Download neuro5

5 October
2011
Section C: Synapses
Section D: Anatomy
Peer Tutors available through
Dr. Grinnell
([email protected])
Ashlee Price, Arselaan
Salehani, David Wynn, Sean
Nguyen, Marshall Diven,
Stefanie Hoffer.
Analysis of Test 1 Multiple Choice
Test 1 MC questions rated “Easy” or “Very Easy”:
E1, E5, E11, E12, E14, E16, E19
G2, G6
T1
Test 1 MC questions rate “Challenging”
N1, N3, N8, N11
E4, E8, E9, E17, E23
T3,
N6,
1QQ # 12 for 8:30 class
1. Which could cause a larger response in a post-synaptic cell?
a)
b)
c)
d)
Keep V-gated Ca++ channels open longer in the presynaptic cell
Very high frequency of action potentials in the presynpatic cell
Block the reuptake of neurotransmitter from the synpatic cleft
Enhance the reuptake of neurotransmitter from the synaptic cleft into
the presynaptic cell or astrocytes
e) 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 class
1. Which could cause a smaller response in a post-synaptic cell?
a)
b)
c)
d)
Keep V-gated Ca++ channels open longer in the presynaptic cell
Very high frequency of action potentials in the presynapatic cell
Increase the reuptake of neurotransmitter from the synapatic cleft
Enhance the reuptake of neurotransmitter from the synaptic cleft into
the presynaptic cell or astrocytes
e) 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.
S1
Unidirectional
Release, diffusion, binding,
Post-synaptic Receptor Types: Inotropic or Metabotropic
Figure 6.25
Classification:
Excitatory (closer to
threshold for AP)
Or
Inhibitory (stabilizes
or hyperpolarizes)
S2
Types of Ligand-Gated Receptors
= ACH = Acetylcholine
Inotropic receptor
Metabotropic receptor
Agonist = Nicotine
Agonist = Muscarine
Antagonist = Curare
Antagonist = Atropine
Types of Acetylcholine Receptors so named for agonist:
Nicotinic AChR and Muscarinic AChR
S3
Priority by proximity
To axon hillock!
S4
Figure 6.28
EPSPs :which ion moving
in which direction?
Duration of PSP vs AP
Synaptic delay
Some ion Channels that allow flux of
Na+ and K+ simultaneously
e.g. nicotinic Acetylcholine Receptor
(nAChR)
S5
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+
S6
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?
S7
Synapses named for
NT used: -ergic
Examples:
Cholinergic
Adrenergic
Serotonergic
GABAergic
Peptidergic
S 11
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