Chapt13 apr lecture

Brenda Holmes MSN/Ed, RNAssociate ProfessorBiology

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South Arkansas Community College

Chapter 13Endocrine System

2Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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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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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Hormone secretion

(a)

(b)

Blood flowSkin

Duct

Thyroidgland

Endocrinegland

Endocrinecell

Exocrine gland(sweat gland)

Exocrinecells

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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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• 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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• 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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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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• 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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• 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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Using Hormones to Improve

Athletic Performance

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• Prostaglandins:• Are paracrine substances• Act locally• 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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• 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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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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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

Hypothalamus Pituitary gland22

Infundibulum

Hypothalamus

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 pituitarygland

Sphenoidalsinus

Posterior lobeof pituitarygland

Oculomotornerve


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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)

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Secretorycells

© Michael Ross/Photo Researchers, Inc.

Chromophobes

Basophils

Acidophils

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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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Growth Hormone Ups and Downs

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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

Pituicytes33

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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

Thyroid Lateral lobes

Isthmus Pyramidal lobe 36


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Follicular cells

Colloid

Extrafollicularcells

© Fred Hossler/Visuals Unlimited

Larynx Colloid

Isthmus

(a)

(b)

Thyroidgland

Follicularcell

Extrafollicularcell


Follicular cells

Colloid Parafollicular (C) cells

Thyroid follicles

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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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• 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

ThyroidglandParathyroidglands

Trachea


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Secretory cells

Capillaries


© R. Calentine/Visuals Unlimited


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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

Chief cells

Oxyphil cells

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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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• 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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Cor

tex

Med

ulla

Capsule

Zonaglomerulosa

Zonafasciculata

Zonareticularis

Chromaffincells


© Ed Reschke

Adrenal gland

Kidney

Adrenal cortex

(a)

Zona glomerulosa

Connective tissue capsule

(b)

Zona fasciculata

Zona reticularis

Adrenal medulla

Adrenal cortex

Adrenalmedulla

Surface ofadrenal gland


CapsuleZona

glomerulosaZona

fasciculataZona

reticularis Adrenal

gland

Adrenal medulla

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Capsule Cortex

Medulla55

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Disorders of the Adrenal Cortex

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Treating Diabetes

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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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Head Neck Body Tail

Pancreas

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Head Neck Body Tail

Structure of the Gland

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Pancreatic islet

Pancreas acini 65

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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


Gallbladder Common bile duct

Pancreatic duct

PancreasDuct

Capillary

Smallintestine

Digestive enzyme-secreting cellsPancreatic islet(Islet of Langerhans)

Hormone-secretingislet cells

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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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Diabetes Mellitus

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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

Melatonin Serotonin SAD PMS

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Thymus (adult)

Thymus (infant)

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Lobe of thymus Lobule of thymus

Cortex of thymus Medulla of thymus Septa of thymus 73

Secondary follicle

Secondary oocyte

Antrum

corona radiata

primary follicle

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ANP

Erythropoietin

Angiotensin II

Calcitriol

IGF-1

Hepcidin

Calcitriol

EPO

Angiotensin

Calcitriol

Heart

Skin

Liver Kidneys

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Enteric hormones

Estrogen

Progesterone

Other pregnancy hormones

Placenta

Stomach and intestines

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

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Read Chapter 14.

Chapt13 apr lecture

Education

Transcript of Chapt13 apr lecture