chapter © 2011 the mcgraw-hill companies, inc. all rights reserved. 30 the endocrine system
TRANSCRIPT
CHAPTER
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
30The Endocrine
System
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30-2
Learning Outcomes
30.1 Define the term endocrine glands.
30.2 Describe the general functions of the endocrine system.
30.3 Define the term hormone.
30.4 Explain the difference in hormone control by positive and negative feedback loops.
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30-3
Learning Outcomes (cont.)
30.5 Describe the locations of the hypothalamus, pituitary gland, pineal body, thyroid gland, parathyroid glands, adrenal glands, pancreas, thymus, and gonads.
30.6 List the hormones released by the pituitary gland and give the functions of each.
30.7 List the hormones released by the thyroid gland and parathyroid glands and give the functions of each.
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30-4
Learning Outcomes (cont.)
30.8 List the hormones released by the adrenal glands and give the functions of each.
30.9 List the names of the endocrine cells of the pancreas, the hormones released by them, and the function of each hormone.
30.10 List the hormones released by the pineal body, thymus, and gonads, and give the functions of each.
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30-5
Learning Outcomes (cont.)
30.11 Name the hormones produced by the kidneys and heart, listing which organ produces the hormone, and the hormone’s function.
30.12 Describe stressors and their effect on the body.
30.13 Describe the causes, signs and symptoms, and treatment of various endocrine disorders.
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30-6
target tissues
Introduction
• The endocrine system includes the organs of the body that secrete hormones directly into body fluids such as blood– Regulates chemical reaction in cells and therefore
control functions of the organs, tissues, and other cells
Glandssecrete
hormones
into
bloodstream
to
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30-7
Hormones
• Endocrine glands – Ductless– Release hormones
• Directly into target tissues• Into bloodstream to be carried to target tissues
• Hormones – chemicals secreted by a cell that affect the functions of other cells
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30-8
Hormones (cont.)
• Many are derived from steroids that easily cross the cell membrane
• Examples of steroidal hormones– Estrogen– Progesterone– Testosterone– Cortisol Hormones
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30-9
Hormones (cont.)
• Nonsteroidal hormones– Made of amino acids or
proteins and cannot cross the cell membrane easily
– Bind to receptors on the surface of the cells
– G-protein – activated by the hormone-receptor complex
• Activates enzymes inside cell
• Prostaglandins– Local, or tissue, hormones– Derived from lipid
molecules– Do not travel in the
bloodstream– Target tissues are located
close by– Produced by organs such
as• Kidneys• Heart• Stomach • Uterus• Brain
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30-10
Feedback Loops
• Control hormone levels
• Negative feedback loop– Hormone release stops in response to
decrease in stimulus• Stimulus (eating) raises blood glucose levels• Pancreas releases insulin in response to elevated
blood glucose• Blood glucose decreases as it is used by the body
or stored in the liver• Insulin release stops as blood glucose levels
normalize
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30-11
Feedback Loops (cont.)
• Positive feedback loop– As long as stimulus is present, action of
hormone continues• Infant nursing at mother’s breast stimulates
hypothalamus stimulates posterior pituitary• Oxytocin released stimulates milk production
and ejection from mammary glands• Milk release continues as long as infant continues
to nurse
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30-12
Apply Your Knowledge
Match the following:
___ Chemicals that effect cell function A. Nonsteroidal hormone
___ Easily cross cell membranes B. Steroidal hormone
___ Made of amino acids C. G-protein
___ Target nearby cells D. Prostaglandins
___ Activated by hormone-receptor E. Hormones complex
___ Cannot cross cell membranes easily
___ Estrogen and cortisol
B
A
D
C
A
B
E
ANSWER:
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30-13
Hypothalamus
• Hormones– Oxytocin– Antidiuretic hormone (ADH)
• Hormones transported to the posterior pituitary for storage
• Directs posterior pituitary to release hormones
Glands
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30-14
Pituitary Gland
• Controlled by the hypothalamus• Located at the base of the brain
– Protected by a bony structure called the sella turcica – The optic chiasm is located just above the pituitary
gland• Carries visual information to the brain for interpretation
• Two lobes– Anterior lobe– Posterior lobe
Glands
Pituitary Gland
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30-15
AnteriorLobe
Growth hormone Prolactin
Adrenocorticotropic (ACTH)
Thyroid-stimulating (TSH)
Follicle-stimulating
Luteinizing
Stimulates milk production
Stimulates the adrenal cortex to release its hormones
Stimulates the thyroid gland to release its hormones
Females: stimulates estrogen production and maturation of the ovaMales: stimulates sperm production
Females: stimulates ovulationand estrogen productionMales: stimulates testosterone production
Pituitary Gland (cont.)
Stimulates increase in size of muscles and bones
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30-16
PosteriorLobe
PosteriorLobe
Antidiuretic hormone (ADH)
Oxytocin
Stimulates the kidneys to conserve water
Females: causes contraction of the uterus and ejection of breast milkMales: stimulates contraction of the prostate and vas deferens during sexual arousal
Pituitary Gland (cont.)
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30-17
Apply Your Knowledge
Match the following:
___ Stored in posterior pituitary A. Follicle-stimulating hormone
___ Milk production B. Prolactin
___ Produced by hypothalamus C. Luteinizing hormone
___ Stimulates sperm production D. ADH
___ Maturation of ova E. Oxytocin
___ Stimulates ovulation
___ Conservation of water
___ Production of testosterone
___ Contraction of uterusE
D
B
D, E
C
A
A
C
D, E
ANSWER:
Super!
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30-18
T3 T4
Thyroid Gland
Located below the larynx Divided into follicles that store some of the hormones
Major hormones
Stimulate protein synthesis and increase cellular energy production
Lowers blood calcium levels by activating osteoblasts that build new bone tissue
Glands
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30-19
Parathyroid Glands
• Four located on the posterior surface of the thyroid gland
• Secrete parathyroid hormone (PTH)– Agonist to calcitonin by raising blood calcium
levels through activation of osteoclasts (dissolve bone)
• As bone dissolves, calcium levels in blood increase
Glands
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30-20
Apply Your Knowledge
True or False:
__ Thyroid hormones stimulate protein synthesis.
__ The thyroid gland does not store hormones.
__ PTH activates osteoblasts.
__ Calcitonin increases cellular energy production.
__ The four parathyroid glands are located on the thyroid gland.
__ Calcitonin lowers blood calcium levels.
F
F
F
T
T
T
ANSWER:
PTH activates osteoclasts.
Thyroid hormone increases cellular energy production.
Thyroid follicles store some hormones.
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30-21
Adrenal Glands
• Located on top of each kidney• Divided into the adrenal medulla and
adrenal cortex• Adrenal medulla
– Central portion– Hormones
• Epinephrine • Norepinephrine• Same effects as sympathetic nervous
system Glands
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30-22
Adrenal Glands (cont.)
• Adrenal cortex– Outermost portion– Secretes many hormones, but main ones are
• Aldosterone– Stimulates body to retain sodium and water– Important in maintaining BP
• Cortisol – Released when stressed– Decreases protein synthesis, resulting in slowed tissue
repair– Decreases inflammation
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30-23
Apply Your Knowledge
Match the following:
____ Adrenal medulla A. Cortisol
____ Sodium retention B. Epinephrine
____ Decreases inflammation C. Aldosterone
____ Sympathetic effects D. Norepinephrine
____ Maintains blood pressure
____ Released during stress
____ Adrenal cortexA, C
B, D
A
C
A
C
B, D
ANSWER:
Excellent!
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30-24
Pancreas
• Located behind the stomach
• Both exocrine gland and endocrine gland– Exocrine – secretes
digestive enzymes into a duct leading to the small intestine
– Endocrine – secretes hormones into bloodstream
Glands
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30-25
Pancreas (cont.)
• Islets of Langerhans secrete hormones into bloodstream– Alpha cells secrete glucagon– Beta cells secrete insulin
Blood glucose concentrations
Protein synthesis
Blood glucose concentrations
Protein synthesis
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30-26
Apply Your Knowledge
What are the effects of insulin and glucagon?
ANSWER: Insulin decreases blood glucose concentration and increases protein synthesis.
Glucagon does just the opposite. It increases blood glucose and decreases protein synthesis.
Yippee!
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30-27
Other Hormone-Producing Organs
• Pineal body– Small gland– Located between
cerebral hemispheres
– Melatonin• Regulates circadian
rhythms• May play a role in
onset of puberty
• Thymus gland– Located between
lungs– Thymosin
• Promotes production of T lymphocytes
Glands
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30-28
Other Hormone-Producing Organs (cont.)
• The gonads– Ovaries
• Estrogen• Progesterone
– Testes • Testosterone
• Stomach– Gastrin
• Small intestine– Secretin– Cholecystokinin
• Heart – Atrial natriuretic
peptide – regulates BP
• Kidneys – Erythropoietin –
stimulates blood cell production
Glands
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30-29
BackBack
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30-30
Apply Your Knowledge
Match the following:
___ Between lungs A. Pineal body
___ Melatonin B. Heart
___ Estrogen/testosterone C. Kidneys
___ Gastrin D. Thymus gland
___ Secretin E. Small intestine
___ Erythropoietin F. Stomach
___ Atrial natriuretic peptide G. Gonads
___ Thymosin
___ Cholecystokinin
C
E
F
G
A
E
D
B
D
ANSWER:
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30-31
The Stress Response
• Stressor – Any stimulus that
produces stress– Types
• Physical factors • Psychological factors• Positive stimuli
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30-32
The Stress Response (cont.)
• Physiologic response to stress caused by hormone release– General stress syndrome
• Increased heart rate, respiratory rate, and BP• Increase in glucose and fatty acids in blood, which
leads to weight loss• Increase in cortisol if stress prolonged
– Decreased body repair– Susceptibility to illness
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30-33
Apply Your Knowledge
Match the following:
___ Extreme heat A. Physical stress
___ Death of friend B. Psychological stress
___ Fractured leg C. Positive stimulus
___ Wedding
___ Exam
___ Hearing an explosion nearby
___ “A” on an exam
___ Flu
___ Car stolen
B
B
B
A
A
C
B
C
A
ANSWER:
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30-34
Common Diseases and Disorders
Disease/Disorder Description
Acromegaly Too much growth hormone produced in adults; enlargement of bones and thickened skin
Addison’s disease Adrenal gland fails to produce enough corticosteroids
Cretinism Extreme form of hypothyroidism present prior to or soon after birth
Cushing’s disease Hypercortisolism; over-production of cortisol
Diabetes insipidus Kidneys fail to reabsorb water, resulting in excessive urination; hyposecretion of ADH
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30-35
Common Diseases and Disorders (cont.)
Disease/Disorder Description
Diabetes mellitus
Type I
Type II
Gestational
Chronic disease characterized by elevated blood glucose levelsInsulin-dependent diabetes mellitus; usually develops in childhood
Noninsulin-dependent diabetes mellitus; primarily in adults but increased incidence in teens
Occurs during pregnancy; usually temporary
Dwarfism Too little growth hormone (somatotropin) produced during childhood
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30-36
Common Diseases and Disorders (cont.)
Disease/Disorder Description
Gigantism Too much growth hormone produced during childhood
Goiter Enlargement of thyroid gland, causing swelling in neck; deficiency of iodine in diet
Graves’ disease Hyperthyroidism; antibodies attach to thyroid gland, causing it to produce too much thyroid hormone
Myxedema Thyroid gland produces inadequate amounts of thyroid hormone; common in females over 50
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30-37
Apply Your Knowledge
True or False:
___ Acromegaly develops as a result of too much growth hormone in a
child.
___ In diabetes insipidus, the kidneys fail to reabsorb water.
___ Too little growth hormone in childhood results in dwarfism.
___ Myxedema is the result of hyperthyroidism.
___ Addison’s disease is the result of too little corticosteroid.
___ Cushing’s disease is the result of too little ACTH.
___ Cretinism is an extreme form of hyperthyroidism present at birth.F
T
T
T
F
F
ANSWER:
F
hypothyroidism
too much ACTH
hypothyroidism
in an adult
Correct!
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30-38
In Summary
30.1Endocrine glands are ductless glands, releasing hormones directly into the bloodstream and tissues.
30.2The organs of the endocrine system produce hormones that regulate the chemical reactions within cells, controlling the functions of organs, tissues, and other cells.
30.3Hormones are chemicals released by cells that affect the functioning of other cells.
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30-39
In Summary (cont.)
30.4 In a negative feedback loop, a stimulus causes a body reaction, which is detected by another area of the body, which stops the reaction. The rise in blood sugar causing the pancreas to release insulin to lower blood sugar is an example. In a positive feedback loop, a stimulus begins a process which will continue as long as the stimulus continues; as happens with a nursing infant, where the suckling releases milk from the mother’s breast until the suckling stops.
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30-40
In Summary (cont.)
30.5The hypothalamus, pituitary, and pineal glands are located within the brain. The thyroid and parathyroid glands are located in the neck. The thymus is found in the mediastinum. The adrenal glands are located above each kidney, and the pancreas is located behind the stomach. In females, the gonads (ovaries) are in the abdominal cavity and in males, the gonads (testes) are found within the scrotal sac.
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30-41
In Summary (cont.)
30.6The pituitary gland releases the following hormones: GH, MSH, ACTH, TSH, FSH, LH, PRL, ADH and OT. Each hormone’s specific function may be found in Table 30-1.
30.7The thyroid gland releases calcitonin, T3, and T4 which are important in growth and protein synthesis. The parathyroid releases PTH which balances the action of calcitonin.
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30-42
In Summary (cont.)
30.8The adrenal medulla secretes epinephrine and norepinephrine, which work with the sympathetic nervous system. The adrenal cortex produces many hormones, but the two major ones are aldosterone for BP maintenance and cortisol, which decreases inflammation.
30.9The endocrine cells of the pancreas are known as the Islets of Langerhans. The two types of cells are Alpha cells, which release glucagon, and Beta cells, which release insulin.
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30-43
In Summary (cont.)
30.10The pineal body releases melatonin to regulate circadian rhythms, the thymus releases thymosin and thymopoietin to promote T cell production, ovaries release estrogen and progesterone (females), and the testes (males) release testosterone.
30.11The kidneys produce erythropoietin, affecting the bone marrow, and the heart produces atrial natriuretic peptide, affecting BP.
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30-44
In Summary (cont.)
30.12Stressors are defined as stimuli that produce a stress response, a physiologic response to the stimulus that changes the body’s functioning in some way.
30.13 The diseases and disorders of the endocrine system are as varied as the organs and hormone dysfunctions that cause them. An overview of these conditions is in Table 30-2, and more detail on the most common of these conditions is found in the Pathophysiology section at the end of this chapter.
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End of Chapter 30
Its not stress that kills us,
it is our reaction to it.
~ Hans Selye