Endocrinology Flashcards
Adrenal Gland
On top of kidney. Made up of Adrenal Cortex and Adrenal Medulla
Adrenal Cortex
When stimulated by stress ACTH hormone produces more than two dozen different steroid hormones, adrenocortical steroids. These are bound to transcortin proteins.
Glucocorticoids
Cortisone and cortisol are involved in glucose regulation and protein metabolism. Raise blood glucose levels by promoting protein breakdown and gluconeogenesis and decreasing protein synthesis. Release amino acids from skeletal muscles and lipids from adipose tissue.
Mineralocorticoids
Aldosterone, regulate plasma levels of sodium and potassium and regulate the total extracellular water volume. Causes active reabsorption of sodium and passive reabsorption of water in the nephron of the kidney –> increase in blood volume and blood pressure
Cortical Sex Hormones
Adrenal cortex secretes small amount of androgens, not a significant amount compared to testes for men so little effect on men. Can have significant effect on women if there is overproduction
Adrenal Medulla
Processes epinephrine and norepinephrine (both catecholamines)
Epinephrine
Increases the conversion of glycogen to glucose in the liver and muscle tissue–> increase in blood glucose levels, increase in basal metabolic rate. Increase heart rate, dilate and constrict blood vessels in such a way to increase blood supply to muscles, heart and brain and decrease blood supply to kidneys, skin and digestive tract. Inhibits certain vegetative functions that are not immediately important for survival.
Norepinephrine
Increase heart rate, dilate and constrict blood vessels in such a way to increase blood supply to muscles, heart and brain and decrease blood supply to kidneys, skin and digestive tract.
Release of Norepinephrine and Epinephrine
Stimulated during sympathetic activation by sympathetic preganglionic fibers, by the sympathetic nervous system in response to stress.
Pituitary Gland
small, trilobed gland at base of brain. Anterior and Posterior= two main lobes. Hangs below hypothalamus and is connected by the infundibulum.
Anterior Pituitary
Synthesizes direct hormones and tropic hormones. Hormone secretions are regulated by the hypothalamic secretions, the inhibiting/releasing factors
Direct Hormones
Anterior Pituitary. Directly stimulate target organs. Growth hormones, Prolactin.
Growth Hormones
Direct. Promotes bone and muscle growth, promotes protein synthesis and lipid mobilization and catabolism.
Acromegaly
Overproduction of GH in adults, disorder characterized by disproportionate overgrowth of bone, localized in the skull, jaw, feet, and hands.
Prolactin
Direct. stimulates milk production and secretion in female mammary glands.
Tropic Hormones
Anterior Pituitary. Stimulate other endocrine glands to release hormones. ACTH, TSH, LH, FSH, MSH, Endorphines.
ACTH (Adrenocorticotropic)
Tropic. Stimulates the adrenal cortex to synthesize and secrete glucocorticoids and is regulated by the releasing hormone corticotrophin-releasing factor.
TSH (Thyroid-Stimulating)
Tropic. Stimulates the thyroid gland to synthesize and release thyroid hormones. (thyroxin)
LH (Luteinizing)
Tropic. Women: stimulates ovulation and formation of corpus luteum, regulate progesterone secretion. Men: stimulates interstitial cells of the testes to synthesize testosterone.
FSH (Follicle-stimulating)
Tropic. Women: causes maturation of ovarian follicles that begin secreting estrogen. Men: stimulates maturation of the seminiferous tubules and sperm production.
MSH (Melanocyte-stimulating)
Tropic. Secreted by the intermediate lobe of the pituitary. Function unknown in mammals. In frogs causes darkening of skin via induced dispersion of molecules of pigment in melanophore cells
Endorphines
Tropic. Neurotransmitters that have pain-relieving properties.
Posterior Pituitary
Neurohypophysis. Does not synthesize hormones, stores and releases peptide hormones (oxytocin and antidiuretic hormone). Stimulated by action potentials descending from the hypothalamus.