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Endocrine SystemEndocrine System

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Endocrine SystemEndocrine System► Primary function: produce ____________Primary function: produce ____________► Works together with __________ system to maintain Works together with __________ system to maintain

________________________► Hormones act on specific target cellsHormones act on specific target cells

to produce specific effectsto produce specific effects► No _________No _________

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CharacteristicCharacteristic Endocrine SystemEndocrine System Nervous SystemNervous System

General FunctionGeneral FunctionMaintain homeostasisMaintain homeostasis Maintain Maintain

homeostasishomeostasisReaction to stimuli Reaction to stimuli

slowslow rapidrapidDuration of effectDuration of effect

longlong shortshortTarget tissueTarget tissue

entire body entire body muscles and glandsmuscles and glandsChemical messengerChemical messenger

hormonehormone neurotransmitterneurotransmitterMessenger producing cell Messenger producing cell

endocrine glandendocrine gland neuronsneuronsDistance to target cellsDistance to target cells

long (via bloodstream)long (via bloodstream) short (across short (across synaptic space)synaptic space)

Endocrine System vs. Nervous Endocrine System vs. Nervous SystemSystem

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GlandGland ExocrineExocrineEndocrineEndocrine

PancreasPancreas digestive enzymesdigestive enzymes insulin, insulin, glucagonglucagon

OvaryOvary eggegg estrogen, estrogen, progesteroneprogesterone

TestesTestes spermsperm testosterone testosterone

KidneyKidney urineurine erythropoietinerythropoietin

Exocrine/Endocrine GlandsExocrine/Endocrine Glands

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► Chemical messengers Chemical messengers produced by endocrine produced by endocrine glandsglands

► Secreted into interstitial Secreted into interstitial

fluid and fluid and absorbed into absorbed into blood vesselsblood vessels Contact all cells in body Contact all cells in body

► Produce effects only on cells Produce effects only on cells containing specific receptorscontaining specific receptors __________ cell__________ cell ‘‘Lock and keyLock and key’’ arrangement arrangement

causes a change in activity of causes a change in activity of target celltarget cell

► Growth hormoneGrowth hormone——all cellsall cells► ProlactinProlactin——mammary tissuemammary tissue

HormonesHormones

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Control of Control of Hormone Hormone SecretionSecretion

___________ feedback systems (like ___________ feedback systems (like a thermostat)a thermostat)

► If hormone If hormone level is lowlevel is low:: Appropriate endocrine gland is Appropriate endocrine gland is

stimulated to stimulated to produce more produce more hormonehormone

► Once adequate hormone concentration Once adequate hormone concentration is attained in the bloodstream:is attained in the bloodstream: Stimulation of endocrine gland is Stimulation of endocrine gland is

reduced and reduced and production of the production of the hormone is stopped/reducedhormone is stopped/reduced

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Control of Hormone Control of Hormone SecretionSecretion

► Direct stimulation from the nervous system Direct stimulation from the nervous system Secretion of some hormones is stimulated by ________________ Secretion of some hormones is stimulated by ________________

nerve impulses when an animal feels threatened. nerve impulses when an animal feels threatened.

► ““Fight or flight" responseFight or flight" response

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HypothalamusHypothalamus► Part of _____________ section of brainPart of _____________ section of brain

► Controls activities of pituitary glandControls activities of pituitary gland Portal system of blood vessels links Portal system of blood vessels links

hypothalamus with anterior portion of hypothalamus with anterior portion of pituitary glandpituitary gland

► Modified neurons in hypothalamus secrete Modified neurons in hypothalamus secrete releasing and inhibiting hormones releasing and inhibiting hormones into into portal blood vesselsportal blood vessels Specific for a particular anterior pituitary Specific for a particular anterior pituitary

hormonehormone

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Hypophyseal Portal Hypophyseal Portal SystemSystem

Posteriorpituitary

OxytocinAntidiuretic hormone (ADH)

GHRH, GHIH (Don’t memorize)Thyrotropin releasing hormone (TRH)Gonadaotropin releasing hormone (GnRH)PRH, PIHCorticotropin releasing hormone (CRH)

Adrenocorticotropic hormone (ACTH)Melanocyte stim hormone (MSH)

Growth hormoneThyroid stim hormone (TSH)Follicle stim hormone (FSH)Luteinizing hormone (LH)Prolactin

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► Modified neurons Modified neurons in in hypothalamus also secrete hypothalamus also secrete antidiuretic hormone (ADH) and antidiuretic hormone (ADH) and oxytocin oxytocin

► Transported to Transported to posterior pituitaryposterior pituitary (along neurons) for storage(along neurons) for storage

► Released into the bloodstream by Released into the bloodstream by nerve impulses from hypothalamus nerve impulses from hypothalamus

HypothalamusHypothalamus

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Pituitary Pituitary Gland Gland

(Hypophysis(Hypophysis))

► Two separate glands with Two separate glands with different structures, functions, different structures, functions, and embryological originsand embryological origins

Anterior pituitary Anterior pituitary - - _______hypophysis; rostral _______hypophysis; rostral portionportion

► Stimulated by hypothalamus Stimulated by hypothalamus (portal system) and direct (portal system) and direct (neg) feedback from target (neg) feedback from target tissues to tissues to produce hormonesproduce hormones

Posterior pituitary Posterior pituitary - - _______hypophysis; caudal _______hypophysis; caudal portionportion

► Stores and releases Stores and releases hormones hormones produced in produced in hypothalamus (oxytocin, ADH)hypothalamus (oxytocin, ADH) Rostral

Caudal

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Growth Hormone (GH)Growth Hormone (GH)► a.k.a. somatotropin and somatotropic hormonea.k.a. somatotropin and somatotropic hormone► Promotes body growth in young animalsPromotes body growth in young animals► Helps Helps regulate metabolism of proteins, carbohydrates, and regulate metabolism of proteins, carbohydrates, and

lipids in all body cellslipids in all body cells

► The effect of GH on protein metabolism is to encourage The effect of GH on protein metabolism is to encourage anabolismanabolism (synthesis of proteins by body cells) (synthesis of proteins by body cells)

► The effects of GH on carb and lipid metabolism are The effects of GH on carb and lipid metabolism are linked.linked.

While lipids are broken down via catabolism for energy While lipids are broken down via catabolism for energy production, the use of carbs (especially glucose) as energy production, the use of carbs (especially glucose) as energy sources is discouraged.sources is discouraged.

Less glucose is removed from the blood and hyperglycemia Less glucose is removed from the blood and hyperglycemia occurs (hyperglycemic effect).occurs (hyperglycemic effect).

Important for the body to maintain a balance between GH and Important for the body to maintain a balance between GH and insulin to control blood glucose levels.insulin to control blood glucose levels.

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ProlactinProlactin

► Helps trigger and maintain Helps trigger and maintain __________ in females__________ in females Secretion of milk by Secretion of milk by

mammary glands mammary glands

► Prolactin production continues Prolactin production continues as long as ________ are as long as ________ are stimulated by nursing or stimulated by nursing or milkingmilking

► When prolactin stimulation When prolactin stimulation stops:stops: Milk production Milk production stopsstops Mammary Mammary gland shrinks gland shrinks to to

original/nonlactating sizeoriginal/nonlactating size

1. Baby sucks/stimulates2. ↓PIH, ↑PRH3-4. Stimulates milk glands

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Thyroid-Thyroid-Stimulating Stimulating Hormone Hormone

(TSH)(TSH)

► a.k.a. a.k.a. Thyrotropin/Thyrotropic Thyrotropin/Thyrotropic HormoneHormone

► Stimulates Stimulates growth/development of growth/development of thyroid gland thyroid gland and causes and causes thyroid to thyroid to produce its produce its hormoneshormones..

► Secretion regulated by:Secretion regulated by:

Feedback (neg) from thyroid Feedback (neg) from thyroid gland hormonegland hormone

► Thyroid hormone levels Thyroid hormone levels too low- too low- TSH production increasesTSH production increases

► Thyroid hormone levels Thyroid hormone levels too too high- TSH production high- TSH production diminishesdiminishes

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Adrenocorticotropic Hormone Adrenocorticotropic Hormone (ACTH)(ACTH)

► Stimulates growth/development of Stimulates growth/development of adrenal cortexadrenal cortex and the release of some and the release of some of its hormonesof its hormones

► Regulated by:Regulated by:

Release of CRF from hypothalamus to Release of CRF from hypothalamus to anterior pituitary through portal anterior pituitary through portal systemsystem

Negative feedback from adrenal Negative feedback from adrenal hormones and administered hormones and administered cortisonescortisones

During sudden stress, ACTH can During sudden stress, ACTH can quickly be released after the quickly be released after the hypothalamus is stimulated to send hypothalamus is stimulated to send out ACTH- releasing factor (CRF/CRH) out ACTH- releasing factor (CRF/CRH) to the anterior pituitary via the portal to the anterior pituitary via the portal systemsystem

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Follicle-Follicle-Stimulating Stimulating Hormone Hormone

(FSH)(FSH)

►FemalesFemales——stimulates stimulates growth/growth/development of development of ovarian folliclesovarian follicles – where – where oogenesis occursoogenesis occurs►Also stimulates the cells lining Also stimulates the cells lining the follicles to the follicles to produce/secrete produce/secrete ________________________►Used to superovulateUsed to superovulate

Males- stimulates Males- stimulates ____________________________________ in in the testesthe testes

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Luteinizing Luteinizing Hormone (LH)Hormone (LH)

► Completes follicle Completes follicle development development in ovary in ovary

► Increasing amounts of estrogens Increasing amounts of estrogens feedback to the anterior pituitary feedback to the anterior pituitary and cause reduced production of and cause reduced production of FSH and increased production of FSH and increased production of LHLH

► LH levels reach a LH levels reach a peak when peak when follicle is fully maturefollicle is fully mature Usually causes Usually causes ______________________________

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Luteinizing Luteinizing Hormone Hormone

(LH)(LH)► After ovulation, LH stimulates After ovulation, LH stimulates

cells in empty follicle to cells in empty follicle to multiply and multiply and develop into develop into ________ __________(CL)________ __________(CL)

CL produces progesterone CL produces progesterone necessary for necessary for maintenance of maintenance of ____________________________

► In males, LH stimulates In males, LH stimulates interstitial cells to produce interstitial cells to produce ______________________________

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Melanocyte-Stimulating Hormone Melanocyte-Stimulating Hormone (MSH)(MSH)

► Controls color changes in Controls color changes in pigment cells (melanocytes) pigment cells (melanocytes) of reptiles, fish, and of reptiles, fish, and amphibiansamphibians

► Administration of artificially Administration of artificially large amounts of MSH to large amounts of MSH to higher mammals can cause higher mammals can cause darkening of skin from darkening of skin from melanocyte stimulation (melanocyte stimulation (↑ ↑ melanin)melanin)

Effect at normal levels in Effect at normal levels in mammals unknownmammals unknown

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Posterior Posterior PituitaryPituitary

► ________(does NOT produce) two ________(does NOT produce) two hormones produced in hormones produced in hypothalamus hypothalamus ______________ _________(ADH) ______________ _________(ADH)

and _______________and _______________

► Transported from hypothalmus to Transported from hypothalmus to post pituitary along post pituitary along axons and axons and stored in nerve endingsstored in nerve endings

► Periodically released into Periodically released into

bloodstream in response to bloodstream in response to

nerve impulses from nerve impulses from

hypothalamushypothalamusPosteriorpituitary

OxytocinADH

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Antidiuretic Antidiuretic Hormone Hormone

(ADH)(ADH)

► Helps Helps prevent diuresisprevent diuresis► Receptors in hypothalamus detect Receptors in hypothalamus detect changes in osmotic pressure changes in osmotic pressure

(concentration) of blood (due to dehydration - (concentration) of blood (due to dehydration - hemoconcentration)hemoconcentration) Generates nerve impulses from hypothalamus- causes release Generates nerve impulses from hypothalamus- causes release

of ADHof ADH► ADH causes kidneys to ADH causes kidneys to reabsorb more water reabsorb more water

from urine and return it to bloodstream from urine and return it to bloodstream ► Urine then Urine then more concentratedmore concentrated

► ADH deficiency causes ADH deficiency causes Diabetes ____________ Diabetes ____________ (PU/PD occurs)(PU/PD occurs)

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OxytocinOxytocin► Effects on uterus: Effects on uterus:

Causes Causes ____________ of myometrium at breeding and at ____________ of myometrium at breeding and at parturition parturition

Induces uterine contractions that Induces uterine contractions that aid transport of aid transport of spermatozoa spermatozoa to oviductsto oviducts

Stimulates uterine contractions that aid in Stimulates uterine contractions that aid in delivery of fetus delivery of fetus and placentaand placenta

► Effect on active mammary glands: Effect on active mammary glands: Stimulation of teat/nippleStimulation of teat/nipple by nursing or milking causes by nursing or milking causes

oxytocin release into bloodstreamoxytocin release into bloodstream Causes contraction of musclelike myoepithelial cells around Causes contraction of musclelike myoepithelial cells around

mammary gland alveoli and small ducts mammary gland alveoli and small ducts Forces milk into lower parts of gland, making it accessible for Forces milk into lower parts of gland, making it accessible for

nursing/milking nursing/milking (______ __________)(______ __________)

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Oxytocin- Oxytocin- positivepositive

feedbackfeedback