Endocrine System Course Study Guide

Endocrine System ● Negative feedback ○ When there is a drop in the blood level of a specific hormone, the drop triggers a chain reaction of responses to increase the amount of hormone in the blood ○ Acts like an air conditioner unit ■ There is a set temperature and when it gets out of range it kicks on ○ Steps ■ The level of thyroxine falls ■ The hypothalamus receives the message ■ Hypothalamus responds by releasing hormone for TSH ■ It goes to the anterior pituitary which responds by releasing TSH ■ TSH stimulates the thyroid gland to produce thyroxine ■ The thyroxine level rises, which causes the hypothalamus to shut off the releasing of TSH ● Pituitary gland ○ Tiny structure about the size of a grape ○ Located at the base of the brain ○ Hormones of the pituitary gland ■ Divided into 2 lobes ■ The larger (anterior) produces 6 hormones ■ Smaller (posterior) consists primarily of nerve fibers and neuroglial cells that support the nerve fibers ● Anterior pituitary lobe ○ GH (somatotropin) ■ Responsible for growth and development. ■ It helps fat to be used for energy ■ Saves glucose and maintains blood sugar ○ PR (prolactin hormone) ■ Develops breast tissue and stimulates the production of milk after child birth. ■ Function in males is unknown ○ TSH (Thyroid stimulating hormone) ■ Stimulates the growth and secretion of the thyroid gland ○ ACTH (adrenocorticotropic hormone) ■ Stimulates the growth and secretion of the adrenal cortex ○ FSH (follicle stimulating hormone) ■ Stimulates the growth of the graafian follicle and the production of estrogen in females, and stimulates the production of sperm in males ○ LH (luteinizing hormone) ■ Stimulates the growth of the graafian follicle, the production of the estrogen ● Intermediate pituitary lobe ○ Stimulates the melanin cells ● Posterior Pituitary lobe ○ Vasopressin ■ Converts to ADH in the bloodstream ○ Oxytocin ■ Released during childbirth, causes some contractions of the uterus ● Pancreas ○ Located behind the stomach ○ Acts as both an exocrine and endocrine gland ● Insulin ○ The B cells in the islets of langerhans produce this ○ Promotes the transmission of glucose in the blood ○ Necessary for maintaining normal levels ● Pineal gland ○ Small pinecone shaped organ attached to the roof of the 3rd ventricle in the brain ○ The hormone melatonin is produced here ● Disorders of the endocrine system ○ Gigantism ■ Overgrowth of the long bones leading to excessive tallness ○ Acromegaly ■ Overdevelopment of the bones of the face, hands, and feet ○ Diabetes insipidus ■ Drop in the amount of ADH ■ Causes excessive loss of water and electrolytes ■ Causes excessive thirst (polydipsia) ○ Hyperthyroidism ■ Overactivity of the thyroid gland ■ Caused by toxic nodules or medication ■ Enlargement of the eyes (goiter) ■ Bulging of the eyeballs (exophthalmos) ○ Hypothyroidism ■ The thyroid gland does not secrete a sufficient amount of thyroxine ● Manifested by low T3 or T4 levels ■ May occur due to iodine deficiency ■ Enlargement of the thyroid gland ■ Myxedema ● Face becomes swollen, weight increases, and memory fails ■ Cretinism ● Lack of mental and physical growth ● Results in mental retardation and malformation ● Do not live past 7-8 years ■ Thyroid cancer ● Most common of the endocrine system ● Affects women more than men ● Survival rates are 90%-100%, if caught early ■ Tetany ● Extremely low calcium levels ● Convulsive twitching, dies of spasms in the respiratory muscles. ■ Pheochromocytoma ● Tumor in the adrenal gland ● Causes excessive secretion of epinephrine ● Is not cancerous, can be removed ● Can be fatal ■ Cushing's syndrome ● Caused from the hypersecretion of glucocorticoid hormones from the adrenal cortex ● More men than women suffer from this ● Hypertension, weakness, obesity, skin lesions, etc. ■ Addson’s disease ● Hypofunctioning of the adrenal cortex ● Bronzing of the skin, decreased levels of glucose, hypotension, etc. ■ Diabetes mellitus ● Decreased secretion of insulin from the islets of langerhans ● Type 1 ○ Juvenile diabetes ○ Usually in children and young adults ○ Caused from an autoimmune reaction ○ Must take insulin and monitor blood sugar ○ Polyuria (excessive urination), polydipsia, polyphagia (excessive hunger), blurred vision, etc. ● Type 2 ○ Common in adults over 45 ○ Illness and tiredness, unusual thirst, frequent urination at night ○ Makes up of 90-95% of diabetics ○ Known cause is obesity