Control and Co-ordination
Human Neural System
- It provides rapid coordination among the organs of the body.
- The coordination may be in the form of electric impulses, which is quick and short-lived.
- Neurons are structural and functional units of nervous system.
- Structure of neuron
- Cell body – Contains Nissl’s granules
- Dendrite – Conducts messages towards cell body
- Axon – Conducts messages away from cell body
- Neurons are of three types:
- Axons are of two types:
- Myelinated nerve fibre
- Fibre is coated with myelin sheath, which is impermeable to ions. Schwann cells enveloped the myelin sheath.
- The place where myelin sheath is not present on the myelinated nerve fibre is called node of Ranvier.
- Conduction of nerve impulse is from node to node in a jumping manner. Hence, the conduction is fast.
- Found in spinal and cranial nerves
- Non-myelinated nerve fibre
- Fibres are not coated by myelin sheath.
- Conduction of nerve impulse occurs along the whole length of nerve fibre. Hence, the conduction is slow.
- Found in autonomous and somatic neural systems
Parts of the nervous system
- Human nervous system divided into- central nervous system (CNS) and peripheral nervous system (PNS)
- CNS consists of the brain and spinal cord
- PNS consists of the nerves that connects the CNS to different parts of the body
- The Brain, spinal cord, and nerves are the important parts of the nervous system
- The brain is enclosed in a bony box called the cranium and spinal cord is protected by vertebral column.
- The brain and spinal cord are externally covered by protective covering called meninges.
- It is made up of three layers namely duramater (outer layer), arachnoid (middle layer), piamater …
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