The diagram alongside shows a section of the human brain and its associated parts. Answer the questions that follow:

(a) Name the parts labelled 1, 2, 3 and 4.

(b) Name the protective membranous covering of the brain. Also mention its three layers.

(c) Name the basic unit of the brain.

(d) Write the important role of the part mentioned as 2.

Two hungry boys (A and B) enter a restaurant and see the menu. Boy B starts salivating but not A. Explain the reason for this difference.

The diagram given below shows the internal structure of spinal cord depicting a phenomenon. Study the diagram and answer the following questions.

(a) Name the phenomenon shown in the figure and define the same.

(b) Identify the parts labelled as 1 and 2. Write one functional difference between these two.

(c) Name the bony protective covering and the membranous protective covering of the spinal cord.

(d) Label the guidelines 3 and 4.

(e) How is the labelled part 3 different from part 4 with respect to its composition (part of neuron)?

(f) Give the technical term for the point of contact between the two nerve cells.

(g) Name the fluid filled inside the central canal of spinal cord.

(h) Name the term used for a small gap between two neurons.

(i) Give one example of a neurotransmitter.

(j) Draw a neat diagram of a nerve cell and label the parts : Perikaryon, Node of Ranvier, Myelin sheath and Axon terminals.

The figure given below is the basic structural and functional unit of the human nervous system. Study the diagram and answer the following questions:

(a) Write the technical term for the diagram.

(b) Name two organs of our nervous system where these cells are richly found.

(c) How are these cells significant for us ?

(d) Name the cell organelle that is absent in these cells and how does it affect our body metabolism ?

(e) Redraw the same figure and label the following — Perikaryon, Axon, Dendrites, Myelin sheath and Node of Ranvier.