Homework set: Physiology
Nervous System
1. What effect would each of the following have on synaptic transmission? (Synaptic transmission is when neurotransmitters from on neuron bind and activate a second neuron.)
a) you administer a drug which inactivates acetylcholinesterase
b) you cut the axon of the postsynaptic cell
c) you administer a drug which binds to the norepinephrine receptor but doesn't cause the activation of the associated G-protein
2. You are testing the effects of drugs on three identical, isolated neurons. You know that if no drug is applied, the neuron (under the appropriate conditions) is capable of EPSP formation, action potential production, and acetylcholine release. What effect would each of the following three drugs have on these three functions?
a) Drug #1 blocks voltage-gated calcium channels
b) Drug #2 blocks voltage-gated sodium channels
c) Drug #3 causes chemically gated sodium channels to open and remain open indefinitely
3. You have four identical Isolated neurons which are capable of forming excitatory ACh synapses on both ends. You treat each of these neurons with a different drug. You then apply acetylcholine to the dendrites of each neuron, and test to see if that neuron is capable of EPSP formation, action potential production, and/or acetylcholine release. The results to your studies are given here:
|
Neuron
|
EPSPs?
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APs?
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ACh released?
|
|
#1 (Drug A)
|
yes
|
yes
|
no
|
|
#2 (Drug B)
|
no
|
no
|
no
|
|
#3 (Drug C)
|
yes
|
no
|
no
|
|
#4 (Drug D)
|
yes
|
yes
|
yes
|
a) Which drug is probably a placebo? Explain.
b) Give a plausible explanation what each of the three other drugs might do, giving cellular and/or chemical details,
4. You have an impermeable membrane bag (i.e. nothing gets through its walls). You insert ACh receptors into the wall of this bag. The ACh receptors are from a synapse that forms IPSPs. Inside this bag there is 3% Na+, 4% K+ and 2% Ca2+. At time=0 sec you place the bag into a beaker of pure water. At time=30 sec, you add acetylcholine to the beaker. At time=60 sec, you add acetylcholinesterase the beaker.
a) Describe what will occur during your experiment.
b) Draw graph showing what happens to the concentration of each ion in the bag from 0 sec to 90 sec,
c) What will happen to the membrane potential of the bag during this experiment?
Muscular System
1. What effect would each of the following drugs have on shortening of the sarcomeres of skeletal muscles?
(a) drug blocks calcium release from terminal cistemae
(b) drug blocks calcium binding sites on troponin
(c) drug enhances ATP hydrolysis by myosin head ATPase
(d) drug blocks myosin head binding sites on actin
(e) drug destroys tropomyosin
(t) drug inactivates acetylcholinesterase
(g) drug blocks acetylcholine receptors
(h) drug destroys troponin
2. What would happen if you administered a drug which completely blocked the norepinephrine receptors of the heart's SA node?
3. Draw 2 complete cycles of an ECG trace that corresponds to a person with a cardiac rate of 120 bpm. Label all waves and axes, and indicate what electrical event each wave (or complex) represents.
4. How far apart (in time) are the R waves on the ECG of a person whose heart rate is 100 bpm?
5. A person's heart rate is 105 bpm. Do they have tachycardia?