Animal Physiology, Spring, 1997

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, Ranvier Node, a beginning biology student, notices that the study of temperature is the most common parameter studied. From this observation she concludes that temperature is the most important aspect of blood physiology. Is this a valid conclusion? Why or why not?

2) Briefly describe what is meant by homeostasis. Using a "flow diagram" (arrows) and a few phrases, describe how homeostasis can be effected via biochemical means over the short term.

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

a) Walter Cannon

b) glial cells

c) Hodgkin and Huxley

d) Goldman equation

e) glutamate or GABA

4) We discussed at least three different ways in which membrane channels can be opened (activated). List and briefly describe two of these ways.

5) Describe the ionic currents which would occur if, in a squid axon you replace all of extracellular Na+ with an impermeable ion such as Mg++ and you stimulate the axon past threshold. Be sure to include a diagram.

6) Compare and contrast relative and absolute refractory. What effect do these periods have on a neuron?

7) Using one of the following equations (a or b) and the values given in (c), determine the contribution of K+ to the membrane potential. Show your work. You will need to use a calculator.

a) Ex = RT ln [X]i where, after converting ln to log and RT=0.058

Fz [X]o F

b) Vm= RT ln PK[K+]o + PNa[Na+]o + PCl[Cl-]i

---- -------------------------------------------

Fz PK[K+]i + PNa[Na+]i + PCl[Cl-]o

c) [K]o=0.04 M, [K]i=0.45 M, [Na]o=0.36 M, [Na]i=0.03 M, [Cl]o=0.15 M, [Cl]i=0.05 M,

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

Essay Questions: Answer the following questions 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) Working in the depths of the Arabian desert, you come upon a new species of terrestrial isopod which you suspect has particularly useful neurons for use by scientists. As a world famous (but modest!) pharmacologist, you name it Artachno plymouthii after your alma mater, and plan to investigate the effects of several pharmacological agents (toxins) on the action potential and the long term resting potential of the neurons in Artachno plymouthii . Describe the experiments that you would perform in order to characterize these neurons. Be sure to cite the toxins that you would use and the results that you would expect if these neurons were to behave like the typical giant squid axon from the sea. (15)