Ch 45: Endocrine Ch 45: Endocrine SystemSystem

Endocrine SystemEndocrine System All of the hormone secreting cells All of the hormone secreting cells Endocrine GlandsEndocrine Glands

Secrete hormonesSecrete hormones Ductless (secrete into bloodstream)Ductless (secrete into bloodstream) Signal Transduction PathwaySignal Transduction Pathway

Most hormones bind to receptor Most hormones bind to receptor proteins in membrane and cause proteins in membrane and cause intracellular responseintracellular response

Chemical Messages (Chemical Messages (signal-transduction signal-transduction pathways)pathways)

Signal Transduction PathwaysSignal Transduction Pathways Activates a series Activates a series

of molecules of molecules within the cell within the cell after signal is after signal is receivedreceived

Allow for small Allow for small amounts of a amounts of a hormone to have hormone to have a large effecta large effect

Intracellular HormonesIntracellular Hormones Some hormones will bind to interior receptors Some hormones will bind to interior receptors

and mediate a responseand mediate a response Generally, these act in the nucleus and stimulate Generally, these act in the nucleus and stimulate

a transcription factor (make some enzymes)a transcription factor (make some enzymes)

Human Endocrine SystemHuman Endocrine System

Tropic hormonesTropic hormones Stimulate other Stimulate other endocrine cells to endocrine cells to secrete hormonessecrete hormones

Humans have nine Humans have nine endocrine glandsendocrine glands

HypothalamusHypothalamus Combines the endocrine and nervous Combines the endocrine and nervous

systemssystems Nuerosecretory cells produce hormonesNuerosecretory cells produce hormones

Releasing hormonesReleasing hormones stimulate the stimulate the anterior pituitary anterior pituitary

Inhibiting hormonesInhibiting hormones prevent the prevent the anterior pituitary from secreting anterior pituitary from secreting hormoneshormones

Anterior PituitaryAnterior Pituitary

Posterior PituitaryPosterior Pituitary Stores and secretes hormones produced by the hypothalamusStores and secretes hormones produced by the hypothalamus

Major HormonesMajor Hormones

More HormonesMore Hormones

Antidiuretic Hormone (ADH)Antidiuretic Hormone (ADH)

Promotes retention of water by the Promotes retention of water by the kidneys.kidneys.

Secretion regulated by water/salt Secretion regulated by water/salt balancebalance

Secreted by post. pituitary after Secreted by post. pituitary after production in hypothalamusproduction in hypothalamus

Anterior Pituitary HormonesAnterior Pituitary Hormones

Growth hormoneGrowth hormone Stimulates growth and metabolismStimulates growth and metabolism Gigantism: excessive GH during Gigantism: excessive GH during

developmentdevelopment Hypopituitary dwarfism: childhood Hypopituitary dwarfism: childhood

GH deficiencyGH deficiency

Anterior Pituitary HormonesAnterior Pituitary Hormones ProlactinProlactin

stimulates milk production and secretionstimulates milk production and secretion GonadotropinsGonadotropins

Follicle-stimulating hormoneFollicle-stimulating hormone (FSH) (FSH)production of sperm and ovaproduction of sperm and ova

Luteinizing hormoneLuteinizing hormone (LH) (LH)stimulates ovaries and testesstimulates ovaries and testes

Anterior Pituitary HormonesAnterior Pituitary Hormones

Thyroid-stimulating hormone (TSH)Thyroid-stimulating hormone (TSH) stimulates thyroid glandstimulates thyroid gland

Melanocyte-stimulating hormoneMelanocyte-stimulating hormone may play a role in fat metabolismmay play a role in fat metabolism

EndorphinsEndorphins inhibit pain perceptioninhibit pain perception mimicked by heroin and other opiatesmimicked by heroin and other opiates

Pineal GlandPineal Gland

Near center of the mammalian brainNear center of the mammalian brain Secretes Secretes melatoninmelatonin

Involved in biological rhythms Involved in biological rhythms associated with reproductionassociated with reproduction

Secretion regulated by light/dark Secretion regulated by light/dark cyclescycles

Thyroid GlandThyroid Gland Two lobes locatedon the ventral Two lobes locatedon the ventral

surfacesurfaceof the tracheaof the trachea

T3 (T3 (triiodothyronine)triiodothyronine) and T4 and T4 ((thyroxine)thyroxine) hormones stimulate and hormones stimulate and maintain metabolic activitymaintain metabolic activity

Secretion of T3 and T4 regulated by Secretion of T3 and T4 regulated by TSH hormone secreted by anterior TSH hormone secreted by anterior pituitarypituitary

Thyroid GlandThyroid Gland

Thyroid GlandThyroid Gland

Animation of Thyroid SecretionAnimation of Thyroid Secretion Animation of Thyroid RegulationAnimation of Thyroid Regulation Goiter AnimationGoiter Animation

Thyroid GlandThyroid Gland Iodine deficiencies lead to goiter (swelling Iodine deficiencies lead to goiter (swelling

of thyroid gland (why salt is “iodized”)of thyroid gland (why salt is “iodized”)

Hyper- and Hypothyroidism results from Hyper- and Hypothyroidism results from too much or too little T3/T4 too much or too little T3/T4

Also secretes calcitoninAlso secretes calcitonin Lowers blood calcium levelsLowers blood calcium levels

Parathyroid GlandsParathyroid Glands four four parathyroid glandsparathyroid glands embedded in the embedded in the

surface of the thyroid glandsurface of the thyroid gland parathyroid hormoneparathyroid hormone (PTH) (PTH)

Raises blood calcium levelsRaises blood calcium levelsbreak down bonebreak down bonereabsorb by kidneyreabsorb by kidney

PTH and calcitonin are antagonisticPTH and calcitonin are antagonistic

Regulation of Calcium Regulation of Calcium LevelsLevels

PancreasPancreas

Endocrine (into blood) and exocrine (into Endocrine (into blood) and exocrine (into ducts)ducts)

Exocrine: Exocrine: bicarbonate ions and digestive bicarbonate ions and digestive enzymesenzymes

Endocrine: insulin and glucagonEndocrine: insulin and glucagon Islets of LangerhansIslets of Langerhans

InsulinInsulin

Secreted by beta cellsSecreted by beta cells Lowers blood glucose levelsLowers blood glucose levels Stimulates all body cells (except brain Stimulates all body cells (except brain

cells) to take up glucosecells) to take up glucose Regulated by glucose in blood (negative Regulated by glucose in blood (negative

feedback).feedback).

DiabetesDiabetes Low or no insulin productionLow or no insulin production High blood sugar levelsHigh blood sugar levels Sugar in urineSugar in urine Severe diabetes leads to fat usage in cell. Severe diabetes leads to fat usage in cell.

respiration and ultimately death (dec. blood respiration and ultimately death (dec. blood pH due to acidic metabolites)pH due to acidic metabolites)

Type IType I: : Autoimmune disorder, present in Autoimmune disorder, present in childhood, treated with insulin injectionschildhood, treated with insulin injections

Type IIType II: Target cells less responsive over : Target cells less responsive over time to insulin. 90% of cases, usually over 40time to insulin. 90% of cases, usually over 40..

GlucagonGlucagon secreted by alpha cellssecreted by alpha cells raises blood glucose levelsraises blood glucose levels liver and skeletal muscle breakdown liver and skeletal muscle breakdown

glycogen storesglycogen stores regulated by glucose in blood (negative regulated by glucose in blood (negative

feedback)feedback)

Blood Sugar RegulationBlood Sugar Regulation

Adrenal GlandsAdrenal Glands Adrenal glandsAdrenal glands

Adjacent to the kidneysAdjacent to the kidneys The The adrenal cortexadrenal cortex is the outer portionis the outer portion The The adrenal medullaadrenal medulla is the inner is the inner

portionportion EpinephrineEpinephrine (adrenaline)(adrenaline) andand

norepinephrinenorepinephrine (noradrenaline)(noradrenaline)Secretion regulated by the nervous Secretion regulated by the nervous system in response to stresssystem in response to stress

Response to Stress (Fight or Response to Stress (Fight or Flight)Flight)

EpinephrineEpinephrine andand norepinephrinenorepinephrine Raises blood glucose level and blood fatty Raises blood glucose level and blood fatty

acid levelacid level Increase metabolic activitiesIncrease metabolic activities Increases heart rate and stroke volume Increases heart rate and stroke volume

andand dilates bronchiolesdilates bronchioles Shunts blood away from skin, digestive Shunts blood away from skin, digestive

organs, and kidneys, and increases blood organs, and kidneys, and increases blood flow to heart, brain, and skeletal muscleflow to heart, brain, and skeletal muscle

Testes (testosterone)Testes (testosterone) AndrogenAndrogen: type of steroids: type of steroids sperm formationsperm formation promote development and maintenance promote development and maintenance

of male sex characteristicsof male sex characteristics regulated by FSH and LHregulated by FSH and LH

OvariesOvaries

Estrogen and progesterone (steroids)Estrogen and progesterone (steroids) EstrogensEstrogens

uterine lining growthuterine lining growth female sex characteristicsfemale sex characteristics Regulated by LH and FSH Regulated by LH and FSH

ProgesteroneProgesterone Uterine lining growthUterine lining growth Reg. by LH and FSHReg. by LH and FSH