Student ID ______

Animal Physiology 2007

Exam II

Name ______

Part I______(10)

Part II______(15)

Part III______(10)

Part IV______(10)

Part V______(15)

Part VI______(10)

Part VII______(10)

Part VIII______(10)

Part IX______(10)

Total______(100)

Please read each question carefully. Make sure you completely answer each question. In some sections, you will be able to choose which questions you would like to answer. Please clearly indicate which of these questions you have chosen. You are more than welcome to use properly labeled graphs, diagrams, illustrations to support your conclusions

No electronic devices may be accessed during this exam.

This exam has eight pages including this title page.

Animal Physiology regrade policy: If you feel a mistake has been made in the grading of your exam, please submit a typed explanation to Dr. Mensinger within one week of your exam being returned. You should detail why you feel your answer deserves more credit.

I) Which of the following senses (taste, olfaction, vision, mechanoreception, auditory, weakly electric, strongly electric, infrared, bioluminescence, anti gravity) were the following used to illustrate or mostly closely aligned with. Do 10 of 13. 1 pt each.

a) Bombyx

b) The fly

c) schooling fish

d) barn owl

e) Malapterus electricus

f) Limulus

g) worm/antiworm

h) the cat

i) cheetah

j) bird of prey (raptor)

k) mormyrid

l) torpedo

m) pit viper

II) Short answer

1) Name the two investigators that did pioneering work on the horseshoe crab. (2 pts)

2) Which retinal cell does light first encounter when it first hits the retina (2 pt)

3) Name two of the five major tastes discussed in lecture and the evolutionary significance of each taste (5 pts)

4) What was the sea slug, Aplysia, used as a model organism for? (2 pts)

5) What compound does the puffer fish contain and how did it help scientist understand the ionic basis of the action potential. What channel did it block(2 pts)

6) What type of photoreceptor would dominate your vision if you looked out the corner of your eye. ( 2 pt)

III: Sketch the membrane potential for each cell in the table boxes to show its reaction to a brief light stimulus. The location(s) of the stimulus is indicated by X. The photoreceptor is contained within the smaller, inside circle and synapses directly to the off- bipolar cell. The off bipolar cell synapses directly to the off center ganglion cell. For these questions you do not have to worry about labeling the axes or drawing a scale bar. You just need to show how the membrane potential will change during a brief light stimulus (1 pts each square; 10 pts total if all correct)

I / II / III
Photoreceptor
(in inner circle)
Off bi polar cell
Off ganglion cell

IV) Longer answer Do 3 of 4. 5 pts each

1) Explain the figure. Make sure you Describe the purpose of the plug, the purpose of two different types of plugs and how the plugs affected the owl’s ability to locate the target. What was learned about sound localization from the experiment.

2) Explain how a small dart tipped with curare can bring down a monkey.

3) Explain why electrical communication is better than acoustical communication in shallow water habit.

4) If one takes a long axon and applies current to the middle of this axon, current will spread in both directions. Yet, if a spike is initiated in the axon hill lock, the action potential will only travel in one direction. Explain. A figure is suggested.

V) Do one of the following 2 questions (nerve gas or shark, shark is on next page). 10 pts

1) While trawling in Lake Superior, you bring aboard a shell labeled DANGER: NERVE GAS. Explain the physiological consequences that your nervous system will undergo if this shell ruptures. Please be specific about what is happening at the synaptic junction and what will be the ultimate cause of death. (7 pts)

Pyridostigmine bromide is a nerve gas antidote. Taking into account what you know about nerve gas, postulate a mechanism that would allow Pyridostigmine bromide to work (3 pts)

2) Label 5 structures on the dogfish brain

VI) Plot the membrane potential (mV) vs time for the following cell. Start at T=0 ms for each scenario. All times are in relation to T=0. The cell has a resting potential of -50mv, a threshold of -30, an ENA of approximately +50. The absolute refractory period of the cell is 3 ms and the relative refractory period lasts an additional 2 ms after the absolute refractory period. Each stimulus is 2 ms in duration. The time constant for the action potential is the same as mentioned in lecture and shown in your textbook. (2.5 pts each)

A) A hyper polarizing stimulus of 25 mv at + 1 ms

B) A depolarizing stimulus of 10 mv at + 1 ms

C) a depolarizing stimulus of 40 mv at +1 ms and a depolarizing stimulus of 40 mv at +4 ms

D) A depolarizing Stimulus of 35 mv at +1ms and a depolarizing stimulus of 50 mv at +8 ms

VII) Do one of the following 10 pts

A) Draw an action potential. Using dotted or dashed lines, Plot gNa+ and gK+ in relation to the action potential. Compound X blocks K+ channels. Redraw the action potential to show the effect of Compound X

B) Compound Y destroys the inactivating particle in voltage gated Na+ channels. Everything else remains intact in the channel. Speculate on what effect this would have following a depolarization past threshold in the neuron following treatment with compound Y. Do not forget to include ENA+in your discussion.

VIII. True or False (Do 3 of 5) 3 pts each (=+1pt for all correct trues/false). Indicate whether the following statements are true or false. If the statement is true, provide a figure/graph that supports the claim. If the statement is false, correct the entire statement.

1) Stimulus modality is encoded by both the amplitude and the duration of the action potential

2) Frequency varies linearly with the size of the receptor potential but cannot exceed the limit set by the refractory period.

3) For an on-center ganglion cell, the firing rate of the cell will increase in response to a small spot of light centered on the cell and decrease in response to a “ring” of light that only covers its surround

4) Simple cells are characteristics of the lateral geniculate nucleus. They are influenced primarily by the on and off center of retinal bipolar cells. They will respond to the proper stimuli anywhere within a large visual field

5) Vertebrate photoreceptors do not release neurotransmitter in the dark because of the dark current. When stimulated by photons, their membrane will depolarize. The stimulus from the photoreceptor is in the form of an action potential. This stimulus travels from photoreceptors to horizontal cells to ganglion cells. At the ganglion cell level, the action potential is converted to a graded potential that is sent directly to the visual cortex.

IX) 10 pts

Neuron A synapses onto Neuron B.

Electrode I is placed at a node of Ranvier along the axon of Neuron A.

Electrode II is placed at a myelinated section along the axon of Neuron A

Electrode III is placed in the dendrites of Neuron B.

For each of the following cases, sketch the voltage recorded by the electrode (for example, if an action potential will be taking place at that location, draw an action potential). Relative scale is more important than absolute scale so you do not have to label the x and y axis. Assume a single action potential in neuron A is sufficient to generate a post synaptic event in neuron B.

TEA blocks most types of K+ channels

Bungarotoxin inhibits neurotransmitter release from the presynaptic terminals

The following cases all follow the generation of an action potential at the axon hill lock in neuron following application of the following:

Case #1no drugs

Case #2 TEA

Case #3Bungarotoxin

2 pt for FIRST correct square, 1 pt for each additional correct square, 10 pts total

I / II / III
#1
#2
#3

1