The Endocrine System

-the 2nd in control-

The Endocrine System

Composed of several ductless glands – Pituitary (anterior & posterior)– Thyroid– Adrenal/ Supraranal– Pineal– Thymus– ALONG w/ the Pancreas, Placenta &

Gonads

endo= within & crine=to secrete

Made of glands • Secrete hormone directly into

bloodstream (ductless glands)

• Specialized epithelial tissue >12.5g

Endocrine

Hormones (hormon = excite)

– Chemical messengers released into the blood & lymph for transport around the body

– Long lasting effect

– Effect target cells or organs

Hormone Function

•reproduction•growth & development•mobilization of body defenses•cellular metabolism & homeostasis

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Mechanisms of

hormone release

(a) Humoral: in response to changing levels of ions or nutrients in the blood

(b) Neural: stimulation by nerves(c) Hormonal: stimulation received from

other hormones

Hormone ControlNegative Feedback

1. Blood level of hormone falls

2. Brain gets message & sends out hormone to stimulate gland

3. Gland secretes hormone

4. When blood level of hormone increases, then brain hormone stops

Hypothalamus

Anterior pituitaryPosterior pituitary

Thyrotropin

ACTH

Somatotropin

LH

FSHProlactin

Vasopressin

Oxytocin

ThyroidAdrenalCortex

AdrenalMedullaPancreas Ovary Testis

Muscles liver Tissues

Liver,muscles

Estradiol TestosteroneInsulin,glucagon,somatostatin

T3 Cortisolaldosterone

Mammary glands

Reproductive organs

Epinephrine

Releasinghormones

Nervous

Pituitary Gland

Anterior Pituitary I

Growth Hormone• stimulates body to grow

& burn carbohydrates (sugars) & fat

Dwarfism hyposecretion

Gigantism hypersecretion

Anterior Pituitary II

Melanocyte-stimulating Hormone• increases amount of pigmentation in skin

Prolactin• stimulates milk production and maintains it

Adrenocorticotropic Hormone• controls the secretion of hormones from the adrenal

cortex

Thyroid Stimulating Hormone• controls the release of hormones from the thyroid gland

Anterior Pituitary III

Follicle-Stimulating Hormone• stimulates development of

ova and estrogen production in ovaries; stimulates sperm production

Lutenizing Hormone• stimulates ovulation and

prepares uterus for possible implantation of fertilized ovum; stimulates the production of testosterone

Posterior Pituitary

Oxytocin• stimulates contraction

of uterus & of the cells surrounding the mammary glands

Antidiuretic hormone• regulates fluid balance

by reabsorbing water in the kidneys; also helps to regulate blood pressure

Thyroid Gland

Thyroxine & Triiodothyronine

• stimulates metabolism; promotes protein synthesis, glucose uptake and lipid metabolism; is regulated by TSH

Calcitonin• reduces Ca and P levels

in blood;  

Thyroid Disorders

CretinismHyposecretion (children)

Myxedema

Hyposecretion (adults)

Graves’ Disease

hypersecretion

Goiter

Adrenal or Suprarenal Glands (adrenal cortex)-

glands on top of kidneysAldosterone• maintains fluid balance

by conserving Na and excretion of K; cause water retention and increased blood pressure

Cortisol• promotes glucogenesis in

liver; inhibits allergic response and reduces inflammation

Androgens and Estrogens• sex hormones 

Adrenal or Suprarenal Glands (adrenal cortex)

disorders

Cushion’s DiseaseAndrogenital syndrome

Adrenal or Suprarenal Glands

(Adrenal Medulla)epinephrine & norepinephrine• copy effects of the sympathetic

nervous system

Pancreas

Glucagon• stimulates conversion

of glycogen to glucose

Insulin• stimulates conversion

of glucose to glycogen; stimulates uptake of glucose by muscle and nerve cells

• Diabetes Mellitus– Hypo/hyper

secretion of insulin

Pineal Gland

Melatonin• regulates diurnal biorhythms;

highest at night

Thymus Gland

Thymosin• stimulates the production of T-

cells

Gonads

Ovaries - Estrogens• stimulates development of sex organs

and secondary sex characteristics

Testes -Testosterone• stimulates development of sex organs

and secondary sex characteristics

Placenta

Human Chorionic Gonadotropin• stimulates production of

estrogen and progesterone during pregnancy

Human Placental Lactogen• prepare breasts for milk

production

Relaxin• loosens mother's pelvic

ligaments and pubic symphysis

Endocrine System…. Professor KS Satyapal 20

ENDOCRINE DISORDERS

GIGANTISM:

• Hyperactive pituitary in preadolescence

• Overgrowth of long bones

Endocrine System…. Professor KS Satyapal 20

ENDOCRINE DISORDERS

ACROMEGALY:

• Hyperactive pituitary in adulthood

• Over development of bones in face, hands, feet

Endocrine System…. Professor KS Satyapal 20

ENDOCRINE DISORDERS

Dwarfism:

• Hypoactive pituitary in childhood

Endocrine System…. Professor KS Satyapal 22

ENDOCRINE DISORDERS

GOITER

• Thyroid hyper secretion

• Enlarged thyroid gland due to iodine insufficiency

Endocrine System…. Professor KS Satyapal 2 1

ENDOCRINE DISORDERS

CRETINISM

• Results from thyroid hormone insufficiency in infancy

Endocrine System…. Professor KS Satyapal 22

ENDOCRINE DISORDERS

Grave’s Disease/Exophthalmos

• Hyperactive thyroid

• Bulging eyes

Endocrine System…. Professor KS Satyapal 22

ENDOCRINE DISORDERS

Hypothyroidism

• Hypoactive thyroid

Endocrine System…. Professor KS Satyapal 23

ENDOCRINE DISORDERS

CUSHING’S SYNDROME

• hypersecretion of adrenal cortex

• Adipose tissue accumulates in cheeks & base of neck

Endocrine System…. Professor KS Satyapal 23

ENDOCRINE DISORDERS

Diabetes

• hyposecretion of insulin

• Untreated = hyperglycemia (too much sugar in blood)

• Overtreated = hypoglycemia (too little sugar in blood)