Essay Nervous Systems Assignment BMS 270/271 Provide as much detail as possible
ID: 3521707 • Letter: E
Question
Essay Nervous Systems Assignment BMS 270/271 Provide as much detail as possible as it is necessary and important. The essay topics are as follows:1) generation and propagation of an action potential in a myelinated axon
2) generation and propagation of an action potential in an unmyelinated axon
3) Functioning of a chemical synapse and description of axoaxonic synapses
4) Information processing in the cell body, IPSPs, EPSPs, summation etc.
Please make sure to include a detailed picture as well for two of the essays. If you decide to provide a detailed picture for all four the other two will be worth extra credit. Essay Nervous Systems Assignment BMS 270/271 Provide as much detail as possible as it is necessary and important. The essay topics are as follows:
1) generation and propagation of an action potential in a myelinated axon
2) generation and propagation of an action potential in an unmyelinated axon
3) Functioning of a chemical synapse and description of axoaxonic synapses
4) Information processing in the cell body, IPSPs, EPSPs, summation etc.
Please make sure to include a detailed picture as well for two of the essays. If you decide to provide a detailed picture for all four the other two will be worth extra credit. Provide as much detail as possible as it is necessary and important. The essay topics are as follows:
1) generation and propagation of an action potential in a myelinated axon
2) generation and propagation of an action potential in an unmyelinated axon
3) Functioning of a chemical synapse and description of axoaxonic synapses
4) Information processing in the cell body, IPSPs, EPSPs, summation etc.
Please make sure to include a detailed picture as well for two of the essays. If you decide to provide a detailed picture for all four the other two will be worth extra credit.
Explanation / Answer
1. GENERATION AND PROPAGATION OF ACTION POTENTIAL IN MYELINATED AXON :-
Vertebrates have evolved
an alternative strategy for increasing the speed of action potential conduction. Vertebrates axons larger than
about 1 micrometer are tightly wraped by many layers of glial cells,creating the second category,the myelinated
axon. Myelination occurs in a repeating pattern with long wrapped regions (internodes that are upto 1-2mm in
length) interrupted by a very short bare region (the nodes of Ranvier). myelin sheath is formed by special type
cells oligodendrocyetes & schwann cells. In myelinated axons, however the Na+ channels are concentated at
the node of Ranvier. The generation of an action potential at each node results in depolarization of several
adjacent nodes and subsequently generation of an action potential delay of only about 20 microsecond reffer
to as saltatory conduction.
Functionally, the myelin acts as an insulator by reducing the leak of electic current through the membrane in
the internodal regions. Which in turn reduces the capcitive current required to charged the internodal
membrane. consequently, current travels rapidly with little loss in the internodal regions to the node of Ranvier.
In myelinated axon current is boosted or regenerated by voltage-gated sodium channels concentrated at the
node . conduction velocity in myelinated axons is proportional to axon diameter greater than 11 micrometer .
The speed of conduction for smaller axons the propotionaliy factor is 4.5. In an average diameter of axon (20
micrometer) has electrochemical transmission with the speed of 120m/s.
2. GENERATION & PROPAGATION OF ACTION POTENTIAL IN UNMYELINATED AXON :-
In unmyelinated axons
the Na+ and K+ channels both taking part in action potential generation. Both ions are distributed along the axon
and the action potential propagates along the length of the axon through local depolarization of each neighboring
membrane causing that membrane to also generate an action potential.
The unmyelinated axon is often loosely surrounded by a glial cell or in some case such as parallel fibers in the
cerebellar molecular layer. The speed of conduction of an action potential in an unmyelinated axon is
proportional to the square root of the axon diameter. Also in unmyelinated axons the Na+ channels are far less in
number and are uniformly distributed , Hence the conduction is slower about 4 milliseconds.
Due to having larger diameter of axon invertebrates (Giant squid) propagates signals more fastly than
vertebrates .
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