why are nerve cells long and have branches ?

A nerve cell is

Unipolar nerve cells can be traced in

The nerve cells do not possess

The packing cells around nerve cells in brain are called

Nerve cells are found in

The human body contains a large number of cells A which are very long and branched, and look like electric wires. The longest branch of this cell is B whereas there are many small branches C. Any two A cells do not join to one another completely in the human body. There is a microscopic gap D between every pair of adjacent A cells through which electric impulse can pass by the release of a chemical substance. (a) What are cells A? (b) What is the name of (i) branch B, and (ii) branches C? (c) What is the microscopic gap D known as? (d) What is the function of cells like A in the human body? (e) The cells A are of three types. Name the three types.

Unipolar nerve cell means