Question

Then on neuron one show me what the neuron is like at resting state, please include:

a. sodium potassium pump The sodium-potassium pump (PDB entries 2zxe and 3b8e ) is found in our cellular membranes, where it is in charge of generating a gradient of ions. It continuallypumps sodium ions out of the cell and potassium ions into the cell, powered by ATP.

b. sodium Na+ It's also called a serum sodium test. Sodium is an essential mineral to your body. It's also referred to as Na+. Sodium is particularly important for nerve and muscle function.

c. potassium K+ The chemical notation for potassium is K⁺. The proper level of potassium is essential for normal cell function.

On neuron two show (via a drawing) me what happens during an action potential (depolarization), describe what happens to the voltage within and without the neuron. Include the movements of the Na+ and K+ ions.

On Neuron three show me via your drawing how a neuron goes back to resting state. Describe the movement of Ions across the neurons membrane and show me where all this takes place on the neuron. Please include hyperpolarization.

Similarly to assignment one, I want you to draw me a close up picture of a synapse (what happens between the Axon terminals of the presynaptic neuron and the dendrites of a post synaptic neuron communicate). Please take a picture of your drawing and attach it to the assignment, in lieu of this write up a document that parallels this assignment as close as possible and attach that to the assignment instead.  Include the following elements and describe briefly what they are doing to produce a synaptic event.

a. vesicles

b. neurotransmitter - explain where it is and what it does

c. synaptic gap

d. reuptake mechanism - describe its function and how it works.

e. receptors

f. extra credit calcium and its channel

Answer 1

Ion concentration gradient and selective movement of ions create a difference in electric potential or voltage across the plasma membrane. This is called membrane potential. In nerve cell, membrane potential is in resting state called resting potential, -60mV.

Neurons are specialized cells that have ability to respond to a stimulus and convert it into an action potential. A nerve impulse is an electric signal produce by flow of ion across the plasma membrane of neuron. Propogation of nerve impulse change the permeability of membrane. The change in permeability cause the change in potential across the axon membrane. When an action potential happen, Na+ channel open on the axon , Na+ rushes in , since Na+ is a positively charge , makes inside of axon more positive. Na+ rushing in untill inside of membrane more positive than outside, become + 30mV . This is called depolarization.

As the action potential spread, membrane potential repolarizes due to K+ channel opening and Na+ channel inactivation. Due to opening of K+ channel , K+ flow outward and so the membrane potential returns to a negative value. The resting level of -60mV is restored in few millisecond. The outflow of K+ make inside more negative that it overahoot resting potential and this overshoot is called hyperpolarization.

The space between pre and postsynaptic neuron is called synaptic cleft. Small gap separating the neuron called synapses, a point where neuron communicate with each other. The presence of small, membrane bound organelle in presynaptic terminal called synaptic vesicle . It is filled with neurotransmitter, a chemical signal secreted from a presynaptic neuron. Neurotransmitter is a chemical agent act as massangers between the communicating neuron. For example acetylcholine. This neurotransmitter bind to receptor present on post synaptic terminal . There are two type of receptor excitatory and inhibitory. Excitatory receptor open channel that admit Na+ ion or both Na+ , K+ ions. Cause depolarization of post synaptic neuron , promoting generation of action potential. Inhibitory receptor open K+ or Cl- channel and cause hyperpolarization , inhibition of generation of action potential in post synaptic cell.

Transmission at chemical synapses occur when an action potential invades the terminal of the presynaptic neuron. The change in membrane potential caused by arrival of the action potential lead to the opening of voltage gated Ca+2 channels in the presynaptic membrane. Opening of this channel cause rapid influx of Ca+2 into presynaptic terminal, with the result that Ca+2 concentration of cytoplasm in terminal transiently rises to much higher value. This allow fusion of synaptic vesicle with the plasmamembrane of presynaptic neuron.