Advertisements
Advertisements
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.
Advertisements
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).
APPEARS IN
संबंधित प्रश्न
Fill in the following blank with suitable word :
A neuron which carries an impulse to the brain is called a ........... neuron.
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 cannot be considered a receptor?
(a) ear
(b) nose
(c) muscle
(d) eye
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?
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:
Lifting up a book: …………………..
What type of reflex is the following?
Solving mathematical sums
In reflex action, the reflex arc is formed by ______
