location and structure of the pituitary gland
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路 Hypothalamus: regulates secretion of the anterior pituitary gland through hormones and action potentials
o Site where nervous and endocrine systems interact
路 Pituitary gland (hypophysis): secretes at least 9 major hormones that regulate numerous body functions and other endocrine glands
路 Infundibulum: connects hypothalamus to posterior pituitary
路 stimulates growth in most tissues and is a regulator of metabolism
o Secretion increases is response to low blood glucose, stress, and an increase in certain amino acids
搂 Plays an important role in regulating blood nutrient levels between meals
o Target tissue: most tissues
o Regulated by 2 hypothalamic hormones: GHRH & GHIH
搂 Growth hormone-releasing hormone (GHRH): released from the hypothalamus, causes release of GH from the anterior pituitary
搂 GHIH: inhibits production of GH by anterior pituitary, secreted in response to high blood glucose levels
Thyriod-stimulating hormone (TSH)路 causes secretion and storage of hormones T3 and T4 from and within the thyroid gland; increases activity of phospholipase that opens Ca2+ channels, increasing Ca2+ concentration in cells of the thyroid gland o Target tissue: thyroid glandAdrenocorticotropic hormone (ACTH)路 causes cortisol secretion from the adrenal cortex o Causes aldosterone secretion from the adrenal cortex o Target tissue: adrenal cortexmelanocyte-stimulating hormone (MSH)路 causes melanocytes to increase production of melanin in the skin o Target tissue: melanocytes in the skinluteinizing hormone (LH)路 ovulation and progesterone production in ovaries; testosterone synthesis and support for sperm cell production in testes o Target tissue: ovaries and testesFollicle-stimulating hormone (FSH)路 follicle maturation and estrogen secretion in ovaries; sperm cell production in testes o Target tissue: follicles in ovaries; seminiferous tubules in malesprolactin路 role in milk production o Target tissue: ovaries and mammary glands in femalesstructure of the thyroid gland路 Located in the anterior neck; consists of two lateral lobes connected by a median tissue called the isthmus o Follicles: produce thyroglobulin o Parafollicular cells: produce calcitonincondition that lead to T3 and T4 secretion and the effects on their target tissues路 Regulated by thyrotroponin-releasing hormone (TRH) and thyroid-stimulating hormone (TSH) 路 TRH from the hypothalamus increases TSH secretion o Increases as a result of chronic exposure to cold o Decreases as a result of food deprivation, injury, and infection 路 TSH from the anterior pituitary increases T3 and T4 secretion 路 Negative feedback mechanismHyperthyroidism路 when the thyroid gland produces too much thyroxin o Causes increase in metabolism, causing weight loss and rapid, irregular heartbeatHypothyroidismA disorder caused by a thyroid gland that is slower and less productive than normalrole of calcitonin in blood calcium level maintenance路 Parafollicular cells secrete calcitonin 路 Blood Ca2+ levels drop = calcitonin levels drop 路 Blood Ca2+ levels rise= calcitonin levels rise Targets the skeleton to: 路 Inhibit osteoclast activity (reduce release of calcium from the bone matrix) 路 Stimulate Ca2+ uptake (incorporation into the bone matrix)role of PTH in maintenance of blood calcium levels路 PTH increases the release of Ca2+ from bones into blood by increasing the number of active osteoclasts o Stimulates osteoclast activitylocation and structure of the parathyroid glands路 4 tiny glands embedded in the posterior aspect of the thyroid o Secrete a polypeptide hormone (PTH)conditions that cause release of PTH and the effect路 Decreased blood Ca2+ levels stimulate PTH secretion 路 Promotes Ca2+ reabsorption by the kidneys and the formation of active vitamin D by the kidneys 路 Active vitamin D increases Ca2+ absorption by the intestinelocation and layers of the adrenal glands路 Paired, pyramid-shaped organs that sit on top of the kidneys 路 Adrenal medulla (inner area): epinephrine and norepinephrine 路 Adrenal cortex (outer area): composed of three layers o Zona glomerulosa o Zona fasciculata o Zona reticularismajor hormones of the adrenal medulla路 Epinephrine (80%) and norepinephrine (20%) o prepare the body for physical activity o Increasing heart rate and force of contraction o Released by the sympathetic division of the ANS in response to emotions, injury, stress, exercise, low blood glucose levelszona glomerulosamineralocorticoids (aldosterone); Regulate electrolytes in extracellular fluidzona fasciculata路 glucocorticoids o Helps the body resist stress by keeping blood sugar levels relatively constant; maintaining blood volume and preventing water shift into tissue 搂 Cortisolzona reticularis路 gonad corticoids o Most are androgens, most important is testosterone, contribute to onset of pubertylocation and structure of the pancreas路 Triangular gland, that has both exocrine and endocrine cells, located behind the stomach o Acinar cells: produce an enzyme-rich juice used for digestion o Pancreatic islets: 搂 Alpha cells produce glucagon 搂 Beta cells product insulintwo major hormones produced by the pancreasinsulin and glucagoninsulino Target tissues: liver, adipose tissue, muscle, satiety center in the hypothalamus o When blood glucose is high, glucose is moved into bodies cellsglucagono Target tissue: liver o Causes the breakdown of glycogen to glucose; stimulates the synthesis of glucose from amino acids o When blood glucose is low, glucose is moved into the bloodstreamtestes路 secrete testosterone o Initiates maturation of male reproductive organsovaries路 secrete estrogen and progesterone o Maturation of reproductive organshow is the placenta a temporary endocrine gland路 Secretes human chorionic gonadotropin (hCG) o Essential for the maintenance of pregnancy -only present during pregnancyhormones secreted by the pineal gland路 Melatonin: can inhibit reproductive maturation; may regulate sleep-wake cyclesthymus路 thymopoietin and thymosin o Essential for the development of T lymphocytesgastrointestinal tractproduces gastrin, secretin, and cholecystokinin (regulate digestive function)kidneys路 produce erythropoietin o Stimulates red blood cell production