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Where are the most proximal voltage gated Na+ channels located?
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| the process of sending a signal from one electrically excitable cell to an adjacent cell through a specialized structure specifically tailored to carry out this signal transfer |
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| contain linked channels (connexons) which allow for direct transfer of electrical signals between adjacent cells |
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| have specialized structures which can take an electrical signal and convert to a chemical signal. then convert back to an electrical signal to be passed further down |
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Electrical synapses:
A) where are they found mainly?
b) type of connections
c) speed and direction of movement
d) problems |
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Definition
a) cardiac and smooth muscle
b) gap junctions
c) fast and bi-directional
d) may not want bidirectional movements and
impedence limits signal strength when a small cell is communicating with a large one. |
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| characteristics of chemical synapse |
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slower and less fidelity than electrical synapse.
No impedence mismatch.
UNIdirectional |
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what prevents presynaptic exocytosis?
what chemical influx and protien allows exocytosis? |
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Definition
a) proteins on cell membrane like v and t snares
b) ca influx protein synaptotagmin |
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characteristics of non peptide neurotransmitters
a) where produced?
b) speed of action
c) effect on ion chann
d) mode of recycling |
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Definition
ie ach
a) axon terminal
b) quick start and end to action
c) directly open ion chan
d) recycled via facil diff via endocytosis into presynaptic terminal |
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characteristics of peptide transmitters
a) where is it produced?
b) speed
c) mode of recycling
d) mode of action |
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Definition
LARGE
a) produced in cell body
b) slow to start and finish its effect
c) not recycled, must be destroyed to terminate its effects
d) uses second messangers to open ion chann. |
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Definition
recpetor and ion ch = same protein.
ligand gated not voltage gated. |
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Definition
| receptor activates a 2nd messanger system which activates an ion chann usually by phosphrylation |
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what receptor type is nicotinic receptor?
why |
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Definition
ionotropic.
opens channel directly. very fast
excites post synap cell by activating na ch to depolarize |
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| what recpetor type is muscarinic and why? |
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Definition
metabotropic.
it activates a g protein 2 nd messenger system which hyperpolarizes the cell by slowly opening k channels inhibits post synaptic cell
SLOW |
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Definition
| one ion channel is activated and produces and additive effect over time |
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| many ion channels interact at the same time |
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| post synaptic mebrane at nmj is known as what |
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Definition
motor end plate
and its potential is end plate potential |
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| difference between graded potential and action potential? |
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Definition
a graded potential transmits over short distances while action potential can travel long distances.
graded potentials become weaker as they spread think of a drop of water. it is a typical post synaptice potential |
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| what are components of nmj? |
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Definition
| axon terminal, muscle cell (fiber) |
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| NMJ produce only what kind of end potential? |
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Definition
only epsp and they can summate
site of summation is adjacent to motor end plate |
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How does this differ from an
action potential in an axon? |
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Definition
| Action potentials do NOT pass from one skeletal muscle to another skeletal muscle cell. |
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| effects neurnal and muscle Na chan |
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| effects neurnal muscle Na chan |
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