Know your nervous system| Divisions of CNS|PNS|

                                            Nervous system

Keywords: Central nervous system| Peripheral nervous system| Somatic |autonomic |Parasympathetic |Sympathetic| white matter| gray matter |ganglion| nuclei| Bilaterians|

The nervous system is a highly complex system that carries information to and from various body parts to the brain and spinal cord.

Table of contents:

Sr.No	Contents
1.	Definition
2.	Central nervous system
3.	Peripheral nervous system
4.	Parasympathetic nervous system
5.	Sympathetic nervous system
6.	Somatic nervous system
7.	Autonomic nervous system
8.	Enteric nervous system

 

 This system coordinates sensory information and motor activities from inside and outside the body. The nervous system detects environmental changes in and around the body and acts accordingly.

 

                                          Divisions of the nervous system 

                                                    Division of the nervous system

In human beings  and other (vertebrates ), the nervous system  consists of two main divisions:

 1. Central nervous system (CNS), and

 2. Peripheral nervous system (PNS).

                                           The central nervous system

The central nervous system consists of the brain and spinal cord. The brain is present in the cranial cavity and the spinal cord in the spinal canal. The CNS is enclosed and protected by three meninges. The three layers  of meninges are from  outside to inside  

1. Dura mater,

2. Arachnoid mater, and

3. Pia mater.

In addition, the CNS is protected by the blood-brain barrier, which prevents many chemicals from entering the CNS. Therefore, the CNS is less susceptible to infections and chemical damage.

                                    The peripheral nervous system

 The nervous system structures outside the central nervous system are the peripheral nervous system. The peripheral nervous system consists mainly of long bundles of nerve fibers, usually present deep under the skin. However, they are exposed to physical damage.

 The sensory efferent nerves carry information from the body to the central nervous system. The motor or afferent nerves carry information from the central nervous system to the body.

                         Divisions of the peripheral nervous system

 The peripheral nervous system  is divided into three parts:

1. Somatic nerves work under voluntary control.

2. Autonomic nervous systems function involuntarily.

3. The enteric nervous system also functions involuntarily and controls the gastrointestinal system.

                          Divisions of the autonomic nervous system

 The autonomic nervous system is further subdivided into

1. Sympathetic, and

2. Parasympathetic nervous system

 The sympathetic nervous system becomes active in an emergency to mobilize energy, while the parasympathetic nerve becomes active in a relaxed condition to conserve energy.

The sympathetic nervous system is known as thoracolumbar outflow because sympathetic nerve fibers arise from all thoracic and lumbar 1^st,2^nd, and 3^rd spinal segments. It is responsible for the body's fight-or-flight response.

The parasympathetic nervous system is also known as craniosacral outflow because parasympathetic nerve fibers arise from some nuclei present in the brainstem and emerge through the 3^rd,7^th,9^th, and 10^th cranial nerves, and lumbar 2^nd, 3^rd, and 4^thsacral spinal segments. It is responsible for the rest and digestion response of the body.

The nervous system has particular neurons or nerve cells with unique structures that allow signals to pass rapidly and precisely to other structures.

What is gray matter?

 The gray matter is a collection of neurons. Its color is pink or light brown in living conditions.

 What is white matter?

The white matter is composed mainly of myelinated axons and takes its color from the myelin.

What is a ganglion?

The collection of neurons in the periphery is a ganglion, and the group of neurons in the brain and spinal cord is nuclei.

 Bilaterians –animals with left and right sides that are almost mirror images of each other.

Hashtags: Central nervous system# Peripheral nervous system# Somatic #autonomic #Parasympathetic #Sympathetic# white matter# gray matter #ganglion# nuclei# Bilaterians#

 

Internal link: 

https://blog.totalphysiology.com/2021/08/hypothalamus-html

https://blog.totalphysiology.com/2021/08/hypothalamus-connections-and-functions.html

https://blog.totalphysiology.com/2021/11/what-is-autonomic-nervous-system-what.html

External link: http://en.m.wikipedia.org/wiki