The Endocrine SystemThe Endocrine System

Endocrine systemEndocrine system

Made of glands and their products Made of glands and their products Release products into the blood to Release products into the blood to

deliver messages to different parts of deliver messages to different parts of the bodythe body

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Gland Function Chart

HormonesHormones

Chemicals released in one part of the Chemicals released in one part of the body that travel through the body that travel through the bloodstream to affect other areas of bloodstream to affect other areas of the bodythe body

Bind to specific receptors on target Bind to specific receptors on target cellscells

Full effect of hormones may take Full effect of hormones may take minutes, hours, or daysminutes, hours, or days

Glands Glands

Exocrine glands release their Exocrine glands release their products through ducts directly to products through ducts directly to organs that use them; include glands organs that use them; include glands that release sweat, tears, and that release sweat, tears, and digestive juicesdigestive juices

Endocrine glands release their Endocrine glands release their secretions into the bloodstreamsecretions into the bloodstream

2 groups of hormones2 groups of hormones

Steroid hormones-are produced from Steroid hormones-are produced from a lipid called cholesterola lipid called cholesterol

Nonsteroid hormones-include Nonsteroid hormones-include proteins, small peptides, and amino proteins, small peptides, and amino acidsacids

Steroid hormonesSteroid hormones

Can cross cell membranes easily, passing Can cross cell membranes easily, passing directly across the lipid bilayer into the directly across the lipid bilayer into the cytoplasm or the nucleuscytoplasm or the nucleus

Binds a receptor-protein to make a Binds a receptor-protein to make a hormone-receptor complexhormone-receptor complex

Complex enters the nucleus and binds to Complex enters the nucleus and binds to DNADNA

Binding DNA initiates transcription of Binding DNA initiates transcription of specific genes to mRNAspecific genes to mRNA

mRNA moves to cytoplasm for translation mRNA moves to cytoplasm for translation into proteinsinto proteins

Steroid hormonesSteroid hormones

Hormone-receptor complexes Hormone-receptor complexes regulate gene expressionregulate gene expression

They can “turn on” or “turn off” They can “turn on” or “turn off” whole sets of geneswhole sets of genes

Can produce dramatic changes in cell Can produce dramatic changes in cell and organism activityand organism activity

Nonsteroid hormonesNonsteroid hormones

Cannot pass through the cell membraneCannot pass through the cell membrane Must bind a receptor on the outside of the Must bind a receptor on the outside of the

cell membranecell membrane Binding the receptor activates an enzyme Binding the receptor activates an enzyme

on the inside of the membraneon the inside of the membrane Enzyme activates secondary messengers Enzyme activates secondary messengers

(Ca(Ca2+2+ ions, cAMP, nucleotides, fatty acids) ions, cAMP, nucleotides, fatty acids) and carry the message to the inside of the and carry the message to the inside of the cellcell

Second messengers can alter other cell Second messengers can alter other cell activitiesactivities

Prostaglandins Prostaglandins

Modified fatty acidsModified fatty acidsAffect only nearby cells and tissuesAffect only nearby cells and tissuesCause smooth muscles to contract, Cause smooth muscles to contract,

such as those in uterus, bronchioles, such as those in uterus, bronchioles, and blood vesselsand blood vessels

Causes sensation of pain in most Causes sensation of pain in most headachesheadaches

Controlling metabolismControlling metabolism

Metabolic activities are controlled by the Metabolic activities are controlled by the levels of thyroxinelevels of thyroxine

Thyroxin is released by the thyroid glandThyroxin is released by the thyroid glandThyroid gland is controlled by the Thyroid gland is controlled by the

hypothalamus and anterior pituitary hypothalamus and anterior pituitary glandgland

Hypothalamus senses a low level of Hypothalamus senses a low level of thyroxine in blood, it secretes thyroid-thyroxine in blood, it secretes thyroid-releasing hormone (TRH)releasing hormone (TRH)

Controlling metabolism contControlling metabolism cont

TRH stimulates anterior pituitary to TRH stimulates anterior pituitary to secrete thyroid-stimulating hormone secrete thyroid-stimulating hormone (TSH)(TSH)

TSH stimulates the release of TSH stimulates the release of thyroxine by the thyroid glandthyroxine by the thyroid gland

High levels of thyroxine in the blood High levels of thyroxine in the blood inhibit the secretion of TRH and TSH inhibit the secretion of TRH and TSH and stops additional release of and stops additional release of thyroxinethyroxine

Body temperatureBody temperature

Also controlled by hypothalamusAlso controlled by hypothalamusSince increased metabolic rates raise Since increased metabolic rates raise

body temperaturebody temperature If low body temperature is sensed by If low body temperature is sensed by

the hypothalamus, TRH and TSH will be the hypothalamus, TRH and TSH will be released to stimulate release of released to stimulate release of thyroxine thyroxine

Thyroxin increases metabolism and thus Thyroxin increases metabolism and thus increases or raises body temperatureincreases or raises body temperature

Maintaining water balanceMaintaining water balance

Hypothalamus is sensitive to water levels Hypothalamus is sensitive to water levels in the bloodin the blood

Loss of water raises the concentration of Loss of water raises the concentration of dissolved materials in blood and signals dissolved materials in blood and signals the hypothalamus to stimulate the the hypothalamus to stimulate the pituitary to release ADH (antidiuretic pituitary to release ADH (antidiuretic hormone)hormone)

ADH travels to kidneys to slow down ADH travels to kidneys to slow down removal of water and triggers sensation of removal of water and triggers sensation of thirstthirst

Water balance contWater balance cont

Water is quickly absorbed when Water is quickly absorbed when consumedconsumed

When water levels in blood increase, When water levels in blood increase, the pituitary releases LESS ADH so the pituitary releases LESS ADH so the kidneys can remove more waterthe kidneys can remove more water

This restores the blood to its normal This restores the blood to its normal concentrationconcentration

Sleep cycleSleep cycle

Controlled through the pineal gland Controlled through the pineal gland by influencing the pituitary gland and by influencing the pituitary gland and producing the hormone melatoninproducing the hormone melatonin

Pineal gland’s functioning is initiated Pineal gland’s functioning is initiated by the amount of light in a 24 hour by the amount of light in a 24 hour periodperiod

Complimentary hormone Complimentary hormone actionaction

Used to regulate calcium levels in the Used to regulate calcium levels in the bloodstreambloodstream

Blood CaBlood Ca2+2+ levels get too high, thyroid gland levels get too high, thyroid gland releases calcitonin so kidneys reabsorb less releases calcitonin so kidneys reabsorb less calcium, less calcium is absorbed in calcium, less calcium is absorbed in intestines and MORE calcium is deposited in intestines and MORE calcium is deposited in bonesbones

Blood CaBlood Ca2+2+ levels get too low, parathyroid levels get too low, parathyroid hormone (PTH) is released from parathyroid hormone (PTH) is released from parathyroid glands so kidneys reabsorb more Caglands so kidneys reabsorb more Ca2+2+, , intestines absorb more Caintestines absorb more Ca2+2+, and bones , and bones release Carelease Ca2+2+ into blood into blood

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PTH Hormones Diagram

Importance of CalciumImportance of Calcium

If calcium levels in blood drop below If calcium levels in blood drop below a normal range:a normal range:Blood doesn’t clotBlood doesn’t clotMuscles don’t contractMuscles don’t contractTransport of materials across cell Transport of materials across cell

membranes will failmembranes will fail

Pituitary glandPituitary gland

Is divided into two parts: anterior Is divided into two parts: anterior pituitary and posterior pituitarypituitary and posterior pituitary

Secretes 9 hormones that directly Secretes 9 hormones that directly regulate body functions and controls regulate body functions and controls actions of other endocrine glandsactions of other endocrine glands

Posterior pituitaryPosterior pituitary

Antidiuretic hormone (ADH)-Antidiuretic hormone (ADH)-stimulates kidneys to reabsorb water stimulates kidneys to reabsorb water from collecting tubulesfrom collecting tubules

Oxytocin-stimulates contractions of Oxytocin-stimulates contractions of uterus during birth; releases milk in uterus during birth; releases milk in nursing mothersnursing mothers

Posterior pituitaryPosterior pituitary

Follicle-stimulating hormone (FSH)-Follicle-stimulating hormone (FSH)-stimulates production of mature eggs stimulates production of mature eggs and spermand sperm

Luteinizing hormone (LH)-stimulates Luteinizing hormone (LH)-stimulates ovaries and testes; prepares uterus ovaries and testes; prepares uterus for implantation of fertilized eggfor implantation of fertilized egg

Thyroid-stimulating hormone (TSH)-Thyroid-stimulating hormone (TSH)-stimulates the synthesis and release stimulates the synthesis and release of thyroxine from the thyroid glandof thyroxine from the thyroid gland

Posterior pituitary cont.Posterior pituitary cont. Adreno-corticotropic hormone (ACTH)-Adreno-corticotropic hormone (ACTH)-

stimulates release of some hormones from stimulates release of some hormones from the adrenal cortex, mainly cortisol the adrenal cortex, mainly cortisol (overproduction of which causes Cushing’s (overproduction of which causes Cushing’s disease)disease)

Growth hormone (GH)-stimulates protein Growth hormone (GH)-stimulates protein synthesis and growth in cellssynthesis and growth in cells

Prolactin-stimulates milk production in Prolactin-stimulates milk production in nursing mothersnursing mothers

Melanocyte-stimulating hormone (MSH)-Melanocyte-stimulating hormone (MSH)-stimulates the melanocytes of the skin, stimulates the melanocytes of the skin, increasing their production of the skin increasing their production of the skin pigment melaninpigment melanin

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hGH Hormone diagram

Hypothalamus Hypothalamus

Controls secretions of pituitary glandControls secretions of pituitary gland Influenced by hormone levels in the Influenced by hormone levels in the

blood and sensory information received blood and sensory information received from nervous systemfrom nervous system

Posterior pituitary made of axons whose Posterior pituitary made of axons whose cell bodies are in the hypothalamuscell bodies are in the hypothalamus

When cell bodies are stimulated, axons When cell bodies are stimulated, axons of posterior pituitary release their of posterior pituitary release their hormoneshormones

Hypothalamus contHypothalamus cont

Indirect affect on anterior pituitaryIndirect affect on anterior pituitaryHypothalamus produces releasing Hypothalamus produces releasing

hormones in the blood that are hormones in the blood that are carried to anterior pituitary to control carried to anterior pituitary to control production and release of hormones production and release of hormones

Thyroid glandThyroid gland

Major role in regulating metabolismMajor role in regulating metabolismProduces thyroxine to increase the rate Produces thyroxine to increase the rate

of protein, carbohydrate, and fat of protein, carbohydrate, and fat metabolismmetabolism

Thyroxine also increases rate of cellular Thyroxine also increases rate of cellular respiration and the amount of energy respiration and the amount of energy and heat releasedand heat released

Decreased levels of thyroxine decrease Decreased levels of thyroxine decrease the rate of cellular respiration and the the rate of cellular respiration and the amount of energy and heat releasedamount of energy and heat released

Hyperthyroidism Hyperthyroidism

Caused by too much thyroxine Caused by too much thyroxine Results in nervousness, elevated Results in nervousness, elevated

body temperature, increased body temperature, increased metabolic rate, increased blood metabolic rate, increased blood pressure, and weight losspressure, and weight loss

Hypothyroidism Hypothyroidism

Caused by too little thyroxineCaused by too little thyroxineResults in lower metabolic rates, Results in lower metabolic rates,

lower body temperature, lack of lower body temperature, lack of energy, and weight gainenergy, and weight gain

Can cause a goiter (enlargement of Can cause a goiter (enlargement of the thyroid gland)the thyroid gland)

Parathyroid glandsParathyroid glands

FourFourHelp control calcium levels in bloodHelp control calcium levels in bloodPromote proper nerve and muscle Promote proper nerve and muscle

function and bone structurefunction and bone structure

Adrenal glandsAdrenal glands

Located on top of kidneysLocated on top of kidneysRelease hormones that help body Release hormones that help body

prepare for and deal with stressprepare for and deal with stressOuter part is adrenal cortex; inner Outer part is adrenal cortex; inner

part is adrenal medullapart is adrenal medulla

Adrenal cortexAdrenal cortex

80% of adrenal gland80% of adrenal glandProduces over 24 corticosteroid Produces over 24 corticosteroid

hormoneshormonesAldosterone-regulates reabsorption of Aldosterone-regulates reabsorption of

sodium ions and excretion of potassium sodium ions and excretion of potassium ions by kidneysions by kidneys

Cortisol-helps control rate of metabolism Cortisol-helps control rate of metabolism of carbohydrates, fats, and proteinsof carbohydrates, fats, and proteins

Over-production of cortisol can lead to Over-production of cortisol can lead to Cushing’s diseaseCushing’s disease

Adrenal medullaAdrenal medulla

Regulated by sympathetic nervous systemRegulated by sympathetic nervous systemPrepares body for energy-intense Prepares body for energy-intense

activitiesactivitiesEpinephrine (80% of total secretions from Epinephrine (80% of total secretions from

adrenal medulla) and norepinephrineadrenal medulla) and norepinephrineFight or flight responseFight or flight response Increase heart rate, blood pressure, blood Increase heart rate, blood pressure, blood

flow to muscles, open air passages, flow to muscles, open air passages, release extra glucose into blood, increases release extra glucose into blood, increases body activitybody activity

Adrenal glandAdrenal gland

Also responsible for causing post-Also responsible for causing post-traumatic stress syndrome (PTSS)traumatic stress syndrome (PTSS)

Release of some hormones from Release of some hormones from adrenal gland causes the person to adrenal gland causes the person to re-experience a traumatic eventre-experience a traumatic event

Pancreas Pancreas

Acts as an exocrine gland by Acts as an exocrine gland by releasing secretions through ducts to releasing secretions through ducts to intestine to help break down foodintestine to help break down food

Acts as an endocrine gland by Acts as an endocrine gland by releasing hormones into the bloodreleasing hormones into the blood

Pancreas (endocrine function)Pancreas (endocrine function)

Hormones released from islets of Hormones released from islets of LangerhansLangerhans

Each islet has beta cells that release insulin Each islet has beta cells that release insulin and alpha cells that release glucagonand alpha cells that release glucagon

Insulin stimulates liver and muscles to Insulin stimulates liver and muscles to remove sugar from the blood and store it remove sugar from the blood and store it as glycogen or fatas glycogen or fat

Glucagon stimulates the liver to break Glucagon stimulates the liver to break down glycogen and release glucose back down glycogen and release glucose back into the blood and the release of fatty acids into the blood and the release of fatty acids from stored fatsfrom stored fats

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Pancreas & Liver

Reproductive glandsReproductive glands

Gonads produce gametes and Gonads produce gametes and secrete sex hormonessecrete sex hormones

Female gonads are ovaries and Female gonads are ovaries and produce eggs (ova)produce eggs (ova)

Male gonads are testes and produce Male gonads are testes and produce spermsperm

Ovaries Ovaries

Estrogen-female sex hormone; Estrogen-female sex hormone; required for development of eggs required for development of eggs and formation of physical traits and formation of physical traits associated with female bodyassociated with female body

Progesterone-prepares uterus for Progesterone-prepares uterus for arrival of developing embryoarrival of developing embryo

Testes Testes

Produce testosteroneProduce testosteroneRequired for normal sperm productionRequired for normal sperm productionDevelopment of physical traits Development of physical traits

associated with male bodyassociated with male body