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3A (iv) & (v).docx

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BIOL 1080
Jim Kirkland

Chapter 3A (iv) - The Endocrine System Endocrine glands: Made of secretory cells that release their products, called hormones. Endocrine system: Consists of endocrine glands and of organs that contain some endocrine tissue. Major organs with endocrine tissue are: Major glands are: - Hypothalamus - Pituitary gland - Thymus - Thyroid gland - Pancreas - Parathyroid gland - Ovaries - Adrenal gland - Heart - Pineal gland - Placenta - Stomach - Small intestine & Kidneys Antagonistic interaction  Effect of one hormone opposes that of another hormone. Synergistic interaction  the response of a tissue to a combination of two hormones is much greater that its response to either individual hormone. Permissive interaction  one hormone must be present for another hormone to exert its effects. Pituitary gland - Suspended from the base of the brain by a short stalk. - Stalk connects the gland to the hypothalamus o  Area of the brain that regulates physiological responses. (Body temperature, water balance, sleeping) - Consists of anterior and posterior lobe - 6 hormones o Growth hormone (GH) o Prolactin (PRL) o Thyroid-stimulating hormone (TSH)  acts on the thyroid gland to release thyroid hormones o Adrenocorticotropic hormone (ACTH)  tropic hormone for adrenal gland o Follicle-stimulating hormone (FSH)  promotes development of egg cells and secretion of the hormone estrogen from the ovaries o Luteinizing hormone (LH)  causes ovulation, release of future egg cell by the ovary in female - secretes estrogen and progesterone Tropic hormone: A hormone produced by one endocrine gland or hormone that influences another endocrine gland. - Anterior Lobe o Larger o Circulatory connection Growth Hormone (GH)  Stimulate growth through increasing in cell size and rate of cell division  Cells of bones, muscle and cartilage  Role in glucose conservation by making fats more available as a source of fuel  Too much leads to gigantism  Acromegaly - enlargement of tongue, and thickening in the bones of the hands, feet, and face. (Happens during adulthood when bones can’t lengthen but thicken)  Dwarfism - not enough Prolactin (PRL)  Stimulates mammary gland to produce milk  Too much leads to sterility - Posterior Lobe o Smaller o Neural connection o Doesn’t produce hormone on its own Antidiuretic hormone (ADH)  Conserve body water by decreasing urine output.  Not enough causes excessive urine production and resultant dehydration. Oxytocin (OT)  Stimulating the uterine contraction of childbirth.  Stimulate milk ejection Thyroid Gland Thyroid Hormone (TH)  Regulates the body’s metabolic rate and production of heat.  Protein synthesis  Breakthrough of lipids  Use of glucose for production of ATP  Cretinism - not enough during fetal development - causes dwarfism and delayed mental development.  Too much - Graves’ disease - a person’s own immune system produced antibodies that mimic the action of FSH. Calcitonin (CT)  Regulate the concentration of calcium in the blood to maintain proper functioning of the muscles cells and neurons. Parathyroid Glands Parathyroid Hormone (PTH)  Increases the level of calcium in the blood  Move from bone and urine into the blood  Too much causes weak bones and high levels of calcium in the blood which can cause kidney stones, and decreased activity of the nervous system. Adrenal Glands Outer region  Adrenal Cortex  Secretes lipid-soluble hormones - steroids Gonadocorticoid  Sex hormones known as Androgens and Estrogens Mineralocorticoid  Affect mineral homeostasis and water balance  Aldosterone - acts on cells of kidneys to increase reabsorption of sodium ions into the blood. - Increases water retention - Promotes secretion of K+ in urine. Glucocorticoids Affect glucose levels  Act on liver to promote the conversion of fat and protein to intermediate substances that are ultimately converted into glucose.  Acts on adipose tissue to breakdown fats into fatty acids Inner region  Adrenal Medulla  Secretes water-soluble hormones  Critical in the fight-or-flight response Epinephrine Norepinephrine Pancreas Endocrine cells  pancreatic islets Somatosin  inhibits secretion of glucagon and insulin. Glucagon  Increases the level of blood sugar  Increasing conversion of glycogen to glucose  Stimulate liver to form glucose from amino acids and lactic acid Insulin Decreases levels of glucose in the blood  Stimulates transport of glucose into muscles cells, white blood cells, and connective tissue cells. Prevents conversion of amino acids and fatty acids to glucose Thymus Gland -Decreases in size as we age Thymopoitein and thymosin  Promote the maturation of white blood cells called T Lymphocytes Pineal Gland Melatonin Local signaling molecules: Act near the s
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