Chapt13 endocrine

Hole’s Human AnatomyHole’s Human Anatomyand Physiologyand Physiology

Twelfth EditionTwelfth Edition

Shier Shier Butler Butler Lewis Lewis

Chapter 13

Endocrine System

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13.1: Introduction13.1: Introduction

2

• 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

3

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Hormone secretion

(a)

(b)

Blood flow

Skin

Duct

Thyroidgland

Endocrinegland

Endocrinecell

Exocrine gland(sweat gland)

Exocrinecells

13.2: General Characteristics 13.2: General Characteristics of the Endocrine Systemof the Endocrine System

4

• 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

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• 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)

Chemistry of HormonesChemistry of Hormones

8

• 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

9

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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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11

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

13

• 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

ProstaglandinsProstaglandins

15

• 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

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

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.

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

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.

23

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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

13.2 Clinical Application13.2 Clinical Application24

Growth Hormone Ups and Downs

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

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

29

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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

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• 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)

Posterior view

Esophagus

Pharynx

Thyroidgland

Parathyroidglands

Trachea

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Structure of the GlandsStructure of the Glands

32

Secretory cells

Capillaries

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© R. Calentine/Visuals Unlimited

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

Structure of the GlandsStructure of the Glands

37

Co

rtex

Med

ull

a

Capsule

Zonaglomerulosa

Zonafasciculata

Zonareticularis

Chromaffincells

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© 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

13.1 From Science to 13.1 From Science to TechnologyTechnology

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Treating Diabetes

13.9: Pancreas13.9: Pancreas

42

• 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

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

Hormones of the Pancreatic Hormones of the Pancreatic IsletsIslets

44

45

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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

13.4 Clinical Application13.4 Clinical Application

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Diabetes Mellitus

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

13.11: Stress and Its Effects13.11: Stress and Its Effects

48

• 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

Types of StressTypes of Stress

49

• Two types of stress:• Physical stress• Psychological stress

Responses to StressResponses to Stress

50

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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

52

• 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.