Download Chapter 26

Chapter 26
Hormones and the
Endocrine System
PowerPoint Lectures for
Biology: Concepts & Connections, Sixth Edition
Campbell, Reece, Taylor, Simon, and Dickey
Lecture by Edward J. Zalisko
Copyright © 2009 Pearson Education, Inc.
Introduction: Gender Benders
 Endocrine disruptors
– Environmental pollutants
– Interfere with the action of hormones
– Some are estrogen mimics in the environment that may
produce
– Demasculinized male alligators
– Bass with male and female characteristics
– Decrease in size and functioning of polar bear genitalia
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THE NATURE OF
CHEMICAL
REGULATION
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26.1 Chemical signals coordinate body functions
 Hormones
– Chemical signals
– Usually carried in the blood
– Cause specific changes in target cells
– Secreted by
– Endocrine glands
– Neurosecretory cells
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Secretory
vesicles
Blood
vessel
Target
cell
Endocrine cell
Hormone
molecules
Blood
vessel
Neurosecretory
cell
Hormone
molecules
Target
cell
26.1 Chemical signals coordinate body functions
 The endocrine system
– Consists of all hormone-secreting cells
– Works with nervous system to regulate body activities
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26.1 Chemical signals coordinate body functions
 The nervous system also
– Communicates
– Regulates
– Uses electrical signals via nerve cells
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26.1 Chemical signals coordinate body functions
 Comparing the endocrine and nervous systems
– Nervous system reacts faster
– Endocrine system responses last longer
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Nerve
cell
Nerve
signals
Neurotransmitter
molecules
Nerve
cell
26.2 Hormones affect target cells by two main
signaling mechanisms
 Hormone signaling involves three key events
– Reception
– Signal Transduction
– Response
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26.2 Hormones affect target cells by two main
signaling mechanisms
 Amino-acid-derived hormones
– Are water-soluble
– Include proteins, peptides, and amines
– Bind to plasma-membrane receptors on target cells
– Initiate a signal transduction pathway
Animation: Water-Soluble Hormone
Copyright © 2009 Pearson Education, Inc.
Water-soluble
hormone
(epinephrine)
Target
cell
1
Receptor
protein
Plasma
membrane
Water-soluble
hormone
(epinephrine)
Target
cell
Relay
molecules
1
Receptor
protein
2
Plasma
membrane
Signal
transduction
pathway
Water-soluble
hormone
(epinephrine)
Target
cell
1
Receptor
protein
2
Plasma
membrane
Signal
transduction
pathway
Relay
molecules
3
Glycogen
Glucose
Cellular response
(in this example, glycogen breakdown)
26.2 Hormones affect target cells by two main
signaling mechanisms
 Steroid hormones
– Nonpolar lipids made from cholesterol
– Can diffuse through plasma membranes
– Bind to a receptor protein in the cytoplasm or nucleus
– Hormone-receptor complex carries out the transduction
of the hormonal signal
Animation: Lipid-Soluble Hormone
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Lipid-soluble
hormone
(testosterone)
Target
cell
Nucleus
1
Lipid-soluble
hormone
(testosterone)
Target
cell
Nucleus
1
2
Receptor
protein
Lipid-soluble
hormone
(testosterone)
Target
cell
Nucleus
DNA
1
2
Receptor
protein
3
Hormonereceptor
complex
Lipid-soluble
hormone
(testosterone)
1
Target
cell
2
Receptor
protein
Nucleus
3
Hormonereceptor
complex
DNA
4
Transcription
mRNA
New
protein
Cellular response:
activation of a gene and
synthesis of new protein
THE VERTEBRATE
ENDOCRINE SYSTEM
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26.3 Overview: The vertebrate endocrine system
consists of more than a dozen major glands
 The vertebrate endocrine system
– Consists of more than a dozen glands
– Secretes more than 50 hormones
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26.3 Overview: The vertebrate endocrine system
consists of more than a dozen major glands
 Glands
– Some are specialized for hormone secretion only
– Some also do other jobs
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Hypothalamus
Pineal gland
Pituitary gland
Thyroid gland
Parathyroid glands
Thymus
Adrenal glands
(atop kidneys)
Pancreas
Ovary
(female)
Testes
(male)
26.3 Overview: The vertebrate endocrine system
consists of more than a dozen major glands
 Hormones
– Some have a very narrow range of targets and effects
– Some have numerous effects on many kinds of target
cells
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26.4 The hypothalamus, which is closely tied to the
pituitary, connects the nervous and endocrine
systems
 The hypothalamus
– Blurs the distinction between endocrine and nervous
systems
– Receives input from nerves about body conditions
– Responds by sending out appropriate nervous or
endocrine signals
– Uses the pituitary gland to exert master control over
the endocrine system
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26.4 The hypothalamus, which is closely tied to the
pituitary, connects the nervous and endocrine
systems
 The pituitary gland consists of two parts
– Posterior pituitary
– Composed of nervous tissue
– Stores and secretes oxytocin and ADH
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Brain
Hypothalamus
Posterior pituitary
Anterior pituitary
(Bone)
Hypothalamus
Hormone
Neurosecretory
cell
Posterior
pituitary
Blood
vessel
Oxytocin
Anterior
pituitary
ADH
Uterine muscles Kidney tubules
Mammary glands
26.4 The hypothalamus, which is closely tied to the
pituitary, connects the nervous and endocrine
systems
 Anterior pituitary
– Synthesizes and secretes hormones that control the
activity of other glands
– Is controlled by the hypothalamus
– Releasing hormones stimulate the anterior pituitary
– Inhibiting hormones inhibit the anterior pituitary
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Neurosecretory
cell
Blood
vessel
Releasing hormones
from hypothalamus
Endocrine cells of
the anterior pituitary
Pituitary hormones
TSH
ACTH
FSH
and
LH
Prolactin
(PRL)
Growth
hormone
(GH)
Thyroid Adrenal Testes or Mammary Entire
body
cortex ovaries
glands
(in mammals)
Endorphins
Pain
receptors
in the brain
Hypothalamus
Inhibition
TRH
Anterior
pituitary
TSH
Thyroid
Thyroxine
Inhibition
HORMONES
AND HOMEOSTASIS
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26.5 The thyroid regulates development and
metabolism
 Thyroid gland hormones
– Thyroxine (T4) and triiodothyronine (T3)
– Regulate
– Metabolism
– Development
– Negative feedback
– Maintain homeostatic levels of T4 and T3 in the blood
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No inhibition
Hypothalamus
TRH
Anterior
pituitary
No inhibition
TSH
No iodine
Thyroid
Thyroid grows
to form goiter
Insufficient
T4 and T3
produced
26.5 The thyroid regulates development and
metabolism
 Thyroid imbalance can cause disease
– Hyperthyroidism
– Too much T4 and T3 in the blood
– Leads to high blood pressure, loss of weight, overheating,
and irritability
– Produces Graves’ disease
– Hypothyroidism
– Too little T4 and T3 in the blood
– Leads to low blood pressure, overweight, often cold,
lethargy
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26.6 Hormones from the thyroid and parathyroids
maintain calcium homeostasis
 Blood calcium level is regulated by a tightly
balanced antagonism between
– Calcitonin from the thyroid
– Parathyroid hormone (PTH) from the parathyroid
glands
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8
7
Calcitonin
Thyroid
gland
releases
calcitonin
Stimulates
Reduces
Ca2+ deposition Ca2+ uptake
in bones
in kidneys
9
6
Stimulus:
Rising
blood Ca2+
level
(imbalance)
Blood Ca2+ falls
Ca2+
level
Homeostasis: Normal blood
calcium level (about 10 mg/100 mL)
Ca2+
level
Stimulus:
Falling
blood Ca2+
level
(imbalance)
1
Blood Ca2+ rises
5
Parathyroid
glands
release parathyroid
hormone (PTH)
Stimulates
Ca2+ release
from bones
2
3
PTH
Increases
Active
Ca2+ uptake
vitamin D in kidneys
Increases
Ca2+ uptake
in intestines
4
Parathyroid
gland
Ca2+
level
Homeostasis: Normal blood
calcium level (about 10 mg/100 mL)
Ca2+
level
Stimulus:
Falling
blood Ca2+
level
(imbalance)
1
Blood Ca2+ rises
5
Parathyroid
glands
release parathyroid
hormone (PTH)
Stimulates
Ca2+ release
from bones
2
3
PTH
Increases
Active
Ca2+ uptake
vitamin D in kidneys
Increases
Ca2+ uptake
in intestines
4
Parathyroid
gland
8
7
Calcitonin
Thyroid
gland
releases
calcitonin
Stimulates
Reduces
2+
Ca deposition Ca2+ uptake
in bones
in kidneys
9
6
Stimulus:
Rising
blood Ca2+
level
(imbalance)
Blood Ca2+ falls
Ca2+
level
Homeostasis: Normal blood
calcium level (about 10 mg/100 mL)
Ca2+
level
26.7 Pancreatic hormones regulate blood glucose
levels
 The pancreas secretes two hormones that control
blood glucose
– Insulin—signals cells to use and store glucose
– Glucagon—causes cells to release stored glucose into
the blood
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Body
cells
take up more
glucose
Insulin
3
2
Beta cells
of pancreas stimulated
to release insulin into
the blood
4
Blood glucose level
declines to a set point;
stimulus for insulin
release diminishes
Liver takes
up glucose
and stores it as
glycogen
1 High blood
glucose level
Stimulus:
Rising blood glucose
level (e.g., after eating
a carbohydrate-rich
meal)
Glucose
level
Homeostasis: Normal blood glucose level
(about 90 mg/100 mL)
Glucose
level
Stimulus:
Declining blood
glucose level
(e.g., after
skipping a meal)
5 Low blood
glucose level
Blood glucose level
rises to set point;
stimulus for glucagon
release diminishes
6
Alpha
cells of
pancreas stimulated
to release glucagon
into the blood
8
Liver
breaks down
glycogen and
releases glucose
to the blood
7
Glucagon
Insulin
Body
cells
take up more
glucose
3
2
Beta cells
of pancreas stimulated
to release insulin into
the blood
4
Liver takes
up glucose
and stores it as
glycogen
1 High blood
glucose level
Stimulus:
Rising blood glucose
level (e.g., after eating
a carbohydrate-rich
meal)
Glucose
level
Homeostasis: Normal blood glucose level
(about 90 mg/100 mL)
Glucose
level
Blood glucose level
declines to a set point;
stimulus for insulin
release diminishes
Glucose
level
Homeostasis: Normal blood glucose level
(about 90 mg/100 mL)
Glucose
level
Stimulus:
Declining blood
glucose level
(e.g., after
skipping a meal)
5 Low blood
glucose
level
Blood glucose level
rises to set point;
stimulus for glucagon
release diminishes
6
Alpha
cells of
pancreas stimulated
to release glucagon
into the blood
8
Liver
breaks down
glycogen and
releases glucose
to the blood
7
Glucagon
26.8 CONNECTION: Diabetes is a common
endocrine disorder
 Diabetes mellitus
– Results from
– A lack of insulin or
– A failure of cells to respond to it
– Affects about 21 million Americans
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26.8 CONNECTION: Diabetes is a common
endocrine disorder
 Two common types of diabetes mellitus
– Type 1 (insulin-dependent)
– Autoimmune disease
– Insulin-producing cells destroyed
– Type 2 (non-insulin-dependent)
– Deficiency of insulin
– More commonly, reduced response to insulin
– More than 90% of diabetics are type 2
– Associated with being overweight and underactive
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Blood glucose (mg/100 mL)
400
350
300
Diabetic
250
200
150
Normal
100
50
0
0
1
2
1
2
4
3
Hours after glucose ingestion
5
26.9 The adrenal glands mobilize responses to
stress
 Hormones from the adrenal glands help maintain
homeostasis when the body is stressed
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26.9 The adrenal glands mobilize responses to
stress
 Nerve signals from the hypothalamus stimulate the
adrenal medulla to secrete
– Epinephrine
– Norepinephrine
 These hormones quickly trigger the fight-or-flight
responses
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26.9 The adrenal glands mobilize responses to
stress
 Adrenocorticotropic hormone (ACTH) from the
pituitary causes the adrenal cortex to secrete
– Glucocorticoids
– Mineralocorticoids
 These hormones
– Boost blood pressure
– Boost energy in response to long-term stress
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Adrenal
gland
Kidney
Stress
Adrenal
medulla
Adrenal
cortex
Nerve
signals
1
Hypothalamus
3
Releasing hormone
Anterior pituitary
Nerve
cell
Spinal cord
(cross section)
4
Nerve cell
Blood vessel
ACTH
5
Adrenal medulla
2
Epinephrine and
norepinephrine
Short-term stress response
1. Glycogen broken down to glucose;
increased blood glucose
2. Increased blood pressure
3. Increased breathing rate
4. Increased metabolic rate
5. Change in blood-flow patterns,
leading to increased alertness and
decreased digestive and kidney activity
Adrenal cortex
ACTH
Mineralocorticoids
Glucocorticoids
Long-term stress response
Mineralocorticoids
Glucocorticoids
1. Proteins and fats
1. Retention of
broken down and
sodium ions and
converted to glucose,
water by kidneys
leading to increased
2. Increased blood
blood glucose
volume and blood
2. Immune system may
pressure
be suppressed
Adrenal
medulla
Adrenal
gland
Adrenal
cortex
Kidney
Nerve
signals
Stress
1
Hypothalamus
3
Releasing hormone
Anterior pituitary
Nerve
cell
Spinal cord
(cross section)
4
Nerve cell
Blood vessel
ACTH
5
Adrenal cortex
Adrenal medulla
2
Epinephrine and
norepinephrine
Short-term stress response
ACTH
Mineralocorticoids
Glucocorticoids
Long-term stress response
Short-term stress response
1. Glycogen broken down to glucose;
increased blood glucose
2. Increased blood pressure
3. Increased breathing rate
4. Increased metabolic rate
5. Change in blood-flow patterns,
leading to increased alertness and
decreased digestive and kidney activity
Long-term stress response
Mineralocorticoids
Glucocorticoids
1. Proteins and fats
1. Retention of
broken down and
sodium ions and
converted to glucose,
water by kidneys
leading to increased
2. Increased blood
blood glucose
volume and blood
pressure
2. Immune system may
be suppressed
26.10 The gonads secrete sex hormones
 Steroid sex hormones
– Include estrogens, progestins, and androgens
– Produced by the gonads in response to signals from
– Hypothalamus
– Pituitary
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26.10 The gonads secrete sex hormones
 Estrogens and progestins
– Stimulate the development of female characteristics
– Maintain the female reproductive system
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26.10 The gonads secrete sex hormones
 Androgens
– Such as testosterone
– Trigger the development of male characteristics
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26.11 EVOLUTION CONNECTION: A single
hormone can perform a variety of functions
in different animals
 Prolactin in humans
– Stimulates mammary glands to grow and produce milk
during late pregnancy
– Suckling by a newborn stimulates further release of
prolactin
– High prolactin during nursing inhibits ovulation
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26.11 EVOLUTION CONNECTION: A single
hormone can perform a variety of functions
in different animals
 Prolactin
– Nonhuman mammals—stimulates nest building
– Birds—regulates fat metabolism and reproduction
– Amphibians—movement to water
– Fish—migration between salt and fresh water
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Watersoluble
hormone
Receptor
protein
Lipidsoluble
hormone
Receptor
protein
Signal
transduction
pathway
Hormonereceptor
complex
DNA
mRNA
Cellular response
New protein
Brain
Posterior pituitary:
Composed of nervous tissue;
stores and secretes hormones
made by hypothalamus
Hypothalamus:
Master control
center of the
endocrine system
Anterior pituitary:
Composed of
endocrine tissue;
controlled by
hypothalamus;
produces and
secretes its
own hormones
1. thyroxine
2. epinephrine
3. androgens
a.
b.
c.
d.
4. insulin
5. melatonin
6. FSH
7. PTH
8. ADH
Pineal gland
Testes
Parathyroid gland
Adrenal medulla
Hypothalamus
Pancreas
Anterior pituitary
Thyroid gland
lowers blood glucose
stimulates ovaries
triggers fight-or-flight
promotes male traits
e. regulates metabolism
f. related to daily rhythm
g. raises blood calcium levels
h. boosts water retention
You should now be able to
1. Explain how endocrine disruptors are causing
environmental problems
2. Compare the mechanisms and functions of the
endocrine and nervous systems
3. Distinguish between the two major classes of
vertebrate hormones
4. Describe the different types and functions of
vertebrate endocrine organs
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You should now be able to
5. Describe the interrelationships between the
hypothalamus and pituitary glands
6. Describe the functions of the thyroid and
parathyroid glands
7. Explain how insulin and glucagon manage blood
glucose levels
8. Describe the causes and symptoms of types 1 and
2 diabetes
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You should now be able to
9. Compare the functions of the adrenal gland
hormones
10. Describe the three major types of sex hormones
and their functions
11. Describe the diverse functions of prolactin in
vertebrate groups
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