Fill in the following blank with suitable word :
A neuron which carries an impulse to the brain is called a ........... neuron.
When you smell a favourite food your mouth begins to water (that is, you secrete saliva). Write down what is the example of the smell of the food?
Which of the following statements is correct about receptors?
(a) gustatory receptors detect taste while olfactory receptors detect smell
(b) both gustatory and olfactory receptors detect smell
(c) auditory receptors detect smell and olfactory receptors detect taste
(d) olfactory receptors detect taste and gustatory receptors detect smell
One of the following gives the correct sequence of the components in a reflex arc. This is :
(a) Receptors → Muscle → Sensory neuron → Motor neuron → Spinal cord
(b) Receptors → Motor neuron → Spinal cord → Sensory neuron → Muscle
(c) Receptors → Spinal cord → Sensory neuron → Motor neuron → Muscle
(d) Receptors → Sensory neuron → Spinal cord → Motor neuron → Muscle
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) (i) and (ii)
(b) (i) and (iii)
(c) (i) and (iv)
(d) (i), (ii) and (iii)
A person walks across a room in barefeet and puts his foot on a drawing pin lying on the floor. He lets out a cry. Explain what happens in his nervous system in bringing about this response.
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.
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)
When you smell a favourite food your mouth begins to water (that is, you secrete saliva). Write down what is the example of the cells in your nasal passages which perceive the smell?
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.
A cell (or group of cells) in a sense organ which is sensitive to a particular type of stimulus is called :
If we happen to touch a hot object unknowingly, we immediately pull back our hand. What is this type of action known as?
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?
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?
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.
Write down the following activities in the correct order for a simple reflex arc:
(a) impulse travels in the motor fibre
(b) impulse travels in the sensory fibre
(c) effector organ stimulated
(d) impulse crosses the synapse
The gustatory receptors of our body are in one of the following organs. This organ is :
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