pt 4: Adrenal gland structure Cortex (steroids) + medulla (catecholamines) Three adrenal cortex layers Zona glomerulosa, fasciculata, reticularis Zona glomerulosa Secretes aldosterone (mineralocorticoid) Aldosterone function Increases Na+ reabsorption, K+ excretion; raises blood pressure Aldosterone release triggered by Low BP, high K+, renin-angiotensin system, ACTH Renin-angiotensin system Low BP → renin → Ang I → Ang II → aldosterone + vasoconstriction Zona fasciculata Secretes cortisol (glucocorticoid) Cortisol function Increases glucose, suppresses immune system, maintains blood pressure High cortisol effects Immune suppression, muscle wasting, hyperglycemia Zona reticularis Secretes adrenal androgens Adrenal androgens Weak sex hormones contributing to puberty and libido Adrenal medulla hormones Epinephrine and norepinephrine Epinephrine effects Increases heart rate, metabolic rate Norepinephrine effects Increases vasoconstriction and blood pressure Pancreas function Exocrine (digestive enzymes) + endocrine (insulin, glucagon) Alpha cells in pancreas Produce glucagon Beta cells in pancreas Produce insulin Glucagon function Increases blood glucose via glycogenolysis and gluconeogenesis Insulin function Decreases blood glucose by increasing cellular uptake Somatostatin from pancreas Inhibits insulin and glucagon release Type 1 diabetes Autoimmune destruction of beta cells → no insulin Type 2 diabetes Insulin resistance; cells do not respond to insulin Effects of insulin Promotes glucose uptake, fat storage, glycogen formation Ovarian hormones Estrogen and progesterone Estrogen function Female development, menstrual cycle regulation Progesterone function Maintains uterus for pregnancy Testicular hormone Testosterone Testosterone functions Male traits, sperm production, libido Placental hormones hCG, estrogen, progesterone hCG function Maintains corpus luteum early in pregnancy Kidney hormone EPO (erythropoietin) EPO function Stimulates RBC production when oxygen is low Heart hormone ANP (atrial natriuretic peptide) ANP function Decreases blood pressure by reducing blood volume GI hormones Gastrin, secretin, CCK regulate digestion Skin hormone precursor Produces vitamin D precursor (cholecalciferol) Adipose hormone Leptin Leptin function Signals satiety and regulates metabolism Cushing’s syndrome Excess cortisol → moon face, buffalo hump, high glucose Addison’s disease Low cortisol/aldosterone → fatigue, low BP, hyperpigmentation Pheochromocytoma Adrenal medulla tumor causing excess epinephrine Conn’s syndrome Excess aldosterone → high BP, low K+ Hyperthyroidism symptoms Weight loss, heat intolerance, anxiety, fast heartbeat Hypothyroidism symptoms Fatigue, weight gain, cold intolerance Goiter Enlarged thyroid due to iodine deficiency or overstimulation Primary endocrine disorder Problem in the gland itself Secondary endocrine disorder Problem in pituitary or hypothalamus Calcitriol (active vitamin D) Increases Ca2+ absorption in intestines Endocrine disruptors Chemicals interfering with hormone actions
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