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प्रश्न
The diagram given below shows the internal structure of a spinal cord depicting a phenomenon. Study the diagram and answer the questions:
1) Name the phenomenon that is depicted in the diagram. Define the phenomenon.
2) Give the technical term for the point of contact between the two nerve cells.
3) Name the parts numbered 1, 2 and 3.
4) How does the arrangement of neurons in the spinal cord differ from that of the brain?
5) Mention two ways by which the spinal cord is protected in our body.
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उत्तर
1) Reflex action
Definition - A quick, automatic, involuntary and often unconscious action brought about when the
receptors are stimulated by external or internal stimuli.
2) Synaptic - Junction
3)
- 1 = Sensory neuron
- 2 = Motor neuron
- 3 = Grey matter with the central canal of the spinal cord
4) The grey matter is present in the cortex (outer side) consisting of cell bodies and white matter is present inside, which consists of myelinated axons in the brain.
In the spinal cord, the grey matter (cell bodies) are present inside, while white matter (Myelinated axon) is present outside.
5) The vertebral column, meninges and cerebrospinal fluid (CSF).
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संबंधित प्रश्न
Name two parts of the body which contain receptors of chemical stimuli.
Which part of the eye contains cells which are sensitive to light?
Fill in the following blanks with suitable words :
Our.............system allows us to react to our surroundings. Information from receptors passes along...........neurons to our brain. Our brain sends impulses along..........neurons to our muscles.
When you smell a favourite food your mouth begins to water (that is, you secrete saliva). Write down what is the example of the gland which is stimulated to secrete saliva.
The contraction of pupil of the eye in the presence of bright light is an example of :
(a) Voluntary reflex
(b) Spinal reflex
(c) Cerebral reflex
(d) Adrenal reflex
A cylindrical structure P in our body begins in continuation with medulla and extends downwards. It is enclosed in a bony cage Q and surrounded by membranes R. As many as x pairs of nerves arise from the structure P. The structure P is involved in the reflex actions of our body and conduction of nerve impulses to and from another organ S of our body with which it forms CNS.
(a) Name the structure P.
(b) Name (i) bony cage Q, and (ii) membranes R.
(c) How much is x?
(d) Name the organs S.
(e) What are the reflexes involving structure P only known as?
Differentiate between natural reflex and conditioned reflex. Give examples to illustrate your answer.
State whether the following is simple reflex, conditioned reflex or neither of the two:
Blushing: ……………….
Explain the following term :
Conditioned reflex
State whether the following is simple reflex, conditioned reflex or neither of the two.
Sneezing
