5 October 2011

Section C: SynapsesSection D: Anatomy

Analysis of Test 1 Multiple Choice

Test 1 MC questions rated “Easy” or “Very Easy”:E1, E5, E11, E12, E14, E16, E19G2, G6T1N1, N3, N8, N11

Test 1 MC questions rate “Challenging”E4, E8, E9, E17, E23T3,N6,

Peer Tutors available through Dr. Grinnell (grinnellnk@wofford.edu)Ashlee Price, Arselaan Salehani, David Wynn, Sean Nguyen, Marshall Diven, Stefanie Hoffer.

1QQ # 12 for 8:30 class1. Which could cause a larger response in a post-synaptic cell?

a) Keep V-gated Ca++ channels open longer in the presynaptic cellb) Very high frequency of action potentials in the presynpatic cellc) Block the reuptake of neurotransmitter from the synpatic cleftd) Enhance the reuptake of neurotransmitter from the synaptic cleft into

the presynaptic cell or astrocytese) Block the action of enzymes in the synpatic cleft that degrade

neurotransmitters.

2. Which are CORRECT concerning chemical synapses?a) Chemical synapses are bi-directional.b) Chemical synapses are ideally suited to synchronize the activity of many

cells.c) Chemical synapses are far more common than electrical synapses in the

CNS of humans.d) Chemical synapses depend upon the influx of Ca++ to release

neurotransmitters.e) At a chemical synapse, the response of the post-synaptic cell is

invariable.

1QQ # 12 for 9:30 class1. Which could cause a smaller response in a post-synaptic cell?

a) Keep V-gated Ca++ channels open longer in the presynaptic cellb) Very high frequency of action potentials in the presynapatic cellc) Increase the reuptake of neurotransmitter from the synapatic cleftd) Enhance the reuptake of neurotransmitter from the synaptic cleft into

the presynaptic cell or astrocytese) Block the action of enzymes in the synapatic cleft that degrade

neurotransmitters.

2. Which are CORRECT concerning chemical synapses?a) Chemical synapses are unidirectional.b) Chemical synapses are ideally suited to synchronize the activity of many

cells.c) Chemical synapses are far less common than electrical synapses in the

CNS of humans.d) Chemical synapses depend upon the influx of Ca++ to release

neurotransmitters.e) At a chemical synapse, the response of the post-synaptic cell is

invariable.

Figure 6.25UnidirectionalRelease, diffusion, binding,Post-synaptic Receptor Types: Inotropic or Metabotropic

Classification:Excitatory (closer to threshold for AP)OrInhibitory (stabilizes or hyperpolarizes)

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Inotropic receptor Metabotropic receptor

Types of Acetylcholine Receptors so named for agonist:Nicotinic AChR and Muscarinic AChR

Types of Ligand-Gated ReceptorsS 2

Agonist = Nicotine Agonist = Muscarine

Antagonist = Curare Antagonist = Atropine

= ACH = Acetylcholine

Priority by proximityTo axon hillock!

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Figure 6.28

EPSPs :which ion moving in which direction?Duration of PSP vs APSynaptic delay

Some ion Channels that allow flux of Na+ and K+ simultaneouslye.g. nicotinic Acetylcholine Receptor (nAChR)

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Figure 6.29

IPSPs :which ion moving in which direction?

Some IPSPs result in no change in membrane potential by opening Chloride channels that stabilize membrane potential at resting value (Nernst Potential for Cl- = -70mV) or in cells that actively transport Cl- out.

EK+

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Figure 6.31

Summation and Synaptic Integration

Different times Different locations

Challenge question: Suppose each IPSP hyperpolarizes by 5 mV and each EPSP depolarizes by 5 mV.If 4 inhibitory synapses are active at the same time, how many excitatory synapses must be active simultaneously to exceed threshold (-55 mV) if the resting membrane potential is -70mV?

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Synapses named for NT used: -ergic

Examples:CholinergicAdrenergicSerotonergicGABAergicPeptidergic

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Pharmacological agents intended to act in brain must be able to cross blood-brain barrier.

Who Cares?

Parkinsons Disease

Treatments for Parkinsonism: a) tablets of L-Dopa (which crosses the BBB) unlike Dopamine (which would have widespread effects)b) neuronal transplants (self, fetal, stem cell, pig), c) electrical stimulation NIH Stem Cell Information

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