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प्रश्न
What is meant by receptors and effectors? Give two examples of each.
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उत्तर
A receptor is a cell present in the sense organs that is sensitive to specific stimuli. Example: The eyes have light receptors which can detect light and the ears have sound receptors which can detect sound.
An effector is a part of body which can respond to a stimulus according to the instructions given from the nervous system.
Example: Muscles and glands of the human body.
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संबंधित प्रश्न
Which part of the eye contains cells which are sensitive to light?
What are the various sense organs in our body?
Give the functions of medulla.
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.
Which of the following statements are true?
(i) sudden action in response to something in the environment is called reflex action
(ii) sensory neurons carry electrical signals from spinal cord to muscles in a reflex action
(iii) motor neurons carry signals from receptors to spinal cord in a reflex action
(iv) the pathway of transmitting signals from a receptor to a muscle is a reflex action
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?
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.
Sudden application of brakes of the cycle on sighting an obstacle in front
Two hungry boys (A and B) enter a restaurant and find a table decorated as follows:
Boy B starts salivating but not A. Explain the reason for this difference.
List in tabular form two differences between reflex action and walking.
List in tabular form three distinguishing features between cerebrum and cerebellum.
State whether the following is
Constriction of pupil
What type of reflex is the following?
Knitting and swimming
Give Reason:
The hand automatically shows the direction to turn a cycle without thinking.
Give an example for conditioned reflexes.
The reflex arc which is made up of one sensory and one motor neuron is ______
Which one of the following is not a simple reflex?
Which of the following is not involved in Knee-jerk reflex?
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.
