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ENDOCRINE SYSTEM. FUNCTION. TYPES OF GLANDS. Endocrine Secrete hormones directly into bloodstream Ductless Exocrine Secrete substance through a duct Sweat , salivary, lacrimal and pancreas. Function of Endocrine System. To secrete hormones Hormones are chemical messengers
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ENDOCRINE SYSTEM FUNCTION
TYPES OF GLANDS • Endocrine • Secrete hormones directly into bloodstream • Ductless • Exocrine • Secrete substance through a duct • Sweat, salivary, lacrimal and pancreas
Function of Endocrine System • To secrete hormones • Hormones are chemical messengers • Hormone release provides immediate body responses because the hormones are directed toward target organ cells
HORMONE CONTROL • Negative feedback – drop in hormone level triggers a chain reaction • Blood level of hormone falls • Brains gets message and sends out hormone to stimulate gland • Gland secretes more hormone • When blood level of hormone increases, brain hormones stop • Nervous control – in some cases, sympathetic nervous system causes direct release of hormone from gland • Example: when stress causes the adrenal medulla to secrete adrenalin
PITUITARY GLAND • The master gland • Anterior pituitary lobe • Growth hormone – GH (somatotropin) responsible for growth and development • Prolactin – develops breast tissue, stimulates production of milk after childbirth • Thyroid-stimulating hormone – TSH – stimulates thyroxine • Adrenocorticotropic hormone – ACTH – stimulates adrenal cortex • Follicle-stimulating hormone – FSH – stimulates growth of graafian follicle and production of estrogen in females, sperm in males • Luteinizing hormone – LH – stimulates ovulation and formation of corpus luteum, which produces progesterone in females
PITUITARY GLAND • Posterior pituitary lobe • Vasopressin – converts to ADH (antidiuretic hormone) in the bloodstream, acts on kidney to concentrate urine and preserve H2O in the body • Oxytocin – released during childbirth causing contractions of the uterus
THYROID and PARATHYROID GLANDS • Thyroid gland • Main hormone, thyroxine, is controlled by secretion of TSH • Thyroxinecontrols the rate of metabolism • Calcitonin, another hormone that controls calcium ion concentration in the body, prevents hypercalcemia • Parathyroid glands • Produce parathormone which helps control blood calcium, prevents hypocalcemia
THYMUS • Endocrine gland and lymphatic organ • Located behind sternum, above and in front of heart • Begins to disappear at puberty
ADRENAL GLANDS • Adrenal cortex secretes corticoids (anti-inflammatory hormones) and sex hormones • Androgens • Male sex hormones • Adrenalin • Hormone from adrenal medulla, powerful cardiac stimulant, “fight or flight” hormone • Ex: getting chased by a dog could trigger adrenal hormone
GONADS • Estrogen • Development of female reproductive organs, secondary sex characteristics • Progesterone • Plays a part in the menstrual cycle • Testosterone • Male reproductive organs and secondary sex characteristics
PANCREAS and PROSTAGLANDINS • Pancreas • Islets of Langerhans – insulin production • Insulinpromotes utilization of glucose by the cells • Prostaglandins • Tissue hormones