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Problem Set #9
Nov.22, 2010 Due Dec. 10th
Name: ________________________
TA: ________________________
1. True or False. 2pts
__F_ a) Acetylcholine is the main neurotransmitter of the CNS.
__T_ b) Electrical synapses are faster than chemical synapses.
__F_ c) Acetylcholine Receptors (AchR) are located in the pre-synaptic terminal.
__T_ d) Gap junctions are part of electrical synapses.
__T_ e) Fusion of pre-synaptic vesicles with the plasma membrane is a calcium dependent
process.
__T_ f) Glutamate generates IPSPs. [careful, metabotropic glutamate receptors can]
__F_ g) The synaptic delay at a chemical synapse is on the order of 10 ms.
__T_ e) The response of the postsynaptic cell depends on the quantity of neurotransmitter
released as well as the density of receptors on it.
2. Describe briefly what happens in synaptic transmission at the level of the presynaptic
terminal if: 1pt.
a) one injects a calcium chelator into the presynaptic terminal.
Synaptic Transmission is Reduced, then completely inhibited.
b) there is an inhibition of acetylcholinesterase.
Acetylcholine re-uptake would be increased, a cycle of increased Ach in vesicles would be
released.
3. a) Match each figure to the explanations below (write the number in the blank) 2pts
ii
---------
i
----------
iv
----------
iii
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i) Spatial summation of epsp’s
ii) Subthreshold, no summation
iii) Temporal summation
iv) Spatial summation of EPSP and IPSP.
4.) 3pts total
a) Indicate two neurotransmitters that are involved in generating the EPSP and IPSP.
Glutamate -exc. Glycine, GABA -inh.
b) What may cause a synaptic depolarization depression ( the depolarization to diminish.)?
(indicate three factors)
neurotransmitter re-uptake,
diffusion of neurotransmitter,
breakdown of neurotranmitter.
c) What changes happen in neurons for long-term memory? (indicate two)
post synaptic receptor levels increase, neurotransmitter levels increase.
5.) What is the neurotransmitter released in the neuromuscular junction? 0.5 Pt.
Acetycholine
6.) In Na+ voltage-gated channels, the S4 transmembrane domain (think voltage switch) has a string
of _______________ charges. Following a depolarizing change in voltage this domain moves
____________ causing the channel to go from a closed to an ______________ state. 0.5pt.
(a)
(b)
(c)
(d)
positive, OUTWARD, open
negative, INWARD, open
negative, OUTWARD, inactivated
positive, INWARD, inactivated
7.) Glutamate is an excitatory neuro-transmitter found in meat and Chinese Food as an additive
(monosodium glutamate), what prevents the onset of seizures when comsuming meat? 0.5pt
The blood brain barrier keeps out unwanted pathogens, as well as amino acids, that may act as
neurochemicals/peptides that are potentially toxic in high doses.
8.)What are two key pieces of evidence for the quantal hypothesis of vesicular transmission of
neurotransmission? (covered in class)0.5pt
a.)The release of spontaneous “packets” even in the absence of stimulation, these mini end plate
potentials were of the same voltage size as evoked potentials.
b.) Heuser performed freeze-fracture electron microscopy at the time of mEPP
recording to find small vesicles were attached to the inner membrane of the presynaptic neuron