explain human nervous system
Answers
The nervous system in animals consists of spinal cord, brain and nerves.
The other subcomponents which help in our system are -
- Receptors
- Effectors
- Sensory Neurons
- Motor Neurons
Receptors our sense organs which receive the stimuli and pastor messages to the brain and the spinal cord. The various types of receptors are photo receptors, phono receptors, olfactory receptors, gustatory receptors and tango receptors.
Effectors are the muscles and glands which respond to the information received by spinal cord and brain through motor neurones.
The sensory nerves are the nerves which carry information from the receptors to the Brain or the spinal cord.
The motor nerves are the nerves which carry information from the brain and spinal cord to the effectors.
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The human nervous system can be classified into three types :-
- The central nervous system which include the brain and the spinal cord.
- The peripheral nervous system which include the spinal nerves emerging from the spinal cord and the cranial nerves emerging from the cranium.
- The autonomous nervous system which helps in controlling the autonomous body organs. It includes sympathetic and parasympathetic nerves. Both of them have opposite action to each other.
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The nerves are basically of four types :-
- The cranial nerves go from your brain to your eyes, mouth, ears and other parts of your head.
- The autonomic nerves are nerves that go from your spinal cord to lungs, heart, stomach, bladdersn intestines and sex organs also called as autonomous body organs.
- The Central nerves are found in your brain and spinal cord.
- The peripheral nerves are the nerves which go from the spinal cord to our arms, hands, legs and feet.
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The Nerves :-
A nerve cell is the structural and functional unit of nervous system.
It consists of a cell body known as cyton containing A nucleus and cytoplasm.
It has several branched structure call dendrites and has a long nerve fibre called axon which is covered by a protective covering known as myelin sheath.
The junction between two neurones is called synapse.
The message passed through the nerve cell in the form of chemical and electrical signals are called nerve impulses.
The dendrites receive the information and starts a chemical reaction which produces electrical impulses which passes through the axon.
Neurotransmitters are the biochemical substances which are found at the synaptic junctions and helps in translating nerve impulses to the dendrites of one nerve cell to the other.
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The Brain :-
The brain is the main coordinating centre of the human body protected by the cranium and covered by 3 membranes called managers filled with fluid called cerebrospinal fluid which protects the brain from shock.
It has three main parts :-
- The Fore brain which consists of cerebrum and olfactory lobes. It is also called as thinking part of the brain and controls voluntary actions.
- The Mid Brain which controls involuntary actions and reflex movement.
- The Hind brain which basically has three parts namely cerebellum, pons and medulla. The cerebellum controls body movements, posture and balance ; pons control the respiration and the medulla controls the actions like coughing, vomiting, sneezing, Heartbeat, BP, etc.
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The Spinal Cord :-
The spinal cord starts from the brain and extends to the vertebral column.
It has 31 pairs of spinal nerves and receives message to and from the brain.
It also controls the reflex actions.
It has 8 pairs of cervical nerves, 12 pairs of thoracic nerves, 5 pairs of lambar nerves, 5 pairs of sacral nerves and pair of coccygeal nerve.
Medulla obolongate is the upper part of the spinal cord.
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