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The Endocrine The Endocrine SystemSystem

Chapter 17Chapter 17

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Endocrine SystemEndocrine System

Overview Overview Endocrinology Endocrinology (endo = into crin (endo = into crin

= secrete)= secrete)

FunctionFunctionHormoneHormone

FYI “ A whopping increase of 165% in newly diagnosed Type 2 diabetes is expected by the year 2050. Among ethnic groups, the biggest increase is expected among black men (363%), with black women expected to see the second highest increase (217%).” From Live a Little, Laugh a Lot by Barb Bancroft

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Overview of Cell Overview of Cell CommunicationsCommunications

MechanismsMechanisms gap junctionsgap junctions

pores in cell membrane pores in cell membrane Direct cell to cell Direct cell to cell

neurotransmittersneurotransmitters synapsesynapse

paracrine (local) paracrine (local) hormoneshormones

secreted into tissue fluids secreted into tissue fluids affect nearby cellsaffect nearby cells

interferoninterferon hormones hormones

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Endocrine vs. Exocrine Endocrine vs. Exocrine GlandsGlands

Exocrine glandsExocrine glands ducts carry secretion to a surface ducts carry secretion to a surface extracellular effects (food extracellular effects (food

digestion)digestion) Endocrine glandsEndocrine glands

no ducts, release hormones into no ducts, release hormones into tissue fluids, capillary networks tissue fluids, capillary networks distribute hormonesdistribute hormones

intracellular effects, alter target intracellular effects, alter target cell metabolismcell metabolism

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HormoneHormone chemical messenger stimulates response chemical messenger stimulates response

in other tissues or organsin other tissues or organs Target cellsTarget cells

Have hormone receptors Have hormone receptors Endocrine glandsEndocrine glands

produce hormonesproduce hormones Endocrine systemEndocrine system

endocrine organs (thyroid, pineal, etc)endocrine organs (thyroid, pineal, etc) hormone producing cells in organs (brain, hormone producing cells in organs (brain,

heart and small intestine)heart and small intestine)

Endocrine System Endocrine System ComponentsComponents

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NervousNervous vs. vs. EndocrineEndocrine Systems Systems

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NervousNervous and and EndocrineEndocrine Systems Systems

Some chemicals are both hormones and Some chemicals are both hormones and neurotransmittersneurotransmitters NE, cholecystokinin, thyrotropin-releasing NE, cholecystokinin, thyrotropin-releasing

hormone, dopamine and ADHhormone, dopamine and ADH Some hormones secreted by Some hormones secreted by

neuroendocrine cells (neurons)neuroendocrine cells (neurons) oxytocin and catecholaminesoxytocin and catecholamines

Systems regulate each otherSystems regulate each other neurons trigger hormone secretionneurons trigger hormone secretion hormones stimulate or inhibit neuronshormones stimulate or inhibit neurons

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NomenclatureNomenclature

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Endocrine OrgansEndocrine Organs

Major Major organs organs

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HypothalamusHypothalamus

Floor and walls Floor and walls of third ventricleof third ventricle

Regulates Regulates functions from functions from water balance to water balance to sex drivesex drive

Many functions Many functions carried out by carried out by pituitary glandpituitary gland

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Hypothalamic HormonesHypothalamic Hormones

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Pituitary Gland Pituitary Gland

(Hypophysis)(Hypophysis) Location and sizeLocation and size Suspended from Suspended from

hypothalamus by stalk hypothalamus by stalk (infundibulum)(infundibulum)

housed in sella turcica housed in sella turcica of sphenoid boneof sphenoid bone

1.3 cm diameter1.3 cm diameter Adenohypophysis Adenohypophysis

(anterior pituitary)(anterior pituitary) NeurohypophysisNeurohypophysis

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Secreted Hormones and the Secreted Hormones and the Portal SystemPortal System

Hormones Hormones travel in portal travel in portal system from system from hypothalamus hypothalamus to anterior to anterior pituitarypituitary

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PRL (prolactin)PRL (prolactin) GH (growth hormone)GH (growth hormone) Tropic hormones target other glandsTropic hormones target other glands

gonadotropins target gonadsgonadotropins target gonads FSH (follicle stimulating hormone) FSH (follicle stimulating hormone) eggs and sperm eggs and sperm LH (luteinizing hormone)LH (luteinizing hormone)

ovulation; corpus luteum ovulation; corpus luteum estrogen, progesterone estrogen, progesterone Interstitial cells Interstitial cells testosterone testosterone

TSH (thyroid stimulating hormone) TSH (thyroid stimulating hormone) TH, gland growth TH, gland growth ACTH (adrenocorticotropic hormone)ACTH (adrenocorticotropic hormone)

Pituitary Pituitary Hormones Hormones Anterior LobeAnterior Lobe

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ACTH or corticotropin (secreted by ACTH or corticotropin (secreted by corticotropes)corticotropes) regulates response to stress, stimulates regulates response to stress, stimulates

adrenal cortex adrenal cortex corticosteroids regulate glucose, fat and corticosteroids regulate glucose, fat and

protein metabolismprotein metabolism PRL (secreted by lactotropes)PRL (secreted by lactotropes)

female - milk synthesis after deliveryfemale - milk synthesis after delivery male - male - LH sensitivity, thus LH sensitivity, thus testosterone testosterone

secretionsecretion

Hormone Actions: Hormone Actions: Anterior LobeAnterior Lobe

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Promotes tissue growth (bone, cartilage and muscle growth)Promotes tissue growth (bone, cartilage and muscle growth) mitosis & cellular differentiationmitosis & cellular differentiation stimulates liver to produce IGF-I (insulin like growth stimulates liver to produce IGF-I (insulin like growth

factors/somatomedins) and IIfactors/somatomedins) and II protein synthesis protein synthesis

DNA transciption, DNA transciption, mRNA, mRNA, proteins proteins amino acid transport into cells, amino acid transport into cells, protein protein

catabolismcatabolism lipid metabolism lipid metabolism

stimulates FFA and glycerol release from stimulates FFA and glycerol release from adipocytes, protein sparingadipocytes, protein sparing

CHO metabolismCHO metabolism glucose sparing effect = less glucose used for glucose sparing effect = less glucose used for

energyenergy Electrolyte balanceElectrolyte balance

promotes Napromotes Na++, K, K++, Cl, Cl-- retention, Ca retention, Ca 2+2+ absorption absorption

Growth Hormone Growth Hormone (Somatotropin)(Somatotropin)

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Childhood and adolescenceChildhood and adolescence bone, cartilage and muscle growthbone, cartilage and muscle growth Stimulates growth at epiphyseal platesStimulates growth at epiphyseal plates

AdulthoodAdulthood increase osteoblastic activity affects bone increase osteoblastic activity affects bone

remodelingremodeling concentration decreases with age concentration decreases with age

Levels of GH (daily fluctuations)Levels of GH (daily fluctuations) during deep sleep, after high protein during deep sleep, after high protein

meals, after vigorous exercisemeals, after vigorous exercise lower after high CHO mealslower after high CHO meals

Growth Hormone and Growth Hormone and AgingAging

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Hormone Actions: Posterior Hormone Actions: Posterior LobeLobe

Produced in hypothalamusProduced in hypothalamus transported to and stored in posterior transported to and stored in posterior

lobe lobe ADH (vasopressin)ADH (vasopressin)

targets kidneystargets kidneys water retention, reduce urinewater retention, reduce urine

also functions as a brain also functions as a brain neurotransmitterneurotransmitter

OxytocinOxytocin labor contractions, lactationlabor contractions, lactation possible role in possible role in

sperm transportsperm transport emotional bondingemotional bonding

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Control of Pituitary: Control of Pituitary: Feedback from Target OrgansFeedback from Target Organs

Negative feedback Negative feedback target organ target organ

hormone levels hormone levels inhibits release of inhibits release of tropic hormonestropic hormones

Positive feedback stretching of uterus OT release, causes more stretching of uterus, until delivery

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Endocrine DisordersEndocrine Disorders Hormone concentration and target cell Hormone concentration and target cell

sensitivity sensitivity Hyposecretion – inadequate hormone releaseHyposecretion – inadequate hormone release

tumor or lesion destroys glandtumor or lesion destroys gland head trauma affects pituitary gland’s head trauma affects pituitary gland’s

ability to secrete ADHability to secrete ADH diabetes insipidus = chronic polyuriadiabetes insipidus = chronic polyuria

Hypersecretion – excessive hormone releaseHypersecretion – excessive hormone release tumors or autoimmune disordertumors or autoimmune disorder

toxic goiter (graves disease) – antibodies toxic goiter (graves disease) – antibodies mimic effect of TSH on the thyroidmimic effect of TSH on the thyroid

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Pituitary Pituitary DisordersDisorders

Hypersecretion of growth hormonesHypersecretion of growth hormones AcromegalyAcromegaly

middle-aged adults   middle-aged adults    abnormal growth of the hands/feet abnormal growth of the hands/feet

     bone changes alter facial features bone changes alter facial features

including the spacing of teeth   including the spacing of teeth    arthritis   arthritis    thick, coarse, oily skin; skin tags; thick, coarse, oily skin; skin tags;

enlarged lips, nose and tongue;   enlarged lips, nose and tongue;    deepening of the voice due to deepening of the voice due to

enlarged sinuses and vocal cords; enlarged sinuses and vocal cords; snoring due to upper airway snoring due to upper airway obstruction;   obstruction;   

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excessive sweating and skin odor; fatigue excessive sweating and skin odor; fatigue and weakness; headaches; impaired vision; and weakness; headaches; impaired vision;      

enlargement of body organs, including the enlargement of body organs, including the liver, spleen, kidneys and heart.liver, spleen, kidneys and heart.

thickening of the bones and soft tissuesthickening of the bones and soft tissues problems in childhood or adolescenceproblems in childhood or adolescence

gigantism = oversecretion; dwarfism = gigantism = oversecretion; dwarfism = hyposecretion hyposecretion

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Pineal GlandPineal Gland Peak secretion ages 1-5; by puberty 75% lowerPeak secretion ages 1-5; by puberty 75% lower May regulate timing of puberty in humansMay regulate timing of puberty in humans Produces serotonin by day, converts it to melatonin Produces serotonin by day, converts it to melatonin

at nightat night Melatonin Melatonin in SAD + PMS; in SAD + PMS; by phototherapy by phototherapy

depression, sleepiness, irritability and depression, sleepiness, irritability and carbohydrate cravingcarbohydrate craving“The pineal gland was called the "third eye" by ancient people. It was

thought to have mystical powers. This may be why the French philosopher Descartes decided that the pineal gland was the seat of the human soul, the location of what we call the mind.

Melatonin is released in the dark, during sleep. Melatonin has been shown to inhibit the growth and metastasis of some tumors in experimental animals, and may therefore play a role in cancer inhibition. Removal of the pineal gland and/or reduction in melatonin output have been implicated in the increased incidence of breast cancer in laboratory animals. Patients who have breast cancer have lower levels of melatonin in the blood. The hormone has also been shown to be protective against genetic damage, and it has a stimulatory effect on the immune system. “www.cayce.egympie.com.au/healthPinealGland.htm

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ThymusThymus

Location: mediastinum, Location: mediastinum, superior to heartsuperior to heart

Involution after pubertyInvolution after puberty Hormones regulate Hormones regulate

development and later development and later activation of T-activation of T-lymphocyteslymphocytes thymopoietin and thymopoietin and

thymosinsthymosins

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Thyroid Gland AnatomyThyroid Gland Anatomy Largest endocrine gland; high rate of blood Largest endocrine gland; high rate of blood

flowflow Anterior and lateral sides of tracheaAnterior and lateral sides of trachea

two large lobes connected by isthmus two large lobes connected by isthmus Thyroid folliclesThyroid follicles

filled with colloid and lined with simple filled with colloid and lined with simple cuboidal epithelial (follicular cells) that cuboidal epithelial (follicular cells) that secretes two hormones, Tsecretes two hormones, T3 3 and Tand T44

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Thyroid GlandThyroid Gland Thyroid hormoneThyroid hormone

body’s metabolic rate and Obody’s metabolic rate and O22 consumptionconsumption

calorigenic effect - calorigenic effect - heat production heat production heart rate and contraction strengthheart rate and contraction strength respiratory raterespiratory rate stimulates appetite and breakdown stimulates appetite and breakdown

CHO, lipids and proteinsCHO, lipids and proteins alertness, bone growth/remodelingalertness, bone growth/remodeling

C (calcitonin or parafollicular) cellsC (calcitonin or parafollicular) cells produce calcitonin produce calcitonin blood Ca blood Ca2+ 2+ , ,

promotes Capromotes Ca2+ 2+ deposition and bone deposition and bone formation especially in childrenformation especially in children

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Thyroid Gland DisordersThyroid Gland Disorders Congenital hypothyroidism (Congenital hypothyroidism ( TH) TH)

abnormal bone development, abnormal bone development, thickened facial features, low thickened facial features, low temperature, lethargy, brain damagetemperature, lethargy, brain damage

Myxedema (adult hypothyroidism, Myxedema (adult hypothyroidism, TH)TH) low metabolic rate, sluggishness, low metabolic rate, sluggishness,

sleepiness, weight gain, constipation, sleepiness, weight gain, constipation, dry skin and hair, cold sensitivity, dry skin and hair, cold sensitivity, blood pressure and tissue swellingblood pressure and tissue swelling

Endemic goiter (goiter = enlarged Endemic goiter (goiter = enlarged thyroid gland)thyroid gland) iodine deficiency, no TH, no - iodine deficiency, no TH, no -

feedback, feedback, TSH TSH Toxic goiter (Graves disease)Toxic goiter (Graves disease)

antibodies mimic TSH, antibodies mimic TSH, TH, TH, exophthalmos exophthalmos

Nodular pretibial myxedema

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Parathyroid GlandsParathyroid Glands

PTH releasePTH release blood Cablood Ca2+ 2+ levelslevels promotes synthesis of promotes synthesis of

calcitriolcalcitriol absorption of Caabsorption of Ca2+ 2+

urinary excretionurinary excretion bone resorptionbone resorption

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Parathyroid DisordersParathyroid Disorders

HypoparathyroidHypoparathyroid surgical excision during thyroid surgerysurgical excision during thyroid surgery fatal tetany 3-4 daysfatal tetany 3-4 days

Hyperparathyroid = excess PTH Hyperparathyroid = excess PTH secretionsecretion tumor in glandtumor in gland causes soft, fragile and deformed bonescauses soft, fragile and deformed bones blood Cablood Ca2+ 2+

renal calculirenal calculi

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Adrenal Adrenal MedullaMedulla

Modified neurons called chromaffin cellsModified neurons called chromaffin cells releases catecholamines (epinephrine, NE)releases catecholamines (epinephrine, NE)

Long lasting hormonal effect Long lasting hormonal effect alertness, anxiety, or fearalertness, anxiety, or fear BP, heart rate and air flowBP, heart rate and air flow raises metabolic rateraises metabolic rate

inhibits insulin secretioninhibits insulin secretion stimulates gluconeogenesis and stimulates gluconeogenesis and

glycogenolysisglycogenolysis Stress causes medullary cells to stimulate Stress causes medullary cells to stimulate

cortexcortex

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Adrenal CortexAdrenal Cortex LayersLayers

zona glomerulosa (outer) zona glomerulosa (outer) zona fasciculata (middle) zona fasciculata (middle) zona reticularis (inner)zona reticularis (inner)

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Adrenal Adrenal CortexCortex

CorticosteroidsCorticosteroids mineralocorticoids (zona glomerulosa)mineralocorticoids (zona glomerulosa)

electrolyte balance, aldosterone electrolyte balance, aldosterone Na Na++ retention & retention & KK++ excretion excretion

glucocorticoids (zona fasciculata)glucocorticoids (zona fasciculata) especially cortisol, especially cortisol, fat and protein catabolism, fat and protein catabolism,

gluconeogenesis (from a.a.’s and FA’s) and gluconeogenesis (from a.a.’s and FA’s) and releases FAs and glucose into bloodreleases FAs and glucose into blood

anti-inflammatory effect becomes immune anti-inflammatory effect becomes immune suppression with long-term usesuppression with long-term use

sex steroids (zona reticularis)sex steroids (zona reticularis) androgen (including DHEA) and estrogen androgen (including DHEA) and estrogen

(important after menopause)(important after menopause)

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Adrenal Adrenal DisordersDisorders Cushing syndrome - excess cortical Cushing syndrome - excess cortical secretionsecretion hyperglycemia, hypertension, weakness, hyperglycemia, hypertension, weakness,

edemaedema Muscle/bone loss occurs with protein Muscle/bone loss occurs with protein

catabolismcatabolism buffalo hump and moon face = fat buffalo hump and moon face = fat

deposition between shoulders or in face deposition between shoulders or in face Adrenogenital syndrome (AGS)Adrenogenital syndrome (AGS)

adrenal androgen hypersecretion; adrenal androgen hypersecretion; accompanies Cushingaccompanies Cushing

enlargement of external sexual organs in enlargement of external sexual organs in children and early onset of pubertychildren and early onset of puberty

masculinizing effects on women (deeper masculinizing effects on women (deeper voice and beard growth)voice and beard growth)

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PancreaPancreass

Location - Retroperitoneal, inferior and dorsal to Location - Retroperitoneal, inferior and dorsal to stomachstomach

Exocrine – digestive enzymesExocrine – digestive enzymes Endocrine Endocrine

1-2 million islets produce hormones1-2 million islets produce hormones Insulin (from Insulin (from cells) cells)

secreted after CHO meal secreted after CHO meal glucose blood levels glucose blood levels stimulates glucose and amino acid uptakestimulates glucose and amino acid uptake nutrient storage effect (stimulates glycogen, nutrient storage effect (stimulates glycogen,

fat and protein synthesis)fat and protein synthesis)

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Pancreatic HormonesPancreatic Hormones Glucagon (from Glucagon (from cells) cells)

secreted in very low carbohydrate secreted in very low carbohydrate and high protein diet or fastingand high protein diet or fasting

stimulates glycogenolysis, fat stimulates glycogenolysis, fat catabolism and absorption of AAs catabolism and absorption of AAs for gluconeogenesis for gluconeogenesis

Somatostatin (from delta (Somatostatin (from delta () ) cells)cells) secreted with secreted with in blood glucose in blood glucose

and AAs after a mealand AAs after a meal paracrine secretion = inhibits paracrine secretion = inhibits

secretion of insulin, glucagon by secretion of insulin, glucagon by and and cells cells

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Pancreatic HormonesPancreatic Hormones Hyperglycemic hormones raise Hyperglycemic hormones raise

blood glucoseblood glucose GH, epinephrine, NE, cortisol and GH, epinephrine, NE, cortisol and

corticosteronecorticosterone Hypoglycemic hormones lower Hypoglycemic hormones lower

blood glucoseblood glucose insulininsulin

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Diabetes MellitusDiabetes Mellitus

Signs and symptoms of hyposecretion of Signs and symptoms of hyposecretion of insulininsulin polyuria, polydipsia, polyphagiapolyuria, polydipsia, polyphagia hyperglycemia, glycosuria, ketonuriahyperglycemia, glycosuria, ketonuria osmotic diuresisosmotic diuresis

blood glucose levels rise above transport blood glucose levels rise above transport maximum of kidney tubules, glucose maximum of kidney tubules, glucose remains in urine (ketones also present)remains in urine (ketones also present)

increased osmolarity draws water into increased osmolarity draws water into urineurine

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Types of Diabetes Types of Diabetes MellitusMellitus

Type I (IDDM) - 10% of casesType I (IDDM) - 10% of cases autoimmune destruction of autoimmune destruction of cells, cells,

diagnosed ~ 12diagnosed ~ 12 treat with diet, exercise, monitoring of treat with diet, exercise, monitoring of

blood glucose and insulin injectionsblood glucose and insulin injections Type II (NIDDM) - 90%Type II (NIDDM) - 90%

insulin resistanceinsulin resistance failure of target cells to respond to failure of target cells to respond to

insulininsulin risk factors: heredity, age (40+) and obesityrisk factors: heredity, age (40+) and obesity treat with weight loss, diet and exercisetreat with weight loss, diet and exercise oral medications improve insulin secretion oral medications improve insulin secretion

or target cell sensitivityor target cell sensitivity

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Pathology of DiabetesPathology of Diabetes Acute pathology: cannot absorb glucose, breakdown Acute pathology: cannot absorb glucose, breakdown

fat and proteins (weight loss, weakness)fat and proteins (weight loss, weakness) fat catabolism fat catabolism FFA’s in blood and ketone bodies FFA’s in blood and ketone bodies ketonuria ketonuria osmotic diuresis, loss of Na osmotic diuresis, loss of Na++ and K and K++

ketoacidosis occurs as ketones ketoacidosis occurs as ketones blood pH blood pH causes dyspnea and eventually diabetic comacauses dyspnea and eventually diabetic coma

Chronic pathologyChronic pathology chronic hyperglycemia leads to neuropathy and chronic hyperglycemia leads to neuropathy and

cardiovascular damage from atherosclerosiscardiovascular damage from atherosclerosis retina and kidneys (common in type I), retina and kidneys (common in type I),

atherosclerosis leads to heart failure (common in atherosclerosis leads to heart failure (common in type II), and gangrenetype II), and gangrene

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HyperinsulinismHyperinsulinism From excess insulin injection or From excess insulin injection or

pancreatic islet tumorpancreatic islet tumor Causes hypoglycemia, weakness and Causes hypoglycemia, weakness and

hungerhunger triggers secretion of epinephrine, GH triggers secretion of epinephrine, GH

and glucagonand glucagonside effects: anxiety, sweating and side effects: anxiety, sweating and HRHR

Insulin shockInsulin shock uncorrected hyperinsulinism with uncorrected hyperinsulinism with

disorientation, convulsions or disorientation, convulsions or unconsciousness unconsciousness

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OvaryOvary Granulosa cells Granulosa cells

produces estradiol, first half of cycleproduces estradiol, first half of cycle Corpus luteum Corpus luteum

follicle after ovulationfollicle after ovulation produce estradiol and progesterone produce estradiol and progesterone

Functions of estradiol and progesteroneFunctions of estradiol and progesterone development of female reproductive development of female reproductive

system and physique including bone system and physique including bone growthgrowth

regulate menstrual cycle, sustain regulate menstrual cycle, sustain pregnancypregnancy

prepare mammary glands for lactation prepare mammary glands for lactation Both secrete inhibin: suppresses FSH secretionBoth secrete inhibin: suppresses FSH secretion

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TestesTestes Interstitial cells (between Interstitial cells (between

seminiferous tubules)seminiferous tubules) produce testosterone and estrogenproduce testosterone and estrogen

FunctionsFunctions development of male reproductive development of male reproductive

system and physiquesystem and physique sustains sperm production and sex sustains sperm production and sex

drivedrive Sustentacular sertoli cellsSustentacular sertoli cells

secrete inhibin which suppresses secrete inhibin which suppresses FSH & stabilizes sperm production FSH & stabilizes sperm production ratesrates

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Endocrine Functions of Other Endocrine Functions of Other OrgansOrgans Heart – Heart –

atrial natriuretic peptide (ANP) released with an atrial natriuretic peptide (ANP) released with an in BPin BP

blood volume and blood volume and BP by BP by Na Na++ and H and H22O loss by O loss by kidneyskidneys

Skin - helps produce vitamin DSkin - helps produce vitamin D3 3 calcitriol calcitriol (( blood blood Ca)Ca)

LiverLiver 15% of erythropoietin (stimulates bone marrow)15% of erythropoietin (stimulates bone marrow) angiotensinogen (a prohormone)angiotensinogen (a prohormone)

precursor of angiotensin II precursor of angiotensin II BP BP source of IGF-I (works with GH)source of IGF-I (works with GH) converts vitamin D3 to calcidiol converts vitamin D3 to calcidiol Hepcidin – promotes intestinal absorption of ironHepcidin – promotes intestinal absorption of iron

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Endocrine Functions of Other Endocrine Functions of Other

OrgansOrgans KidneysKidneys erythropoietin – stimulates production of RBC’serythropoietin – stimulates production of RBC’s convert angiotensinogen to angiotensin Iconvert angiotensinogen to angiotensin I converts calcidiol to calcitriol (active form of vitamin converts calcidiol to calcitriol (active form of vitamin

D) D) absorption by intestine and inhibits loss in the absorption by intestine and inhibits loss in the

urineurine more Camore Ca2+ 2+ available for bone depositionavailable for bone deposition

Stomach and small intestines (10 enteric hormones)Stomach and small intestines (10 enteric hormones) coordinate digestive motility and secretion coordinate digestive motility and secretion

PlacentaPlacenta secretes estrogen, progesterone and otherssecretes estrogen, progesterone and others

regulate pregnancy, stimulate development of fetus regulate pregnancy, stimulate development of fetus and mammary glandsand mammary glands

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Hormone ChemistryHormone Chemistry SteroidsSteroids

derived from cholesterolderived from cholesterol sex steroids, sex steroids,

corticosteroidscorticosteroids Peptides and glycoproteinsPeptides and glycoproteins

OT, ADH; all releasing OT, ADH; all releasing and inhibiting hormones and inhibiting hormones of hypothalamus; most of of hypothalamus; most of anterior pituitary anterior pituitary hormoneshormones

Monoamines (biogenic Monoamines (biogenic amines)amines) derived from amino acidsderived from amino acids

catecholamines catecholamines (norepinephrine, (norepinephrine, epinephrine, epinephrine, dopamine) and thyroid dopamine) and thyroid hormoneshormones

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Hormone Synthesis: Steroid Hormone Synthesis: Steroid HormonesHormones

Synthesized from Synthesized from cholesterol – cholesterol – differs in differs in functional groups functional groups attached to 4-attached to 4-ringed steroid ringed steroid backbonebackbone

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Hormone TransportHormone Transport Monoamines and peptides are hydrophilic Monoamines and peptides are hydrophilic

mix easily with blood plasma mix easily with blood plasma Steroids and thyroid hormone are hydrophobic Steroids and thyroid hormone are hydrophobic

must bind to transport proteins for transportmust bind to transport proteins for transport bound hormonebound hormone - attached to transport protein, - attached to transport protein,

prolongs half-life to weeksprolongs half-life to weeks protects from enzymes and kidney filtrationprotects from enzymes and kidney filtration

unbound hormoneunbound hormone leaves capillary to reach target leaves capillary to reach target cell (half-life a few minutes)cell (half-life a few minutes)

Transport proteins in blood plasmaTransport proteins in blood plasma albumin, thyretin and TGB (thyroxine binding albumin, thyretin and TGB (thyroxine binding

globulin) bind to thyroid hormoneglobulin) bind to thyroid hormone steroid hormones bind to globulins (transcortin)steroid hormones bind to globulins (transcortin) aldosterone - no transport protein, 20 min. half-lifealdosterone - no transport protein, 20 min. half-life

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Hormone ReceptorsHormone Receptors

Located on plasma membrane, Located on plasma membrane, mitochondria, other organelles, or in mitochondria, other organelles, or in nucleusnucleus

Usually thousands for given hormoneUsually thousands for given hormone hormone binding turns metabolic hormone binding turns metabolic

pathways on or offpathways on or off Exhibit specificity and saturationExhibit specificity and saturation

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Hormone Mode of ActionHormone Mode of Action

Hydrophobic Hydrophobic hormoneshormones penetrate penetrate

plasma plasma membrane – membrane – enter nucleusenter nucleus

Hydrophilic Hydrophilic hormones hormones must bind to must bind to

cell-surface cell-surface receptorsreceptors

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Hormone ClearanceHormone Clearance

Hormone signals must be turned offHormone signals must be turned off Take up and degraded by liver and Take up and degraded by liver and

kidneykidney Excreted in bile or urineExcreted in bile or urine Metabolic clearance rate (MCR)Metabolic clearance rate (MCR) Half-life - time required to clear 50% Half-life - time required to clear 50%

of hormoneof hormone

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Hormone InteractionsHormone Interactions

Most cells sensitive to more than one Most cells sensitive to more than one hormone and exhibit interactive effectshormone and exhibit interactive effects

Synergistic effectsSynergistic effects Permissive effectsPermissive effects

one hormone enhances response to a second one hormone enhances response to a second hormonehormone

Antagonistic effects Antagonistic effects

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Stress and Adaptation Stress and Adaptation

StressStress upsets homeostasis and threatens upsets homeostasis and threatens

well-beingwell-being General adaptation syndrome General adaptation syndrome

way body reacts to stressway body reacts to stress occurs in 3 stagesoccurs in 3 stages

1.1. alarm reactionalarm reaction

2.2. stage of resistancestage of resistance

3.3. stage of exhaustionstage of exhaustion

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Alarm ReactionAlarm Reaction

Initial responseInitial response epinephrine and norepinephrine levelsepinephrine and norepinephrine levels HR and HR and BP BP blood glucose levelsblood glucose levels Sodium and water retention Sodium and water retention

(aldosterone)(aldosterone)

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Stage of ResistanceStage of Resistance

After a few hours, glycogen reserves After a few hours, glycogen reserves gonegone

ACTH and cortisol levelsACTH and cortisol levels Fat and protein breakdownFat and protein breakdown GluconeogenesisGluconeogenesis Depressed immune functionDepressed immune function Susceptibility to infection and ulcersSusceptibility to infection and ulcers

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Stage of ExhaustionStage of Exhaustion Stress that continues until fat reserves Stress that continues until fat reserves

are goneare gone Protein breakdown and muscle wasting Protein breakdown and muscle wasting Loss of glucose homeostasisLoss of glucose homeostasis Hypertension and electrolyte imbalances Hypertension and electrolyte imbalances

(loss of K(loss of K++ and H and H++)) Hypokalemia and alkalosis leads to deathHypokalemia and alkalosis leads to death

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Paracrine SecretionsParacrine Secretions Chemical messengers that diffuse short Chemical messengers that diffuse short

distances and stimulate nearby cellsdistances and stimulate nearby cells not produced in neurons or transported in bloodnot produced in neurons or transported in blood

Examples and their functionsExamples and their functions histamine histamine

from mast cells in connective tissue from mast cells in connective tissue causes relaxation of blood vessel smooth musclecauses relaxation of blood vessel smooth muscle

nitric oxide nitric oxide from endothelium of blood vessels, causes vasodilationfrom endothelium of blood vessels, causes vasodilation

somatostatin somatostatin inhibits secretion of islet alpha and beta cellsinhibits secretion of islet alpha and beta cells

catecholamines catecholamines diffuse from adrenal medulla to cortexdiffuse from adrenal medulla to cortex

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Eicosanoids: a Paracrine Eicosanoids: a Paracrine SecretionSecretion LeukotrienesLeukotrienes

mediates allergic and inflammatory reactionsmediates allergic and inflammatory reactions Prostacyclin Prostacyclin (by cyclooxygenase)(by cyclooxygenase)

inhibits blood clotting and vasoconstrictioninhibits blood clotting and vasoconstriction Thromboxanes Thromboxanes (by cyclooxygenase)(by cyclooxygenase)

produced by blood platelets after injury; produced by blood platelets after injury; override prostacyclin, stimulates override prostacyclin, stimulates vasoconstriction and clottingvasoconstriction and clotting

Prostaglandins Prostaglandins (by cyclooxygenase)(by cyclooxygenase): : diverse; diverse; includesincludes PGE: relaxes smooth muscle in bladder, PGE: relaxes smooth muscle in bladder,

intestines, bronchioles, uterus and stimulates intestines, bronchioles, uterus and stimulates contraction of blood vesselscontraction of blood vessels

PGF: opposite effectsPGF: opposite effects

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ReviewReview

ThyroidThyroid

PancreasPancreas

PinealPineal

ThymusThymus

melatoninmelatonin

thymopoietthymopoietinin

calcitonincalcitonin

glucagonglucagon

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FSHFSH

GnRHGnRH

ADHADH

EstrogenEstrogen

OTOT

LHLH

PTHPTH

Parathyroid hormoneParathyroid hormone

Antidiuretic hormoneAntidiuretic hormone

Luteinizing hormoneLuteinizing hormone

Follicle stimulating Follicle stimulating hormonehormone

OxytoxinOxytoxin

Gonadotropin Gonadotropin releasing hormonereleasing hormone

EstrogenEstrogen

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