Endocrinology The study of hormones, the endocrine system, and their role in the physiology of the...
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Transcript of Endocrinology The study of hormones, the endocrine system, and their role in the physiology of the...
EndocrinologyEndocrinology
The study of hormones, the endocrine The study of hormones, the endocrine system, and their role in the physiology of system, and their role in the physiology of the body the body
The Endocrine SystemThe Endocrine System
The body’s slow chemical communication The body’s slow chemical communication system; a set of glands that secrete system; a set of glands that secrete hormones into the blood stream.hormones into the blood stream.
Principal functions of the Principal functions of the endocrine systemendocrine system
Maintenance of the internal environment in the Maintenance of the internal environment in the body (maintaining the optimum biochemical body (maintaining the optimum biochemical environment)environment)
Integration and regulation of growth and Integration and regulation of growth and developmentdevelopment
Control, maintenance and instigation of sexual Control, maintenance and instigation of sexual reproduction, including gametogenesis, coitus, reproduction, including gametogenesis, coitus, fertilization, fetal growth and development and fertilization, fetal growth and development and nourishment of the newbornnourishment of the newborn
HormonesHormones
A chemical released from living cells that A chemical released from living cells that travels some distance to target tissues to travels some distance to target tissues to have a biological effecthave a biological effect Secreted 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 gene Regulates cell reactions by affecting gene
expression (often gene transcription factors)expression (often gene transcription factors)
Behavioral EndocrinologyBehavioral Endocrinology
The study of the relationship between hormones and behavior
Hormones affect behavior and behavior feeds back to affect hormones
Hormones↔Behavior
Endocrine vs. Nervous SystemEndocrine vs. Nervous System Major communication systems in the bodyMajor communication systems in the body Integrate stimuli and responses to changes Integrate stimuli and responses to changes
in external and internal environmentin external and internal environment Both are crucial to coordinated functions of Both are crucial to coordinated functions of
highly differentiated cells, tissues and highly differentiated cells, tissues and organsorgans
Unlike the nervous system, the endocrine Unlike the nervous system, the endocrine system is anatomically discontinuoussystem is anatomically discontinuous
Hormones travel via the Hormones travel via the bloodstream to target cellsbloodstream to target cells
• The endocrine system broadcasts its hormonal messages to essentially all cells by secretion into blood and extracellular fluid.
• Like a radio broadcast, it requires a receiver to get the message - in the case of endocrine messages, cells must bear a receptor for the hormone being broadcast in order to respond.
A cell is a target because it has a A cell is a target because it has a specific receptor for the hormonespecific receptor for the hormone
Most hormones circulate in the blood, coming into contact with essentially all cells. However, a given hormone usually affects only a limited number of cells, which are called target cells. A target cell responds to a hormone because it bears receptors for the hormone.
Hormones DO NOT act like “faucets” in which behavior spews forth if the hormone spigot is open.
Hormone-behavior relationships are complex.
It is NOT appropriate to say that hormones “cause” behavior.
Rather, hormones change the probability that a particular behavior will be displayed in the appropriate social context – hormones simply influence behavior.
HormonesHormones and Behaviorand Behavior
First endocrinology experimentFirst endocrinology experiment
Berthold’s ExperimentBerthold’s Experiment
1)1) Background: Naturalistic observations of Background: Naturalistic observations of changes in behavior and appearance of changes 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) Re-implanted a testis in 2 roosters.Re-implanted a testis in 2 roosters.
4)4) Transplanted a testis from another bird in 2 Transplanted a testis from another bird in 2 roosters.roosters.
5)5) Left 2 castrated roosters to develop into Left 2 castrated roosters to develop into capons.capons.
Normal Rooster Normal Rooster Capon
Major endocrine glandsMajor endocrine glands
The HypothalamusThe Hypothalamus
Small structure at Small structure at the base of the the base of the brain brain
Regulates many Regulates many body functions, body functions, including appetite including appetite and body and body temperaturetemperature
Regulates the Regulates the pituitary glandpituitary gland
The Pituitary GlandThe Pituitary Gland
A sort of master A sort of master glandgland
It is a cherry-sized It is a cherry-sized endocrine glandendocrine gland
The hormones it The hormones it secretes affect the secretes affect the growth and growth and secretion of other secretion of other endocrine glandsendocrine glands
The real boss is the The real boss is the hypothalamushypothalamus
Embryologically distinct Embryologically distinct Release different hormonesRelease different hormones
– Anterior Pituitary releases Luteinizing Anterior Pituitary releases Luteinizing hormone and growth hormonehormone and growth hormone
– Posterior Pituitary releases OxytocinPosterior Pituitary releases Oxytocin
Anterior and Posterior PituitaryAnterior and Posterior Pituitary
PancreasPancreas Both endocrine (hormones) and exocrine Both endocrine (hormones) and exocrine
(enzymes) tissue(enzymes) tissue Releases the hormone insulinReleases the hormone insulin
The Adrenal GlandsThe Adrenal Glands
A pair of endocrine glands just above the A pair of endocrine glands just above the kidneyskidneys
They secrete epinephrine and norepinephrine They secrete epinephrine and norepinephrine In common with the pituitary, adrenals are two In common with the pituitary, adrenals are two
glands with distinct embryological origins.glands with distinct embryological origins.– Adrenal medullaAdrenal medulla– Adrenal cortexAdrenal cortex
Both parts of the adrenals work Both parts of the adrenals work together to regulate metabolism together to regulate metabolism and cope with stress.and cope with stress.
Sex HormonesSex Hormones
Sex hormones are secreted by the Sex hormones are secreted by the gonads and by the adrenal glandsgonads and by the adrenal glands
AndrogensAndrogens
Masculinizing hormonesMasculinizing hormones
EstrogensEstrogens
Feminizing hormonesFeminizing hormones
Gonads: TestesGonads: Testes
Male gonadsMale gonads Two functionsTwo functions
– SteroidogenicSteroidogenic– GametogenicGametogenic
Primary Testicular HormonesPrimary Testicular Hormones
Steroid HormonesSteroid Hormones– AndrogensAndrogens– EstrogensEstrogens
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 TESTOSTERONE and AGGRESSIONAGGRESSION
600
650
700
750
Married Once Remarried
Never Married Married and divorced
Testosterone and MarriageTestosterone and Marriage
Gonads: OvariesGonads: Ovaries Female gonadsFemale gonads Two compartmentsTwo compartments
– SteroidogenicSteroidogenic– GametogenicGametogenic
Cyclic in functionCyclic in function Hormones associated with gamete Hormones associated with gamete
maturation were co-opted over maturation were co-opted over evolutionary time to regulate evolutionary time to regulate sexual behaviors.sexual behaviors.
Primary Ovarian HormonesPrimary Ovarian Hormones
Steroid HormonesSteroid Hormones– EstrogensEstrogens– ProgesteroneProgesterone– TestosteroneTestosterone
The female menstrual cycleThe female menstrual cycle
Consists of 3 main phasesConsists of 3 main phases
Menses Menses
Follicular PhaseFollicular Phase
Luteal PhaseLuteal Phase Each phase has differing relevant Each phase has differing relevant
physiological changesphysiological changes
OvulationOvulation
Ovulation has been the target of Ovulation has been the target of most studies on the menstrual cyclemost studies on the menstrual cycle
Other mammals have stereotyped Other mammals have stereotyped sexual receptivitysexual receptivity
Human ovulation is “cryptic”Human ovulation is “cryptic” Ovulation = once/month regulated Ovulation = once/month regulated
by hormonesby hormones
Do women advertise fertility?Do women advertise fertility?
More interest in sex?More interest in sex? Fantasies Fantasies Clothing preferencesClothing preferences GaitGait Topless dancer studyTopless dancer study
1 2
Menstrual Cycle Menstrual Cycle
Penton-Voak et al. 1999, Nature
0%
5%
10%
15%
20%
Japanese faces Caucasian faces
% f
emin
izat
ion
pre
ferr
ed low conception risk
high conception risk Significant effect of conception risk
Feminised Masculinised
Perrett et al. 1998, Nature
What do women prefer?What do women prefer?
When ovulating, women prefer more When ovulating, women prefer more masculine faces.masculine faces.
When not ovulating, they prefer only slightly When not ovulating, they prefer only slightly masculine faces.masculine faces.
High estrogen women showed especially High estrogen women showed especially strong shifts across the ovulatory cycle.strong shifts across the ovulatory cycle.