Animal Physiology, Spring, 1995

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. The number of points that each question is worth follows the questions in parentheses. These questions can be answered in 2-4 sentences or a labeled diagram and 1-2 sentences.

1) List a few reasons and briefly describe why, in order to be able to understand and analyze physiological adaptations, it is important to understand the environment in which the animal lives. (6)

2) Provide at least two examples of how an animal's biochemistry can be regulated homeostatically. (6)

3) Identify four (out of five) following in one or two sentences: (12)

a) Claude Bernard

b) glial cells

c) Hodgkin and Huxley

d) hypothalamus

e) glutamate

4) Using one of the following equations (a or b) and the values given in (c), determine the contribution of K+ to the membrane potential. You will need to use a calculator. (5)

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=0.03 M, [K]i=0.39 M, [Na]o=0.29 M, [Na]i=0.02 M, [Cl]o=0.11 M, [Cl]i=0.06 M

5) Describe the ionic currents which would occur if, in a squid axon you depolarize and clamp the axon to the Na+ equilibrium potential (as determined by the Nernst equation). Be sure to include a diagram. (6)

6) Briefly describe the evidence that suggests that the action potential "late current" is carried by K+. (8)

7) We discussed at least three different ways in which membrane channels can be opened (activated). List and briefly describe two of these ways. (8)

8) Neurotransmitters can cause short term depolarizations of the post-synaptic membrane. In addition they can induce longer neuromodulatory changes via "second messengers". List at least two second messengers and describe their possible actions. (6)

9) Thyroxin and insulin are both hormones that help to maintain homeostasis. Describe how either works to do this. (8)

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) You are a scientific historian working on an article for American Scientist in which you will describe the major discoveries and techniques that allowed scientists of the 1950s and 60s to understand the basis of neuronal excitability. Describe some of these discoveries and techniques, and perhaps a few of the investigators of this era. (20)

2) 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/integrating capability. Be sure to use drawings and graphs here! (15)