Endocrine Organs

             3 Endocrine organs, describe their role.
             Thymus gland and thymosins/thymopoetins: transforms lymphocytes into T cells, which identify and destroy infected body cells. Hormones stimulate differentiation and development of T cells. These in turn stimulate other immune cells such as leukocytes.
             b. Adipose tissue and leptin: leptin is synthesized and released from cells in proportion to the amount of fat in tissue. Leptin acts on the hypothalamus causing a reduction in hunger, and stimulates the thyroid for increased metabolism.
             c. Heart and atrial natriuretic factor: the heart produces hormones that help regulate its own workload. In many ways, the endocrine heart appears as a modulator of systems such as the sympathetic nervous system, the renin-angiotensin-aldosterone system and other determinants of vascular tone and renal function . For example, they inhibit renin release, increase glomerular filtration rate, decrease tubular sodium reabsorption, increase renal blood flow, inhibit aldosterone synthesis and release, relax vascular smooth muscle, inhibit salt and water appetite, decrease baroreflex activity and even regulate vascular smooth muscle cell proliferation.
             2. Describe synthesis of bile salts and transport into bile canaliculi. Bile is a complex fluid containing water, electrolytes and a battery of organic molecules including bile acids, cholesterol, phospholipids, and bilirubin that flows through the biliary tract into the SI. Salts are formed in hepatocytes by a series of enzyme-catalyzed steps converting cholesterol to cholic acid. That is conjugated with glycine or taurine, then secreted as Bile satls. This allows them to be amphipathic and water soluble. Active transport pumps secrete the majority of bile salts, while a lesser portion goes through by non-ionic diffusion and micelles. These are forced into the bile ducts by pressure gradient.
             3. Eumelanin and Pheomelanin differences, eumelanosomes and pheomelanosomes: eumelanin is brown to black in color, and present in individuals with those hair colors.