Nervous system

Nervous coordination

Due to an electro chemical change in the nerves, impulses are transmitted through nerves. A proper coordination is maintained between the receptor and the effector. The nervous coordination takes place with the involvement of the nervous system.

The structural unit of the nervous system is the neuron. There are three types of neurons in the nervous system.

• Sensory neuron
• Motor neuron
• Inter neuron

The nervous system is mainly composed of two components. They are the central nervous system and peripheral nervous system. The structure of it can be shown by the following simplified diagram.

Central nervous system

Central nervous system is very important in controlling of activities and coordination. Brain and spinal cord belong to central nervous system. Skull provides protection to the brain. Vertebral column provides protection to the spinal cord. Brain and spinal cord are covered by meninges. There is a special fluid found within the cavities of brain and between meninges. It is known as cerebro spinal fluid. The functions of cerebro spinal fluid are given below

• Support bouncy to brain and spinal cord
• Absorption of shocks and jerks
• Protection against microbial infections and desiccation
• Protect from temperature fluctuations.

 Brain

Brain is protected by the cranium and surrounded by three linings called meninges. The brain is about 1/50 of the body weight. There are about hundred billion of neurons. Other than neurons another accessory cells called neuroglia are present in brain. The brain is composed of three main parts, as Cerebrum, Cerebellum and Medulla oblongata.

The peripheral region of the brain is composed of grey matter made up of cell bodies and the interior with white matter due to myelin sheath made up of nerve fibres.

Cerebrum

 

Cerebrum is the largest and most highly developed part of the brain. It is divided into left and right hemispheres. The cortex of the cerebrum is highly convoluted to increase the surface area. The left cerebral hemisphere controls the right half of the body and the right cerebral hemisphere controls the left part of the body.

Functions of cerebrum

• Perception of impulses from receptors, identification of received sensory information and storage of those information.
• Perception of senses about vision, taste, smell, hearing, pain and temperature
• Perform high mental activities such as learning, intelligence and thinking.
• Controlling of voluntary muscle contraction.

Cerebellum

This is located just below the latter part of the cerebrum. It consists of two hemispheres. It is of grey matter in the outer layer and white matter in the interior layer

Functions of cerebellum

• Maintenance of body balance
• Control of voluntary muscle activity
• Involve in maintenance of body movement 

Medulla oblongata

It is located anteriorly interior to cerebellum. It is an important centre in controlling many life processes.

Functions of medulla oblongata

• Control involuntary actions such as rate of heart beat and rate of respiration
• Control reflex actions such as vomiting, coughing and swallowing.

 Spinal cord

It is a tubular structure starting from medulla oblongata inferiorly and runs through vertebral column. Peripherally white matter and interiorly grey matter is present in the spinal cord. The spinal nerves start symmetrically at either side of the spinal cord.