Question

What are the characteristics of the resting potential that make its presence essential for neuronal conduction?

Answer 1

Human body has nerves that connect brain to the rest of the organs & muscles, for example If we want your hand to move, the brain sends signals through nerves to hand to move the muscles to contract. As nerves send lots of electrical impulses (called action potentials) to different muscles i allowing to move the hand with great precision.

Neurons are a special type of cell with the sole purpose of transferring information around the body. Neurons are similar to other cells in that they have a cell body with a nucleus and organelles.

Dendrites: receive signals from neighboring neurons.

Axon: transmit signals over a distance .

Axon terminal: transmit signals to other neuron dendrites or tissues .

Myelin sheath: speeds up signal transmission along the axon

Concentration gradients are behind the action potential work & potential gradient is the difference in the concentration of ions, between the neuron & outside the neuron. Therefore if there is ahigher concentration of positively charged ions outside the cells compared to the inside of the cells, there would be a large concentration gradients

Resting membrane potential :

As it is known that neurons have a negative concentration gradient ,& there are more positively charged ions outside ,than inside the cell. This regular phenomena of a negative concentration gradient is called resting membrane potential. During the resting membrane potential there are:

more sodium ions (Na +) outside than inside the neuron

more potassium ions (K+) inside than outside the neuron

The ions are flowing in & out of the neurons constantly & try to equalize their concentrations Thus the cells maintain a negative concentration gradient.

The neuron cell membrane is permeable to potassium ions, so potassium passes out of the neuron through the cell wall.

The neuron cell membrane is partially permeable to sodium ions, therefore sodium atoms slowly moves into the neuron through sodium channels.

The cells maintain a negative resting membrane potential, so it pumps back potassium into the cell & pumps sodium out of the cell

Working of potentials : Action potentials are the temporary shift in the neuron membrane , potential cause by ions suddenly to & fro out of the neuron. During the resting stage all the gates are closed The voltage gates of of sodium has two gates while potassium has one gate.

Three main events take place during an action potential 1) Depolarization2) Repolarization 3) Hyperpolarization.

Many exictatory graded potentials have to depolarize the cell body to trigger the action potential.

GRADED POTENTIAL ACTION POTENTIAL.

At the dendrites & cell body At the axons

Excitatory Always excitatory

Smaller in size Larger voltage difference

Triggered by inputs from out side Triggered by membrane depolarizatio

Many can happen at once only at one time

Can come in different sizes In same sizes.