Each Problem is worth 5 points (25 points total). Answers should be short, but complete. Usually several sentences are required to answer each question thoroughly. When using diagrams, be sure to draw clearly and label completely. Answers maybe typed or neatly hand written (legible please!!) A problem answer key will be handed out prior to the exam and the problem set will be returned to you with your exam.

1. As you know the sympathetic nervous system uses the neurotransmitters Norepinephrine (NE) and the closely related molecule Epinephrine to influence the activity of target organs such as the heart and skeletal muscles during the flight or fight response. Since the same transmitter is used to signal to all target organs, how is it possible for pharmaceutical companies to design drugs which specifically target only one organ? For example "Beta Blockers" are used to decrease sympathetic stimulation of the heart and decrease the blood pressure, and yet they have no effect on the normal sympathetic stimulation of organs such as the digestive system. Briefly describe the underlying mechanism of drug action as it relates to the sympathetic nervous system.

2. In the space below draw the structure of the neuromuscular junction. Indicate the important cellular components that allow signaling between the motor neuron and its target muscle cell (ligands and receptors). Also indicate the ionic events which underlie the electrical and signaling activity at the neuromuscular junction for both the nerve and muscle cell.

3. Skeletal muscle contraction is a complex process. To understand it fully it is helpful to break it down into a series of steps and define the events of each step. Using a brief written description, indicate the events that occur during each of the steps listed below:

I. Neuromuscular Junction Signaling

II. Action Potential of Muscle Cell

III. T Tubule and SR Interaction

IV. Activation of Contractile Machinery

4. A transplanted heart has no sympathetic or parasympathetic innervation. This is because it is not possible to surgically reconnect these pathways to the transplanted heart. Despite of this problem, transplanted hearts respond readily to changes in the circulatory demand of the patient and produce the compensation of output required to meet the changing demand. How is this modulation of output accomplished without nervous input? (hint: there are two mechanisms which explain this phenomenon, think about how sympathetic stimulation is normally accomplished as well as the functioning properties of heart muscle)

5. Fill in the details concerning the properties and functioning of each of the types of vessels found in the circulatory system listed below. In the space provided draw a cross-section of each vessel and indicate the types of cells found within it. Which of these vessels have high resistance? Which have low resistance? Which vessels contain valves to control the direction of blood flow? Which vessels are used to regulate the blood flow to specific organ systems in the body? In which vessels does exchange with tissues occur?

I. Arteries

II. Arterioles

III. Capillaries

IV. Veins