Question 4-WRITE IN DETAIL-
1. How do messages reach the brain?
2. Define stimulus and response.
3. Write difference between brain and spinal cord.
4. Describe the human central nervous system along with its parts and functions.
5. Write pathway of reflex arc.
Answers
Answer:
1 . the peripheral nervous system transmits messages to and from the sense organs and is responsible for voluntary actions such as cycling swimming and so on.incoming messages enter the spinal cord from all parts of the body and reach the brain which sends back the messages to various body parts through the spinal cord.
2. stimulus: any condition in an environment which causes a reaction in an organism is known as a stimulus.
response: the reaction of an organism to a stimulus is called a response.
3. brain: the brain is the main control centre of the nervous system. the human brain is highly developed organ and is situated in the cranium of the skull. it controls your thinking feelings movement and senses. the brain is enveloped by three membrane is called meninges. the membranes have a fluid called cerebrospinal fluid between them. the cerebrospinal fluid nourishes the brain and protects it from shocks by absorbing them. the brain is divided into three regions cerebrum cerebellum and medulla oblongata.
spinal cord: the spinal cord is the continuation of the medula oblongata of the brain.it is like a cord that emerges from a hole at the base of the skull and runs through the vertebral column. the spinal cord is also protected by the meninges with cerebrospinal fluid within it.a cross-section of the spinal cord shows two similar half fused together to form a small canal in the centre called Central canal. the central canal is surrounded by an h shaped area called grey matter. it consists of cell bodies of neurones.the outer portion is the white matter which consists of nerve fibres. the spinal cord conducts reflex is below the neck. it conducts sensory impulses from the skin and muscles to the brain. it conducts motor responses from the brain to the muscles of the trunk and limbs.
4. the central nervous system consists of the brain and the spinal cord. it is a sight for all information processing in the body. it is responsible for processing every sensation and thought a human being experiences.
5. an automatic spontaneous and mechanical response to a stimulus controlled by the spinal cord without the involvement of the brain is called reflex action. the nerve pathway of a reflex action is called a reflex arc. the reflex arc involves three neurones sensory neurones association neurones and motor neurones.
Explanation:
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