Nervous system

Hormonal system

1.

The nervous system controls the various functions by the units called neurons.

1.

Hormones are chemical messangers secreted by endocrine (ductless) glands.

2.

Neurons form two types of nerves (a) sensory nerves which receive the information to convey to brain or spinal cord.

2.

Hormones are directly poured into blood. Later on they diffuse to body cells, and also cell to cell.

(b) Motor nerves which carry the response message to muscles or glands.

They are synthesised at a places away from where they act and simple diffuse to the area of action.

3.

Nervous system has a network of nerves spread through out the body.

3.

Hormonal system does not has such a network.

4.

(a)    Dendrites of a neuron acquire information.

4.

Cells have special molecules on their surface to recognise information carried by hormones to act up accordingly.

(b)    Information travels as an electric impulse through cell body and axon.

Hormones are not conducted through electrical impulses.

(c) The impulse is converted into a chemical signals for onward transmission.

5.

Nervous system does not use feedback mechanism in generating electrical impulse or producing neurochemical transmitter (especially at synapsis).

5.

The timing and amount of hormone released are regulated by feedback mechanisms.

6.

In nervous system, electrical impulses are generated for quick transmission of information. But there are limitation— (i) impulses will reach only those cells that connect by nervous tissue.

6.

Hormones are chemical messenger that diffuse to a cells of the body. The body cells, using special molecules on their surfaces, recognise information and even transmit it. Hormones are synthesised at places away from where they act.

(ii) Once an electrical impulse is generated in a cell and transmitted, the cell takes some time to generate another impulse. That is cells cannot continuously create and transmit electrical impulses.

Hormones can reach all cells of the body (through blood in animals), regardless of nervous connections and it can be done steadily and persistently.