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Physiology
Endocrine System
Behrouz Mahmoudi
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1
Overview of the Endocrine System
• What are the Properties of the Endocrine
System?
– Controls longer term metabolic processes
– Shares some functions with nervous system
– Releases hormones from endocrine cells
•
•
•
•
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Hormones are chemicals
Hormones change metabolism of many cells
Release controlled by negative feedback
Hormones act on target cells
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Overview of the Endocrine System
•An Overview of
the Endocrine
System
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Figure 10-1
3
• What is the Structure of Hormones?
– Three chemical families
• Amino acid derivatives
• Peptides and proteins
– Chains of amino acids
• Lipid derivatives
– Steroids (e.g., testosterone)
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• Target Cells
Peripheral cells that can respond to a
particular hormone
• Hormone receptor
A protein in the cell membrane, or within the
cytoplasm or nucleus, to which a hormone
specifically binds to trigger its actions on a
target cell.
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• The Role of Target Cell Receptors in Hormonal
Action
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Figure 10-2
•Mechanisms of
Hormone Action
Figure 10-3(b)
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•Key Note
•Hormones control cells on a sustained
basis. They circulate in the blood and
bind to specific receptors on or in target
cells. They change membrane
permeability, activate or inactivate key
enzymes, or change genetic activity.
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•What is the Hypothalamus and Endocrine
Control?
– Three steps of action
• Hypothalamus releases hormones as an
endocrine organ
• Hypothalamus releases regulatory hormones to
control pituitary gland endocrine cells
• Autonomic centers cause direct neural control of
adrenal medullae
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•Three
Mechanisms of
Hypothalamic
Control over
Endocrine Organs
Figure 10-4
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The Pituitary Gland
• What is the Pituitary Gland?
– Also called the hypophysis
– Releases nine important hormones
• All are peptide hormones
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The Pituitary Gland
• The Location and Anatomy of the Pituitary Gland
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Figure 10-5
The Pituitary Gland
• What are the Anterior Pituitary Hormones?
– Thyroid-Stimulating Hormone (TSH)
• Triggers thyroid hormone release
– Adrenocorticotropic Hormone (ACTH)
• Stimulates glucocorticoid release from adrenal gland
– Follicle-Stimulating Hormone (FSH)
• Stimulates estrogen secretion, egg production
(females), sperm production (males)
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The Pituitary Gland
• What are the Anterior Pituitary Hormones?
(continued)
– Luteinizing Hormone (LH)
• Triggers ovulation, progestin production (females),
androgen production (males)
– Prolactin (PRL)
• Stimulates mammary gland development and milk
secretion
– Growth hormone (hGH)
• Stimulates cell growth
• Melanocyte Stimulating Hormone (MSH)
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The Pituitary Gland
• What is the Posterior Pituitary Gland?
– Antidiuretic Hormone (ADH)
• Reduces water loss in the urine
• Increases thirst
– Oxytocin
• Stimulates uterine contraction, milk delivery
• Stimulates prostate gland smooth muscle
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The Pituitary Gland
• Pituitary Hormones and Their Targets
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Figure 10-8
The •Key
Pituitary
Gland
Note
•Hypothalamic regulatory factors control the
anterior pituitary (source of seven hormones).
Most of these control other glands (thyroid,
adrenal, gonads). It also produces growth
hormone. The posterior pituitary releases two
hormones produced in the hypothalamus, ADH
(restricts water loss) and oxytocin (stimulates
contractions in the mammary glands and uterus,
and the prostate gland).
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The Thyroid Gland
• What is the Anatomy of the Thyroid
Gland?
– Lies near thyroid cartilage of larynx
– Has a rich blood supply
– Contains numerous thyroid follicles
• Produce, store, release thyroid hormones
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The Thyroid Gland
• What are the Thyroid Follicles and Thyroid
Hormones?
– Production requires adequate iodine in the diet
– Occurs in two forms, thyroxine (T4) and
triiodothyronine (T3)
– Increases metabolism and heat production
(calorigenic effect)
– Required for normal development
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The
Thyroid
Gland
• The Thyroid Gland
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Figure 10-9
The Thyroid Gland
• What is the function of the C Cells of
the Thyroid Gland?
– Secrete calcitonin
• Lowers blood Ca2+ levels
• Increases urinary calcium loss
– Caused by high blood Ca2+ level
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The Parathyroid Glands
•
•
•
•
What are the Parathyroid Glands?
Chief cells produce parathyroid hormone
Low blood Ca2+ triggers secretion
PTH raises blood Ca2+
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Increased excretion
of calcium
in kidneys
Thyroid gland
produces
calcitonin
Blood calcium
levels decline
Calcium deposition in
bone (inhibition
of osteoclasts)
Uncertain significance
in a healthy
nonpregnant adult
HOMEOSTASIS
DISTURBED
Rising calcium
levels in blood
HOMEOSTASIS
DISTURBED
HOMEOSTASIS
RESTORED
HOMEOSTASIS
Normal calcium
levels
(8.5-11 mg/dl)
HOMEOSTASIS
RESTORED
Falling calcium
levels in blood
Release of stored
calcium from bone
(stimulation of
osteoclasts, inhibition
of osteoblasts)
Parathyroid
glands secrete
parathyroid
hormone (PTH)
Enhanced
reabsorption
of calcium in kidneys
Stimulation of
calcitriol production
at kidneys;
enhanced Ca2+, PO43absorption by
digestive tract
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Blood calcium
levels
increase
23
The Parathyroid Glands
•The Parathyroid Glands
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Figure 10-11
The Parathyroid Glands
•Key Note
•The thyroid gland produces (1) hormones that
adjust tissue metabolic rates, and (2) a hormone
that usually plays a minor role in calcium ion
homeostasis by opposing the action of
parathyroid hormone.
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The Adrenal Glands
• What is the Adrenal Gland
Anatomy?
– Lie along superior border of each
kidney
– Made of two parts
• Adrenal cortex (outer)
• Adrenal medulla (inner)
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The Adrenal Glands
• The Adrenal Gland
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The Adrenal Glands
• What is the Adrenal Cortex?
– Makes steroid hormones (corticosteroids)
• Glucocorticoids (e.g., cortisol)
• Mineralocorticoids (e.g., aldosterone)
• Androgens (male hormone)
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The Adrenal Glands
• What is the Adrenal Medulla?
– Produces two related hormones
• Epinephrine (adrenaline)
• Norepinephrine (noradrenaline)
– Increases heart rate and force, releases
glucose, fatty acids into blood, opens airways
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The Adrenal Glands
•Key Note
•The adrenal glands produce hormones that
adjust metabolic activities at specific sites,
affecting either the pattern of nutrient
utilization, mineral ion balance, or the rate of
energy consumption by active tissues.
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The Pineal Gland
• What is the Pineal Gland?
– Produces melatonin
• Stops reproductive function
• Allows daily wake-sleep cycle
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The Pancreas
• What is the Overview of the Pancreas?
– Lies behind stomach and beneath liver
– Endocrine cells organized into islets of
Langerhans
– Islet cells secrete insulin and glucagon
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The Pancreas
• The Endocrine Pancreas
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The Pancreas
•The Endocrine
Pancreas
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The Pancreas
• What are the Actions of Insulin and
Glucagon?
– Insulin
• Lowers blood glucose concentration
– Glucagon
• Raises blood glucose concentration
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Increased rate of
glucose transport
into target cell
Increased rate of
glucose utilization
and ATP generation
Beta cells
secrete
insulin
Increased conversion
of glucose to glycogen
(liver, skeletal muscle)
Blood glucose
concentration
declines
Increased amino acid
absorption and
protein synthesis
Increased fat
synthesis
(adipose tissue)
HOMEOSTASIS
DISTURBED
Rising blood
glucose levels
HOMEOSTASIS
DISTURBED
Declining blood
glucose levels
HOMEOSTASIS
Normal glucose
levels
(70-110 mg/dl)
HOMEOSTASIS
RESTORED
HOMEOSTASIS
RESTORED
Increased breakdown
of glycogen to glucose
(liver, skeletal muscle)
Alpha cells
secrete
glucagon
Increased breakdown
of fats to fatty acids
(adipose tissue)
Increased synthesis
and release of
glucose (liver)
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Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Blood glucose
concentration
rises
36
Increased rate of
glucose transport
into target cell
Increased rate of
glucose utilization
and ATP generation
Beta cells
secrete
insulin
Increased conversion
of glucose to glycogen
(liver, skeletal muscle)
Blood glucose
concentration
declines
Increased amino acid
absorption and
protein synthesis
Increased fat
synthesis
(adipose tissue)
HOMEOSTASIS
DISTURBED
Rising blood
glucose levels
HOMEOSTASIS
Normal glucose
levels
(70-110 mg/dl)
www.soran.edu.iq
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
HOMEOSTASIS
RESTORED
37
HOMEOSTASIS
DISTURBED
Declining blood
glucose levels
HOMEOSTASIS
Normal glucose
levels
(70-110 mg/dl)
HOMEOSTASIS
RESTORED
Increased breakdown
of glycogen to glucose
(liver, skeletal muscle)
Alpha cells
secrete
glucagon
Increased breakdown
of fats to fatty acids
(adipose tissue)
Blood glucose
concentration
rises
Increased synthesis
and release of
glucose (liver)
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Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
38
Figure 10-14
15 of 16
Increased rate of
glucose transport
into target cell
Increased rate of
glucose utilization
and ATP generation
Beta cells
secrete
insulin
Increased conversion
of glucose to glycogen
(liver, skeletal muscle)
Blood glucose
concentration
declines
Increased amino acid
absorption and
protein synthesis
Increased fat
synthesis
(adipose tissue)
HOMEOSTASIS
DISTURBED
Rising blood
glucose levels
HOMEOSTASIS
DISTURBED
Declining blood
glucose levels
HOMEOSTASIS
Normal glucose
levels
(70-110 mg/dl)
HOMEOSTASIS
RESTORED
HOMEOSTASIS
RESTORED
Increased breakdown
of glycogen to glucose
(liver, skeletal muscle)
Alpha cells
secrete
glucagon
Increased breakdown
of fats to fatty acids
(adipose tissue)
Increased synthesis
and release of
glucose (liver)
www.soran.edu.iq
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Blood glucose
concentration
rises
39
Patterns of Hormonal Interaction
• What Hormones are Needed for Normal
Growth?
– Growth Hormone
– Thyroid Hormones
– Insulin
– Parathyroid Hormone
– Calcitriol
– Reproductive Hormones
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Patterns of Hormonal Interaction
• What are Hormones and Behavior?
– Sex hormones
• Testosterone causes aggressiveness
• Estrogen causes sexual receptivity
– Thyroid hormones
• Excess leads to nervousness, restlessness
• Deficiency leads to sluggishness
– Antidiuretic hormone
• Leads to feeling of thirst, water intake
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