Where is the highest concentration of voltage-gated sodium channels?

Where is the highest concentration of voltage-gated sodium channels?

dorsal root ganglion
SCN 9A which encodes the voltage-gated sodium channel 1.7 and is located on chromosome 2. It is highly concentrated in the dorsal root ganglion and sympathetic ganglion; it amplifies small depolarizations and acts on the threshold and modulation of excitability of the channel.

Which part of a neuron is a region with a high density of voltage-gated sodium channels at with action potentials initiated?

axon initial segment
The axon initial segment (AIS) is a specialized region in neurons where action potentials are initiated. It is commonly assumed that this process requires a high density of voltage-gated sodium (Na(+)) channels.

Which part of the neuron has a very high concentration of voltage-gated Na+ channels?

axon hillock
The axon hillock contains a very high concentration of voltage-gated Na+ channels that become activated once a critical membrane potential is reached, the threshold potential.

Where are Na+ voltage-gated channels located?

Voltage-gated sodium channels exist throughout the body in various cell types, while epithelial sodium channels are located primarily in the skin and kidney.

Where are voltage-gated sodium channels concentrated in myelinated axons?

In myelinated axons the voltage-regulated sodium channels are concentrated at the nodes of Ranvier.

Which part of a neuron has the highest concentration of Na+ channels per square micrometer of cell membrane?

In dorsal root ganglion cells, the cell body is thought to have approximately 1 voltage-gated sodium channel per square micrometre, while the axon hillock and initial segment of the axon have about ~100–200 voltage-gated sodium channels per square micrometre; in comparison, the nodes of Ranvier along the axon.

Which is the main receptive portion of the neuron?

dendrites
The dendrites make up the receptive portion of the neuron, and receive most synaptic afferent inputs from upstream neurons. Cell body. The cell body, also the soma, is the integrative portion of the neuron, where incoming signals from dendrites are summed together.

Which part of a neuron has the highest concentration of Na channels per square micrometer of cell membrane?

The correct answer is E. The nodes of Ranvier along the axon are regions between the myelin sheaths that include high concentrations of Na+ channels to enhance propagation of the action potential.

How many membrane spanning regions do voltage-gated Na+ channels have?

6 membrane spanning
Voltage-gated sodium channels and calcium channels are made up of a single polypeptide with four homologous domains. Each domain contains 6 membrane spanning alpha helices.

Where are Na+ channels located?

There are two major classes of sodium channels in mammals: The voltage-gated sodium channel (VGSC) family and the epithelial sodium channel (ESC). Voltage-gated sodium channels exist throughout the body in various cell types, while epithelial sodium channels are located primarily in the skin and kidney.

What is myelinated axon?

The myelinated axon can be likened to an electrical wire (the axon) with insulating material (myelin) around it. Myelin is formed in the central nervous system (CNS; brain, spinal cord and optic nerve) by glial cells called oligodendrocytes and in the peripheral nervous system (PNS) by glial cells called Schwann cells.

What portion of the peripheral nervous system communicates with effector organs?

The site of communication between two neurons or between a neuron and an effector cell is called a synapse. Bundle of axons located in the PNS is called a Nerve. Cranial nerves connect the brain to the periphery, whereas spinal nerves connect the spinal cord to the periphery.

Where is the action potential of an axon initiated?

The action potential is initiated at the beginning of the axon, at what is called the initial segment. There is a high density of voltage-gated Na + channels so that rapid depolarization can take place here.

Why are voltage gated Na + channels inactivated at the peak of depolarization?

As that depolarization spreads, new voltage-gated Na + channels open and more ions rush into the cell, spreading the depolarization a little farther. Because voltage-gated Na + channels are inactivated at the peak of the depolarization, they cannot be opened again for a brief time (absolute refractory period).

How does sodium affect the resting potential of the cell?

Because sodium is a positively charged ion, it will change the relative voltage immediately inside the cell relative to immediately outside. The resting potential is the state of the membrane at a voltage of -70 mV, so the sodium cation entering the cell will cause it to become less negative.

How does the membrane potential start an electrical signal?

To get an electrical signal started, the membrane potential has to become more positive. This starts with the opening of voltage-gated Na+ channels in the neuron membrane.