Endocrine System

What it is…. The endocrine system consists of a group of organs (sometimes referred to as glands of internal secretion) whose main function is to produce and secrete hormones directly into the bloodstream. Hormones serve as messengers to coordinate activities of various parts of the body.

Consists of… The major organs of the endocrine system are the hypothalamus, the pituitary gland, the thyroid gland, the parathyroid glands, the islets of the pancreas, the adrenal glands, the testes, and the ovaries.

The Glands

Hypothalamus It is an area of the brain that produces the "controlling" hormones that regulate body processes and the release of hormones from various glands. Stimulates the anterior pituitary to release hormones Inhibits the posterior pituitary from releasing hormones..

Anterior Pituitary Secretes several major hormones: TSH (thyroid stimulating hormone) ACTH (adrenocorticotropic hormone) FSH (follicle stimulating hormone) LH (lutenizing hormone) GH (growth hormone) Prolactin: (lactogenic hormone)

Posterior Pituitary ADH: antiduretic hormone, regulates water reabsorption in the kidneys..ie.. Decreases urine output Oxytocin: during pregnancy to initiate labor…contractions, and milk “let down”

Thyroid Thyroxine: T4 Tri-iodothyronine: T3 Calcitonin T3 &T4: stimulate cellular metabolism..speeds up cellular release of energy from foods Calcitonin: decreases concentration of calcium in the blood..by keeping it in bones

Adrenal Glands Adrenal cortex: Glucocorticoids Mineralocorticoids Androgens

Mineralocorticoids Increase blood Na+, and decrease body K+ by accelerating kidney reabsorption of Na+ and excretion of K+

Glucocorticoids Helps maintain blood glucose levels by increasing gluconeogenesis..from amino acids and conversion to glucose of fatty acids from adipose tissue… Plays and essential part in maintaining blood pressure..make it possible for epinephrine and norepinephrine to maintain a normal level of vasoconstriction

Glucocorticoids Act with epinephrine and norepinephrine to produce an antiinnflammatory effect to bring about normal recovery from inflammation of various kinds Produces antimmunity: antiallergy effect: brings about a decrease in the # of lymphocytes and plasma cells and therefore a decrease in amount of antibodies formed

Glucocorticoids Quickly increases when body is thrown into stressful situations.

Adrenal Medulla Norepinephrine Epinephrine: adrenalin Stress response hormones