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प्रश्न
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?
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उत्तर
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- The structure P is the spinal cord. It is a cylindrical structure that begins in continuation with the medulla and extends downwards.
- (i) The bony cage Q is the vertebral column. The spinal cord is enclosed by the vertebral column.
- x represent the number of pairs of spinal nerves. They are 31 in number.
- S is the brain. The central nervous system consists of the brain and the spinal cord.
- The reflex actions involving the spinal cord (P) are known as spinal reflexes.
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संबंधित प्रश्न
Name one gustatory receptor and one olfactory receptor present in human beings.
Explain the difference between of the following pair of terms :
cerebrum and cerebellum
What is the difference between a voluntary and an involuntary action? Which kind of action is digestion? Explain your choice.
What is a reflex action? Explain with the help of an example.
Give the various functions of brain.
Which of the following cannot be considered a receptor?
(a) ear
(b) nose
(c) muscle
(d) eye
One of the following controls the peristaltic movements of alimentary canal. This one is :
(a) cerebrum
(b) cerebellum
(c) pons
(d) medulla
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
Complete the following statement by choosing the correct alternative from the choice given in bracker:
Reflex action is controlled by
(i) brain (ii) spinal cord
(iii) autonomic (iii) peripheral nervous system
State whether the following is simple reflex, conditioned reflex or neither of the two:
Sneezing: …………….
Explain the mechanism of reflex action with the help of a suitable diagram.
Define the following:
Reflex action
State whether the following is
Constriction of pupil
State whether the following is simple reflex, conditioned reflex or neither of the two.
Lifting up a book
Give Reason:
The hand automatically shows the direction to turn a cycle without thinking.
Mention, if the following statement is True or False
A reflex action is a spontaneous response to a stimulus.
Mention, if the following statement is True or False
Reflex action is a unit of nervous action
A change in the environment that causes an animal to react is called ______.
Categorise the following under stimulus and response.
Seeing a green light turning into red at a road crossing before applying the brakes.
The diagram given below shows the internal structure of a spinal cord depicting a phenomenon. Study the diagram and answer the following questions.
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- Name the phenomenon shown in the figure and define the same.
- Identify the parts labelled as 1 and 2. Write one functional difference between these two.
- Name the bony protective covering and the membranous protective covering of the spinal cord.
- Label the guidelines 3 and 4.
- How is the labelled part 3 different from part 4 with respect to its composition (part of neuron)?
- Give the technical term for the point of contact between the two nerve cells.
- Name the fluid filled inside the central canal of spinal cord.
- Name the term used for a small gap between two neurons.
- Give one example of a neurotransmitter.
- Draw a neat diagram of a nerve cell and label the parts: Perikaryon, Node of Ranvier, Myelin sheath and Axon terminals.
