Nerve Impulse Transmission

If a mosquito / insect bites on our hand, how can we tell if we feel it? Or is it the feeling of being bitten or how do we get it? its Nerve Impulse Transmission.

There is a system in our whole body called the nervous system. For all the nerves we feel any touch, smell or pain.

The nervous system is an organ system that forms a complex and specialized network of cells called neurons, transmitting signals throughout the body and between different parts of the body and giving different sensations.

Neurons, glial cells, and axons, among the components of the nervous system, work together to send nerve signals throughout the body. There are two main parts of our body's nervous system-

• 1. The brain, spinal cord, and retina of the eye are the central nervous system (CNS). The brain is surrounded by the skull and the spinal cord is surrounded by the vertebrae of the spine.
• 2. Peripheral nervous system or PNS. PNS helps maintain body contact with the CNS.

Neurons: The structural and functional unit of the nervous system is called a neuron. The brain is made up of billions of neurons. The human brain alone has 1,000 billion nerve cells. And these are connected to each other, as well as hundreds of billions of nerves throughout the body. Its main functions are:

• 1. By taking information from different parts of the body through electric impulses and sending the information to the brain through other neurons, it generates reports accordingly.
• 2. It stores all the memories in the brain.
• 3. It regulates the functions of the various organs and systems of the body and coordinates them.
• 4. It adopts the plan and implements it.

Neurons can be divided into many ways, but they can be divided into 3 ways based on work:

• 1. Sensory neuron: He grabbed a very hot ball with his hand! Sensory neurons in the hand will send this information to your brain (CNS) that you are holding a very hot object in your hand! That is, the function of the sensory neuron is to carry the senses inside or outside the body to the brain (CNS).
• 2. Motor neuron: The brain will direct the various muscles of your hand through the motor neuron that the ball you are holding in your hand is very hot and the muscles of your hand will instruct you to release the ball. That is, the motor neuron provides the commands of the brain to various organs, muscles, glands.
• 3. Inter neurons: The 1,000 billion neurons in our brain connect to each other and help exchange information. Inter neurons live only in the brain.

The subject of our discussion is Nerve Impulse Transmission and exactly how the feelings / pains go to our brains! How does a pain killer work? How Anesthesia Works! For this we need to look at the structure of neurons

• 1. Cell body: It is the main part of the neuron and it has different shapes like round, oval, conical, pointed etc.
• 2. Axon: Axon is the name given to a very long and branchless fiber produced by the cell body. The ends of the axons split and form tiny branches. A neural joint is formed by synapse between the axons of the first and the dendrites of the next two neurons
• 3. Dendrite: The small fibrous branched part formed around the cell body is called dendrite. A neuron contains many dendrites. Dendrites are actually the part of the human body that receives information from different senses or from other neurons.

The greater the number of dendrites, the greater the ability of a neuron to receive information. The number of dendrites in a neuron can be up to 400,000!

That is, the axons of one neuron are connected to the dendrites of many other neurons, the axons of these neurons are connected to the dendrites of many other neurons, so many neurons are connected to each other to form a huge network throughout the body, and all are centered in the spinal cord of the spine. Through the brain. Then we see that one neuron forms a synapse with another neuron or is simply connected.

How do neurons carry feelings / impulse?

Impulse is the electrical charge that flows from one neuron to another through a sodium-potassium pump. But how?

Neurons have 10 times more Na + & Cl-ions outside the action than inside the plasma (inside) and 25 times more K + ions than outside the action (inside). The state maintains an electrical potential, called resting potential. In this condition the neurons remain inactive, meaning that no emotion flows. In this condition some K + ions can go out but the ions cannot come in, so there is a negative charge inside the neuron and a positive charge outside. The Na + / K + ion pump controls the movement of ions.

Then the total neuron has an extra positive (+) charge outside and a negative (-) charge inside. The internal negative charge is usually -70mv. This -70mV is the resting membrane potential i.e. in this condition the neuron does not exchange any impulse.

Since the neuron has a negative voltage (-70mV) inside and an extra positive sodium ion (Na +) outside, the positive sodium ion (Na +) will want to enter and neutralize the negative voltage! Similarly, the potassium inside the neuron will want to come out! But the sodium-potassium pump (regulates Na + and K +) doesn't let that happen!

If sodium ions enter, this pump emits Na + and similarly when K + goes out, it pulls in. And that's how -70mV puts this neuron. This is called polarized.

When we get an injury, this sodium-potassium pump shuts off! And sodium ions enter from the outside of the neuron and potassium ions from outside.

And as a result there will be a positive charge inside the neuron and a negative charge outside. There will be a positive charge inside the neuron (from -70 mV to + 30mV) and there will be a negative charge outside. This is called depolarized.

Thus the charge continues to move forward in the form of blocks, when it goes to the end of the action when this signal passes through another neuron.

When this action reaches the end of the potential neuron, the calcium channel there opens and the calcium ion (Ca2 +) enters the neuron. As a result, the membrane-bound neurotransmitters (NTs) come out and attach to the receptors in the next nucleus.

Now two things can happen:

• 1. If the injury / action potential is high, the ion will enter the next nucleus by opening the positive ion channel (Na + channe) as before and excite the neuron and move forward in the form of charge block towards the next neuron. This will make you feel pain in your head.
• 2. If the injury / Action potential is low then Na + channel will not open. When the chloride ion channel opens, the membrane becomes hyperpolarized and the signal no longer travels to the next neuron! That means we will not feel pain!

াহThen if we don't want to feel pain then our main job will be

• 1. Preventing sodium ions from entering neurons
• 2. Do not allow the calcium channel to open
• 3. Potassium and chloride ion channels open!

If we can control this sodium and calcium, we will not get pain anymore!

Anesthesia / Anesthesia medicine works but it mainly starts by stopping the guru of these 2 nuts of Nerve Impulse Transmission!

In short,

• 1. Normal state (outside Na + and inside K +, -70mV) ➤ Injury ➤ Na + / K + pump off ➤ Na + inside the neuron and K + goes out (voltage is from -70mV to + 30mV) Ca Ca2 + opens the channel at the end of the action and enters Ca2 +. Ca2 + and vesicles collide and the neurotransmitter is released.
• 2. The released neurotransmitters are connected to the receptor of the next neuron and enter the ➤ Na + neuron and flow the action potential to the next neuron as before.