The Endocrine SystemThe Endocrine System

Dr. Tamie LietoDr. Tamie Lieto

EndocrineEndocrine

Endo=withinEndo=within Krino= separateKrino= separate The word implies that intercellular chemical The word implies that intercellular chemical

signals are produced within and secreted from signals are produced within and secreted from endocrine glands, but that the chemical signal endocrine glands, but that the chemical signal have effects at locations that are away from or have effects at locations that are away from or or separate from the endocrine glands that or separate from the endocrine glands that secrete them. The chemical signals are secrete them. The chemical signals are transported by way of the bloodtransported by way of the blood

HormonesHormones HormonesHormones – the intercellular chemical signals – the intercellular chemical signals

that are secreted by the endocrine glandsthat are secreted by the endocrine glands Hormone means “set in motion” because Hormone means “set in motion” because

hormones set things in motionhormones set things in motion Hormones are distributed in the blood to all Hormones are distributed in the blood to all

parts of the body BUT only certain tissues parts of the body BUT only certain tissues called called Target tissuesTarget tissues respond respond

Regulation of Hormone SecretionRegulation of Hormone Secretion

Negative Feed Mechanism based on the following:Negative Feed Mechanism based on the following: blood levels of chemicals blood levels of chemicals

eg glucose and insulineg glucose and insulin

hormoneshormones

eg some hormones control other hormoneseg some hormones control other hormones

Nervous SystemNervous System

eg epinephrine is released from adrenal eg epinephrine is released from adrenal medulla because of nervous stimulationmedulla because of nervous stimulation

Endocrine Glands and Their Endocrine Glands and Their HormonesHormones

Look at Table 10.3 Endocrine Glands, Look at Table 10.3 Endocrine Glands, Hormones and their Target TissuesHormones and their Target Tissues

Classification of HormonesClassification of Hormones

Proteins/ Amino AcidsProteins/ Amino Acids thyroidthyroid posterior pituitaryposterior pituitary

LipidsLipids SteroidsSteroids EicosanoidsEicosanoids

Pituitary GlandPituitary Gland

The pituitary gland is located posterior to the The pituitary gland is located posterior to the optic chiasm and beneath the hypothalamus.optic chiasm and beneath the hypothalamus.

It is connected to the hypothalamus by a stalk It is connected to the hypothalamus by a stalk called the infundibulumcalled the infundibulum

It is divided into anterior and posterior partsIt is divided into anterior and posterior parts It is part of the Hypothalamus Pituitary AxisIt is part of the Hypothalamus Pituitary Axis

Pituitary GlandPituitary Gland

Pituitary Pituitary

The Pituitary Gland is divided intoThe Pituitary Gland is divided into Anterior and Posterior PartsAnterior and Posterior PartsHormones from the pituitary control control the Hormones from the pituitary control control the

function of many other endocrine glandsfunction of many other endocrine glands such as the ovaries , testes, thyroid gland and adrenal such as the ovaries , testes, thyroid gland and adrenal

coortexcoortexAlso secretes hormones that affect growth, kidney Also secretes hormones that affect growth, kidney

function, birth and milk production by the breastfunction, birth and milk production by the breastRelease of Hormones from the Pituitary is under the Release of Hormones from the Pituitary is under the

control of the control of the HypothalamusHypothalamus

Hormones secreted by the PituitaryHormones secreted by the Pituitary

Growth Hormone- stimulates growth of bone Growth Hormone- stimulates growth of bone and organs by increasing protein synthesisand organs by increasing protein synthesis

It resists protein breakdown during food It resists protein breakdown during food deprivation and promotes fat breakdown deprivation and promotes fat breakdown insteadinstead

Growth hormone is under the control of Growth hormone is under the control of Growth hormone releasing factor (GHRF) and Growth hormone releasing factor (GHRF) and Growth Hormone Inhibiting Factor)Growth Hormone Inhibiting Factor)

Hormones secreted from the Hormones secreted from the pituitary glandpituitary gland

AnteriorPituitary Posterior PituitaryAnteriorPituitary Posterior Pituitary Antidiuretic HormoneAntidiuretic Hormone Growth Hormone Oxytocin Growth Hormone Oxytocin Thyroid stimulating hormoneThyroid stimulating hormone (TSH)(TSH) Adrenocorticotrophic hormoneAdrenocorticotrophic hormone ( ACTH)( ACTH) Melanocyte Stimulating hormoneMelanocyte Stimulating hormone Luteinizing HormoneLuteinizing Hormone Follicle Stimulating HormoneFollicle Stimulating Hormone ProlactinProlactin

Growth Hormone (GH)Growth Hormone (GH)

Growth Hormone- increases protein synthesis and Growth Hormone- increases protein synthesis and growth of tissue and organs, breakdown of lipids, growth of tissue and organs, breakdown of lipids, and release of fatty acids, increase blood glucose and release of fatty acids, increase blood glucose levelslevels

Target Tissue : Most Tissue Target Tissue : Most Tissue

Deficient of Deficient of Growth Growth

HormoneHormonePituitaryPituitaryDwarfismDwarfism

Excess Growth HormoneExcess Growth HormoneGigantismGigantism

Exces growth hormone can Exces growth hormone can

result from hormones secreting result from hormones secreting

tumors of the pituitary glandtumors of the pituitary gland

AcromegalyAcromegaly

IF growth hormone continues to be in excess IF growth hormone continues to be in excess after the growth plates are closed bones will after the growth plates are closed bones will grow wider . This condition is called grow wider . This condition is called acromegalyacromegaly

Thyroid Stimulating Hormone Thyroid Stimulating Hormone (TSH)(TSH)

Thyroid Stimulating Hormone (TSH) Thyroid Stimulating Hormone (TSH) Target tissue: binds to the receptors on the thyroid Target tissue: binds to the receptors on the thyroid

gland and causes the thyroid gland to secrete thyroid gland and causes the thyroid gland to secrete thyroid hormonehormone

Too much TSH over stimulates the Thyroid Too much TSH over stimulates the Thyroid gland ( enlarges)gland ( enlarges)

Too little TSH under stimulates the Thyroid Too little TSH under stimulates the Thyroid gland (Shrinks)gland (Shrinks)

TSH is under the control of the Thyroid Releasing TSH is under the control of the Thyroid Releasing Hormone released form the hypothalmus Hormone released form the hypothalmus

Adrenocorticotropic Hormone Adrenocorticotropic Hormone ACTHACTH

Adrenocorticotropic HormoneAdrenocorticotropic Hormone Target Tissue: Binds to receptors on the adrenal cortex gland Target Tissue: Binds to receptors on the adrenal cortex gland

and stimulates release of the Glucocorticoid hormones such as and stimulates release of the Glucocorticoid hormones such as cortisolcortisol

Target Tissue: Binds to melanocytes in the skin and increase Target Tissue: Binds to melanocytes in the skin and increase skin pigmentaionskin pigmentaion

ACTH is under the control of the ACTH releasing hormone ACTH is under the control of the ACTH releasing hormone secreted by the hypothalmussecreted by the hypothalmus

GonadotropinsGonadotropins

Target Tissue: Bind to the receptors on the Target Tissue: Bind to the receptors on the gonads(ovaries and testes)gonads(ovaries and testes)

Luteinizing HormoneLuteinizing Hormone Follicle Stimulating HormoneFollicle Stimulating Hormone Under control by the GNRH or gonadotropin Under control by the GNRH or gonadotropin

releasing hormones of the hypothalamusreleasing hormones of the hypothalamus

Luteinizing Hormone (LH)Luteinizing Hormone (LH)

Females- target tissue ovary, promotes ovulation Females- target tissue ovary, promotes ovulation and progesterone in the ovary and progesterone in the ovary

Males- target tissue testis, causes testosterone Males- target tissue testis, causes testosterone synthesis and supports sperm cell production in synthesis and supports sperm cell production in testistestis

tt

Follicle Stimulating Hormone Follicle Stimulating Hormone (FSH)(FSH)

-Female -Female

Target tissue :Follicles in ovary. Promotes Target tissue :Follicles in ovary. Promotes follicle maturation and estrogen secretion in follicle maturation and estrogen secretion in ovary. ovary.

- Male - Male

Target tissue- Seminiferous tubules in male Target tissue- Seminiferous tubules in male causing Sperm productioncausing Sperm production

ProlactinProlactin

Female- Female-

Target Tissue: receptors in the breast and ovary Target Tissue: receptors in the breast and ovary

Helps promote breast development during Helps promote breast development during pregnancy and stimulates the production of milk. pregnancy and stimulates the production of milk. Prolongs progesterone secretion following ovulation Prolongs progesterone secretion following ovulation and during pregnancy.and during pregnancy.

Male - Target tissue-testis increses sensitivity to LHMale - Target tissue-testis increses sensitivity to LH

Under control of the releasing hormones from the Under control of the releasing hormones from the hypothalamushypothalamus

Site of Prolactin Action is the Site of Prolactin Action is the Mammary GlandMammary Gland

Melanocyte Stimulating Melanocyte Stimulating Hormone (MSH)Hormone (MSH)

Target Tissue: MSH binds to receptors on the Target Tissue: MSH binds to receptors on the skin and increase the production of skin and increase the production of melanocytes causing them to synthesize melanocytes causing them to synthesize melaninmelanin

Causes the skin to darkenCauses the skin to darken Under the control of releasing hormones that Under the control of releasing hormones that

increase or decrease its productionincrease or decrease its production

Antidiuretic HormoneAntidiuretic Hormone

ADHADH Target Tissue: binds to receptors in the kidney Target Tissue: binds to receptors in the kidney

that increase water reabsorption by kidney that increase water reabsorption by kidney tubules. This results in less water loss as urine.tubules. This results in less water loss as urine.

OxytocinOxytocin

Target Tissue: Binds to membrane bound Target Tissue: Binds to membrane bound

receptors in uterus and mammary glands.receptors in uterus and mammary glands. Causes contraction of the smooth muscle in Causes contraction of the smooth muscle in

the uterus and milk let down in breastthe uterus and milk let down in breast

The Thyroid The Thyroid

made up of two lobes connected by a made up of two lobes connected by a narow band called the ithmusnarow band called the ithmus

lobes are on either side of the trachea lobes are on either side of the trachea highly vascularhighly vascular contains follicles filled with the protein contains follicles filled with the protein

hormonehormone Secretes Thyroid HormoneSecretes Thyroid Hormone

Thyroid HormoneThyroid Hormone Target Tissue : most cells of the bodyTarget Tissue : most cells of the body regulates your rate of metabolismregulates your rate of metabolism also important for growth and developmentalso important for growth and development The thyroid gland requires iodine to synthesize thyroid The thyroid gland requires iodine to synthesize thyroid

hormonehormone deficiency of iodine in the diet can lead to thyroid deficiency of iodine in the diet can lead to thyroid

hormone deficiencyhormone deficiency regulation is through feed back mechanism Fig10.14 regulation is through feed back mechanism Fig10.14

Hypothalamus-Pituitary- Hypothalamus-Pituitary- Thyroid AxisThyroid Axis

Lack of thyroid hormone is called Lack of thyroid hormone is called HypothyroidismHypothyroidism

Excess amout of thyroid hormone can lead to Excess amout of thyroid hormone can lead to

GRAVES DISEASEGRAVES DISEASE

Parathyroid GlandParathyroid Gland

Four glands that are embedded in the Four glands that are embedded in the posterior wall of the thyroidposterior wall of the thyroid

Secretes Secretes

Parathyroid hormoneParathyroid hormone

CalcitoninCalcitonin

hormones which regulates calcium metabolismhormones which regulates calcium metabolism

Parathyroid HormoneParathyroid Hormone Target tissue : bone and kidneyTarget tissue : bone and kidney

PTH binds to membrane bound receptors of cells and increases PTH binds to membrane bound receptors of cells and increases the absorption of calcium from the intestines which increases the absorption of calcium from the intestines which increases active Vitamin Dactive Vitamin D

PTH also causes the resorption by incresing the rate of bone PTH also causes the resorption by incresing the rate of bone breakdown by osteoclasts of bone tissue to release Ca (calcium) breakdown by osteoclasts of bone tissue to release Ca (calcium) into the circulation and decreases the rate at which Ca is lost in into the circulation and decreases the rate at which Ca is lost in the urinethe urine

PTH acts on tissue to raise blood Calcium Levels to normal PTH acts on tissue to raise blood Calcium Levels to normal

CalcitoninCalcitonin

Target Tissue – BoneTarget Tissue – Bone

Decreases the rate of bone breakdown, Decreases the rate of bone breakdown, prevents large increase in blood calcium levels prevents large increase in blood calcium levels following a meal following a meal

Adrenal Gland Adrenal Gland

Divided into Divided into

Adrenal Cortex (outer)Adrenal Cortex (outer)

Glucocorticoids (cortisol)Glucocorticoids (cortisol)

AldosteroneAldosterone

Adrenal AndrogensAdrenal Androgens

Adrenal MedullaAdrenal Medulla

Epinephrine and NorepinephrineEpinephrine and Norepinephrine

Layers of the Adrenal GlandLayers of the Adrenal Gland

Arenal Cortex HormonesArenal Cortex Hormones

Mineralocorticoids- Aldosterone – regulation Mineralocorticoids- Aldosterone – regulation of NA and K and water balance.of NA and K and water balance.

Glucorticoids- Cortisol – decreases Glucorticoids- Cortisol – decreases inflammation, increases glucoseinflammation, increases glucose

Adrenal Androgens DHEA- axillary and Adrenal Androgens DHEA- axillary and pubic hair in femalespubic hair in females

Excess Adrenal Androgens Excess Adrenal Androgens (DHEA) in females (DHEA) in females

Cushing Syndrome Cushing Syndrome ( excess cortisol)( excess cortisol)

The PancreasThe Pancreas

Both Endocrine and Exocrine GlandBoth Endocrine and Exocrine Gland The Endocrine partThe Endocrine part

pancreatic Islets which secrete pancreatic Islets which secrete

insulin (beta cells)insulin (beta cells)

glucagon( alpha cells)glucagon( alpha cells)

Pancreatic Islet cellsPancreatic Islet cells

Blood Glucose controlBlood Glucose control

Under the control of insulin and glucagonUnder the control of insulin and glucagon It is very important to maintain blood glucose It is very important to maintain blood glucose

levels within a normal range of values.levels within a normal range of values. A decline in blood glucose level below its A decline in blood glucose level below its

normal range causes the nervous system to normal range causes the nervous system to malfunction because glucose is the nervous malfunction because glucose is the nervous system’s main source of energysystem’s main source of energy

InsulinInsulin

Insulin is released from the beta cells primarily in Insulin is released from the beta cells primarily in response to the elevated blood glucose levels and response to the elevated blood glucose levels and increased parasympathetic stimulation that is increased parasympathetic stimulation that is associated with the digestion of a meal.associated with the digestion of a meal.

Increased blood levels of certain amino acids also Increased blood levels of certain amino acids also stimulate insulin secretion. stimulate insulin secretion.

Decreased insulin secretion results from decreasing Decreased insulin secretion results from decreasing blood glucose and from stimulation by the blood glucose and from stimulation by the sympathetic division of the nervous system This sympathetic division of the nervous system This allows blood glucose to be conserved to provide the allows blood glucose to be conserved to provide the brain with glucose.brain with glucose.

GlucagonGlucagon

Binds to receptors on liver cells and causes the Binds to receptors on liver cells and causes the release of glucose from glycogenrelease of glucose from glycogen

The glucose is then released in the blood to The glucose is then released in the blood to increase blood glucose levels increase blood glucose levels

Glucagon secretion is reduced after a mealbGlucagon secretion is reduced after a mealb

Diabetes Mellitus Diabetes Mellitus Two TypesTwo Types

Type I - secretion of too little insulin from the Type I - secretion of too little insulin from the pancreaspancreas

- onset childhood, very thin , require insulin- onset childhood, very thin , require insulin

Type 2 - insufficient numbers of insulin receptors Type 2 - insufficient numbers of insulin receptors on target cells or defective recepetorson target cells or defective recepetors

- adult onset, usually overweight, can take - adult onset, usually overweight, can take medications that help increase endogenous insulin medications that help increase endogenous insulin activity.activity.

Diabetes Mellitus Type I Diabetes Mellitus Type I The signs and symptomsThe signs and symptoms

As a result, tissues can not take up glucose As a result, tissues can not take up glucose and the blood becomes Hyperglycemicand the blood becomes Hyperglycemic

Satiety center responds as if there is no Satiety center responds as if there is no glucose and patients feeel hungry glucose and patients feeel hungry

Excess glucose is secreted in urine and they Excess glucose is secreted in urine and they become dehydratedbecome dehydrated

Fats and protein become energy source and Fats and protein become energy source and body wasting occurs body wasting occurs

Table 10.4 Table 10.4

Effects of Insulin and Glucagon on Target Effects of Insulin and Glucagon on Target TissueTissue

Testes and OvairesTestes and Ovaires Testes secrete testosterone- growth of male and Testes secrete testosterone- growth of male and

development of male reproductive structures, muscle development of male reproductive structures, muscle enlargement, hair, voice change and male sexual enlargement, hair, voice change and male sexual drivedrive

Ovaries secrete estrogen and progesterone- female Ovaries secrete estrogen and progesterone- female characteristicscharacteristics

Both are under control of FSH and LH form the Both are under control of FSH and LH form the pituitarypituitary

Pineal GlandPineal Gland

Small gland superior and posterior to the Small gland superior and posterior to the thalamus thalamus

Secretes a hormone called melatonin which Secretes a hormone called melatonin which decreases LH and FSH by decreasing GNRH decreases LH and FSH by decreasing GNRH which may help regulate the onset of puberty which may help regulate the onset of puberty by acting on the hypothalmusby acting on the hypothalmus

ThymusThymus

Secretes thymosin which enhances the ability Secretes thymosin which enhances the ability of the immune systemof the immune system

Thymosin helps in the production of the white Thymosin helps in the production of the white cells ( called T cells)cells ( called T cells)

Other HormonesOther Hormones

Prostaglandins- role in inflammationProstaglandins- role in inflammation Erythropoietin-comes from kidney and Erythropoietin-comes from kidney and

stimulates red blood cell productionstimulates red blood cell production HCG ( human chorionic gonadotropin) – HCG ( human chorionic gonadotropin) –

secreted by the placenta during pregnancy to secreted by the placenta during pregnancy to maintain the pregnacy.maintain the pregnacy.

Age Related Changed in the Age Related Changed in the Endocrine SystemEndocrine System

Age related changes include a gradual decreaseAge related changes include a gradual decrease

GH inpeople who do not exerciseGH inpeople who do not exercise

MelatoninMelatonin

Thyroid HormoneThyroid Hormone

Reproductive HormonesReproductive Hormones

Thymus HormonesThymus Hormones

Increase in DiabetesIncrease in Diabetes