Objectives

Learning Objectives 6

Renin / Angiotensin / Aldosterone / ANP

1. Discuss the actions of aldosterone on Na⁺ retention, with special reference to the biochemical mechanism of the stimulation of Na⁺ reabsorption in the distal convoluted tubules.

2. Interrelate angiotensinogen, angiotensin I and angiotensin II at the chemical level and define the role of the proteolytic enzymes, renin and ACE.

3. Distinguish that angiotensin II stimulates aldosterone biosynthesis in the ZG by raising intracellular calcium, and ANP lowers aldosterone by reducing intracellular calcium.

4. Explain the chemistry and control of ANP secretion and its many actions including the way it links the heart, kidneys, adrenals and blood vessels.

5. Describe the mechanism of ANP action via a receptor with intrinsic guanylate cyclase activity, cGMP, second messenger and G-Kinase mediated events leading to intracellular calcium lowering.

Sex Steroid Biosynthesis

1 Delineate the pathway of androgen biosynthesis in the testes.

2. Discuss the physiological and biological roles of the testicular hormones.

3. Highlight estrogen biosynthesis and discuss synthetic agonists and antagonists of estrogen and the progestins.

4. Explain the role of estrogens in breast cancer and relate how antiestrogens, such as tamoxifen and nafoxidine, would be efficacious in treating this serious disease.

5. Discuss how estrogens operate directly on bone cells and on monocytes to curb excess osteoclastic resorption and prevent osteoporosis.

Glucose Homeostasis

1. List the effects of insulin and glucagon on glucose and fatty acid homeostasis.

2. Describe the roles of the pancreas, liver, muscle, adipose and brain in the glucose/fatty acid/ketone body cycle.

3. Discuss the fates of dietary glucose and fats in the well-fed state.

4. Describe the role of amino acids derived from muscle protein breakdown in response to starvation.

5. List the roles of glucagon, adrenaline and glucocorticoids in regulating the metabolic adaption to starvation and stress.

6. Identify the metabolic events and organ interrelationships associated with the three primary phases of starvation: post-absorptive, gluconeogenic and prolonged.