Animal Physiology, Spring, 1996

Bi 377, Hour Exam I

Instructions:

1) After receiving the exam, you are free to work on the answers in any classroom in Boyd Hall.

2) You may not use any information other than what you have stored in your brain (no notes, books, etc.)

3) Please limit your answers to the space provided beneath each answer. Feel free to use labeled diagrams to enhance your answers. Write clearly and concisely.

4) You have 1.5 hours to complete this examination. Remember that you have agreed not to discuss this examination with anyone else in the class until all have taken it (I will let you know in class).

5) Please sign below if you agree to the above policies.

GOOD LUCK!

Honor Statement: I have read the above instructions and agree to them. I promise to neither give nor receive any help on this examination.

Signed,

Short Answer. Choose seven out of the following eight questions. Each is worth 10 points. These questions can be answered in 3-6 sentences or a labeled diagram and 2-3 sentences.

1) When performing a literature search on the effects of several environmental parameters on blood physiology, Jasper, a beginning biology student, notices that the study of temperature is the most common parameter studied. Is this a valid assumption? Why or why not?

2) Diagram a negative feedback loop describing how blood glucose levels are "controlled" right after a meal.

3) Identify/define four (out of five) following in one or two sentences: (10)

a) Walter Cannon

b) homeostasis

c) cAMP

d) allosteric inhibition

e) isozymes

4) Given the following concentrations of ions, calculate the driving force of Na+ across the membrane:

[K]o=0.06 M [Na]o=0.03 M [Cl]o=0.15 M

[K]i=0.15 M [Na]i=0.18 M [Cl]i=0.18 M

5) The resting potential is caused by the Na+/K+ coupled pump. Refute or defend.

6) Describe the ionic currents which would occur if, in a squid axon you replace most of extracellular Na+ with an impermeable ion such as Mg++, such that [Na]i=[Na]o and you stimulate the axon past threshold. Be sure to include a diagram and explain why you would see these currents. (6)

7) You are investigating the electrophysiology of several neurons in the M5 ganglion of a leech. Upon inserting your recording electrode into a cell you are amazed to find spontaneous action potentials (bursts) that apparently arise from an unstable resting potential. The bursts of APs last for 0.5 sec with a frequency of 50/sec (Hz). Then you remember that you had discussed bursting cells in Animal Physiology back in the 21st century at Plymouth State College. Based on what you learned there, what is/are the underlying mechanisms that allow this neuron to be spontaneously active?

8) If the frog sciatic nerve lab had worked as expected: 1) we would have been able to stimulate the nerve and record several thousand compound action potentials (CAPs) from each nerve even if we prevented the nerve from making ATP by applying a poison. 2) However the size of the CAPs would have decreased over time. Explain these two experimental results.

Essay Questions: Answer the following question in essay format (a paragraph or two with topic sentences followed by information supporting the topic sentence). You can also use the back side of this sheet of paper. DIAGRAMS (FIGURES) ARE ALSO STRONGLY ENCOURAGED!

1) Neurons do not just faithfully pass on information (action potentials) from one cell to another but they help to process and integrate/interpret information. Describe the physiological basis of this processing capability. Be sure to use drawings and graphs here! (15)

2) Neuroscientists claim that the structure of the neuronal cell membrane forms the basis for excitability. Support this statement. (15)