45 lecture presentation

8/2/2019 45 Lecture Presentation

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Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

PowerPoint ® Lecture Presentations for

Biology

Eighth Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp

Chapter 45

Hormones and the

Endocrine System




Overview: The Body’s Long-Distance Regulators

• Animal hormones are chemical signals thatare secreted into the circulatory system andcommunicate regulatory messages within thebody

• Hormones reach all parts of the body, but onlytarget cells are equipped to respond

• Insect metamorphosis is regulated byhormones




• Two systems coordinate communicationthroughout the body: the endocrine system andthe nervous system

• The endocrine system secretes hormonesthat coordinate slower but longer-actingresponses including reproduction,development, energy metabolism, growth, and

behavior• The nervous system conveys high-speed

electrical signals along specialized cells called

neurons; these signals regulate other cells




Concept 45.1: Hormones and other signalingmolecules bind to target receptors, triggeringspecific response pathways

• Chemical signals bind to receptor proteins ontarget cells

• Only target cells respond to the signal




Types of Secreted Signaling Molecules

• Secreted chemical signals include

– Hormones

– Local regulators

– Neurotransmitters

– Neurohormones

– Pheromones




Hormones

• Endocrine signals (hormones) are secreted intoextracellular fluids and travel via thebloodstream

• Endocrine glands are ductless and secretehormones directly into surrounding fluid

• Hormones mediate responses to environmental

stimuli and regulate growth, development, andreproduction



Fig. 45-2

Bloodvessel Response

Response

Response

Response

(a) Endocrine signaling

(b) Paracrine signaling

(c) Autocrine signaling

(d) Synaptic signaling

Neuron

Neurosecretorycell

(e) Neuroendocrine signaling

Bloodvessel

Synapse

Response


http://slidepdf.com/reader/full/45-lecture-presentation 8/95Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

• Exocrine glands have ducts and secretesubstances onto body surfaces or into bodycavities (for example, tear ducts)



Local Regulators

• Local regulators are chemical signals thattravel over short distances by diffusion

• Local regulators help regulate blood pressure,

nervous system function, and reproduction

• Local regulators are divided into two types

– Paracrine signals act on cells near thesecreting cell

– Autocrine signals act on the secreting cellitself



Fig. 45-2a

Bloodvessel Response

Response

Response

(a) Endocrine signaling

(b) Paracrine signaling

(c) Autocrine signaling



Neurotransmitters and Neurohormones

• Neurons (nerve cells) contact target cells atsynapses

• At synapses, neurons often secrete chemical

signals called neurotransmitters that diffuse ashort distance to bind to receptors on the targetcell

• Neurotransmitters play a role in sensation,memory, cognition, and movement



Fig. 45-2b

Response

(d) Synaptic signaling

Neuron

Neurosecretorycell

(e) Neuroendocrine signaling

Bloodvessel

Synapse

Response



• Neurohormones are a class of hormones thatoriginate from neurons in the brain and diffusethrough the bloodstream



Pheromones

• Pheromones are chemical signals that arereleased from the body and used tocommunicate with other individuals in thespecies

• Pheromones mark trails to food sources, warnof predators, and attract potential mates



Chemical Classes of Hormones

• Three major classes of molecules function ashormones in vertebrates:

– Polypeptides (proteins and peptides)

– Amines derived from amino acids

– Steroid hormones



• Lipid-soluble hormones (steroid hormones)pass easily through cell membranes, whilewater-soluble hormones (polypeptides andamines) do not

• The solubility of a hormone correlates with thelocation of receptors inside or on the surface oftarget cells



Cellular Response Pathways

• Water and lipid soluble hormones differ in theirpaths through a body

• Water-soluble hormones are secreted by

exocytosis, travel freely in the bloodstream,and bind to cell-surface receptors

• Lipid-soluble hormones diffuse across cell

membranes, travel in the bloodstream bound totransport proteins, and diffuse through themembrane of target cells




• Signaling by any of these hormones involvesthree key events:

– Reception

– Signal transduction

– Response

Fig 45 5 1



Fig. 45-5-1

NUCLEUS

Signalreceptor

(a) (b)

TARGETCELL

Signal receptor

Transport

protein

Water-soluble

hormone

Fat-solublehormone

Fig 45-5-2



Fig. 45-5-2

Signalreceptor

TARGETCELL

Signal receptor

Transport

protein

Water-soluble

hormone

Fat-solublehormone

Generegulation

Cytoplasmicresponse

Generegulation

Cytoplasmicresponse

OR

(a)NUCLEUS

(b)




Pathway for Water-Soluble Hormones

• Binding of a hormone to its receptor initiates asignal transduction pathway leading toresponses in the cytoplasm, enzyme activation,or a change in gene expression

Animation: Water-Soluble Hormone

http://45_05awatersolublehormone_a.html/




• The hormone epinephrine has multiple effectsin mediating the body’s response to short-termstress

• Epinephrine binds to receptors on the plasmamembrane of liver cells

• This triggers the release of messenger

molecules that activate enzymes and result inthe release of glucose into the bloodstream

Fig 45-6-1



Fig. 45 6 1

cAMPSecondmessenger

Adenylylcyclase

G protein-coupledreceptor

ATP

GTP

G protein

Epinephrine

Fig. 45-6-2



Fig. 45 6 2

cAMPSecondmessenger

Adenylylcyclase

G protein-coupledreceptor

ATP

GTP

G protein

Epinephrine

Inhibition ofglycogen synthesis

Promotion ofglycogen breakdown

Proteinkinase A

P h f Li id S l bl H




Pathway for Lipid-Soluble Hormones

• The response to a lipid-soluble hormone isusually a change in gene expression

• Steroids, thyroid hormones, and the hormonal

form of vitamin D enter target cells and bind toprotein receptors in the cytoplasm or nucleus

• Protein-receptor complexes then act as

transcription factors in the nucleus, regulatingtranscription of specific genes

Animation: Lipid-Soluble Hormone

Fig. 45-7-1

http://45_05blipidsolublehormone_a.html/



g

Hormone(estradiol)

Hormone-receptorcomplex

Plasmamembrane

Estradiol(estrogen)receptor

Fig. 45-7-2



g

Hormone(estradiol)

Hormone-receptorcomplex

Plasmamembrane

Estradiol(estrogen)receptor

DNA

Vitellogenin

mRNAfor vitellogenin

M lti l Eff t f H




Multiple Effects of Hormones

• The same hormone may have different effectson target cells that have

– Different receptors for the hormone

– Different signal transduction pathways

– Different proteins for carrying out the response

• A hormone can also have different effects indifferent species

Fig. 45-8-1



g

Glycogen

deposits

receptor

Vesseldilates.

Epinephrine

(a) Liver cell

Epinephrine

receptor

Glycogenbreaks downand glucose

is released.

(b) Skeletal muscleblood vessel

Same receptors but differentintracellular proteins (not shown)

Fig. 45-8-2



Glycogen

deposits

receptor

Vesseldilates.

Epinephrine

(a) Liver cell

Epinephrine

receptor

Glycogenbreaks downand glucose

is released.

(b) Skeletal muscleblood vessel

Same receptors but differentintracellular proteins (not shown)

Epinephrine

receptor

Different receptors

Epinephrine

receptor

Vesselconstricts.

(c) Intestinal bloodvessel

Si li b L l R l t




Signaling by Local Regulators

• In paracrine signaling, nonhormonal chemicalsignals called local regulators elicit responsesin nearby target cells

• Types of local regulators: – Cytokines and growth factors

– Nitric oxide (NO)

– Prostaglandins




• Prostaglandins help regulate aggregation ofplatelets, an early step in formation of bloodclots

C t 45 2 N ti f db k d t i ti




Concept 45.2: Negative feedback and antagonistichormone pairs are common features of theendocrine system

• Hormones are assembled into regulatorypathways

Fig. 45-10

Major endocrine glands:



Major endocrine glands:

Adrenalglands

Hypothalamus

Pineal gland

Pituitary gland

Thyroid gland

Parathyroid glands

Pancreas

Kidney

Ovaries

Testes

Organs containingendocrine cells:

Thymus

Heart

Liver

Stomach

KidneySmallintestine

Simple Hormone Pathways




Simple Hormone Pathways

• Hormones are released from an endocrine cell,travel through the bloodstream, and interactwith the receptor or a target cell to cause aphysiological response

Fig. 45-11Pathway Example



Pathway Example

Stimulus Low pH induodenum

S cells of duodenumsecrete secretin ( )

Endocrinecell

Bloodvessel

PancreasTargetcells

Response Bicarbonate release

–




• A negative feedback loop inhibits a responseby reducing the initial stimulus

• Negative feedback regulates many hormonal

pathways involved in homeostasis

Insulin and Glucagon: Control of Blood Glucose




Insulin and Glucagon: Control of Blood Glucose

•Insulin and glucagon are antagonistichormones that help maintain glucosehomeostasis

• The pancreas has clusters of endocrine cellscalled islets of Langerhans with alpha cellsthat produce glucagon and beta cells thatproduce insulin

Fig. 45-12-1



Homeostasis:Blood glucose level

(about 90 mg/100 mL)

Insulin

Beta cells ofpancreas

release insulininto the blood.

STIMULUS:Blood glucose level

rises.

Fig. 45-12-2

Body cells



Homeostasis:Blood glucose level


Insulin

Beta cells of

pancreasrelease insulininto the blood.

STIMULUS:Blood glucose level

rises.

Liver takesup glucoseand stores it

as glycogen.

Blood glucoselevel declines.

Body cellstake up moreglucose.

Target Tissues for Insulin and Glucagon




Target Tissues for Insulin and Glucagon

• Insulin reduces blood glucose levels by

– Promoting the cellular uptake of glucose

– Slowing glycogen breakdown in the liver

– Promoting fat storage




• Glucagon increases blood glucose levels by

– Stimulating conversion of glycogen to glucosein the liver

– Stimulating breakdown of fat and protein intoglucose

Diabetes Mellitus




Diabetes Mellitus

• Diabetes mellitus is perhaps the best-knownendocrine disorder

• It is caused by a deficiency of insulin or a

decreased response to insulin in target tissues• It is marked by elevated blood glucose levels




• Type I diabetes mellitus (insulin-dependent) isan autoimmune disorder in which the immunesystem destroys pancreatic beta cells

• Type II diabetes mellitus (non-insulin-dependent) involves insulin deficiency orreduced response of target cells due to changein insulin receptors

Concept 45 3: The endocrine and nervous systems act




Concept 45.3: The endocrine and nervous systems actindividually and together in regulating animalphysiology

• Signals from the nervous system initiate andregulate endocrine signals

Coordination of Endocrine and Nervous Systems




Coordination of Endocrine and Nervous Systemsin Vertebrates

• The hypothalamus receives information fromthe nervous system and initiates responsesthrough the endocrine system

• Attached to the hypothalamus is the pituitarygland composed of the posterior pituitary andanterior pituitary




• The posterior pituitary stores and secreteshormones that are made in the hypothalamus

• The anterior pituitary makes and releases

hormones under regulation of thehypothalamus

Fig. 45-14



Spinal cord

Posteriorpituitary

Cerebellum

Pinealgland

Anteriorpituitary

Hypothalamus

Pituitarygland

Hypothalamus

Thalamus

Cerebrum

Table 45-1



Table 45-1a



Table 45-1b



Table 45-1c



Table 45-1d



Posterior Pituitary Hormones




oste o tu ta y o o es

• The two hormones released from the posteriorpituitary act directly on nonendocrine tissues

Fig. 45-15

Hypothalamus



Posteriorpituitary

Anteriorpituitary

Neurosecretorycells of thehypothalamus

Hypothalamus

Axon

HORMONE OxytocinADH

Kidney tubulesTARGET Mammary glands,uterine muscles




• Oxytocin induces uterine contractions and the

release of milk

• Suckling sends a message to thehypothalamus via the nervous system to

release oxytocin, which further stimulates themilk glands

• This is an example of positive feedback,

where the stimulus leads to an even greaterresponse

• Antidiuretic hormone (ADH) enhances waterreabsorption in the kidneys

Fig. 45-16Pathway Example



SucklingStimulus

Hypothalamus/posterior pituitary

P o s i t i v e f e e d b a c k

Sensory

neuron

Neurosecretorycell

Bloodvessel

Posterior pituitarysecretes oxytocin ( )

Targetcells

Response

Smooth muscle inbreasts

Milk release

+

Anterior Pituitary Hormones




y

• Hormone production in the anterior pituitary iscontrolled by releasing and inhibiting hormonesfrom the hypothalamus

• For example, the production of thyrotropin releasing hormone (TRH ) in the hypothalamusstimulates secretion of the thyroid stimulating hormone (TSH ) from the anterior pituitary

Fig. 45-17



Hypothalamicreleasing andinhibiting

hormones

Neurosecretory cellsof the hypothalamus

HORMONE

TARGET

Posterior pituitary

Portal vessels

Endocrine cells ofthe anterior pituitary

Pituitary hormones

Tropic effects only:FSHLHTSHACTH

Nontropic effects only:ProlactinMSH

Nontropic and tropic effects:GH

Testes orovaries

Thyroid

FSH and LH TSH

Adrenalcortex

Mammaryglands

ACTH Prolactin MSH GH

Melanocytes Liver, bones,other tissues

Hormone Cascade Pathways




y

• A hormone can stimulate the release of aseries of other hormones, the last of whichactivates a nonendocrine target cell; this iscalled a hormone cascade pathway

• The release of thyroid hormone results from ahormone cascade pathway involving thehypothalamus, anterior pituitary, and thyroid

gland

• Hormone cascade pathways are usuallyregulated by negative feedback

Fig. 45-18-1Pathway Example



ColdStimulus

Bloodvessel

Sensoryneuron

Hypothalamus secretesthyrotropin-releasinghormone (TRH )

Neurosecretorycell

Fig. 45-18-2 Pathway Example



ColdStimulus


Sensory

neuron

Neurosecretorycell

Bloodvessel

+

Anterior pituitary secretesthyroid-stimulatinghormone (TSHor thyrotropin )

Fig. 45-18-3

Cold

Pathway

Stimulus

Example



ColdStimulus


N e g a t i v e f e e d b a c k

Sensoryneuron

Neurosecretorycell

Bloodvessel

Anterior pituitary secretes

thyroid-stimulatinghormone (TSHor thyrotropin )

Targetcells

Response

Body tissues

Increased cellularmetabolism

–

Thyroid gland secretesthyroid hormone(T3 and T4 )

–

Tropic Hormones




• A tropic hormone regulates the function ofendocrine cells or glands

• The four strictly tropic hormones are

– Thyroid-stimulating hormone (TSH)

– Follicle-stimulating hormone (FSH)

–

Luteinizing hormone (LH)

– Adrenocorticotropic hormone (ACTH)

Nontropic Hormones




• Nontropic hormones target nonendocrinetissues

• Nontropic hormones produced by the anterior

pituitary are – Prolactin (PRL)

– Melanocyte-stimulating hormone (MSH)




• Prolactin stimulates lactation in mammals buthas diverse effects in different vertebrates

• MSH influences skin pigmentation in some

vertebrates and fat metabolism in mammals

Growth Hormone




• Growth hormone (GH) is secreted by theanterior pituitary gland and has tropic andnontropic actions

• It promotes growth directly and has diversemetabolic effects

• It stimulates production of growth factors

• An excess of GH can cause gigantism, while alack of GH can cause dwarfism

Concept 45.4: Endocrine glands respond to diverse




• Endocrine signaling regulates metabolism,homeostasis, development, and behavior

stimuli in regulating metabolism, homeostasis,development, and behavior

Thyroid Hormone: Control of Metabolism and




Development

• The thyroid gland consists of two lobes on theventral surface of the trachea

• It produces two iodine-containing hormones:triiodothyronine (T

3

) and thyroxine (T4

)




• Thyroid hormones stimulate metabolism andinfluence development and maturation

• Hyperthyroidism, excessive secretion of thyroidhormones, causes high body temperature,weight loss, irritability, and high blood pressure

• Graves’ disease is a form of hyperthyroidism inhumans

• Hypothyroidism, low secretion of thyroidhormones, causes weight gain, lethargy, andintolerance to cold

Fig. 45-19



Normaliodineuptake

High leveliodineuptake




• Proper thyroid function requires dietary iodinefor hormone production

Parathyroid Hormone and Vitamin D: Control of Bl d C l i




Blood Calcium

• Two antagonistic hormones regulate thehomeostasis of calcium (Ca2+) in the blood ofmammals

– Parathyroid hormone (PTH) is released bythe parathyroid glands

– Calcitonin is released by the thyroid gland

Fig. 45-20-1



PTH

Parathyroid gland(behind thyroid)

STIMULUS:Falling blood

Ca2+ level

Homeostasis:Blood Ca2+ level


Fig. 45-20-2

Stimulates Ca2+Activeit i D



PTH

Parathyroid gland(behind thyroid)

STIMULUS:Falling blood

Ca2+ level

Homeostasis:Blood Ca2+ level


Blood Ca2+

level rises.

Stimulates Ca2+ uptake in kidneys

StimulatesCa2+ releasefrom bones

IncreasesCa2+ uptakein intestines

vitamin D




• PTH increases the level of blood Ca2+

– It releases Ca2+ from bone and stimulatesreabsorption of Ca2+ in the kidneys

– It also has an indirect effect, stimulating thekidneys to activate vitamin D, which promotesintestinal uptake of Ca2+ from food

• Calcitonin decreases the level of blood Ca2+

– It stimulates Ca2+ deposition in bones andsecretion by kidneys

Adrenal Hormones: Response to Stress




• The adrenal glands are adjacent to the kidneys

• Each adrenal gland actually consists of twoglands: the adrenal medulla (inner portion) andadrenal cortex (outer portion)

Catecholamines from the Adrenal Medulla




• The adrenal medulla secretes epinephrine(adrenaline) and norepinephrine(noradrenaline)

• These hormones are members of a class ofcompounds called catecholamines

• They are secreted in response to stress-

activated impulses from the nervous system• They mediate various fight-or-flight responses




• Epinephrine and norepinephrine

– Trigger the release of glucose and fatty acidsinto the blood

– Increase oxygen delivery to body cells

– Direct blood toward heart, brain, and skeletalmuscles, and away from skin, digestivesystem, and kidneys

• The release of epinephrine and norepinephrineoccurs in response to nerve signals from thehypothalamus

Fig. 45-21



Stress

Adrenalgland

Nervecell

Nervesignals

Releasing

hormone

Hypothalamus

Anterior pituitary

Blood vessel

ACTH

Adrenal cortex

Spinal cord

Adrenal medulla

Kidney

(a) Short-term stress response (b) Long-term stress response

Effects of epinephrine and norepinephrine:

2. Increased blood pressure

3. Increased breathing rate

4. Increased metabolic rate

1. Glycogen broken down to glucose; increased blood glucose

5. Change in blood flow patterns, leading to increasedalertness and decreased digestive, excretory, andreproductive system activity

Effects ofmineralocorticoids:

Effects ofglucocorticoids:

1. Retention of sodiumions and water bykidneys

2. Increased bloodvolume and bloodpressure

2. Possible suppression ofimmune system

1. Proteins and fats broken downand converted to glucose, leadingto increased blood glucose

Fig. 45-21a



Stress

Adrenalgland

Nervecell

Nervesignals

Releasinghormone

Hypothalamus

Anterior pituitary

Blood vessel

ACTH

Adrenalcortex

Spinal cord

Adrenalmedulla

Kidney

Fig. 45-21b

Adrenal medulla



(a) Short-term stress response

Effects of epinephrine and norepinephrine:

2. Increased blood pressure

3. Increased breathing rate4. Increased metabolic rate

1. Glycogen broken down to glucose; increased blood glucose

5. Change in blood flow patterns, leading to increasedalertness and decreased digestive, excretory, andreproductive system activity

Adrenalgland

Kidney

Steroid Hormones from the Adrenal Cortex




• The adrenal cortex releases a family of steroidscalled corticosteroids in response to stress

• These hormones are triggered by a hormonecascade pathway via the hypothalamus andanterior pituitary

• Humans produce two types of corticosteroids:

glucocorticoids and mineralocorticoids

Fig. 45-21c



(b) Long-term stress response

Effects ofmineralocorticoids:

Effects ofglucocorticoids:

1. Retention of sodiumions and water bykidneys

2. Increased bloodvolume and bloodpressure

2. Possible suppression ofimmune system

1. Proteins and fats broken downand converted to glucose, leadingto increased blood glucose

Adrenalgland

Kidney

Adrenal cortex




• Glucocorticoids, such as cortisol, influenceglucose metabolism and the immune system

• Mineralocorticoids, such as aldosterone,affect salt and water balance

• The adrenal cortex also produces smallamounts of steroid hormones that function as

sex hormones

Gonadal Sex Hormones




• The gonads, testes and ovaries, produce most

of the sex hormones: androgens, estrogens,and progestins

• All three sex hormones are found in both malesand females, but in different amounts




• The testes primarily synthesize androgens,

mainly testosterone, which stimulatedevelopment and maintenance of the malereproductive system

• Testosterone causes an increase in muscleand bone mass and is often taken as asupplement to cause muscle growth, which

carries health risks

Fig. 45-22



Embryonic

gonad removedChromosome Set

Appearance of Genitals

XY (male)

XX (female)

Male

Female Female

Female

No surgery

RESULTS




• Estrogens, most importantly estradiol, are

responsible for maintenance of the femalereproductive system and the development offemale secondary sex characteristics

• In mammals, progestins, which includeprogesterone, are primarily involved inpreparing and maintaining the uterus

• Synthesis of the sex hormones is controlled byFSH and LH from the anterior pituitary

Melatonin and Biorhythms




• The pineal gland, located in the brain,

secretes melatonin

• Light/dark cycles control release of melatonin

• Primary functions of melatonin appear to relateto biological rhythms associated withreproduction

Fig. 45-UN2 Pathway Example

–



Stimulus Low blood glucose

Pancreas secretesglucagon ( )

Endocrinecell

Bloodvessel

LiverTargetcells

ResponseGlycogen breakdown,glucose releaseinto blood

Fig. 45-UN3



Patient X

No drug

Normal

Dexamethasone

C o r t i s o l l e v e l

i n

b l o o d

Fig. 45-UN4



You should now be able to:




1. Distinguish between the following pairs of

terms: hormones and local regulators,paracrine and autocrine signals

2. Describe the evidence that steroid hormones

have intracellular receptors, while water-soluble hormones have cell-surface receptors

3. Explain how the antagonistic hormones insulin

and glucagon regulate carbohydratemetabolism

4. Distinguish between type 1 and type 2diabetes



5. Explain how the hypothalamus and the

pituitary glands interact and how theycoordinate the endocrine system

6. Explain the role of tropic hormones in

coordinating endocrine signaling throughoutthe body

7. List and describe the functions of hormones

released by the following: anterior andposterior pituitary lobes, thyroid glands,parathyroid glands, adrenal medulla, adrenal

d i l l d

45 lecture presentation

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