endocrine system human anatomy & physiology university of washington pmt

Endocrine SystemEndocrine System

Human Anatomy & PhysiologyHuman Anatomy & Physiology

University of Washington PMTUniversity of Washington PMT

The Endocrine SystemThe Endocrine System

Endocrine SystemEndocrine System The Endocrine SystemThe Endocrine System

Regulates long-term processesRegulates long-term processes GrowthGrowth DevelopmentDevelopment ReproductionReproduction

Uses chemical messengers to relay information and Uses chemical messengers to relay information and instructions between cellsinstructions between cells Direct communicationDirect communication Paracrine communicationParacrine communication Endocrine communicationEndocrine communication

Hormonal ActionHormonal Action

Target Cells Target Cells Are specific cells that possess receptors needed to Are specific cells that possess receptors needed to

bind and bind and ““readread”” hormonal messages hormonal messages

HormonesHormones Stimulate synthesis of enzymes or structural Stimulate synthesis of enzymes or structural

proteinsproteins Increase or decrease rate of synthesisIncrease or decrease rate of synthesis Turn existing enzyme or membrane channel Turn existing enzyme or membrane channel ““onon”” or or

““offoff””

Hormone ActionsHormone Actions

““Lock and KeyLock and Key”” approach: describes the approach: describes the interaction between the hormone and its interaction between the hormone and its specific receptor.specific receptor. Receptors for nonsteroid hormones are Receptors for nonsteroid hormones are

located on the cell membranelocated on the cell membrane Receptors for steroid hormones are found in Receptors for steroid hormones are found in

the cellthe cell’’s cytoplasm or in its nucleuss cytoplasm or in its nucleus

Non Lipid Soluble Non Lipid Soluble Hormonal ActionHormonal Action

Hormones and Plasma Membrane Receptors Hormones and Plasma Membrane Receptors

Bind to receptors in plasma membraneBind to receptors in plasma membrane

Cannot have direct effect on activities inside target Cannot have direct effect on activities inside target

cellcell

Use intracellular intermediary to exert effectsUse intracellular intermediary to exert effects

First messenger:First messenger: leads to leads to second messengersecond messenger

may act as enzyme activator, inhibitor, or cofactor may act as enzyme activator, inhibitor, or cofactor

results in change in rates of metabolic reactionsresults in change in rates of metabolic reactions

Lipid Soluble Hormonal Lipid Soluble Hormonal ActionAction

Steroid Hormones: Steroid Hormones: Lipid solubleLipid soluble Diffuse through cell membranesDiffuse through cell membranes Endocrine organsEndocrine organs

Adrenal cortexAdrenal cortex OvariesOvaries TestesTestes ThyroidThyroid

Pituitary GlandPituitary Gland

A marble-sized gland A marble-sized gland at the base of the at the base of the brainbrain

Controlled by the Controlled by the hypothalamus or hypothalamus or other neural other neural mechanisms and mechanisms and therefore the middle therefore the middle man.man.

The Pituitary Gland and its The Pituitary Gland and its HormonesHormones

Posterior LobePosterior Lobe Antidiuretic hormone (ADH)Antidiuretic hormone (ADH) OxytocinOxytocin

Anterior LobeAnterior Lobe Adrenocorticotropic (ACTH)Adrenocorticotropic (ACTH) Growth hormone (GH)Growth hormone (GH) Thyroid-stimulating hormone (TSH)Thyroid-stimulating hormone (TSH) Follicle-stimulating hormone (FSH)Follicle-stimulating hormone (FSH) Luteinizing hormone (LH)Luteinizing hormone (LH) Prolactin (PRL)Prolactin (PRL)

Endocrine ReflexesEndocrine Reflexes

HypothalamusHypothalamus

Thyroid GlandThyroid Gland

Thyroid GlandThyroid Gland Located along the midline of the neckLocated along the midline of the neck Secretes two nonsteroid hormonesSecretes two nonsteroid hormones

Triiodothyronine (T3)Triiodothyronine (T3) Thyroxine (T4)Thyroxine (T4) Calcitonin: calcium metabolism (osteoblast)Calcitonin: calcium metabolism (osteoblast)

Regulates metabolismRegulates metabolism increases protein synthesisincreases protein synthesis promotes glycolysis, gluconeogenesis, glucose uptakepromotes glycolysis, gluconeogenesis, glucose uptake

Thyroid GlandThyroid Gland

Parathyroid GlandsParathyroid Glands

Embedded in Embedded in posterior surface of posterior surface of the thyroid glandthe thyroid gland

Parathyroid hormone Parathyroid hormone (PTH)(PTH) Produced by chief Produced by chief

cellscells In response to low In response to low

concentrations of Caconcentrations of Ca2+2+

Parathyroid GlandParathyroid Gland

Suprarenal (Adrenal) Suprarenal (Adrenal) GlandGland

Lie along superior border of Lie along superior border of

each kidneyeach kidney

Subdivided into: Subdivided into: Superficial suprarenal cortexSuperficial suprarenal cortex

Stores lipids, especially Stores lipids, especially

cholesterol and fatty acidscholesterol and fatty acids

Inner suprarenal medullaInner suprarenal medulla Secretory activities controlled by Secretory activities controlled by

sympathetic division of ANSsympathetic division of ANS


Adrenal MedullaAdrenal Medulla Contains two types of secretory cellsContains two types of secretory cells

EpinephrineEpinephrine (70-75% of mass) (70-75% of mass) Increase H.R. and B.P.Increase H.R. and B.P. Increase respirationIncrease respiration Increase metabolic rateIncrease metabolic rate Increase glycogenolysisIncrease glycogenolysis BronchodilationBronchodilation

Norepinephrine (20-25% of mass)Norepinephrine (20-25% of mass) VasoconstrictionVasoconstriction


Adrenal CortexAdrenal Cortex Mineralocorticoids (Zona Glomerulosa)Mineralocorticoids (Zona Glomerulosa)

Aldosterone: maintains electrolyte balanceAldosterone: maintains electrolyte balance NaNa++ reabsorption by kidneys & reabsorption by kidneys & K K++ urinary loss urinary loss

Glucocorticoids (Zona Fasciculate)Glucocorticoids (Zona Fasciculate) Cortisol (Hydrocortisone): Cortisol (Hydrocortisone):

Stimulates gluconeogenisisStimulates gluconeogenisis Mobilization of free fatty acidsMobilization of free fatty acids Anti-inflammatory agentAnti-inflammatory agent

Androgens (Zona Recticularis)Androgens (Zona Recticularis) Bone growth, muscle growth & blood formationBone growth, muscle growth & blood formation

Pineal GlandPineal Gland

Lies in posterior portion Lies in posterior portion of roof of third ventricleof roof of third ventricle

Contains pinealocytesContains pinealocytes Synthesize hormone Synthesize hormone

melatoninmelatonin Inhibits reproductive Inhibits reproductive

functionsfunctions Protects against Protects against

damage from free damage from free radicalsradicals

Setting circadian Setting circadian rhythmsrhythms

PancreasPancreas

Exocrine / Endocrine Exocrine / Endocrine GlandGland

Endocrine Pancreas Endocrine Pancreas consists of consists of ““clustersclusters”” of of cells called Islets of cells called Islets of LangerhansLangerhans

4 types of cells of 4 types of cells of endocrine pancreasendocrine pancreas

Comprise only 1% of Comprise only 1% of entire pancreasentire pancreas

PancreasPancreas

InsulinInsulin A peptide hormone released by beta cellsA peptide hormone released by beta cells

Affects target cells by:Affects target cells by: Accelerate glucose uptakeAccelerate glucose uptake Accelerate glucose utilization and enhances ATP Accelerate glucose utilization and enhances ATP

formationformation Stimulate glycogen formationStimulate glycogen formation Stimulate amino acid absorption and protein synthesisStimulate amino acid absorption and protein synthesis Stimulate triglyceride formation in adipose tissueStimulate triglyceride formation in adipose tissue

PancreasPancreas

GlucagonGlucagon Released by alpha cellsReleased by alpha cells Mobilizes energy reservesMobilizes energy reserves

Affects target cells:Affects target cells: Stimulates breakdown of glycogen in skeletal Stimulates breakdown of glycogen in skeletal

muscle and liver tissuemuscle and liver tissue Stimulates breakdown of triglycerides in adipose Stimulates breakdown of triglycerides in adipose

tissuetissue Stimulates production of glucose in liverStimulates production of glucose in liver

Sex Organs (Testes & Sex Organs (Testes & Ovaries)Ovaries)

Testes (Gonads)Testes (Gonads) Produce androgens in Produce androgens in

interstitial cells interstitial cells TestosteroneTestosterone is the is the

most important male most important male hormonehormone

Secrete Secrete inhibininhibin in in nurse nurse (sustentacular) cells(sustentacular) cells Support differentiation Support differentiation

and physical maturation and physical maturation of spermof sperm

Ovaries (Gonads)Ovaries (Gonads) Produce Produce estrogensestrogens

Principle estrogen is Principle estrogen is estradiolestradiol

After ovulation, follicle After ovulation, follicle cellscells Reorganize into corpus Reorganize into corpus

luteumluteum Release estrogens and Release estrogens and

progestinsprogestins, especially , especially progesteroneprogesterone

ThymusThymus

Produces Produces thymosinsthymosins

(blend of thymic (blend of thymic

hormones) hormones)

That help develop and That help develop and

maintain normal maintain normal

immune defensesimmune defenses

Endocrine Tissues of Endocrine Tissues of Other OrgansOther Organs

Kidneys:Kidneys: Produce calcitriol and erythropoietinProduce calcitriol and erythropoietin Produces enzyme reninProduces enzyme renin

Heart:Heart: Produces natriuretic peptides (ANP & BNP)Produces natriuretic peptides (ANP & BNP)

When blood volume becomes excessiveWhen blood volume becomes excessive Action opposes angiotensin IIAction opposes angiotensin II Resulting in reduction of blood pressure & volumeResulting in reduction of blood pressure & volume

Hormone InteractionsHormone Interactions

General Adaptation Syndrome (GAS) General Adaptation Syndrome (GAS) Also called Also called stress responsestress response How body responds to stress-causing How body responds to stress-causing

factorsfactors Is divided into three phases: Is divided into three phases:

1.1. Alarm phase Alarm phase

2.2. Resistance phaseResistance phase

3.3. Exhaustion phaseExhaustion phase

endocrine system human anatomy & physiology university of washington pmt

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