Exam #2.  Answer key.

1. a. b. parasympathetic    b. acetylcholine    c. slow down heart rate, decrease strength of contraction

2. These cells are in an environment with high osmotic pressure.   The organic solutes increase the osmotic pressure inside of the cell, so cells don't lose water to the surrounding environment.

3.  A. Blood proteins are made by the liver, so the cells that are increasing protein synthesis must be liver cells.
B. Osteoporosis has been associated with a decrease in activity of osteoblasts, which normally secrete the protein collagen into the matrix, and an increase in activity of osteoclasts, which normally secrete collagenase to break down the collagen.   Since the statement made described a decrease in protein synthesis, one could suggest that cortisol's effect is to decrease protein synthesis in osteoblasts, such that less collagen is deposited into the matrix, and the bone is less dense.    (You got partial credit for some creative alternative answers.)

4. A. x   B. x  C. y  D. x  E. x   F. y  G. x  H. x=y (NK's are nonspecific, first and second response are alike)  I. y  M. x  N. y 
J. y.  The Na/K ATPase creates high Na+ conc in ISF, low concentration inside cell.  This leads to high conc gradient across luminal membrane, which pulls Na+ in through channels. 
K. x.  Concentrated urine is produced only if the collecting duct descends into an area of high osmotic pressure., since water exits only via osmosis.   The area of high osmotic pressure is creasted by the loop of Henle pumping Na+ out.   The longer the loop, the greater the gradient.  
L. x. A decrease in blood pressure stimulates kidney to release renin, which converts angiotensinogen to angiotensin I.  So immediately after blood pressure rises, angiotensinogen in the blood decreases, as it's used to make angio I.  

5. A. MHCII is found on antigen-presenting cells, like macrophages, which present Ag to Th, binding to Th via T Cell Receptor and CD4.  The macrophage release IL-1 and the Th releases IL-2.   The superantigen mimics this binding, since it can grab onto both the macrophage via MHCII and the Th via the TCR.  This stimulates IL release, but in this case, it's released nonspecifically, that is, many kinds of T cells are involved, and many ILs are released, in many parts of the body. 
B. IL's increase capillary permeability.  Protein leaves the blood to the surrounding tissue, increasing the osmotic pressure there.   Water follows by osmosis, causing a decrease in blood volume, and a decrease in blood pressure.

7.  Integrins are cell adhesion molecules, that allow the white blood cells to bind to the endothelium, and move out of the capillaries.   In the interstitium, they particpate in the inflammatory response, phagocytizing bacteria, secreting cytokines (interleukins, defensins, etc).  With fewer integrins there'd be fewer wbc's in the tissue, and a less effective inflammatory response. 

8.  Your answer should have indicated that you'd considered the proposed experiment in some detail, and that you were aware of the parameters we discussed in class that might affect the design and interpretation of experiments.  Some questions your experiment might have been designed to test:

Is phagocytic activity the only aspect of the immune system that was affected by sleep loss?  Your experiment might aim to investigate other cells, cytokine release, etc.
Does the body "get used to" repeated sleep loss, such that the effect on the immune response decreases with time?  You might design an experiment to look at repeated instances of sleep deprivation.
How long does this affect last?  Rather than limiting blood samples to the time when subjects awoke, continue to monitor phagocyte activity for several hours/days afterwards to see how soon it returns to normal.
Does this decrease in immune function occur with shorter periods of sleep deprivation, which would be more like the resident would experience?  Vary the number of hours of sleep deprivation.  Some suggested conducting this study on actual residents since the lab situation might not mimic the intense stress of the former situation.
Does this statistical decrease in immune response actually reflect a greater risk of disease?  Study people who've had insomnia for years, or worked in jobs that require frequent awakenings, and see whether they develop more serious disease.