chapt13 endocrine
TRANSCRIPT
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Hole’s Human AnatomyHole’s Human Anatomyand Physiologyand Physiology
Twelfth EditionTwelfth Edition
Shier Shier Butler Butler Lewis Lewis
Chapter 13
Endocrine System
1Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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13.1: Introduction13.1: Introduction
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• The endocrine system assists the nervous system with communication and control of the body• The cells, tissues, and organs are called endocrine glands
• They are ductless• They use the bloodstream• They secrete hormones• There are also similar glands called paracrine and autocrine glands that are quasi-endocrine
• Other glands that secrete substances are the exocrine glands • They have ducts• They deliver their products directly to a specific site
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Hormone secretion
(a)
(b)
Blood flow
Skin
Duct
Thyroidgland
Endocrinegland
Endocrinecell
Exocrine gland(sweat gland)
Exocrinecells
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13.2: General Characteristics 13.2: General Characteristics of the Endocrine Systemof the Endocrine System
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• The endocrine and nervous systems communicate using chemical signals
• Neurons release neurotransmitters into a synapse affecting postsynaptic cells• Endocrine glands release hormones into the bloodstream to specific target cell receptors
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(a)
(b)
Nerve impulse
Bloodstream
Neurontransmitsnerveimpulse
Glandularcells secretehormone intobloodstream
Neurotransmitterreleased intosynapse
Post-synapticcell responds
Target cells(cells with hormonereceptors) respondto hormone
Hormones have noeffect on other cells
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13.3: Hormone Action13.3: Hormone Action
7
• Hormones are released into the extracellular spaces surrounding endocrine cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Hypothalamus
Pituitary gland
Thyroid gland
Thymus
Adrenal gland
Pancreas
Parathyroid gland
Pineal gland
Kidney
Testis(in male)
Ovary(in female)
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Chemistry of HormonesChemistry of Hormones
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• Chemically, hormones are either:• Steroid or steroid-like hormones such as:
• Sex hormones• Adrenal cortex hormones
• Non-steroid hormones such as:• Amines• Proteins• Peptides• Glycoproteins
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
O
H3C
(a) Cortisol
(d) Oxytocin
OH
HO C
HO
(b) Norepinephrine
H H
OH H
C NH2
C
H
H
C C
H
H
C
H
H
C
H
H
H
HH
H
C
CCCC
(e) Prostaglandin PGE2
HOHH
H H OH
C
H
H
H
H
C
H
C
C
H
H
C C
H
H
CO
OH
HH
HH
C
HOH3C
C O
C
O
C
Ala
Val
Asp His Ser Arg Gly Arg Arg Asp Ser Glu Pro Arg Asp Ala
Ser Glu Glu Phe Ile Gly Asp His His Ser Leu Leu
Met
Ala
ProProAlaAlaGluGluLeuAspSerGlyGlu Glu Glu
Arg
Gly
Cys
Cys
Asp
Glu
Ile
Pro Leu Gly
His Ileu Met Glu Ser Phe Ala Leu Glu
SerAspIleLeuLeuLeuAspGluLeu Gly Glu
S
S
CH2OH
Val Lys Lys
Lys
LysVal
Lys Lys Lys
Val Lys Tyr Val Val Lys
Lys Lys Try Val
Tyr
(c) Parathyroid ho rm one (PTH)
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Action of HormonesAction of Hormones
12
• Steroid Hormones Hormone molecule
Ribosome
Nucleus
1
2
3
5
4
Newly formingprotein molecule
Cellmembrane
Hormone-receptorcomplex
Intracellularreceptor molecule
mRNA
mRNA
DNA
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Action of HormonesAction of Hormones
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• Non-steroid Hormones Cell membrane
G protein
Cytoplasm
Nucleus
ATPcAMP
1
2
3
5
4
Membrane-boundreceptor molecule
Nonsteroidhormonemolecule
Hormone-receptorcomplex
Adenylatecyclase
Proteinkinases(inactive)
Substrate(inactive)
Proteinkinases(active)
Substrate(active)
Cellularchanges
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13.1 Clinical Application13.1 Clinical Application14
Using Hormones to Improve
Athletic Performance
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ProstaglandinsProstaglandins
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• Prostaglandins:• Are paracrine substances• Are very potent in small amounts• Are not stored in cells but synthesized just before release• Rapidly inactivate• Regulate cellular responses to hormones• Can activate or inhibit adenylate cyclase
• Controls cAMP production• Alters a cells response to hormones
• Has a wide variety of effects
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13.4: Control of 13.4: Control of Hormonal SecretionsHormonal Secretions
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• Primarily controlled by negative feedback mechanism• Hormones can be short-lived or may last for days• Hormone secretions are precisely regulated
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Control SourcesControl Sources
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too high
too low
Control centerEndocrine glandinhibited.
ReceptorsHormone controlmechanism senseschange.
EffectorsHormone secretiondecreased.
StimulusHormone levels rise orcontrolled processincreases.
ResponseHormone levelsreturn towardnormal.
Normalhormonelevels
StimulusHormone levels drop orcontrolled processdecreases.
ResponseHormone levelsreturn towardnormal.
ReceptorsHormone controlmechanism senseschange.
EffectorsHormone secretionincreased.
Control centerEndocrine glandstimulated.
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Control SourcesControl Sources
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Nervous system
(a) (b) (c)
Target cells
Action
Target cells
Action
–
– – –
Anterior pituitary gland
Action
Hypothalamus
Peripheralendocrine
gland
Target cells
Endocrinegland
Changing levelof substance
in plasma
Endocrinegland
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13.5: Pituitary Gland13.5: Pituitary Gland
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• Lies at the base of the brain in the sella turcica• Consists of two distinct portions:
• Anterior pituitary (adenohypophysis)• Posterior pituitary (neurohypophysis)
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Optic nerve
Sphenoid bone
Hypothalamus
Optic chiasma
Sella turcica
Third ventricle
Trochlear nerve
Basilar artery
Anterior cerebralartery
Pituitary stalk(Infundibulum)
Anterior lobeof pituitary gland
Sphenoidalsinus
Posterior lobeof pituitarygland
Oculomotornerve
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Anterior Pituitary HormonesAnterior Pituitary Hormones
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• Hypothalamic releasing hormones stimulate cells of anterior pituitary to release hormones• Nerve impulses from hypothalamus stimulate nerve endings in the posterior pituitary gland to release hormones
Hypophyseal veins
Optic chiasma
Capillary bed
Posterior lobe of pituitary gland
Third ventricle
Hypothalamus
Anterior lobe of pituitary gland
Capillary bed
Hypophysealportal veins
Secretory cellsof anteriorpituitary gland
Neurosecretorycells that secretereleasing hormones
Superior hypophysealartery
Neurosecretory cellsthat secrete posteriorpituitary hormones
Inferior hypophysealartery
Sella turcica ofsphenoid bone
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Anterior pituitary
Peripheral endocrine gland
Hypothalamus
Target cells
(Hormone 3)
+
––
–
+
+ Inhibition
Stimulation
Releasinghormone(Hormone 1)
Anterior pituitaryhormone(Hormone 2)
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Secretorycells
© Michael Ross/Photo Researchers, Inc.
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ThyroidMammary gland Ovary TestisBone Muscle
Hormones from Anterior Pituitary
Hormones from Hypothalamus
GHRHGrowth hormone-releasinghormone
SSSomatostatin
PRFProlactin-releasingfactor
PIHProlactin-releaseinhibiting hormone
TRHThyrotropin-releasinghormone
CRHCorticotropin-releasinghormone
GnRHGonadotropin-releasinghormone
GHGrowthhormone
PRLProlactin
TSHThyroid-stimulatinghormone
ACTHAdrenocorticotropichormone
LHLuteinizinghormone
FSHFollicle-stimulatinghormone
Adiposetissue
Adrenalcortex
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13.2 Clinical Application13.2 Clinical Application24
Growth Hormone Ups and Downs
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Posterior Pituitary HormonesPosterior Pituitary Hormones
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• Structurally consists of nerve fibers and neuroglia v. glandular epithelial cells of the anterior pituitary gland• The nerve fibers originate in the hypothalamus• Two hormones are produced:
• Antidiuretic hormone (vasopressin)• Oxytocin
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13.6: Thyroid Gland13.6: Thyroid Gland
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• The thyroid gland has two lateral lobes and lies just below the larynx• It produces three hormones:
• T3 (thyroxine)• T4 (triiodothyronine)• Calcitonin
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Structure of the GlandStructure of the Gland
28
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Follicular cells
Colloid
Extrafollicularcells
© Fred Hossler/Visuals Unlimited
LarynxColloid
Isthmus
(a)
(b)
Thyroidgland Follicular
cell
Extrafollicularcell
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Thyroid HormonesThyroid Hormones
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OH
O
I I
CH2
I I
OH
O
I
CH2
I I
NH2CHCOOH NH2CHCOOH
Thyroxine (T4) Triiodothyronine (T3)
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© Mediscan/Visuals Unlimited © Mediscan/Visuals Unlimited © Mediscan/Visuals Unlimited
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13.7: Parathyroid Glands13.7: Parathyroid Glands
31
• The parathyroid glands are on the posterior surface of the thyroid gland• There are typically four parathyroid glands• It secretes one hormone:
• PTH (parathyroid hormone or parathormone)
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Posterior view
Esophagus
Pharynx
Thyroidgland
Parathyroidglands
Trachea
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Structure of the GlandsStructure of the Glands
32
Secretory cells
Capillaries
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
© R. Calentine/Visuals Unlimited
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Parathyroid HormoneParathyroid Hormone
33
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Liver
Intestinal enzymes
Ultraviolet light in skin
Kidney Stimulated by PTH
Hydroxycholecalciferol
Foods
Ca+2
Ca+2
Ca+2
Cholesterol
Provitamin D
Vitamin D(Cholecalciferol)
Also obtained directlyfrom foods
Dihydroxycholecalciferol(active form of vitamin D)
Controls absorption ofcalcium in intestine
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PTH Ca+2
+PTH
PTH
Ca+2
+Ca+2
Bloodstream
–Stimulation
Inhibition
Release intobloodstream
Parathyroid glands (onposterior of thyroid gland)
Decreased blood calciumstimulates parathyroidhormone secretion
Increased bloodcalcium inhibitsPTH secretion
Kidneysconserve Ca+2 and activate Vitamin D
Bonereleases Ca+2
Intestineabsorbs Ca+2
ActiveVitamin D
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13.8: Adrenal Glands13.8: Adrenal Glands
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• The adrenal glands are closely associated with the kidneys• The gland sits like a cap on each kidney• Hormones are secreted from two different areas of the gland, the adrenal cortex and the adrenal medulla• Numerous hormones are secreted by the adrenal glands
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Structure of the GlandsStructure of the Glands
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Co
rtex
Med
ull
a
Capsule
Zonaglomerulosa
Zonafasciculata
Zonareticularis
Chromaffincells
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
© Ed Reschke
Adrenal gland
Kidney
Adrenal cortex
(a)
Zona lomerulosa
Connectivetissue capsule
(b)
Zonafasciculata
Zonareticularis
Adrenal medulla
Adrenal cortex
Adrenalmedulla
Surface ofadrenal gland
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Hormones of the Adrenal Hormones of the Adrenal MedullaMedulla
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Hormones of the Adrenal Hormones of the Adrenal CortexCortex
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13.3 Clinical Application13.3 Clinical Application
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Disorders of the Adrenal Cortex
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13.1 From Science to 13.1 From Science to TechnologyTechnology
41
Treating Diabetes
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13.9: Pancreas13.9: Pancreas
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• The pancreas has two major types of secretory tissue• This is why it is a dual functioning organ as both an exocrine gland and endocrine gland• Three hormones are secreted from the islet cells:
• Alpha cells secrete glucagon• Beta cells insulin• Delta cells secrete somatostatin
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Structure of the GlandStructure of the Gland
43
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Pancreatic islet (Islet of Langerhans)
From Kent M. Van De Graaff and Stuart Ira Fox, Concepts of Human Anatomy and Physiology, 2nd ed. ©1989 Wm. C. Brown Publishers, Dubuque, Iowa. All Rights
Reserved. Reprinted with permission
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Gallbladder Common bile duct
Pancreatic duct
PancreasDuct
Capillary
Smallintestine
Digestive enzyme-secreting cells
Pancreatic islet(Islet of Langerhans)
Hormone-secretingislet cells
Know
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Hormones of the Pancreatic Hormones of the Pancreatic IsletsIslets
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too high
too low
Control centerBeta cells secreteinsulin
ReceptorsBeta cells detect a risein blood glucose
EffectorsInsulin• Promotes movement of glucose into certain cells• Stimulates formation of glycogen from glucose
StimulusRise in blood glucose
ResponseBlood glucose drops towardnormal (and inhibits insulinsecretion)
Normalblood glucoseconcentration
StimulusDrop in blood glucose
ResponseBlood glucose rises towardnormal (and inhibits glucagonsecretion)
ReceptorsAlpha cells detect a dropin blood glucose
EffectorsGlucagon• Stimulates cells to break down glycogen into glucose• Stimulates cells to convert noncarbohydrates into glucose
Control centerAlpha cells secreteglucagon
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13.4 Clinical Application13.4 Clinical Application
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Diabetes Mellitus
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13.10: Other Endocrine Glands13.10: Other Endocrine Glands
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Pineal Gland• Secretes melatonin• Regulates circadian rhythms
Thymus Gland• Secretes thymosins• Promotes development of certain lymphocytes• Important in role of immunity
Reproductive Organs• Ovaries produce estrogens and progesterone• Testes produce testosterone• Placenta produces estrogens, progesterone, and gonadotropin
Other organs: digestive glands, heart, and kidney
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13.11: Stress and Its Effects13.11: Stress and Its Effects
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• Survival depends on maintaining homeostasis• Factors that change the internal environment are potentially life-threatening• Sensing such dangers directs nerve impulses to the hypothalamus• This can trigger a loss of homeostasis
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Types of StressTypes of Stress
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• Two types of stress:• Physical stress• Psychological stress
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Responses to StressResponses to Stress
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Sympathetic impulses
CRH released
ACTH released
Cortisol released
Long-term adjustment or resistance stage
• Increase in blood concentration of amino acids.• Increased release of fatty acids.
• Blood glucose increases.• Blood glycerol and fatty acids increase.• Heart rate increases.• Blood pressure rises.• Breathing rate increases.• Air passages dilate.• Pupils dilate.
Anterior pituitary
Hypothalamus
Adrenal cortex
Adrenal medulla
Neural signals
Hormonal signalsStress results from changesin the external environment
Signals fromsensory receptors
Epinephrine andnorepinephrinereleased
Norepinephrinereleased
Short-term “fight or flight” or alarm stage.
• Blood flow redistributes.
• Increased glucose formed from noncarbohydrates—amino acids (from proteins) and glycerol (from fats).
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13.12: Lifespan Changes13.12: Lifespan Changes
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• Endocrine glands decrease in size• Muscular strength decreases as GH levels decrease• ADH levels increase due to slower break down in liver and kidneys• Calcitonin levels decrease; increase risk of osteoporosis• PTH level changes contribute to risk of osteoporosis• Insulin resistance may develop• Changes in melatonin secretion affect the body clock• Thymosin production declines increasing risk of infections
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Important Points in Chapter 13:Outcomes to be Assessed
13.1: Introduction
Define hormone.
Distinguish between endocrine and exocrine glands.
13.2: General Characteristics of the Endocrine System
Explain what makes a cell a target cell for a hormone.
List some important functions of hormones.
13.3: Hormone Action
Describe how hormones can be classified according to their chemical composition.
Explain how steroid and non-steroid hormones affect their target cells.
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Important Points in Chapter 13:Outcomes to be Assessed
13.4: Control of Hormone Secretion
Discuss how negative feedback mechanisms regulate hormone secretion.
Explain how the nervous system controls hormone secretion.
13.5-13.10: Pituitary Gland – Other Endocrine Glands
Name and describe the locations of the major endocrine glands and list the hormones that they secrete.
Describe the actions of the various hormones and their contributions to homeostasis.
Explain how the secretion of each hormone is regulated.
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Important Points in Chapter 13:Outcomes to be Assessed
13.11: Stress and Its Effects
Distinguish between physical and psychological stress.
Describe the general stress response.
13.12: Lifespan Changes
Describe some of the changes associated with aging of the endocrine system.