Exam 4 Review:  Chapter 24:  Regulation of Metabolism

insulin - The protein hormone secreted by the beta cells of the pancreatic islets of Langerhans; it reduces the concentration of glucose in the blood by targeting the liver to promote glycogenesis, i.e., the formation of glycogen from glucose, and it targets most cells of the body, other than nervous tissue, to take glucose from the blood and use it as metabolic fuel; its deficiency or failure to perform causes the disease diabetes mellitus.

glucagon - The protein hormone secreted by the alpha cells of the pancreatic islets of Langerhans; it is an insulin antagonist, raising the concentration of glucose in the blood by targeting the liver to promote glycogenolysis, i.e., the degradation of glycogen to glucose, and gluconeogenesis, the synthesis of new glucose from non-carbohydrate precursors; it uses cyclic AMP as its second messenger.

insulin antagonists - The group of regulatory substances which oppose the action of insulin (insulin lowers blood glucose levels and is most active during the absorptive state a few hours after a meal has been eaten); these regulatory substances elevate blood glucose levels by encouraging glycogenolysis, gluconeogenesis, and glucose release from the liver and they are most active during the post-absorptive state, from approximately four-five hours after the last meal until one-two hours after the next meal; these substances include the hormones glucagon (pancreas), human growth hormone (anterior pituitary), glucocorticoids (adrenal cortex), epinephrine (adrenal medulla), thyroid hormones (T₃ & T₄), etc.

glucocorticoids - The class of steroid hormones produced by the middle layer of the adrenal cortex, whose release is stimulated by adenohypophyseal ACSH; examples include cortisol, cortisone, and hydrocortisone; the glucocorticoids are involved in carbohydrate, protein, and fat metabolism, and have anti-inflammatory properties; they are insulin antagonists contributing to increasing blood glucose levels and fat catabolism; they play a role in maintaining arterial blood pressue, alter the response of connective tissue to injury, reduce the number of circulating lymphocytes, and play a role in the functioning of the CNS.

cortisol - The main steroid hormone produced by the middle layer of the adrenal cortex, whose release is stimulated by adenohypophyseal ACSH; this glucocorticoid is involved in carbohydrate, protein, and fat metabolism, and has anti-inflammatory properties; it is aninsulin antagonist contributing to increasing blood glucose levels and fat catabolism; it plays a role in maintaining arterial blood pressue, alters the response of connective tissue to injury, reduces the number of circulating lymphocytes, and plays a role in the functioning of the CNS.

epinephrine = adrenalin - A catecholamine  neurohormone derived from the amino acid tyrosine in the same pathway which produces norepinephrine, from which epinephrine is derived; it is released by the adrenal medulla and interacts with all target cells which have adrenergic receptors to ready the body for increased skeletal muscular activity or fight-or-flight emergencies.

human growth hormone (hGH) = somatotropin - A protein hormone secreted by the anterior lobe of the pituitary gland/adenohypophysis which targets most body tissues, particularly the liver, skeletal muscle, bone and cartilage, and promotes growth of the body, especially by stimulating release of somatomedins from the liver abd other tissues, and which stimulates protein catabolism; it is an insulin antagonist contributing to increasing blood glucose levels and fat catabolism.

feeding center = hunger center - Collections of neurons in the hypothalamus which evaluate and respond to changes in the blood levels of various nutritional metabolites, e.g., blood glucose, by issuing commands to brain stem centers that initiate behaviors leading to ingestion of foods

satiety center - The ventromedial region of the hypothalamus which is activated by hyperglycemia and by stretching sensations from the stomach to act to inhibit the feeding center of the hypothalamus, thus inhibiting food intake.

          GLP-1 (glucagon-like peptide), serotonin
          hyperglycemia and elevated plasma amino acid levels
          elevated plasma fatty acid levels and leptin
          insulin and CCK (cholecystokinin)
          increased body temperature
          psychological factors

 9.  5 hormones which can be termed "insulin antagonists."

          glucagon (pancreas)
          human growth hormone (anterior pituitary)
          glucocorticoids (adrenal cortex)
          epinephrine (adrenal medulla)
          thyroid hormones (T₃ & T₄)