Endocrine

Function Produce hormones-released into bloodstream Maintain homeostasis Works through negative feedback: Obtaining a desired response to a hormone inhibits further production or secretion of that hormone. Example- when blood glucose levels are high, insulin is produced to remove glucose from blood. Glucose is stored in the cells. When blood glucose levels are low, glucagon is produced to cause cells to release stored glucose into the blood. When desired level is reached, hormone production is turned off.

Other example of negative feedback- when body doesn’t take in enough water it becomes dehydrated. Anti diuretic hormone(ADH) will be produced to tell large intestine to absorb as much water as possible.

Hormone- substance produced in one area (like a gland) that has an effect in another area or target cell. Glands produce and release hormones into blood stream.

2 types of hormones Steroid-fat soluble- move through cell membrane easily Nonsteroid- need a receptor on cell membrane to bind to it. This sends signal inside cell that causes another enzyme to act as messenger to cause effect.

Hypothalmus-in brain Master gland- controls nervous system and endocrine system. Will stimulate pituitary gland to release its own hormones to stimulate other glands.

Pituitary Gland-in skull Pituitary GlandHormoneAction PosteriorADHKidneys reabsorb water PosteriorOxytocinUterine contractions and milk production AnteriorFSHProduction of egg and sperm LHPrepares uterus for implantation TSHRelease thyroxin from thyroid GHProtein synthesis in cells ProlactinMilk production ACTHStimulates adrenal cortex

Thyroid Gland In base of the neck Regulates body’s metabolism by production of Thyroxine Too much- hyperthyroidism- weight loss, nervousness Too little- hypothyroidism- weight gain, lethargy

Parathyroid Gland Located behind thyroid Parathyroid Hormone regulates calcium levels

Adrenal Gland-Cortex Aldosterone- regulates Na reabsorption and excretion of K Cortisol-controls rate of metabolism of carbs, fats and proteins

Adrenal Gland- Medulla Epinephrine and Norepinephrine Fight or flight reflex Under control of your sympathetic and parasympathetic nervous system Normal conditions- parasympathetic system Fight or flight- sympathetic system signals medulla to produce epinephrine and norepinephrine. Cause your heart rate to increase, breathing rate increase, eyes dilate, increase blood flow to muscles

Pancreas Insulin- reduced blood sugar levels Glucagon- increases blood sugar levels Diabetes Mellitus- pancreas stops production (Type I)or insulin has no efffect(Type II)

Reproductive glands Testes- produce testosterone-required for sperm production. Also responsible for secondary sex characteristics Ovaries- produce estrogen required for egg development and secondary sex characteristics. Ovaries also produce progesterone which is important in preparing the uterus for embryo implantation.