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PowerPoint® Lecture Slide Presentation
by Patty Bostwick-Taylor,
Florence-Darlington Technical College
The Endocrine
System
9
PART A
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
The Endocrine System
 Second-messenger system of the body
 Uses chemical messengers (hormones) that are
released into the blood
 Hormones control several major processes
 Reproduction
 Growth and development
 Mobilization of body defenses
 Maintenance of much of homeostasis
 Regulation of metabolism
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormone Overview
 Hormones are produced by specialized cells
 Cells secrete hormones into extracellular fluids
 Blood transfers hormones to target sites
 These hormones regulate the activity of other
cells
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The Chemistry of Hormones
 Hormones are classified chemically as
 Amino acid–based, which includes
 Proteins
 Peptides
 Amines
 Steroids—made from cholesterol
 Prostaglandins—made from highly active
lipids
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Mechanisms of Hormone Action
 Hormones affect only certain tissues or organs
(target cells or target organs)
 Target cells must have specific protein receptors
 Hormone-binding alters cellular activity
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Effects Caused by Hormones
 Changes in plasma membrane permeability or
electrical state
 Synthesis of proteins, such as enzymes
 Activation or inactivation of enzymes
 Stimulation of mitosis
 Promotion of secretory activity
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The Chemistry of Hormones
 Two mechanisms in which hormones act
 Direct gene activation
 Second-messenger system
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Direct Gene Activation
(Steroid Hormone Action)
1. Diffuse through the plasma membrane of target
cells
2. Enter the nucleus
3. Bind to a specific protein within the nucleus
4. Bind to specific sites on the cell’s DNA
5. Activate genes that result in synthesis of new
proteins
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Steroid
hormone
Nucleus
Cytoplasm
Receptor
protein
Hormone-receptor
complex
DNA
mRNA
New
protein
Plasma
membrane
of target
cell
Figure 9.1a
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Steroid
hormone
Cytoplasm
Nucleus
Plasma
membrane
of target
cell
Figure 9.1a, step 1
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Steroid
hormone
Cytoplasm
Nucleus
Plasma
membrane
of target
cell
Figure 9.1a, step 2
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Steroid
hormone
Nucleus
Cytoplasm
Receptor
protein
Hormone-receptor
complex
Plasma
membrane
of target
cell
Figure 9.1a, step 3
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Steroid
hormone
Nucleus
Cytoplasm
Receptor
protein
Hormone-receptor
complex
DNA
Plasma
membrane
of target
cell
Figure 9.1a, step 4
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Steroid
hormone
Nucleus
Cytoplasm
Receptor
protein
Hormone-receptor
complex
DNA
mRNA
Plasma
membrane
of target
cell
Figure 9.1a, step 5
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Steroid
hormone
Nucleus
Cytoplasm
Receptor
protein
Hormone-receptor
complex
DNA
mRNA
New
protein
Plasma
membrane
of target
cell
Figure 9.1a, step 6
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Second-Messenger System
(Nonsteroid Hormone Action)
1. Hormone binds to a membrane receptor
2. Hormone does not enter the cell
3. Sets off a series of reactions that activates an
enzyme
4. Catalyzes a reaction that produces a secondmessenger molecule
5. Oversees additional intracellular changes to
promote a specific response
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Nonsteroid
hormone (first
messenger)
Cytoplasm
Enzyme
ATP
cAMP
Receptor
protein
Plasma
membrane
of target cell
Second
messenger
Effect on cellular function,
such as glycogen
breakdown
Figure 9.1b
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Nonsteroid
hormone (first
messenger)
Cytoplasm
Receptor
protein
Plasma
membrane
of target cell
Figure 9.1b, step 1
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Nonsteroid
hormone (first
messenger)
Cytoplasm
Enzyme
Receptor
protein
Plasma
membrane
of target cell
Figure 9.1b, step 2
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Nonsteroid
hormone (first
messenger)
Cytoplasm
Enzyme
ATP
cAMP
Second
messenger
Receptor
protein
Plasma
membrane
of target cell
Figure 9.1b, step 3
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Nonsteroid
hormone (first
messenger)
Cytoplasm
Enzyme
ATP
cAMP
Receptor
protein
Plasma
membrane
of target cell
Second
messenger
Effect on cellular function,
such as glycogen
breakdown
Figure 9.1b, step 4
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Major Endocrine Glands and Hormones
Table 9.1 (1 of 4)
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Major Endocrine Glands and Hormones
Table 9.1 (2 of 4)
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Major Endocrine Glands and Hormones
Table 9.1 (3 of 4)
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Major Endocrine Glands and Hormones
Table 9.1 (4 of 4)
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Control of Hormone Release
 Hormone levels in the blood are mostly
maintained by negative feedback
 A stimulus or low hormone levels in the blood
triggers the release of more hormone
 Hormone release stops once an appropriate level
in the blood is reached
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3 Types of Endocrine Gland
Stimuli
 Hormonal
 Humoral
 Neural
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Slide
9.11
Hormonal Stimuli of Endocrine Glands
 Most common stimuli
 Endocrine glands are
activated by other hormones
 Examples:
 Anterior pituitary
hormones
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Humoral Stimuli of Endocrine Glands
 Changing blood levels of
certain ions stimulate
hormone release
 Humoral indicates various
body fluids such as blood
and bile
 Examples:
 Parathyroid hormone
 Calcitonin
 Insulin
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Neural Stimuli of Endocrine Glands
 Nerve impulses stimulate
hormone release
 Most are under the control
of the sympathetic nervous
system
 Examples: norepinephrine
and epinephrine by the
adrenal medulla
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Major Endocrine Organs
 Pituitary gland
 Thyroid gland
 Parathyroid glands
 Adrenal glands
 Pineal gland
 Thymus gland
 Pancreas
 Gonads (Ovaries and Testes)
 Hypothalamus
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Location of Major Endrocrine Organs
Figure 9.3
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Pituitary Gland
 Size of a pea
 Hangs by a stalk from the hypothalamus in the
brain
 Protected by the sphenoid bone
 Has two functional lobes
 Anterior pituitary—glandular tissue
 Posterior pituitary—nervous tissue
 Often called the “master endocrine gland”
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Hormones of the Anterior Pituitary
 Six anterior pituitary hormones
 Two affect non-endocrine targets
 Growth hormone
 Prolactin
 Four stimulate other endocrine glands (tropic
hormones)
 Thyroid-stimulating hormone (thyrotropic
hormone)
 Adrenocorticotropic hormone
 Two gonadotropic hormones
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Hormones of the Anterior Pituitary
 Characteristics of all anterior pituitary hormones
 Proteins (or peptides)
 Act through second-messenger systems
 Regulated by hormonal stimuli, mostly
negative feedback
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Hormones of the Anterior Pituitary
Figure 9.4
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Hormones of the Anterior Pituitary
 Growth hormone
 General metabolic hormone
 Major effects are directed to growth of skeletal
muscles and long bones
 Plays a role in determining final body size
 Causes amino acids to be built into proteins
 Causes fats to be broken down for a source of
energy
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Hormones of the Anterior Pituitary
 Growth hormone (GH) disorders
 Pituitary dwarfism results from hyposecretion
of GH during childhood
 Gigantism results from hypersecretion of GH
during childhood
 Acromegaly results from hypersecretion of GH
during adulthood
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Hormones of the Anterior Pituitary
Gigantism
Figure 9.5a
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Hormones of the Anterior Pituitary
Dwarfism
Figure 9.5b
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Hormones of the Anterior Pituitary
 Prolactin (PRL)
 Stimulates and maintains milk production
following childbirth
 Function in males is unknown
 Adrenocorticotropic hormone (ACTH)
 Regulates endocrine activity of the adrenal
cortex
 Thyroid-stimulating hormone (TSH)
 Influences growth and activity of the thyroid
gland
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Hormones of the Anterior Pituitary
 Gonadotropic hormones
 Regulate hormonal activity of the gonads
 Follicle-stimulating hormone (FSH)
 Stimulates follicle development in
ovaries
 Stimulates sperm development in
testes
 Luteinizing hormone (LH)
 Triggers ovulation of an egg in females
 Stimulates testosterone production in
males
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Pituitary–Hypothalamus Relationship
 Hormonal release is regulated by releasing and
inhibiting hormones produced by the
hypothalamus
 Hypothalamus produces two hormones
 These hormones are transported to
neurosecretory cells of the posterior pituitary
 Oxytocin
 Antidiuretic hormone
 The posterior pituitary is not strictly an endocrine
gland, but does release hormones
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Hormones of the Posterior Pituitary
 Oxytocin
 Stimulates contractions of the uterus during
labor, sexual relations, and breastfeeding
 Causes milk ejection in a nursing woman
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Hormones of the Posterior Pituitary
 Antidiuretic hormone (ADH)
 Inhibits urine production by promoting water
reabsorption by the kidneys
 In large amounts, causes vasoconstriction
leading to increased blood pressure
 Also known as vasopressin
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Hormones of the Posterior Pituitary
Figure 9.6
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Thyroid Gland
 Found at the base of the throat
 Consists of two lobes and a connecting isthmus
 Produces two hormones
 Thyroid hormone
 Calcitonin
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Thyroid Gland
Figure 9.7a
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Thyroid Gland
 Thyroid hormone
 Major metabolic hormone
 Composed of two active iodine-containing
hormones
 Thyroxine (T4)—secreted by thyroid
follicles
 Triiodothyronine (T3)—conversion of T4 at
target tissues
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Thyroid Gland
Figure 9.7b
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Thyroid Gland
 Thyroid hormone disorders
 Goiters
 Thyroid gland enlarges due to lack of
iodine
 Salt is iodized to prevent goiters
 Cretinism
 Caused by hyposecretion of thyroxine
 Results in dwarfism during childhood
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Thyroid Gland
Figure 9.8
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Thyroid Gland
 Thyroid hormone disorders (continued)
 Myxedema
 Caused by hypothyroidism in adults
 Results in physical and mental
slugishness
 Graves’ disease
 Caused by hyperthyroidism
 Results in increased metabolism, heat
intolerance, rapid heartbeat, weight loss,
and exophthalmos
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Thyroid Gland
Figure 9.9
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Thyroid Gland
 Calcitonin
 Decreases blood calcium levels by causing its
deposition on bone
 Antagonistic to parathyroid hormone
 Produced by parafollicular cells
 Parafollicular cells are found between the
follicles
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Thyroid Gland
Figure 9.7b
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Parathyroid Glands
 Tiny masses on the posterior of the thyroid
 Secrete parathyroid hormone (PTH)
 Stimulate osteoclasts to remove calcium from
bone
 Stimulate the kidneys and intestine to absorb
more calcium
 Raise calcium levels in the blood
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Hormonal Regulation of Calcium in Blood
Calcitonin
stimulates
calcium salt
deposit
in bone
Calcitonin
Thyroid gland
releases
calcitonin
Thyroid
gland
Rising
blood
Ca2+
levels
Falling
blood
Ca2+
levels
Calcium homeostasis of blood
9–11 mg/100 ml
Thyroid
gland
Osteoclasts
degrade bone
matrix and release
Ca2+ into blood
Parathyroid
glands
PTH
Parathyroid
glands release
parathyroid
hormone (PTH)
Figure 9.10
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Hormonal Regulation of Calcium in Blood
Rising
blood
Ca2+
levels
Calcium homeostasis of blood
9–11 mg/100 ml
Figure 9.10, step 1
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Hormonal Regulation of Calcium in Blood
Thyroid
gland
Rising
blood
Ca2+
levels
Calcium homeostasis of blood
9–11 mg/100 ml
Figure 9.10, step 2
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Hormonal Regulation of Calcium in Blood
Calcitonin
Thyroid gland
releases
calcitonin
Thyroid
gland
Rising
blood
Ca2+
levels
Calcium homeostasis of blood
9–11 mg/100 ml
Figure 9.10, step 3
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormonal Regulation of Calcium in Blood
Calcitonin
Thyroid gland
releases
calcitonin
Calcitonin
stimulates
calcium salt
deposit
in bone
Thyroid
gland
Rising
blood
Ca2+
levels
Calcium homeostasis of blood
9–11 mg/100 ml
Figure 9.10, step 4
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormonal Regulation of Calcium in Blood
Calcitonin
Thyroid gland
releases
calcitonin
Calcitonin
stimulates
calcium salt
deposit
in bone
Thyroid
gland
Rising
blood
Ca2+
levels
Calcium homeostasis of blood
9–11 mg/100 ml
Figure 9.10, step 5
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormonal Regulation of Calcium in Blood
Calcium homeostasis of blood
9–11 mg/100 ml
Falling
blood
Ca2+
levels
Figure 9.10, step 6
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormonal Regulation of Calcium in Blood
Calcium homeostasis of blood
9–11 mg/100 ml
Falling
blood
Ca2+
levels
Thyroid
gland
Parathyroid
glands
Figure 9.10, step 7
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormonal Regulation of Calcium in Blood
Calcium homeostasis of blood
9–11 mg/100 ml
Falling
blood
Ca2+
levels
Thyroid
gland
Parathyroid
glands
PTH
Parathyroid
glands release
parathyroid
hormone (PTH)
Figure 9.10, step 8
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormonal Regulation of Calcium in Blood
Calcium homeostasis of blood
9–11 mg/100 ml
Falling
blood
Ca2+
levels
Thyroid
gland
Parathyroid
glands
Osteoclasts
degrade bone
matrix and release
Ca2+ into blood
PTH
Parathyroid
glands release
parathyroid
hormone (PTH)
Figure 9.10, step 9
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormonal Regulation of Calcium in Blood
Calcium homeostasis of blood
9–11 mg/100 ml
Thyroid
gland
Parathyroid
glands
Osteoclasts
degrade bone
matrix and release
Ca2+ into blood
PTH
Parathyroid
glands release
parathyroid
hormone (PTH)
Figure 9.10, step 10
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormonal Regulation of Calcium in Blood
Calcitonin
stimulates
calcium salt
deposit
in bone
Calcitonin
Thyroid gland
releases
calcitonin
Thyroid
gland
Rising
blood
Ca2+
levels
Falling
blood
Ca2+
levels
Calcium homeostasis of blood
9–11 mg/100 ml
Thyroid
gland
Osteoclasts
degrade bone
matrix and release
Ca2+ into blood
Parathyroid
glands
PTH
Parathyroid
glands release
parathyroid
hormone (PTH)
Figure 9.10, step 11
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Adrenal Glands
 Sit on top of the kidneys
 Two regions
 Adrenal cortex—outer glandular region has
three layers
 Mineralocorticoids secreting area
 Glucocorticoids secreting area
 Sex hormones secreting area
 Adrenal medulla—inner neural tissue region
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Hormones of the Adrenal Cortex
Figure 9.11
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Hormones of the Adrenal Cortex
 Mineralocorticoids (mainly aldosterone)
 Produced in outer adrenal cortex
 Regulate mineral content in blood
 Regulate water and electrolyte balance
 Target organ is the kidney
 Production stimulated by renin and
aldosterone
 Production inhibited by atrial natriuretic
peptide (ANP)
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Hormones of the Adrenal Cortex
Figure 9.12
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Hormones of the Adrenal Cortex
 Glucocorticoids (including cortisone and cortisol)
 Produced in the middle layer of the adrenal
cortex
 Promote normal cell metabolism
 Help resist long-term stressors
 Released in response to increased blood
levels of ACTH
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Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
Short term
More prolonged
Stress
Hypothalamus
Nerve impulses
Releasing hormone
Corticotropic cells of
anterior pituitary
Spinal cord
Preganglionic
sympathetic
fibers
ACTH
Adrenal
cortex
Adrenal
medulla
Mineralocorticoids
Catecholamines
(epinephrine and
norepinephrine)
Short-term
stress response
1. Increased heart rate
2. Increased blood pressure
3. Liver converts glycogen to
glucose and releases glucose
to blood
4. Dilation of bronchioles
5. Changes in blood flow
patterns, leading to increased
alertness and decreased
digestive and kidney activity
6. Increased metabolic rate
Glucocorticoids
Long-term stress response
1. Retention of sodium
and water by kidneys
2. Increased blood
volume and blood
pressure
1. Proteins and fats
converted to glucose
or broken down for
energy
2. Increased blood
sugar
3. Suppression of
immune system
Figure 9.13
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Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
Short term
Stress
Hypothalamus
Figure 9.13, step 1
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
Short term
Stress
Hypothalamus
Nerve impulses
Spinal cord
Figure 9.13, step 2
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
Short term
Stress
Hypothalamus
Nerve impulses
Spinal cord
Preganglionic
sympathetic
fibers
Adrenal
medulla
Figure 9.13, step 3
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
Short term
Stress
Hypothalamus
Nerve impulses
Spinal cord
Preganglionic
sympathetic
fibers
Adrenal
medulla
Catecholamines
(epinephrine and
norepinephrine)
Short-term
stress response
Figure 9.13, step 4
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
Short term
Stress
Hypothalamus
Nerve impulses
Spinal cord
Preganglionic
sympathetic
fibers
Adrenal
medulla
Catecholamines
(epinephrine and
norepinephrine)
Short-term
stress response
1. Increased heart rate
2. Increased blood pressure
3. Liver converts glycogen to
glucose and releases glucose
to blood
4. Dilation of bronchioles
5. Changes in blood flow
patterns, leading to increased
alertness and decreased
digestive and kidney activity
6. Increased metabolic rate
Figure 9.13, step 5
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
Stress
More prolonged
Hypothalamus
Figure 9.13, step 6
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
Stress
More prolonged
Hypothalamus
Releasing hormone
Corticotropic cells of
anterior pituitary
Figure 9.13, step 7
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
Stress
More prolonged
Hypothalamus
Releasing hormone
Corticotropic cells of
anterior pituitary
ACTH
Adrenal
cortex
Figure 9.13, step 8
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
Stress
More prolonged
Hypothalamus
Releasing hormone
Corticotropic cells of
anterior pituitary
ACTH
Adrenal
cortex
Mineralocorticoids
Long-term stress response
Figure 9.13, step 9
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
More prolonged
Stress
Hypothalamus
Releasing hormone
Corticotropic cells of
anterior pituitary
ACTH
Mineralocorticoids
Adrenal
cortex
Glucocorticoids
Long-term stress response
Figure 9.13, step 10
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
More prolonged
Stress
Hypothalamus
Releasing hormone
Corticotropic cells of
anterior pituitary
ACTH
Mineralocorticoids
Adrenal
cortex
Glucocorticoids
Long-term stress response
1. Retention of sodium
and water by kidneys
2. Increased blood
volume and blood
pressure
Figure 9.13, step 11
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
More prolonged
Stress
Hypothalamus
Releasing hormone
Corticotropic cells of
anterior pituitary
ACTH
Mineralocorticoids
Adrenal
cortex
Glucocorticoids
Long-term stress response
1. Retention of sodium
and water by kidneys
2. Increased blood
volume and blood
pressure
1. Proteins and fats
converted to glucose
or broken down for
energy
2. Increased blood
sugar
3. Suppression of
immune system
Figure 9.13, step 12
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Roles of the Hypothalamus and
Adrenal Glands in the Stress Response
Short term
More prolonged
Stress
Hypothalamus
Nerve impulses
Releasing hormone
Corticotropic cells of
anterior pituitary
Spinal cord
Preganglionic
sympathetic
fibers
ACTH
Adrenal
cortex
Adrenal
medulla
Mineralocorticoids
Catecholamines
(epinephrine and
norepinephrine)
Short-term
stress response
1. Increased heart rate
2. Increased blood pressure
3. Liver converts glycogen to
glucose and releases glucose
to blood
4. Dilation of bronchioles
5. Changes in blood flow
patterns, leading to increased
alertness and decreased
digestive and kidney activity
6. Increased metabolic rate
Glucocorticoids
Long-term stress response
1. Retention of sodium
and water by kidneys
2. Increased blood
volume and blood
pressure
1. Proteins and fats
converted to glucose
or broken down for
energy
2. Increased blood
sugar
3. Suppression of
immune system
Figure 9.13, step 13
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Adrenal Cortex
 Sex hormones
 Produced in the inner layer of the adrenal
cortex
 Small amounts are made throughout life
 Mostly androgens (male sex hormones) are
made but some estrogens (female sex
hormones) are also formed
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Adrenal Glands
 Adrenal cortex disorders
 Addison’s disease
 Results from hyposecretion of all adrenal
cortex hormones
 Bronze skin tone, muscles are weak,
burnout, susceptibility to infection
 Hyperaldosteronism
 May result from an ACTH-releasing tumor
 Excess water and sodium are retained
leading to high blood pressure and edema
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Adrenal Glands
 Adrenal cortex disorders
 Cushing’s syndrome
 Results from a tumor in the middle cortical
area of the adrenal cortex
 “Moon face,” “buffalo hump” on the upper
back, high blood pressure, hyperglycemia,
weakening of bones, depression
 Masculinization
 Results from hypersecretion of sex
hormones
 Beard and male distribution of hair growth
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Adrenal Medulla
 Produces two similar hormones (catecholamines)
 Epinephrine (adrenaline)
 Norepinephrine (noradrenaline)
 These hormones prepare the body to deal with
short-term stress (“fight or flight”) by
 Increasing heart rate, blood pressure, blood
glucose levels
 Dilating small passageways of lungs
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Adrenal Cortex
Figure 9.11
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Pancreatic Islets
 The pancreas is a mixed gland and has both
endocrine and exocrine functions
 The pancreatic islets produce hormones
 Insulin—allows glucose to cross plasma
membranes into cells from beta cells
 Glucagon—allows glucose to enter the blood
from alpha cells
 These hormones are antagonists that maintain
blood sugar homeostasis
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Pancreatic Islets
Figure 9.14a–b
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Pancreatic Islets
Figure 9.14b–c
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Insulin-secreting
cells of the pancreas
activated; release
insulin into the
blood
Elevated
blood sugar
levels
Stimulus:
rising blood
glucose levels
(e.g., after
eating four
jelly doughnuts)
Uptake of glucose
from blood is enhanced in most
body cells
Blood glucose
levels decline
to set point;
stimulus for
insulin release
diminishes
Liver takes up
glucose and stores
it as glycogen
Stimulus:
declining blood
glucose levels
(e.g., after
skipping a meal)
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Low blood
sugar levels
Rising blood
glucose levels
return blood sugar
to homeostatic set
point; stimulus for
glucagon release
diminishes
Liver breaks down
glycogen stores and
releases glucose to
the blood
Glucagon-releasing
cells of pancreas
activated;
release glucagon
into blood; target
is the liver
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 9.15
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Figure 9.15, step 1
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Stimulus:
rising blood
glucose levels
(e.g., after
eating four
jelly doughnuts)
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Figure 9.15, step 2
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Elevated
blood sugar
levels
Stimulus:
rising blood
glucose levels
(e.g., after
eating four
jelly doughnuts)
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Figure 9.15, step 3
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Insulin-secreting
cells of the pancreas
activated; release
insulin into the
blood
Elevated
blood sugar
levels
Stimulus:
rising blood
glucose levels
(e.g., after
eating four
jelly doughnuts)
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Figure 9.15, step 4
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Insulin-secreting
cells of the pancreas
activated; release
insulin into the
blood
Uptake of glucose
from blood is enhanced in most
body cells
Elevated
blood sugar
levels
Stimulus:
rising blood
glucose levels
(e.g., after
eating four
jelly doughnuts)
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Figure 9.15, step 5
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Insulin-secreting
cells of the pancreas
activated; release
insulin into the
blood
Elevated
blood sugar
levels
Stimulus:
rising blood
glucose levels
(e.g., after
eating four
jelly doughnuts)
Uptake of glucose
from blood is enhanced in most
body cells
Liver takes up
glucose and stores
it as glycogen
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Figure 9.15, step 6
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Insulin-secreting
cells of the pancreas
activated; release
insulin into the
blood
Elevated
blood sugar
levels
Stimulus:
rising blood
glucose levels
(e.g., after
eating four
jelly doughnuts)
Uptake of glucose
from blood is enhanced in most
body cells
Liver takes up
glucose and stores
it as glycogen
Blood glucose
levels decline
to set point;
stimulus for
insulin release
diminishes
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Figure 9.15, step 7
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Stimulus:
declining blood
glucose levels
(e.g., after
skipping a meal)
Figure 9.15, step 8
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Stimulus:
declining blood
glucose levels
(e.g., after
skipping a meal)
Low blood
sugar levels
Figure 9.15, step 9
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Stimulus:
declining blood
glucose levels
(e.g., after
skipping a meal)
Low blood
sugar levels
Glucagon-releasing
cells of pancreas
activated;
release glucagon
into blood; target
is the liver
Figure 9.15, step 10
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Stimulus:
declining blood
glucose levels
(e.g., after
skipping a meal)
Low blood
sugar levels
Liver breaks down
glycogen stores and
releases glucose to
the blood
Glucagon-releasing
cells of pancreas
activated;
release glucagon
into blood; target
is the liver
Figure 9.15, step 11
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Stimulus:
declining blood
glucose levels
(e.g., after
skipping a meal)
Low blood
sugar levels
Rising blood
glucose levels
return blood sugar
to homeostatic set
point; stimulus for
glucagon release
diminishes
Liver breaks down
glycogen stores and
releases glucose to
the blood
Glucagon-releasing
cells of pancreas
activated;
release glucagon
into blood; target
is the liver
Figure 9.15, step 12
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Insulin-secreting
cells of the pancreas
activated; release
insulin into the
blood
Elevated
blood sugar
levels
Stimulus:
rising blood
glucose levels
(e.g., after
eating four
jelly doughnuts)
Uptake of glucose
from blood is enhanced in most
body cells
Blood glucose
levels decline
to set point;
stimulus for
insulin release
diminishes
Liver takes up
glucose and stores
it as glycogen
Stimulus:
declining blood
glucose levels
(e.g., after
skipping a meal)
Homeostasis: Normal blood glucose
levels (90 mg/100ml)
Low blood
sugar levels
Rising blood
glucose levels
return blood sugar
to homeostatic set
point; stimulus for
glucagon release
diminishes
Liver breaks down
glycogen stores and
releases glucose to
the blood
Glucagon-releasing
cells of pancreas
activated;
release glucagon
into blood; target
is the liver
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 9.15, step 13
Pineal Gland
 Found on the third ventricle of the brain
 Secretes melatonin
 Helps establish the body’s wake and sleep
cycles
 Believed to coordinate the hormones of
fertility in humans
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Location of Major Endrocrine Organs
Figure 9.3
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Thymus Gland
 Located posterior to the sternum
 Largest in infants and children
 Produces thymosin
 Matures some types of white blood cells
 Important in developing the immune system
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Gonads
 Ovaries
 Produce eggs
 Produce two groups of steroid hormone
 Estrogens
 Progesterone
 Testes
 Produce sperm
 Produce androgens, such as testosterone
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Location of Major Endrocrine Organs
Figure 9.3
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Ovaries
 Estrogens
 Stimulate the development of secondary
female characteristics
 Mature female reproductive organs
 With progesterone, estrogens also
 Promote breast development
 Regulate menstrual cycle
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Ovaries
 Progesterone
 Acts with estrogen to bring about the
menstrual cycle
 Helps in the implantation of an embryo in the
uterus
 Helps prepare breasts for lactation
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Hormones of the Testes
 Produce several androgens
 Testosterone is the most important androgen
 Responsible for adult male secondary sex
characteristics
 Promotes growth and maturation of male
reproductive system
 Required for sperm cell production
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Other Hormone-Producing Tissues and Organs
 Parts of the small intestine
 Parts of the stomach
 Kidneys
 Heart
 Many other areas have scattered endocrine cells
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Other Hormone-Producing Tissues and Organs
Table 9.2 (1 of 2)
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Other Hormone-Producing Tissues and Organs
Table 9.2 (2 of 2)
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Endocrine Function of the Placenta
 Produces hormones that maintain the pregnancy
 Some hormones play a part in the delivery of the
baby
 Produces human chorionic gonadotropin (hCG) in
addition to estrogen, progesterone, and other
hormones
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Developmental Aspects of the Endocrine System
 Most endocrine organs operate smoothly until old
age
 Menopause is brought about by lack of
efficiency of the ovaries
 Problems associated with reduced estrogen
are common
 Growth hormone production declines with age
 Many endocrine glands decrease output with
age
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings