A & P Chapter 16

Hypothalamic-hypophyseal tract

(cluster of axons within CNS) connects hypothalamus with posterior pituitary

Diabetes Mellitus

-"Sugar diabetes: -Type 1: beta islet cells die, can't produce insulin , INSULIN DEPENDENT -Type 2: Most common. Beta islet cells produce insulin, but cells that bear the insulin receptors (basically every cell in the body) are not sensitive to that insulin - NON-INSULIN DEPEDENDENT -Elevated blood glucose -Polyuria (more glucose in urine, osmosis) -Polydipsia -Polyphagia Breaks down fat, turns into ketone bodies- acidic - ketoacidosis - low blood pH, Ketourea -Diabetes Mellitus - in pregnancy, likely to develop type 2 later in life - overweight pregnant women or women who gain a ton of weight during pregnancy

Amino Acid Based

-1 or more amino acid (amines, peptides, protein hormones) -WATER SOLUBLE, CANNOT CROSS PLASMA MEMBRANE

Hypo - Aldosteronism

-ADDISON'S DISEASE -Hyposecretion of adrenal cortex -Includes: mineralcorticoids, glucocorticoids -Symptoms: severe dehydration, hypotension, low blood glucose, low Na+, high K+

Hyper - Aldosteronism

-ALDOSTERONISM -Adrenal cortex tumor -Overactivity of cells in zona glomerulosa -Symptoms: Hypertension & edema, loss of K+

Hypo-cortisol Secretion

-Addison's disease -Glucocorticoid and mineral corticoid deficits -Lack of ACTH, or suppressed activity of adrenal cortex -Hypoglycemic -Can't stimulate aldosterone secretion - low blood volume, sodium, pressure

Leptin

-Adipocytokine that regulates food intake & energy expenditure -Decreases food intake -Increases energy expenditure -Decreases body weight -Leptin receptor in hypothalamus

cAMP Second Messenger

-Amino Acid-Based hormone signaling -Catecholamines, Calcitonin, ACTH, FSH, LH, Glucagon, PTH, TSH 1. Hormone (1st messenger) binds to receptor on membrane 2. Receptor activates G protein 3. G protein activates Adenylate Cyclase 4. Adenylate Cyclase converts ATP to cAMP 5. cAMP activates protein kinases PROTEIN KINASES TRIGGERS RESPONSES OF TARGET CELL

Relationship b/w Anterior pituitary and hypothalamus

-Anterior lobe - adenohypophysis -PROPER GLAND --->Made of glandular tissue --->Produces & secretes hormones -Hypothalamus & anterior lobe are INDEPENDENT, DISTINCT STRUCTURES --->However, hormones secreted by anterior pituitary are still under control of hypothalamus 1. Hormones produced in hypothalamic cell bodies secreted into PRIMARY CAPILLARY PLEXUS -AXONS FROM HYPOTHALAMUS NEVER LEAVE THE HYPOTHALAMUS TO GO INTO THE ANTERIOR PITUITARY -Release hormones into SUPERIOR HYPOPHYSEAL ARTERY/PORTAL SYSTEM 3. Blood enters the artery, picks up hormones, carries them down to anterior pituitary -These hormones from hypothalamus will stimulate or inhibit secretion of hormones from anterior pituitary 4. Anterior pituitary secretes hormones if stimulated into SECONDARY CAPILLARY PLEXUS, THIS EMPTIES INTO GENERAL CIRCULATION -GROWTH HORMONE (GH), LH, FSH, ACTH, TSH, PRL

Eicosanoid

-Biologically active lipids with LOCAL hormone-like activity -NOT A TRUE HORMONE SINCE THEY ACT LOCALLY

Glucagon

-Breakdown of glycogen in liver, releasing into blood, elevating blood glucose -By ALPHA ISLET CELLS -Breakdown of glycogen to glucose -Synthesis of glucose from lactic acid & non carb molecules - GLUCONEOGENESIS -Release of glucose to body by liver cells, causing blood glucose levels to rise

Parathyroid Gland

-Cells arranged in cords containing OXYPHIL and CHIEF CELLS -CHIEF CELLS SECRETE PTH -PARATHYROID HORMONE - (PTH) -RAISES BLOOD CALCIUM LEVELS -Secretes when blood calcium levels are LOW -Very potent -STIMULATES OSTEOCLAST ACTIVITY - releases calcium into blood stream - LEACHES BONES -INCREASES CALCIUM REABSORPTION IN KIDNEYS -ACTIVATES VITAMIN D IN KIDNEYS - has action in small intestine that promotes ABSORPTION OF CALCIUM FROM FOOD -NEGATIVE FEEDBACK HYPERPARATHYROIDISM -Rare - leaching of bones - porous, flexible -KIDNEY STONES -Paget's disease HYPOPARATHYROIDISM -HYPOCALCEMIA -Membrane potential rises to threshold -->INCREASES SPONTANEOUS DEPOLARIZATION (contraction) --->Prone to muscle cramping, heart likely to spontaneously contract out of rhythm

Hypothyroid disorder

-Children - CRETINISM -Low metabolic rate -Growth retardation -Developmental delay -Can be due to deficient of iodine in the mother's diet during pregnancy -Scaly skin, brittle hair, layer of fat under skin -Adults - MYXEDEMA -Low metabolic rate - weight gain -Skin & tissue abnormalities -Fatigue -Cognitive regression -Scaly skin, brittle hair GOITER from iodine deficiency - cells searching for iodine - over work & hypertrophy

Hyper-cortisol Secretion

-Cushing's -Cushing's syndrome - excess glucocorticoid, don't know why -Cushing's disease - excess ACTH --->associated with anterior pituitary tumor causing elevated ACTH --->Secrete more aldosterone and ACTH than normal Symptoms: -Hyperglycemia -Hyperaldemia -Skeletal muscle atrophy due to proteolysis -Loss of bone mass -Edema - thanks to aldosterone & increased body water -Redistribution of adipose BUFFALO HUMP -Poor wound healing - suppressed immune system

Steroids

-Derived from cholesterol -LIPID SOLUBLE, CAN CROSS PLASMA MEMBRANE

Sex Steroids

-ESTROGEN - steroid hormone -Maturation of reproductive organs -Sex characteristics -Development of endometrial lining in uterus -PROGESTERONE- Steroid - supplements estrogen w/ endometrial lining development -Nutrients within lining -Breast development -Menstrual cycle regulation Menopause - cessation of menstruation -->1 complete year w/out menopause b/c preppies -TESTOSTERONE - testes convert to testosterone -Protein production, bone mass, sperm production, erectile function, prostate size, hair, red blood cell formation -LH in anterior pituitary produces testosterone -Andropause - age related decline in circulating testosterone

Pancreas

-Endocrine & exocrine gland -Secretes glucagon and insulin -->Regulate blood glucose, antagonistic to each other, amino acid based, HUMORAL REGULATED -Glucagon - raises blood glucose -Insulin - lowers blood glucose -NEGATIVE FEEDBACK CONTROL

Cortisol

-Glucocorticoid -Stress hormone -INCREASES BLOOD GLUCOSE -Circadian Pattern - high in early morning then decreases throughout day -->Said to help wake up since brain needs glucose to be conscious, and cortisol is a glucocorticoid so it increases blood glucose -Hypothalamus -> CRH -> Anterior Pituitary -> ACTH -> Adrenal Cortex -> Cortisol -Negative feedback control -Associated with sympathetic - Increased BP, HR, Blood sugar, decreased GI flow

Hyperthyroid Disorder

-Grave's Disease -->Autoimmune disorder -Overactivity of thyroid gland - GOITER - hypertrophy -Inflammation of tissues around eyes -High metabolic rate, sweating, rapid & irregular heart beat, nervousness, weightless, exopthalmos

Hormones associated with ANTERIOR PITUITARY

-Growth hormone (GH) -Thyroid Stimulating Hormone (TSH) -Adrenocorticotropic Hormone (ACTH) -Gonadotropins - (FSH & LH) -Prolactin (PRL)

Chronic Stress Pathway

-HPA Axis - hypothalamic pituitary adrenal pathway -Cortisol always increases blood glucose -But, if chronically elevated: -Increased Gluconeogenesis -Increased Lipolysis -Increased Proteolysis -Increased Insulin Resistance -Decreased inflammation -Decreased immune function -SAVES ENERGY & NUTRIENTS FOR BRAIN

Steroid Based Intracellular Hormone Action

-How we get our secondary sex characteristics -Hormone diffuses into target cells, bind & activate intracellular receptor -This activated receptor complex moves to the nuclear chromatin and binds to specific region of DNA -Binding initiates transcription of gene to mRNA -The new mRNA directs protein synthesis

Phosphodiesterase

-Inhibits Adenylate Cyclase in the cAMP second messenger system -this means that no extracellular controls are necessary to stop activity

PIP Mechanism

-Intracellular calcium ions act as 2nd messenger -Uses G Protein & phospholipase C which splits PIP2 to DAG and IP3 --->DAG activates protein kinase enzyme, triggers responses within target cell --->IP3 releases Ca2+ from intracellular storage sites ------>Ca2+ (2nd messenger) binds to Calmodulin, activating enzymes that amplify cellular response -Used by: catecholamines, TRH, ADH, GnRH, Oxytocin

Elevated Blood Volume & Pressure (Aldosterone Regulation)

-Involves heart, INHIBITORY, ANTAGONISTIC -Activated w/ increase in blood volume - heart doesn't like to be stressed out by volume overload -CAUSES ATRIAL NATRIURETIC PEPTIDE SECRETION (ANP) -ANP INHIBITS ALDOSTERONE SECRETION -Secreted by atria when walls of atria are over stretched - volume overload Causes: decrease in renin, decrease in sodium reabsorption, since there's no renin angiotensin II can't be made from angiotensin I, vasodilation, decreased blood volume This causes ANP secretion to stop (NEGATIVE FEEDBACK)

How are hormones removed from the blood?

-Kidneys -Liver -BODY EXCRETES BREAKDOWN PRODUCTS IN URINE/FECES

Calcitonin

-LOWERS BLOOD CALCIUM -Amino acid based - binds to membrane bound receptors -When blood Ca2+ rises above 9-11mg/100ml -Calcium is 2+ - twice as potent - affects resting membrane potential if not regulated -Too much : hyper polarized cells -Too little: hypo polarized cells -INHIBITS PARATHYROID -STIMULATES OSTEOBLASTS TO TAKE CALCIUM AND DEPOSIT IT IN BONE - BONE DEPOSITION - BONE MINERALIZATION -HUMORAL SECRETION - Calcium ion concentration in blood -NEGATIVE FEEDBACK -Not a primary hormone

Gonadocorticoids

-Main secretions are ANDROGENS - precursor to testosterone --> Testosterone is a precursor to estrogen -Androstenedione & DHEA are gonadocorticoids - not precursors to testosterone but they're generally converted to testosterone HYPER SECRETION OF GONADOCORTICOIDS ANDRENOGENITAL SYNDROME -MALES: early puberty, male sex characteristics, sex drive -FEMALES: masculinization, beard, body hair, increased sex drive, enlarged clitoris - irreversible, permanent

Thyroid Hormone (TH)

-Major metabolic hormone -PERMISSIVE HORMONE - allows other hormones to do their jobs properly -PROPER GROWTH & DEVELOPMENT - deficiencies lead to growth issues -ONLY AMINO ACID BASED HORMONE THAT IS LIPID SOLUBLE - BINDS TO INTRACELLULAR RECEPTOR B/C IT PASSESS THROUGH MEMBRANE -Consists of 2 tyrosines (amino acid - peptide hormone) -Iodine attached to tyrosine --->T4 - thyroxine - 4 iodines attached to 2 tyrosines --->T3 - triiodothyronine - 2 tyrosine and 3 iodine -Iodine is from iodinated salt, ocean fish, mountain streams -If you don't get enough iodine you'll be deficient -Goiter - swollen thyroid - cells looking for iodine over work, hypertrophy -Plays a role in: -Glucose oxidation -Increasing metabolic rate -Heat production -Maintaining BP -Regulating tissue growth -Developing skeletal & nervous systems -Maturation & reproductive capabilities -PERMISSIVE HORMONE -Hypothalamus -> TRH -> Anterior Pituitary -> TSH -> Thyroid -> T3 & T4

Aldosterone

-Mineralcorticoid -CAUSES REABSORPTION OF SODIUM AND WATER, GETS RID OF POTASSIUM -Regulates body water long term - like weeks -Steroid - BINDS TO INTRACELLULAR RECEPTORS -NEGATIVE FEEDBACK

Primary human mineralcorticoid & glucocorticoid

-Mineralcorticoid - aldosterone -Glucocorticoid - cortisol

Nervous vs. Endocrine System

-NERVOUS: neurons act directly on target --->Local, quick, direct, short-lasting -ENDOCRINE: releases into body fluids, HORMONE HAS TO CIRCULATE THROUGHOUT THE BODY --->Less localized, less rapid, longer lasting

Hypothalamus

-Nervous & endocrine - NEUROENDOCRINE GLAND -MASTER REGULATOR OF ENDOCRINE SYSTEM -CELL BODIES THAT SYNTHESIZE HORMONES -Regulates & controls a bunch of hormones --->From anterior & posterior pituitary, thyroid, adrenal, & gonads

Stress (Aldosterone Regulation)

-Not primary -Hypothalamus detects stress level -SECRETES CRH, which travels to anterior pituitary which SECRETES ACTH -ADRENAL CORTEX SECRETES ALDOSTERONE -Causes water retension

Insulin

-Only hormone that lowers blood glucose secreted within body -By BETA ISLET CELLS -Insulin circulates, binds to insulin receptors, causing those cells to transport glucose across the membrane -Glucose from blood to inside of cell- blood glucose decreases, alleviating stimulus -GLUCOSE UPTAKE BY CELLS AND GLUCOSE TO GLYCOGEN -Enhances membrane transport of glucose into body cells -Inhibits breakdown of glycogen to glucose -Inhibits conversion of amino acids or fats to glucose -Oxidyzes glucose for ATP production -Joins glucose molecules to form glycogen -Converts glucose to fat

Relationship b/w Posterior pituitary and hypothalamus

-Posterior lobe - neurohypophysis --->EXTENSION OF HYPOTHALAMUS -NO HORMONES ARE PRODUCED HERE BUT THERE ARE HORMONES SECRETED HERE -DIRECT connection to hypothalamus via infundibulum -Neurons from hypothalamus extend through HYPOTHALAMIC-HYPOPHYSEAL TRACT into posterior pituitary - long cluster of axons that travel -HORMONES STORED IN AXON TERMINALS AND BOUTONS -When AP arrives, hormones released into INFERIOR HYPOPHYSEAL ARTERY --->Transports hormones to circulatory system 1. Hypothalamic neurons (cell bodies) synthesize hormone 2. Hormones transported down axon via transcytosis to anterior pituitary (through hypothalamic-hypophyseal tract) in infundibulum 3. Hormones stored in axon terminals in the posterior pituitary 4. AP travels down axon, triggers exocytosis, secretes hormones into inferior hypophyseal artery - then they enter general circulation -OXYTOCIN & ADH

Increase in Blood Potassium (Aldosterone Regulation)

-Primary regulator -Elevated blood potassium effects membrane potentials - this is bad -STIMULATES HUMORAL PRODUCTION OF ALDOSTERONE --->affects cells in cortex directly to secrete aldosterone --->makes way to kidneys --->reabsorption of sodium & elimination of potassium REQUIRES ATP (SODIUM POTASSIUM PUMP) -Reabsorption of sodium CREATES OSMOTIC GRADIENT, reabsorb water, increase blood volume & pressure

Decrease in Blood Volume/Pressure (Aldosterone regulation)

-Primary regulator -If blood pressure drops, activate RAAS -Kidneys detect drop, secrete renin, which produces angiotensin II which stimulates aldosterone secretion RAAS TO REGULATE BP -Activated when BP drops -Causes water retention - aldosterone & ADH -Angiotensinogen constantly secreted from liver -Renin (enzyme) secreted from kidneys when BP drops --> CAUSES CONVERSION OF ANGIOTENSINOGEN TO ANGIOTENSIN 1 -->ACE CONVERTS ANGIOTENSIN I TO ANGIOTENSIN II in blood vessels of lungs, the active & potent form -Angiotensin II - vasoconstriction, water retention, increase BP, enhanced Na+ reabsorption, increased aldosterone secretion, secretion of ADH -When water is reabsorbed and BP restored, neg. feedback stops secretion of renin -ACE INHIBITORS - inhibits conversion of angiotensin I to angiotensin II - lowers BP -ANGIOTENSIN II RECEPTOR BLOCKERS - prevents angiotensin II from binding to receptor - lowers BP

Major processes that hormones control/regulate: (5)

-Reproduction -Growth & development -Maintenance of blood electrolyte, water, & nutrient balance -Reg. of cellular metabolism and energy balance -Mobilization of body defenses

Autocrines & Paracrines

-SHORT DISTANCE SIGNALS --> NOT HORMONES!!! hormones are long distance signals -Autocrines - effects on same cells that secreted them -Paracrines - effects locally within the same tissue

Gonadotropins (FSH & LH)

-Secreted by anterior pituitary -FSH - Follicle Stimulating Hormone --->Stimulates gamete (egg or sperm) production -LH - Luteinizing Hormone --->Regulates function of ovaries & testes -Triggered by hypothalamic GnRH, gonadotropin-releasing hormone -During and after puberty -NEGATIVE FEEDBACK: -Rising blood levels of estrogen or testosterone inhibit hypothalamus from secreting GnRH -Deficiency - failure of sexual maturation -IN FEMALES: -LH and FSH maturation of ovarian follicle -LH works alone to trigger ovulation -LH promotes synthesis and release of estrogens and progesterone -IN MALES: -LH stimulates interstitial cells of testes to produce testosterone -LH referred to as interstitial cell stimulating hormone (ICSH)

Prolactin (PRL)

-Secreted by anterior pituitary -IN FEMALES, STIMULATES BREAST MILK PRODUCTION -Triggered by hypothalamic PRH - prolactin releasing hormone -Inhibited by hypothalamic PIH - prolactin inhibiting hormone --->DOPAMINE, inhibits prolactin secretion at anterior pituitary -MECHANICAL STIMULATION: -SUCKLING STIMULATES PRH, ABOLISHES PIH COMPLETELY -No milk 24-48 hours after birth, but still breastfeed immediately to establish connection, check baby's reflexes, INHIBIT PIH, PROMOTE PRL -Baby still receives COLOSTRUM - fatty clear liquid with glucose before the milk comes out DEFICIENCY: poor milk production EXCESS: -FEMALES: inappropriate milk production -MALES: impotence and enlarged breasts

Growth Hormone (GH)

-Secreted by anterior pituitary -PERMISSIVE - depends upon Thyroid Hormone to function -Produced by SOMATOTROPIC CELLS -FUNCTIONS: tissue growth: bone & muscle, and makes sure that energy substrates such as fatty acids & glucose are available for the tissues trying to grow -STIMULATES GROWTH INDIRECTLY, DIRECTLY PROVIDES ENERGY TO SUPPORT THAT GROWTH --->Increase in blood glucose & blood fatty acids -Directly stimulates: Energy for cells - secretion of glucose and fatty acids into blood ANTI-INSULIN ACTIONS -Indirectly stimulates: IGF (somatomedins) actually stimulate growth - INSULIN LIKE GROWTH FACTORS (IGF) -Regulated by the hypothalamus - antagonistically -GHRH -GHIH -NEGATIVE FEEDBACK CONTROL DEFICIENCY: -Infant - hypoglycemia - developmental delays -Childhood - pituitary dwarfism - proportional -Adult - loss of lean tissue mass EXCESS: -Childhood - pituitary gigantism - proportional -Adult - ACROMEGALY - after bone plates have sealed, some keep growing so -extremities enlargement -ELEVATED BLOOD FATS AND BLOOD GLUCOSE

Adrenocorticotropic Hormone (ACTH)

-Secreted by anterior pituitary -STIMULATES ADRENAL CORTEX TO RELEASE CORTICOSTEROIDS - CORTISOL -Triggered by hypothalamic CRH - corticotropin-releasing hormone --->Stress hormone -NEGATIVE FEEDBACK ---> Rising blood levels of Cortisol inhibit hypothalamus from secreting CRH -Internal stressers, fever, hypoglycemia, can trigger release of CRH

Thyroid Stimulating Hormone (TSH)

-Secreted by anterior pituitary -STIMULATES THE NORMAL DEVELOPMENT AND SECRETION OF THYROID GLAND -Triggered by hypothalamic TRH - thyrotropin-releasing hormone -Causes anterior pituitary to secrete TSH -NEGATIVE FEEDBACK: ---> Rising blood levels of thyroid hormone T3 & T4 inhibit hypothalamus from secreting TRH

Antidiuretic Hormone (ADH)

-Secreted by the posterior pituitary -HELPS TO AVOID DEHYDRATION BY PREVENTING URINE FORMATION -OSMORECEPTORS - on the dendrites & cell bodies of neurons in the hypothalamus - detect salt concentrations -High salt concentrations - HIGH OSMOLARITY - ADH preserves water by reabsorption -Low salt concentrations - LOW OSMOLARITY - ADH not released, causing water loss -ADH stimulates AQUAPORINS TO OPEN & REABSORB MORE WATER WITHIN COLLECTING DUCTS OF NEPHRONS --->Only causes water reabsorption - not salt -Proximal convoluted tubule absorbs water (PCT) -Loop of Henle absorbs more water -ALCOHOL INHIBITS ADH RELEASE, causes copious urine output -ADH DEFICIENCY - More urine, less concentrated -DIABETES INSIPIDUS - tasteless urine -->Abnormal increase in urine output, fluid intake, & often thirst -SYMPTOMS: dilute urin & increased frequency, nocturne, enuresis -CAUSE: death of ADH producing cells in hypothalamus/posterior pituitary gland -ADH OVERPRODUCTION- Less urine, more concentrated -SYNDROME OF INAPPROPRIATE ADH SECRETION (SIADH) -SYMPTOMS: hyponaturemia, high urine osmolarity, excessive urine sodium secretion, decreased serum osmolarity -CAUSES: hypovolemia, ADH-secreting tumor (non-pituitary)

Oxytocin

-Secreted by the posterior pituitary -STIMULATES UTERINE CONTRACTION -Amino acid based hormone -POSITIVE FEEDBACK MECHANISM: leads to increased intensity of uterine contractions, ending in birth -Oxytocin -> contractions -> more oxytocin -> stronger contractions, etc. -Triggers milk ejection "let down" reflex -Used to induce labor -Role in sexual arousal & satisfaction in males & non-lactating females

Adrenal Medulla

-Secretes CATECHOLAMINES: EPINEPHRINE & NOREPINEPHRINE -Norepinephrine- neurotransmitter - secreted by neurons acts locally & quickly -Epinephrine - hormone - secreted by adrenal medula- hormone has to circulate - takes longer - less local -Short term stress: adrenal medulla - sympathetic nervous system -Long term stress: adrenal cortex -glucocorticoids & mineral corticoids -Short term- adrenal medulla - autonomic nervous system - pre-ganglionic fiber innervates adrenal medulla - secretes aCH and stimulates epinephrine production -Epinephrine = adrenaline -Overproduction (tumor) of epinephrine: -PHEOCHROMACYTOMA -Hyperglycemia -Elevated basal metabolic heart rate -Elevated HR -Hypertension -Sweating -All other short term stress responses

Pineal Gland

-Secretes melatonin - derived from serotonin -Circadian rhythm -Induces sleep -->Light lowers melatonin secretion -->Effects shift workers

Infundibulum

-Stalk connecting hypothalamus with pituitary gland -Hypothalamic-hypophyseal tract - (cluster of axons within CNS) connects hypothalamus with posterior pituitary

What is the endocrine system?

-The body's SECOND great regulatory system -INTEGRATED SYSTEM OF SMALL ORGANS THAT INVOLVE THE RELEASE OF EXTRACELLULAR SIGNALING MOLECULES KNOWN AS HORMONES -ALL SECRETE HORMONES INTO THE INTERIOR OF THE BODY, CIRCULATE IN FLUIDS WITHIN THE BODY

Importance of Classifications of Hormones

-The chemical structure of a hormone determines how it acts -CRITICAL PROPERTY: SOLUBILITY IN WATER --->This determines how it's transported, how long it can last before degraded, and which receptors it can act upon 1. Amino Acid Based 2. Steroids

Amino Acid-Based Hormone Signaling

-Water soluble, can't cross membrane -Exert effects by: 1. Binding to receptor on membrane 2. Activating events generation of 2ndmessenger 3. 2nd messenger triggers processes

How do we regulate hormone activity? (2)

1. HORMONE CONCENTRATION -Rate of release -Speed at which it's inactivated & removed from body --->Inactivation & 1/2 life 2. RECEPTOR CONCENTRATION -Cells can increase or decrease the # of receptors expressed --->Up-regulation and down-regulation

How are endocrine glands regulated? (3)

1. HUMORAL STIMULUS - Hormone release caused by ALTERED LEVELS OF CERTAIN CRITICAL IONS OR NUTRIENTS IN BLOOD --->Elements in blood or body fluids -Ex: Blood glucose, blood sodium, blood calcium -SOMETHING IN THE BLOOD THAT'S NOT A HORMONE THAT IS CAUSING THIS REGULATION 2. NEURAL STIMULUS - Hormone release caused by NEURAL INPUT -Ex: Sympathetic activity causes release of catecholamines (epinephrine & norepinephrine) 3. HORMONAL STIMULUS - Hormone release caused by ANOTHER HORMONE (a tropic hormone) -Ex: Hormones from hypothalamus cause anterior pituitary to secrete hormones

Major Endocrine Glands: (7)

1. HYPOTHALAMUS --->MASTER REGULATOR of endocrine system, either directly or indirectly controls a whole bunch of hormones, has neural and endocrine functions so it's NEUROENDOCRINE 2. PITUITARY GLAND --->There's an anterior & posterior, all hormones secreted by pituitary gland are under the control of the hypothalamus, STORAGE & SECRETION REGULATION 3. THYROID & PARATHYROID --->Parathyroid embedded in thyroid 4. PANCREAS --->Endocrine AND exocrine gland, regulates things circulating AND digestion 5. ADRENAL GLANDS --->Sit on top of kidneys, role in VARIETY OF FUNCTIONS 6. GONADS 7. OTHER: --->Adipose cells --->Pockets of cells in walls of small intestine --->Stomach --->Kidneys --->Heart

4 Means of Aldosterone Regulation

1. Increase in blood potassium 2. Decrease in blood volume/pressure 3. Stress 4. Increase in blood volume/pressure (inhibitory)

Two types of hormone receptors:

1. Membrane bound (integral protein) 2. Intracellular (exists within cytosol of cell)

Interaction of hormones @ target cells (3)

1. PERMISSIVENESS - one hormone cannot exert its effects without another hormone being present -Ex: growth hormone won't stimulate bone growth unless thyroid hormone is present 2. SYNERGISM - more than one hormone provides the same effects on a target cell -Ex: growth hormone and glucagon both increase blood glucose independently 3. ANTAGONISM - one or more hormones oppose action of another hormone -Ex: glucagon increases blood glucose and insulin decreases blood glucose

Adrenal Glands

2 Glands in 1 -ADRENAL MEDULA - Neural tissue that acts as a part of the SNS -ADRENAL CORTEX - Secretes STEROID HORMONES -->Synthesizes & releases steroid hormones called CORTICOSTEROIDS -3 layers of adrenal cortex, each layer produces different corticosteroid -Mineralcorticoids -Glucocorticoids -Gonadocorticoids

Hormone

Chemical messenger secreted by cells into EXTRACELLULAR FLUIDS of body, ACT ON OTHER PARTS OF BODY -Lag times ranging from seconds to hours -Longer lasting effects LONG DISTANCE CONNECTION

Hormones associated with POSTERIOR PITUITARY

Oxytocin ADH

How do hormones exert biological effect on tissue?

RECEPTORS! -All major hormones circulate to virtually all tissues, but ONLY INFLUENCE ACTIVITY IF THE TISSUE HAS A RECEPTOR FOR IT -THIS CELL IS CALLED A TARGET CELL - THEY HAVE TARGET CELL SPECIFICITY

Function of the Endocrine System

REGULATES cellular activities by means of HORMONES -HORMONES act AT SITES INDEPENDENT OF SECRETION

Thyroid gland hormones

Thyroid hormone & calcitonin