Download Endocrine and Reproductive Systems

Name
Class
Date
Endocrine and
Reproductive Systems
Homeostasis
Q: How does the body use chemical signals to maintain homeostasis?
WHAT I KNOW
34.1 How does
the body send and
receive chemical
signals?
34.2 What
life processes
are regulated by
hormones?
34.3 What body
structures enable
humans to produce
offspring?
34.4 How does
a human develop
from a single cell to
a newborn baby?
WHAT I LEARNED
SAMPLE ANSWER:
The body has
hormones that carry chemical
signals.
Chemical
messengers called hormones
travel through the blood and
bind to receptors on or in
target cells. Hormones are
produced and released by
endocrine glands.
SAMPLE ANSWER:
Hormones
regulate many life processes
such as reproduction.
SAMPLE ANSWER:
Hormones
regulate many cycles such as
reproductive and sleep cycles.
They also help maintain
homeostasis through
feedback mechanisms that
control temperature, blood
sugar levels, mineral levels in
blood, and water balance.
SAMPLE ANSWER:
Humans have
male and female reproductive
organs that produce sperm
and eggs.
SAMPLE ANSWER:
Human
reproductive organs, ovaries
and testes, are endocrine
glands regulated by pituitary
hormones. These glands
produce hormones that help
produce eggs and sperm and
secondary sex characteristics.
SAMPLE ANSWER:
SAMPLE ANSWER:
The first cell of
a new individual forms from
the fertilization of an egg by
a sperm.
SAMPLE ANSWER:
Following
fertilization, repeated
mitosis and the migration of
cells into three cell layers lead
to the formation of an embryo.
The embryo develops into a
fetus that emerges through the
vagina during childbirth.
Chapter 34 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
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34.1 The Endocrine System
Lesson Objectives
Describe the structure and function of the endocrine system.
Explain how hormones work.
Lesson Summary
Hormones and Glands The endocrine system is made up of endocrine glands that
release hormones into the blood.
▶ Hormones are chemicals made in one part of the body that affect cells in other parts of
the body. Hormones travel throughout the body in the bloodstream.
• Hormones bind to target cells, which are cells that have specific receptors for a
hormone either in the cell membrane or inside the cell.
• A hormone will not affect a cell that does not have receptors for the hormone.
▶ Glands are organs that release secretions. The body has two types of glands.
• Exocrine glands release their secretions through ducts either outside the body or into
the digestive system.
• Endocrine glands release hormones directly into the bloodstream. Other structures
that are not usually considered glands, such as bones, fat tissue, the heart, and the small
intestine, also produce and release hormones.
▶ All cells, except for red blood cells, produce hormonelike substances called
prostaglandins. Prostaglandins are modified fatty acids that usually affect only nearby
cells and tissues. They are sometimes called “local hormones.”
Hormone Action There are two types of hormones.
▶ Steroid hormones are produced from cholesterol. They can cross cell membranes of target
cells, bind with their receptors, and enter the nucleus. The hormone-receptor complexes
change the expression of genes in the target cell, often resulting in dramatic changes in the
cell’s activity.
▶ Nonsteroid hormones can be proteins, small peptides, or modified amino acids. They
cannot cross cell membranes. The receptors for nonsteroid hormones are on the cell
membrane. Compounds called secondary messengers carry the messages of nonsteroid
hormones inside target cells.
Hormones and Glands
For Questions 1–4, write True if the statement is true and False if the statement is false.
True
1. Hormones are chemical messengers that are transported by the
bloodstream.
False
2. Any cell can be a target cell for a hormone.
False
3. The body’s response to hormones is the same as it is for nerve
impulses.
True
4. Insulin and glucagon are two opposing hormones.
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5. Complete the table that summarizes major endocrine glands of the human body.
Gland
Hormone(s) Produced
Function
Parathyroid
Parathyroid hormone
Regulates the level of calcium in
the blood
Pineal
Melatonin
Regulates rhythmic activities
Thyroid
Thyroxine
Regulates the body’s metabolism
Adrenal
Corticosteroids, epinephrine,
norepinephrine
Helps the body respond to stress
Pancreas
Insulin, glucagon
Maintains the level of glucose in the
blood
Ovaries
Estrogen, progesterone
Regulates formation of eggs and
development of secondary female sex
characteristics; prepares uterus for
fertilization
Testes
Testosterone
Regulates production of
sperm and secondary male sex
characteristics
6. What are prostaglandins? How is their action different from that of hormones?
Prostaglandins are modified fatty acids that are produced by nearly every cell and
that act like hormones. They act only on nearby cells and tissues, whereas hormones
can act on target cells throughout the body.
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Hormone Action
7.
Steroid and nonsteroid hormones affect their target cells in different
ways. In the spaces below, draw diagrams that show how each type of hormone affects its
target cells. Be sure to label the cell membrane, cytoplasm, nucleus, the hormones, and
their receptors.
How Steroid Hormones Work
How Nonsteroid Hormones Work
See the textbook for what this drawing
should look like. Drawings should show
the hormone binding with the receptor
complex inside the cell and then entering
the nucleus of the cell.
See the textbook for what this drawing
should look like. Drawings should show
the hormone binding with the receptor on
the cell membrane of the cell.
8. Summarize the action of a steroid hormone on a target cell.
A steroid hormone passes through the cell membrane and binds with a receptor inside
the cell. The hormone-receptor complex then passes into the nucleus. The complex
binds to a region of DNA that controls gene expression. This causes certain genes to
be transcribed into mRNA that goes into the cytoplasm and directs protein synthesis.
9. Summarize the action of a nonsteroid hormone on a target cell.
A nonsteroid hormone binds to a receptor on the cell membrane. This activates
enzymes inside the cell. The enzymes cause the release of secondary messengers, which
are molecules that activate or inhibit cell activities.
10. Compare the release of a hormone to the broadcast of a television commercial.
SAMPLE ANSWER:
A television commercial only affects the behavior of people who are
interested in buying the product the commercial advertises (the target audience). A
circulating hormone only affects the activities of cells with receptors (target cells) for
that hormone. Neither the commercial nor the hormone will affect a “non-target.”
Lesson 34.1 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
532
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34.2 Glands of the Endocrine System
Lesson Objectives
Identify the functions of the major endocrine glands.
Explain how endocrine glands are controlled.
Lesson Summary
The Human Endocrine Glands Endocrine glands are scattered throughout the body.
▶ The pituitary gland is a bean-size structure at the base of the brain. Consisting of two
parts, the anterior pituitary and the posterior pituitary, it secretes hormones that regulate
body functions and control the actions of other endocrine glands.
▶ The hypothalamus controls the secretions of the pituitary gland and is the link between
the central nervous system and the endocrine system. The hypothalamus controls the
posterior pituitary through neurosecretory cells. The hypothalamus produces releasing
hormones that control the secretions of the anterior pituitary.
▶ An adrenal gland sits on top of each kidney. The adrenal glands make hormones that help
the body prepare for and deal with stress. They consist of a cortex and a medulla.
• The adrenal cortex produces more than two dozen corticosteroids, which help
maintain homeostasis.
• The adrenal medulla produces the “fight or flight” hormones epinephrine and
norepinephrine, which help the body respond to stress.
▶ The pancreas is both an exocrine gland and an endocrine gland. As an exocrine gland, the
pancreas releases digestive enzymes.
▶ Insulin and glucagon, hormones produced by the islets of Langerhans in the pancreas,
help keep levels of glucose in the blood stable.
▶ The thyroid gland wraps around the trachea at the base of the neck. The four parathyroid
glands are on the back surface of the thyroid gland. Thyroxine, produced by the thyroid
gland, regulates metabolism. A hormone from the thyroid gland, calcitonin, and one
from the parathyroid glands, parathyroid hormone, work together to maintain blood
calcium levels.
▶ Reproductive glands, or gonads, make gametes and secrete sex hormones. The female
gonads, ovaries, produce eggs. The male gonads, testes, produce sperm.
Control of the Endocrine System Feedback mechanisms involving hormones help
maintain homeostasis. In feedback inhibition, increasing levels of a substance inhibit the
process that produced the substance. Secretions of the hypothalamus and pituitary gland
regulate the activity of other endocrine glands in this way.
▶ Actions of the hypothalamus and posterior pituitary gland regulate water balance. The
hypothalamus signals the posterior pituitary gland to increase (in the case of dehydration)
or decrease (in the case of overhydration) its release of anti-diurectic hormone (ADH). In
response to ADH levels the kidneys produce less or more urine.
▶ The hypothalamus and anterior pituitary regulate metabolism and body temperature by
controlling the amount of thyroxine produced by the thyroid gland.
Lesson 34.2 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
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The Human Endocrine Glands
For Questions 1–4, complete each statement by writing the correct word or words.
brain
1. The pituitary gland is located at the base of the
anterior
Neurosecretory
2.
released by the
posterior
pituitary and the
posterior pituitary
pituitary.
hypothalamus
cells in the
and consists of the
produce hormones that are
.
3. The two hormones released from the posterior pituitary are oxytocin and
antidiuretic hormone .
4. Releasing hormones secreted into blood vessels leading to the
anterior
pituitary control its secretions.
For Questions 5–9, match each pituitary hormone with its action.
Hormone
Action
E
5. MSH
A. Stimulates ovaries and testes
B
6. TSH
B. Stimulates the release of thyroxine
A
7. LH
C. Stimulates release of hormones from adrenal cortex
D
8. GH
D. Stimulates protein synthesis and growth in cells
C
9. ACTH
E. Stimulates melanocytes to increase production of
melanin in the skin
10. Complete the table. Fill in the missing information about each adrenal gland.
Part of the Adrenal Gland
Hormone(s) Produced
Function
Adrenal cortex
Corticosteroids
Regulating blood volume
and pressure, metabolism
Adrenal medulla
Epinephrine,
norepinephrine
Producing “fight or flight”
response
11. How does the pancreas use insulin and glucagon together to control blood glucose levels
in the body?
When blood glucose rises after a person eats, the pancreas releases insulin to promote
the uptake of glucose from the blood. Once the level drops, the pancreas releases glucagon to stimulate the release of glucose into the blood.
12. What is diabetes mellitus?
It is a condition that develops when the pancreas fails to produce insulin or body cells
do not properly respond to insulin.
Lesson 34.2 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
534
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Class
Date
For Questions 13–19, write True if the statement is true. If the statement is false, change the
underlined word or words to make the statement true.
True
iodine
hypothyroidism
True
13. A major role of the thyroid gland is controlling the body’s metabolism.
14. The body needs calcium in order to produce thyroxine.
15. Too little thyroxine leads to a condition called hyperthyroidism.
16. Calcitonin is a hormone produced by the thyroid gland.
thyroid
17. The parathyroid glands are located on the back of the pituitary gland.
True
18. Parathyroid hormone promotes the proper functioning of nerves and
muscles.
gonads
19. The reproductive organs are referred to as gametes.
Control of the Endocrine System
20. What is feedback inhibition?
Feedback inhibition is a process in which an increase in a product slows or stops the
process that produces the product.
21. Complete the flowchart to show how feedback controls regulate the thyroid gland.
Inhibition
Hypothalamus
TRH
Anterior
pituitary
TSH
Thyroid
Thyroxine
22. Explain how feedback control regulates the rate of metabolism.
The hypothalamus produces thyroid-releasing hormone (TRH), which stimulates the
anterior pituitary to produce thyroid-stimulating hormone (TSH), which causes the
thyroid gland to produce thyroxine, which increases the rate of metabolism. Rising
levels of TSH and thyroxine in the blood both cause the hypothalamus to slow or stop
production of TRH, which leads to the slowing of the metabolic rate.
23. Which gland, the hypothalamus or the pituitary gland, should be given the title “master
gland”? Explain your choice.
SAMPLE ANSWER:
The hypothalamus should really be called the “master gland.” Even
though the pituitary gland’s hormones affect many of the body’s organs and functions, the hypothalamus controls the secretions of the pituitary gland.
Lesson 34.2 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
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