Nursing 212

Health Differences Across the Lifespan 2 Study Guide The thyroid gland determines the rate of cellular metabolism. In children, hormones are responsible for normal development of the skeletal, muscular, and nervous system. Calcitonin targets bone and kidney cells to regulate calcium ion concentration in body fluids. Thyroxine (T4) and triiodothyronine (T3) bind to the mitochondria and nucleus of cells to increase ATP production. Parathyroid glands monitor and maintain circulating concentration of calcium ions by secreting parathyroid hormone (PTH), which increases serum calcium levels. PTH glands stimulate osteoclasts, inhibit osteoblasts, promote calcium absorption by the intestines, and decrease renal excretion of calcium. The pancreas (islets of Langerhans) regulates blood glucose levels. Alpha cells produce glucagon to break down stored fat and carbohydrates (CHO) into glucose in response to low glucose level. Beta cells produce insulin to transport glucose across the cell membrane and delta cells produce somatostatin that inhibits production of glucagon and insulin. The adrenal medulla increases cellular energy use and muscular strength endurance. It also mobilizes energy reserves. It secretes epinephrine (adrenaline) and norepinephrine (noradrenaline) to the receptors on skeletal muscle fibers, adipose tissues, and the liver. The adrenal medulla mobilizes glycogen reserves, metabolizes glucose for ATP, and increases cardiac rate and force of contraction. The adrenal cortex hormones play a vital role for survival and affect metabolism of many different tissues including: • Glucocorticosteroids: cortisol (hydrocortisone), corticosterone, and cortisone stimulate most cells to increase the rate of glucose synthesis, glycogen formation, release of fatty acids, and break down fatty acids; it exerts an anti-inflammatory effect to suppress the immune system • Mineralocorticoids: aldosterone stimulates the kidneys to increase reabsorption of sodium and water, reduces sodium and water loss by sweat glands, and stimulates salivary glands and the digestive tract • Produces a small amount of androgens Female gonads (ovaries) regulate secondary sexual characteristics and reproduction. Estrogens stimulate most cells to develop secondary sex characteristics andbehaviors, follicle maturation, and growth of uterine lining. They provide negative feedback to anterior pituitary glands to stop FSH secretion. Progestins stimulate the uterus to prepare for implantation and the mammary glands for lactation. Male gonads (testes) regulate secondary sexual characteristics and reproduction. Androgens, primarily testosterone, stimulate most cells for protein synthesis, maturation of sperm, secondary sexual characteristics, and behaviors. Inhibin, secreted for negative feedback to anterior pituitary gland, is used to stop the secretion of FSH.

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