Download Chapter Two Line Title Here and Chapter Title Here and Here

CHAPTER
26
Hormones and the Endocrine System
Chapter Objectives
Opening Essay
Explain how testosterone affects male lions.
The Nature of Chemical Regulation
26.1
26.1
26.2
Compare the mechanisms and functions of the endocrine and nervous systems,
noting areas of overlap.
Distinguish between hormones, local regulators, pheromones, and
neurotransmitters.
Distinguish between the two major classes of vertebrate hormones and compare
the two general mechanisms by which hormones trigger changes in target cells.
The Vertebrate Endocrine System
26.3
26.4
Describe the different types of vertebrate endocrine organs noting their specific
functions.
Describe the functions of and interrelationships between the hypothalamus and
the anterior and posterior pituitary glands.
Hormones and Homeostasis
26.5
Describe the functions of the thyroid gland. Describe the symptoms of hypothyroidism, hyperthyroidism, and goiter.
26.6 Explain how the thyroid and parathyroid glands maintain calcium homeostasis.
26.7 Explain how insulin and glucagon manage blood glucose levels.
26.8 Compare the causes and symptoms of type 1 diabetes, type 2 diabetes, and
hypoglycemia.
26.9 Compare the functions of the hormones released by the adrenal medulla and the
adrenal cortex. Describe the benefits and risks of using glucocorticoid drugs.
26.10 Describe the three major categories of sex hormones and their functions.
26.11 Describe the diverse functions of prolactin in vertebrate groups.
Lecture Outline
I. Introduction
A. In lions, the hormone testosterone promotes the development and maintenance of male
traits including
1. growth and maintenance of the mane and
2. increased height and weight.
316
Copyright © 2012 Pearson Education, Inc.
II. The Nature of Chemical Regulation
A. 26.1 Chemical signals coordinate body functions
1. The endocrine system
a. consists of all hormone-secreting cells and
b. works with the nervous system in regulating body activities.
2. The nervous system also
a. communicates,
b. regulates, and
c. uses electrical signals via nerve cells.
3. Comparing the endocrine and nervous systems
a. the nervous system reacts faster.
b. the responses of the endocrine system last longer.
4. Hormones are
a. chemical signals,
b. produced by endocrine glands,
c. usually carried in the blood, and
d. responsible for specific changes in target cells.
5. Hormones may also be released from specialized nerve cells called neurosecretory
cells.
B. 26.2 Hormones affect target cells using two main signaling mechanisms
1. Two major classes of molecules function as hormones in vertebrates.
a. The first class includes hydrophilic (water-soluble), amino-acid-derived
hormones. Among these are
i. proteins,
ii. peptides, and
iii. amines.
b. The second class of hormones are steroid hormones, which include small, hydrophobic molecules made from cholesterol.
2. Hormone signaling involves three key events:
a. reception,
b. signal transduction, and
c. response.
3. An amino-acid-derived hormone
a. binds to plasma-membrane receptors on target cells and
b. initiates a signal transduction pathway.
4. A steroid hormone can
a. diffuse through plasma membranes,
b. bind to a receptor protein in the cytoplasm or nucleus, and
c. form a hormone-receptor complex that carries out the transduction of the hormonal
signal.
III. The Vertebrate Endocrine System
A. 26.3 Overview: The vertebrate endocrine system consists of more than a dozen major
glands
1. Some endocrine glands (such as the thyroid) primarily secrete hormones into the
blood.
2. Other glands (such as the pancreas) have
a. endocrine and
Copyright © 2012 Pearson Education, Inc.
CHAPTER 26
Hormones and the Endocrine System
317
b. nonendocrine functions.
3. Other organs (such as the stomach) are primarily nonendocrine but have some cells
that secrete hormones.
4. The following figure shows the locations of the major endocrine glands.
5. The following table summarizes the main hormones produced by the major endocrine
glands and indicates how they
a. function and
b. are controlled.
6. Two endocrine glands are not discussed further.
a. The pineal gland
i. is pea-sized, located near the center of the brain, and
ii. secretes melatonin, a hormone that links environmental light conditions with
biological rhythms.
b. The thymus gland
i. lies above the heart, under the breastbone, and
ii. secretes a peptide that stimulates the development of T cells.
Key Terms
adrenal cortex
adrenal gland
adrenal medulla
amino-acid-derived
hormones
anterior pituitary
endocrine gland
endocrine system
hormone
hypothalamus
neurosecretory cell
pancreas
parathyroid glands
pineal gland
pituitary gland
posterior pituitary
steroid hormone
thymus gland
thyroid gland
ad- = above; -renal = kidney (adrenal gland: an endocrine gland that sits on top of the kidney and
secretes hormones that regulate the stress response; adrenal medulla: the central portion of an
adrenal gland, controlled by nerve signals; secretes the fight-or-flight hormones epinephrine and
norepinephrine)
andro- = male; -gen = produce (androgens: the principal male steroid hormones, such as testosterone, which stimulate the development and maintenance of the male reproductive system and
secondary sex characteristics)
318
INSTRUCTOR GUIDE FOR CAMPBELL BIOLOGY: CONCEPTS & CONNECTIONS
Copyright © 2012 Pearson Education, Inc.
cortex- = shell (adrenal cortex: the outer portion of an adrenal gland, controlled by ACTH from
the anterior pituitary; secretes hormones called glucocorticoids and mineralocorticoids)
-cortico = the shell (corticosteroid: a steroid sex hormone secreted by the gonads that promotes the
development and maintenance of the male reproductive system and male body features)
endo- = within (endorphin: a pain-inhibiting hormone produced by the brain and anterior pituitary)
epi- = above, over (epinephrine: an amine hormone, also called adrenaline, secreted by the adrenal
medulla that prepares body organs for action)
gluco- = sweet (glucagon: a peptide hormone, secreted by the islets of Langerhans in the pancreas,
that raises the level of glucose in the blood; glucocorticoid: a corticosteroid hormone secreted by
the adrenal cortex that increases the blood glucose level and helps maintain the body’s response to
long-term stress)
glyco- = sugar (hypoglycemia: an abnormally low level of glucose in the blood that results when
the pancreas secretes too much insulin into the blood)
hypo- = below (hypothalamus: the ventral part of the vertebrate forebrain, located below the
thalamus, that functions in maintaining homeostasis, especially in coordinating the endocrine and
nervous systems);
-lact = milk (prolactin: a protein hormone secreted by the anterior pituitary that stimulates milk
production in mammals)
neuro- = nerve (neurosecretory cell: a nerve cell that synthesizes hormones and secretes them into
the blood, and also conducts nerve signals)
para- = beside, near (parathyroid glands: four endocrine glands, embedded in the surface of the
thyroid gland, that secrete parathyroid hormone and raise blood calcium levels)
pro- = before; gest- = carry (progestin: one of a family of steroid hormones produced by the
mammalian ovary that prepare the uterus for pregnancy)
tri- = three; -iodo = violet (triiodothyronine: an amine hormone secreted by the thyroid gland that
stimulates metabolism in virtually all body tissues)
Copyright © 2012 Pearson Education, Inc.
CHAPTER 26
Hormones and the Endocrine System
319