
Glucagon
Insulin
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201
Activity 3
1. a. The hypothalamus secretes gonadotropin-releasing hormone (GnRH), which stimulates follicle-stimulating
hormone (FSH) and luteinizing hormone (LH). These hormones then stimulate the release of testosterone. If
testosterone levels are high, GnRH, FSH, and LH secretion will be inhibited.
b. Anabolic steroids have the same inhibitory actions as testosterone (they turn off secretion of GnRH, FSH, and
LH)
c. Synthetic testosterone exerts a negative feedback effect on the hypothalamo-hypophyseal axis lowering GnRH,
FSH, and LH secretion, which are necessary for sperm production.
d. If he stops taking the anabolic steroids, his testosterone levels should increase again over time and sperm
production should resume.
2. a. Cushing syndrome
b. Excess levels of cortisol
c. Medications are sometimes used. Also, surgical removal of the adrenal glands or the pituitary may be necessary.
3. a. Hypothyroidism
b. The pituitary is producing more TSH in an effort to stimulate the thyroid gland to produce more thyroid
hormone.
c. Autoimmune disease, medications
d. Daily use of synthetic thyroid hormone at physiologic doses
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ANSWERS TO POST- LAB ASSIGNMENTS
PART I. Check Your Understanding
Activity 1: Exploring the Organs of the Endocrine System
1. Identify the structures of the endocrine organs in the accompanying diagrams.
a.
b.
c.
d.
e.
f.
g.
h.
hypothalamus
posterior pituitary gland
anterior pituitary gland
parathyroid glands
thyroid gland
adrenal medulla
adrenal cortex
pancreas
2. Match each of the following endocrine organs to the hormone(s) that it produces.
5, 10
12, 13, 15
2, 6, 17
9
3, 18
4
8, 11, 14
1
7
a.
b.
c.
d.
e.
f.
g.
h.
i.
thyroid gland
pituitary gland
hypothalamus
pineal gland
pancreas
parathyroid gland
adrenal gland
ovary
testis
1.
2.
3.
4.
5.
6.
7.
8.
9.
estrogen
oxytocin
glucagon
parathyroid hormone
calcitonin
thyroid-releasing hormone
testosterone
aldosterone
melatonin
10.
11.
12.
13.
14.
15.
16.
17.
18.
T3
epinephrine
prolactin
T4
cortisol
growth hormone
somatostatin
antidiuretic hormone
insulin
Activity 2: Examining the Microscopic Anatomy of the Pituitary Gland, Thyroid Gland,
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CHAPTER 18 The Endocrine System
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Parathyroid Gland, Adrenal Gland, and Pancreas
1. adrenal gland
a. zona reticularis
b. zona glomerulosa
c. zona fasciculata
2. pancreas
d. acinar cells
e. islet cells
3. thyroid gland
f. colloid
g. follicle cells
h. parafollicular cells
4. Match each of the following cell types to the hormone(s) that it produces.
204
3
a. beta cells
1. parathyroid hormone
6
b. follicle cells
2. epinephrine
4
c. parafollicular cells
3. insulin
1
d. chief cells
4. calcitonin
5
e. neuroendocrine cells
5. oxytocin
2
f. chromaffin cells
6. thyroid hormones
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Activity 3: Investigating Endocrine Case Studies: Clinician’s Corner
1. Synthetic testosterone exerts a negative feedback effect on the hypothalamic-hypophyseal axis resulting in a
decrease in FSH + LH, which are both necessary for sperm production.
2. Cortisone (synthetic cortisol) is used to treat inflammation. Too much cortisone suppresses the immune system.
3. TSH stimulates the thyroid gland to release T3 and T4 . Rising T3 /T4 levels exert a negative feedback
effect on TSH release: with hypothyroidism, no such negative feedback occurs due to follicular cells being unable to
produce adequate T3 or T4 amounts, so TSH release increases to stimulate the thyroid to produce more T3 and T4
PART II. Putting It All Together
A. Review Questions
Answer the following questions using your lecture notes, your textbook, and your lab notes.
1.
Adrenal gland
Endocrine organ only,
although the adrenal
medulla is composed of
modified sympathetic
postganglionic cells
Adrenal gland and
pituitary gland
Pituitary gland
Both contain two portions
Neuroendocrine organ
One portion is controlled
both by hormones and the
other by nerve impulses
Hangs from brain by the
infundibulum
Both endocrine glands have
portions with nervous tissue
(posterior pituitary and
adrenal medulla)
Adrenal cortex arranged
into three distinct layers
2. Complete the following chart.
Hormone
Specific Source
Control of Release
Oxytocin
Neurosecretory cells of the
hypothalamus
Nerve impulses traveling from hypothalamus
to posterior pituitary
Insulin
Beta cells of pancreas
High blood glucose levels
T3 and T4
Follicle cells of thyroid gland
TSH from anterior pituitary
Epinephrine
Adrenal medulla
Sympathetic nerve fibers
Prolactin
Anterior pituitary
Releasing hormone from hypothalamus
Aldosterone
Adrenal cortex (zona
glomerulosa)
ACTH from anterior pituitary
Antidiuretic hormone
Neurosecretory cells of the
hypothalamus
Nerve impulses traveling from hypothalamus to
posterior pituitary
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Parathyroid hormone
Chief cells of parathyroid gland
Low blood calcium levels
Growth hormone
Anterior pituitary
Releasing factor from the hypothalamus
Estrogen
Growing follicle in ovary
FSH from the anterior pituitary gland
Cortisol
Cells of the zona fasciculata
ACTH from the anterior pituitary gland
B. Concept Mapping
1. Fill in the blanks to complete this concept map outlining the regulation of reproductive hormone function.
Anterior pituitary gland
gonadotropins
hypothalamus
testis
testosterone
2. Construct a unit concept map to show the relationships among the following set of terms. Include all of the terms in
your diagram. Your instructor may choose to assign additional terms.
adrenal cortex
parafollicular cells
chromaffin cells
parathyroid gland
chief cells
zona glomerulosa
estrogen
neurosecretory cells
oxytocin
prolactin
Answers will vary.
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