Question

Many choice: Which of the following would correct elevated blood sugar in a type 1 diabetic? Select one or more: a. A drug that caused Glut4 to be inserted into plasma membranes any time blood glucose rises b. A drug that caused insulin receptors to function normally c. Artificial beta cells that would not be destroyed by the immune system d. A molecule that binds any immune receptor that recognizes a pancreatic beta cell

Many choice The female oral contraceptive pill relies on

Select one or more:

a. Negative feedback to prevent development of follicles in the ovary

b. Negative feedback to inhibit secretion of hormones that promote ovulation

c. Positive feedback to promote the LH surge

d. Positive feedback to prevent the LH surge

Answer 1

1. Type 1 diabetes mellitus is caused by decreased production by beta cells of islets of Langerhans of pancreas. It is also caused if beta cells are destroyed by immune attack. Type II diabetes mellitus is caused by insulin resistance. In insulin resistance, insulin cannot act on target cells via its receptor to increase expression of Glucose transporters such as GLUT4. GLUT4 should be localized on cell membrane for increasing transport of glucose into target cells for glycolysis.

Thus, effects on beta cells if reversed will be more beneficial to type I diabetes treatment than type II diabetes. If immune attack resistant beta cells are artificially synthesized and inserted into pancreas, they will produce enough insulin, which acts to increase GLUT4 on cells. This will increase glucose metabolism and reverse the high glucose levels. Similarly, if the drug inhibits immune cell receptor-beta cell interaction, then beta cells will not be destroyed. As a result, insulin secretion will increase and glucose levels will decline.

If insulin receptors function normally or GLUT 4 is localized to plasma membrane, insulin resistance is overcome. This helps in management of type II diabetes.

Right choice:

c. Artificial beta cells that would not be destroyed by the immune system

d. A molecule that binds any immune receptor that recognizes a pancreatic beta cell.

2. Female oral contraceptive pill contains combinations of estrogen and progesterone. Major action of the contraceptive pill is through progestagen (progesterone). As they contain progesterone, they will inhibit follicular development. Follicular development requires only estrogen. Progesterone decreases the pulsatile release of GnRH from the hypothalamus. This will inhibit FSH secretion and thus, inhibit follicle development due to less production of estrogen. Due to low estrogen levels, LH is not produced by the pituitary to induce ovulation. FSH, Estrogen and LH are hormones involved in ovulation.

Estrogen causes negative feedback on the anterior pituitary to inhibit FSH secretion. However this action is less severe that progesterone negative effect.

There is no positive feedback mechanism acting via progesterone or estrogen. If LH surge occurs, ovulation occurs.

Right choice:

a. Negative feedback to prevent development of follicles in the ovary.

b. Negative feedback to inhibit secretion of hormones that promote ovulation.