lecture 5 hormones

8/7/2019 Lecture 5 Hormones

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EndocrinologyEndocrinology

The study of hormones, the endocrineThe study of hormones, the endocrine

system, and their role in the physiology ofsystem, and their role in the physiology of

the bodythe body


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The Endocrine SystemThe Endocrine System

The bodys slow chemical communicationThe bodys slow chemical communication

system; a set of glands that secretesystem; a set of glands that secrete

hormones into the blood stream.hormones into the blood stream.


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Principal functions of thePrincipal functions of the

endocrine systemendocrine system Maintenance of the internal environment in theMaintenance of the internal environment in the

body (maintaining the optimum biochemicalbody (maintaining the optimum biochemical

environment)environment)

Integration and regulation of growth andIntegration and regulation of growth and

developmentdevelopment

Control, maintenance and instigation of sexualControl, maintenance and instigation of sexual

reproduction, including gametogenesis, coitus,reproduction, including gametogenesis, coitus,fertilization, fetal growth and development andfertilization, fetal growth and development and

nourishment of the newbornnourishment of the newborn


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HormonesHormones

A chemical released from living cells thatA chemical released from living cells that

travels some distance to target tissues totravels some distance to target tissues to

have a biological effecthave a biological effectSecreted in very small amountsSecreted in very small amounts

Transported, usually, in the bloodTransported, usually, in the blood

Target cells have specific receptorsTarget cells have specific receptors

Regulates cell reactions by affecting geneRegulates cell reactions by affecting gene

expression (often gene transcription factors)expression (often gene transcription factors)


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Behavioral EndocrinologyBehavioral Endocrinology

The study of the relationship between hormonesand behavior

Hormones affect behavior and behavior feedsback to affect hormones

HormonesBehavior


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Endocrine vs. Nervous SystemEndocrine vs. Nervous System

Major communication systems in the bodyMajor communication systems in the body

Integrate stimuli and responses to changesIntegrate stimuli and responses to changes

in external and internal environmentin external and internal environment Both are crucial to coordinated functions ofBoth are crucial to coordinated functions of

highly differentiated cells, tissues andhighly differentiated cells, tissues andorgansorgans

Unlike the nervous system, the endocrineUnlike the nervous system, the endocrinesystem is anatomically discontinuoussystem is anatomically discontinuous


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Hormones travel via theHormones travel via the

bloodstream to target cellsbloodstream to target cells The endocrine system broadcastsits hormonal messages to

essentially all cells by secretion intoblood and extracellular fluid.

Like a radio broadcast, it requires

a receiver to get the message - inthe case of endocrine messages,cells must bear a receptor for thehormone being broadcast in order

to respond.


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A cell is a target because it has aA cell is a target because it has a

specific receptor for the hormonespecific receptor for the hormoneMost hormones circulate in the blood, coming intocontact with essentially all cells. However, a givenhormone usually affects only a limited number of cells,

which are called target cells. A target cell responds toa hormone because it bears receptors for thehormone.


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Hormones DO NOT act like faucets inwhich behavior spews forth if thehormone spigot is open.

Hormone-behavior relationships are complex.It is NOT appropriate to say that hormones causebehavior.

Rather, hormones change the probability that aparticular behavior will be displayed in theappropriate social context hormones simplyinfluence behavior.

HormonesHormones and Behaviorand Behavior


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First endocrinology experimentFirst endocrinology experiment


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Bertholds ExperimentB

ertholds Experiment1)1) Background: Naturalistic observations ofBackground: Naturalistic observations of

changes in behavior and appearance ofchanges in behavior and appearance of

roosters with age and season.roosters with age and season.

2)2) Castrated 6 roosters.Castrated 6 roosters.

3)3) ReRe--implanted a testis in 2 roosters.implanted a testis in 2 roosters.

4)4) Transplanted a testis from another bird in 2Transplanted a testis from another bird in 2roosters.roosters.

5)5) Left 2 castrated roosters to develop intoLeft 2 castrated roosters to develop into

capons.capons.


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Normal RoosterNormal Rooster

Capon


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Major endocrine glandsMajor endocrine glands


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The HypothalamusThe Hypothalamus

Small structure at theSmall structure at thebase of the brainbase of the brain

Regulates many bodyRegulates many bodyfunctions, includingfunctions, includingappetite and bodyappetite and bodytemperaturetemperature

Regulates the pituitaryRegulates the pituitaryglandgland


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The Pituitary GlandThe Pituitary Gland

A sort of master glandA sort of master gland It is a cherryIt is a cherry--sizedsized

endocrine glandendocrine gland The hormones itThe hormones it

secretes affect thesecretes affect thegrowth and secretiongrowth and secretion

of other endocrineof other endocrineglandsglands The real boss is theThe real boss is the

hypothalamushypothalamus


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Embryologically distinctEmbryologically distinct

Release different hormonesRelease different hormones

AnteriorPituitary releases LuteinizingAnteriorPituitary releases Luteinizinghormone and growth hormonehormone and growth hormone

PosteriorPituitary releases OxytocinPosteriorPituitary releases Oxytocin

Anterior and PosteriorPituitaryAnterior and PosteriorPituitary


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PancreasPancreas

Both endocrine (hormones) and exocrineBoth endocrine (hormones) and exocrine

(enzymes) tissue(enzymes) tissue

Releases the hormone insulinReleases the hormone insulin


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The Adrenal GlandsThe Adrenal Glands

A pair of endocrine glands just above the kidneysA pair of endocrine glands just above the kidneys

They secrete epinephrine and norepinephrineThey secrete epinephrine and norepinephrine

In common with the pituitary, adrenals are twoIn common with the pituitary, adrenals are twoglands with distinct embryological origins.glands with distinct embryological origins. Adrenal medullaAdrenal medulla

Adrenal cortexAdrenal cortex

Both parts of the adrenals workBoth parts of the adrenals work

together to regulate metabolismtogether to regulate metabolism

and cope with stress.and cope with stress.


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Sex HormonesSex Hormones

Sex hormones are secreted by the gonadsSex hormones are secreted by the gonadsand by the adrenal glandsand by the adrenal glands

AndrogensAndrogens

Masculinizing hormonesMasculinizing hormones

EstrogensEstrogensFeminizing hormonesFeminizing hormones


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Gonads: TestesGonads: Testes

Male gonadsMale gonads

Two functionsTwo functions

SteroidogenicSteroidogenic

GametogenicGametogenic


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Primary TesticularHormonesPrimary TesticularHormones

Steroid HormonesSteroid Hormones

AndrogensAndrogens

EstrogensEstrogens


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In most mammals, males are more aggressive, and castration reduces

aggressive behavior.

Inter-male and territorial aggression increase after puberty.

After a fight, the winner has higher, the looser lower levels of testosterone.

Criminals: Age at first violent offense correlates with testosterone levels.

Violent women prisoners have higher testosterone levels than non-violent ones.

TESTOSTERONE and AGGRESSIONTESTOSTERONE and AGGRESSION


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600

650

700

750

Married Once Remarried

Never Married Married and divorced

Testosterone and MarriageTestosterone and Marriage


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Gonads: OvariesGonads: Ovaries

Female gonadsFemale gonads

Two compartmentsTwo compartments

SteroidogenicSteroidogenic

GametogenicGametogenic

Cyclic in functionCyclic in function

Hormones associated with gameteHormones associated with gamete

maturation were comaturation were co--opted overopted overevolutionary time to regulate sexualevolutionary time to regulate sexualbehaviors.behaviors.


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Primary Ovarian HormonesPrimary Ovarian Hormones

Steroid HormonesSteroid Hormones

EstrogensEstrogens

ProgesteroneProgesterone TestosteroneTestosterone


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The female menstrual cycleThe female menstrual cycle

Consists of 3 main phasesConsists of 3 main phases

MensesMenses

FollicularPhaseFollicularPhase

Luteal PhaseLuteal Phase

Each phase has differing relevantEach phase has differing relevantphysiological changesphysiological changes


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OvulationOvulation

Ovulation has been the target ofOvulation has been the target ofmost studies on the menstrual cyclemost studies on the menstrual cycle

Other mammals have stereotypedOther mammals have stereotypedsexual receptivitysexual receptivity

Human ovulation is crypticHuman ovulation is cryptic

Ovulation = once/month regulatedOvulation = once/month regulatedby hormonesby hormones


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Do women advertise fertility?Do women advertise fertility?

More interest in sex?More interest in sex?

FantasiesFantasies

Clothing preferencesClothing preferences GaitGait

Topless dancer studyTopless dancer study


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1 2


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Menstrual CycleMenstrual Cycle

Penton-Voak etal. 1999,Nature0%

5%

10%

15%

20%

Japanese faces Caucasian faces

%feminization

preferred

low conception risk

high conception risk Significanteffect of

conceptionrisk


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Feminised Masculinised

Perrett et al. 1998, Nature


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What do women prefer?What do women prefer?

When ovulating, women prefer moreWhen ovulating, women prefer more

masculine faces.masculine faces.

When not ovulating, they prefer only slightlyWhen not ovulating, they prefer only slightly

masculine faces.masculine faces.

High estrogen women showed especiallyHigh estrogen women showed especially

strong shifts across the ovulatory cycle.strong shifts across the ovulatory cycle.


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lecture 5 hormones

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