Neuron

Neuron Anatomy & Physiology

1. NEURON Presented by- Shruti Richa Assistant Professor Central Institute of Pharmacy

2. A Neuron

3. ANATOMY Neurons are the basic unit of the nervous system. All cells of the nervous system are comprised of neurons. The nervous system helps us to sense and respond to our environment.  Neurons pass messages to each other using a special type of electrical signal. Some of these signals bring information to the brain from outside of the body, such as the things we can see, hear, and smell. Other signals are instructions for our organs, glands and muscles. So, the neurons (or nerve cells) are specialized cells that transmit and receive electrical signals in the body.

4. Neurons are composed of three main parts: dendrites, a cell body, and an axon. Neurons receive their signals from the neighbouring neurons through their dendrites. From there, the signal travels to the main cell body, known as the soma. Next, the signal leaves the soma and travels down the axon to the synapse. Dendrites Cell body (soma) Axon Synapse

5. Dendrites It means tree like or branches like. It receives the signals and forwards it to the cell body.

6. Cell body The cell body is called as perikaryon since its nucleus is always found at periphery. It has following components: Nucleus  - It contains genetic material (chromosomes) including information for cell development and synthesises proteins, necessary for cell maintenance and survival. It is covered by a membrane. Nucleolus  - It produces ribosomes necessary for translation of genetic information into proteins. Nissl Bodies  - It is the groups of ribosomes used for protein synthesis.

7. Endoplasmic reticulum (ER)  - The system of tubes for transport of materials within cytoplasm. It has ribosomes (rough ER) or no ribosomes (smooth ER). With ribosomes , the ER is important for protein synthesis. Golgi Apparatus  - The membrane-bound structure important in packaging proteins. Microfilaments/ Neurotubules  - The system to transport materials within a neuron and may be used for structural support as well. Mitochondria  - It produces energy to fuel cellular activities.

8. Axon Axons are the structure found on a single axis. It is cylindrical in shape. They are also called as nerve fibres. It varies in length (can be over 1 meter long). The longest axon is called the dorsal root ganglion (DRG), from the skin to the brain.  Most axons are covered by a white, waxy substance called myelin sheath. This coating insulates nerves and increases the speed at which impulses travel. Myelin is created by Schwann cells in the peripheral nervous system and oligodendrocytes in the CNS.

9. There are some structures related to axon: 1. Axon hillock: The cell body and axon where joins, they form a triangle like structure. It is called as axon hillock. 2. Axon collateral: When an axon joins with the axon of another axons, then this is called as axon collateral. 3. Initial segment: It is the point where axon gets started. 4. Trigger zone: The space between axon hillock and initial segment is termed as trigger zone. There are small gaps in the myelin coating, called nodes of Ranvier . The action potential jumps from gap to gap, allowing the signal to move much quicker.

10. HOW FASTLY THE MYLEIN SHEATH SENDS THE SIGNAL

11. physiology 1. Dendrites: It r eceive electrical impulses from neighboring neurons. 2. Soma: The cell body which contains most of the cell’s organelles. 3. Nucleus: It contains the cell’s DNA. 4. Axon: It transfers electrical impulse signals from the cell body to the synapse. 5. Myelin sheaths: It Cover the axon and work like insulation to help keep electrical signals inside the cell, which allows them to move more quickly. 6. Synapses: It Sends electrical impulses to neighboring neurons.

12. So, it is the complexity of neuronal networks that gives us our personalities and our consciousness. They are responsible for the most basic of actions, and the most intricate. From automatic reflex actions to deep thoughts.

13. References https://www.khanacademy.org/science/high-school-biology/hs-human-body-systems/hs-the-nervous-and-endocrine-systems/v/anatomy-of-a-neuron https://www.thoughtco.com/neurons-373486 https://askabiologist.asu.edu/sites/default/files/resources/coloring_pages/pdf/aab_neuron_anatomy_activity_0.pdf https://faculty.washington.edu/chudler/cells.html https://www.medicalnewstoday.com/articles/320289.php#carry_message

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