THE ENDOCRINE THE ENDOCRINE SYSTEMSYSTEM

Chapter 16Chapter 16

OVERVIEWOVERVIEW Group of Group of

unimpressive, unimpressive, discontinuous organsdiscontinuous organs

Coordinates and Coordinates and integrates body integrates body activity through the activity through the use of use of hormoneshormones produced produced in in ductless glandsductless glands

Differs from nervous Differs from nervous system because its system because its work is strictly work is strictly chemicalchemical

Exocrine Exocrine glands use glands use ducts to deliver their ducts to deliver their secretionssecretions

OrgansOrgans Pineal, hypothalamus, Pineal, hypothalamus, pituitary, thyroid, pituitary, thyroid, parathyroid, thymus, parathyroid, thymus, adrenal, pancreas, testis, adrenal, pancreas, testis, ovary, placenta, tumors, ovary, placenta, tumors, cells within the digestive cells within the digestive tract, heart, kidney, etc.tract, heart, kidney, etc.

AdrenalPinealPituitaryThyroid

Ovaries

ThymusDigestive hormonesTestes

Pancreas

HypothalamusParathyroid

1

2

34

56

7

8

9

51126

89

74

13

Thyroid gland

hypothalamus

anteriorpituitary

gonadotropic hormones:follicle-stimulatinghormone (FSH) & luteinizing hormone (LH)

Mammaryglandsin mammals

Musclesof uterus

Kidneytubules

posteriorpituitary

thyroid-stimulating hormone(TSH)

antidiuretic hormone(ADH)

Adrenalcortex

Boneand muscle Testis Ovary

Melanocytein amphibian

adrenocorticotropic

hormone (ACTH)melanocyte-stimulating hormone(MSH)

oxytocin

prolactin (PRL)

grow

th h

orm

one (

GH)

tropic hormones

HormonesHormones Chemicals released into Chemicals released into

extracellular fluids that extracellular fluids that regulate metabolic functions regulate metabolic functions of other cellsof other cells

Ex: growth, development, Ex: growth, development, metabolism immune metabolism immune response, electrolyte & water response, electrolyte & water balance, blood pressure, RBC balance, blood pressure, RBC productionproduction

Hormones fall into one of 2 Hormones fall into one of 2 categories:categories:Amino-acid based – most Amino-acid based – most hormones in this category; ex: hormones in this category; ex: thyroxine, insulin, melatonin, thyroxine, insulin, melatonin, ADH, etc.ADH, etc.

Steroid- (cholesterol based) Steroid- (cholesterol based) ex: sex hormones (estrogen, ex: sex hormones (estrogen, FSH, LH, testosterone), FSH, LH, testosterone), aldosteronealdosterone

Function by binding to and Function by binding to and influencing activity of a target cell influencing activity of a target cell (cell containing receptors for that (cell containing receptors for that hormone); ex: most body cells hormone); ex: most body cells have receptors for human growth have receptors for human growth hormone and thyroxinehormone and thyroxineProvoke a secondary messenger Provoke a secondary messenger activityactivityOROR

Directly influence DNA activity of Directly influence DNA activity of the cellthe cell

Once bound, hormones:Once bound, hormones:Change plasma membrane Change plasma membrane permeabilitypermeability

Promote production of Promote production of regulatory molecules; regulatory molecules; enzymesenzymes

Activate or deactivate Activate or deactivate enzymesenzymes

Induce secretory activity of Induce secretory activity of the cellthe cell

Control is by feedback Control is by feedback mechanism mechanism

Ex: Negative FeedbackEx: Negative Feedback Gland is stimulated due to low Gland is stimulated due to low levels of hormonelevels of hormone

Hormone is Hormone is releasedreleased

Hormone levels Hormone levels increase in increase in bloodstream bloodstream

Increased levels Increased levels deactivate gland deactivate gland

Maintaining homeostasisMaintaining homeostasis

high

low

hormone 1

lowersbody condition

hormone 2

gland

specific body condition

raisesbody condition gland

Negative FeedbackModel

Controlling Body TemperatureControlling Body Temperature

high

low

nerve signals

sweat

nerve signals

brain

body temperature

shiver brain

dilates surfaceblood vessels

constricts surfaceblood vessels

Nervous System ControlNervous System ControlFeedback

liver

pancreas

liver

Regulation of Blood SugarRegulation of Blood Sugar

blood sugar level

insulin

body cells takeup sugar

from blood

liver storessugar

reducesappetite

glucagon

pancreas

liver releases

sugartriggershunger

high

low

FeedbackEndocrine System ControlEndocrine System Control

nephron

nephron

low

Blood OsmolarityBlood Osmolarity

blood osmolarityblood pressure

ADH

increasedwater

reabsorption

increasethirst

renin

increasedwater & saltreabsorption

high

FeedbackEndocrine System ControlEndocrine System Control

pituitary

angiotensin

nephron(JGA)

adrenalgland

aldosterone

JuxtaGlomerularApparatus

Regulation of Blood CalciumRegulation of Blood Calcium

blood calcium level(10 mg/100mL)

calcitonin

PTH

Ca++ uptakein intestines

high

low

FeedbackEndocrine System ControlEndocrine System Control

kidney reabsorbs Ca++

bones release Ca++

kidney filters Ca++

Ca++ depositedin bones

activated Vitamin D parathyroid

corpusluteumovary

Female reproductive cycleFemale reproductive cycle

pregnancy

maintainsuterus lining

no

yes

Feedback

estrogenegg

matures &is released(ovulation)

builds up uterus lining

FSH & LHprogesterone

progesterone

fertilized egg

HCG

corpus luteum breaks downprogesterone drops =

menstruation

maintainsuterus lining

GnRH

hypothalamus

Control falls into one of 3 Control falls into one of 3 categories:categories: Hormonal stimuliHormonal stimuli – Ex: FSH – Ex: FSH from pituitary stimulates ovary from pituitary stimulates ovary to release progesterone and to release progesterone and estrogen; this in turn shuts estrogen; this in turn shuts down FSH = rhythmdown FSH = rhythm

Humoral Humoral stimulistimuli – – Ex: blood Ex: blood sugar sugar levels levels stimulate stimulate pancreas pancreas to release to release insulin; insulin; this lowers this lowers sugar sugar levels levels which in which in turn turn reduces reduces insulin insulin productionproduction

Neural stimuliNeural stimuli – Ex: – Ex: stress triggers stress triggers adrenal gland to adrenal gland to release adrenalinerelease adrenaline

Organs/HormonesOrgans/HormonesAnterior PituitaryAnterior Pituitary – HGH, – HGH, TSH, ACTH, FSH, LH, PRLTSH, ACTH, FSH, LH, PRL

HypothalamusHypothalamus – oxytocin, – oxytocin, ADHADH

ThyroidThyroid – thyroxine, – thyroxine, calcitonincalcitonin

ParathyroidParathyroid – PTH – PTH

AdrenalAdrenal – glucocorticoids, – glucocorticoids, androgens, androgens,

aldosterone, aldosterone, adrenalineadrenalinePancreasPancreas – insulin, – insulin, glucagonglucagon

GonadsGonads – testosterone, – testosterone, estrogen, progesteroneestrogen, progesterone

PinealPineal – melatonin – melatoninThymusThymus – thymopoietin, – thymopoietin, thymosinthymosin

GoiterGoiterIodine deficiency Iodine deficiency causes thyroid to causes thyroid to enlarge as it tries to enlarge as it tries to produce thyroxineproduce thyroxine

Robert Wadlow1918-1940

8' 11"

Excessive HGH

Graves - hyperthyroid

hypothyroidism

Hyperthyroidism

Cushing’s Disease