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प्रश्न
How do we detect the smell of an agarbatti (incense stick)?
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उत्तर
When the smell of the incense stick reaches our nose, then the factory receptors present in our nose detect it and send this information to the forebrain in the form of electrical signals. The brain interprets this information as the smell of incense sticks where it is already stored.
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संबंधित प्रश्न
Name the most important part of the human brain.
Fill in the following blank with suitable word :
A neuron which carries an impulse to the brain is called a ........... neuron.
Explain the difference between of the following pair of terms :
cerebrum and cerebellum
Which of the following are cerebral reflexes?
(i) a person pulls away his hand on touching a hot object
(ii) a person spits out immediately when a fly enters his mouth while talking
(iii) A person walking bare foot lifts his foot at once on stepping on to a nail
(iv) A person's pupil contracts at once in the presence of bright light
(a) (i) and (ii) (b) (ii) and (iii) (c) (iii) and (iv) (d) (ii) and (iv)
P is a cell (or group of cells) in the human body which is sensitive to a particular type of stimulus and conveys the messages to CNS through nerves Q. On the other hand, R is a part of the human body which can respond to a stimulus according to the instructions sent from the CNS through nerves S.
(a) What is P? Name five organs which contain cells (or group of cells) like P.
(b) Name the nerves Q.
(c) What is R? Give two examples of R.
(d) Name nerves S.
(e) How do messages travel through the nerves Q and S?
When we touch a hot plate unknowingly, then this heat is sensed by a receptor P present in our fingers. The receptor triggers and impulse in neuron Q which transmits the message to an organ R which is a part of the central nervous system. Here the impulse is passed on to a neuron S which in turn passes it to a yet another neuron T. The neuron T passes the impulse to a tissue U in our arm. The tissue U then contracts and pulls our hand away from the hot plate.
(a) What is the name of (i) receptor P (ii) neuron Q, and (iii) organ R?
(b) What is (i) neuron S, and (ii) neuron T?
(c) Name the tissue U.
(d) What name is given to the phenomenon in which hand is pulled away quickly from the hot plate?
(e) Name the effector in this whole process.
Note the relationship between the first two words and suggest the suitable word/words for the fourth place.
Receptor : Sensory nerve :: Motor nerve : ______.
State whether the following is simple reflex, conditioned reflex or neither of the two.
Contraction of eye pupil
State whether the following is simple reflex, conditioned reflex or neither of the two:
Lifting up a book: …………………..
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.
State whether the following is
Sneezing
State whether the following is
Playing on the Keyboard
What type of reflex is the following?
Sweating in summer
What type of reflex is the following?
Solving mathematical sums
Give Reason:
The hand automatically shows the direction to turn a cycle without thinking.
Complete the following sentence with appropriate Word
Which of the following is not a natural reflex action?
Which of the following is not involved in Knee-jerk reflex?
Why have reflex arcs evolved in animals?
Categorise the following under stimulus and response.
Pain in the eye if something falls into it.
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.
