Q.1 What is graded potential? is local (small) change in the
membrane potential. e.g. : 1- motor end plate potential 2- EPSP 3-
IPSP Q2. What is action potential? Brief, sudden, rapid, large
(100mV) changes in membrane potential during which potential
actually reverses. Travels from 1 point to another point. 2
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Graded Potential Action Potential 1. Stimulus does not reach
threshold level. 2. Stimulus causes local change in membrane
potential e.g. -70 to -60mv 3. It dies down over short distance. 4.
Can be summated. 5. Does not obey all or none law. 1. Stimulus
reaches threshold level therefore causes AP. 2. Stimulus causes
depolarization to threshold level. 3. It is propagated. 4. Can not
be summated. 5. Obeys all or none law. 3
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Q4. Draw diagram of AP of Neuron. Show depolarization,
repolarization and hyper polarization phase and give the cause of
each phase. 4
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Q5. Nerve fiber can be stimulated easily, when it is at RMP or
at hyper polarization stage. Give reason for your answer. At RMP
because it wont need more stimulation to reach the threshold. More
over, hyper polarization would be more ve and needs stronger
stimulus to reach the threshold Q6. What is absolute refractory
period? Absolute Refractory= (none responding) Period It is that
period of action potential during which no new action potential can
be initiated even by strong stimulus. Q7. What is relative
refractory period? Relative Refractory period It is that period
during which second action potential can be produced by very strong
stimulus. 5
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Q8. Draw AP and show absolute and relative refractory period?
Total depolarization phase +1\3 rd of the repolarization phase
Last2\3rd of the repolarization phase 6
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Q10. Where AP is generated in neuron? Axon Hillock Q11. What
are the differences between contiguous conduction and saltatory
conduction? Continuous or Contiguous conductionsaltatory Conduction
occurs in UNMYELINATED nerve fibers. Slower-walking- occurs in
MYELINATED nerve fibers Faster-jumping- 8
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Q12. What is myelin sheath? a thick layer composed of lipids
covering the Axon (Nerve fiber) produced by (peripheral nerve=
Schwann cells) (central nerve= oligodendrocytes). Q13. What is node
of Ranvier? Gaps between the myelin sheath Q14. What factors affect
nerve conduction? 1) Diameter of the nerve fiber 2) Axon (Nerve
fiber) is Myelinated or Unmyelinated 3) Temperature Q15. What is
synapse? JUNCTION BETWEEN TWO NEURON 9
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Q16. Draw the diagram of chemical synapse 10
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Q17. What is excitatory post synaptic potential (EPSP) Q18.
What is inhibitory post synaptic potential (IPSP) EPSPs and IPSPs
are graded potential [local]. They can be summated [added]. EPSP=
excitation =depolarization always!! Definition: depolarization
graded potential in the post synapse or-post synaptic membrane.
IPSP= hyper polarization graded potential that occurs in post
synapse or post synaptic membrane. Q19. What is neuromuscular
junction? junction between Motor neuron and Skeletal muscle fiber.
They are linked chemically. 12
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Q20. What is a neurotransmitter at neuromuscular junction?
acetylcholine Q21. How acetylcholine is destroyed?
acetylcholinesterase It is located in the Motor end plate (Muscle
membrane). Q22. What is myasthenia gravis? disease of Neuromuscular
junction. Q23. What is the treatment of myasthenia gravis? Drug
such as Neostigmine that inhibits enzyme AChE (Acetylcholinestrase)
is given. This drug prolongs the action of acetylcholine at
neuromuscular junction. 14
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Q1. Abeer, a medical student, had a tooth ache. She went to the
dentist and the dentist advised her filling in a cavity in tooth.
The dentist injected a local anesthetic in the nerve pathway which
carries the nerve impulses from the area of tooth. Due to
injection, Abeer did not feel any pain during the drilling and
filling procedure. Information local anesthetic block voltage gated
Na+ channels. Explain how this action of local anesthetic prevents
the transmission of pain impulses to the brain? (Reference See page
131 in Human Physiology by Lauralee Sherwood) 15