Endocrine System

A transmitter of chemical “messengers”

Consists of :-GLANDS that release “chemical messengers” called HORMONES.

Hormones are carried by blood and affect distal target cells.

Hypothalamus- Controls pituitary gland

Pituitary gland- regulate other glands

Parathyroid glands- regulates level of calcium in blood

Thymus- T cell development, immunity

Adrenal glands- respond to stress

Pineal gland- melatonin for rhythmic activities ( sleep-wake)

Thyroid – thyroxine for metabolism

Pancreas – insulin for glucose levels

Ovary- estrogen for female eggs, sex characteristics; progesterone to prepare uterus for a fertilized egg

Testis – testosterone for sperm development and male sex characteristics

Glands

Pituitary gland• Master gland of body• Located in the depression of sphenoid bone• Produces many hormones that affect other

glands– thyroid stimulating hormone– Somatotropin- growth hormone– Lutenizing (LH)- causes ovulation– ICSH- causes testes to secrete testosterone– Melanocyte stimulating- distribution of melanin in

skin– ADH- antidiuretic hormone ( slows down water

removal from blood)

• Giantism- oversecretion of growth hormone ( GH) before puberty

• Dwarfism- undersecretion of GH. Cause: tumor, injury, infection, genetics

• Produces hormones that control metabolism and calcium in blood. – hyperthyroidism ( when

too much thyroxine)- results in weight loss, increased blood pressure, elevated body temp.

– hypothyroidism ( too little thyroxine)- results in low metabolic rates, low body temp, lack of energy, weight gain.

Thyroid Gland

Iodine- for normal thyroxine production

• Sit on top of kidneys;• Help the body prepare

for and deal with stress;• Has two structural parts:

adrenal cortex

( involved in metabolism) and adrenal medulla

( “fight or flight” response);

Adrenal Glands

Pancreas

-Help break down food

-Secrete hormones “insulin” and “ glucagon” ; Both help to keep the levels of glucose in the blood stable.

-- When pancreas fail to produce or use insulin, diabetes occurs.

2 Groups of Hormones: STEROID and NONSTEROID

They need a specific receptor on a specific cell to do their job

Control of the Endocrine System

• Regulated by feedback mechanism that function to maintain homeostasis

( increase in substance “ feeds back” to stop the process that produced the substance)

Example:

Hypothalamus TRH Anterior Pituitary Thyroid TSH Thyroxine

regulates

by meansof the

by meansof the

by meansof the

by meansof the

by meansof the

by meansof the

GrowthWater

balanceReproduction Metabolism

Calciumand glucose

levels

Responseto stress

The Endocrine System

Pituitary

Ovaries

Testes Thyroid Pancreas Adrenals

Parathyroids