Question

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 impulses 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.

Answer 1

1. A represents neurons. Neurons are the largest cells in the human body, which look like electric wires.
2. (i) B represents the axon.

(ii) C represents the dendrites.

3. The microscopic gap D is known as a synapse. A synapse is a functional junction between a pair of adjacent neurons over which nerve impulses can pass.
4. A neuron transmits messages to and from the central nervous system. It is the structural and functional unit of the nervous system.
5. The three types of neurons are sensory neurons, motor neurons and relay neurons.