Q.2 Name the types of coordination. Explain the components of a coordinated action in detail.
Answer:
TYPES OF COORDINATION:
There are two types of coordination in organisms:
(i) Nervous coordination
It is brought about by nervous system.
(ii) Chemical coordination
It is brought about by endocrine system. Animals have both the nervous and chemical coordination systems in their bodies while plants and other organisms have only chemical coordination.”
Components of coordinated action
A coordinated action has five components.
i. Stimuli
Definition
A stimulus is defined as any change in environment (external and internal), which can provoke a response in organism.
Examples
Examples of stimuli are heat, cold, pressure, sound waves, presence of chemicals, microbial infections etc.
ii. Receptors
Definition
HE Iเฎฐเฏ The organs, tissues or cells which are specifically built to detect particular type of stimuli are called receptors.
Examples
Sound waves are detected by ears, light is detected by eyes, chemicals in air are detected by nose.
iii. Coordinators
Definition
These are the organs that receive information from receptors and send messages to particular organs for proper action.
Examples
(i) In nervous coordination, brain and spinal cord are coordinators. They receive information and send messages through neurons in the form of nerve impulses.
(ii) On the other hand, in chemical coordination, various endocrine glands play the role of coordinators. They receive information in the form of various chemicals and send messages by secreting particular hormones in blood.
iv. Effectors
Definition
These are the parts of body which receive messages from coordinators and produce particular responses.
Examples
(i) In nervous coordination, neurons carry messages from coordinators (brain and spinal cord) to muscles and glands, which act as effectors.
(ii) In chemical coordination, particular hormones carry messages from coordinators, (endocrine glands) to particular target tissues, which act as effectors. For some hormones, nephrons act as effectors. Similarly, bones and liver act as effectors for many hormones.
v. Response.
Definition
On receiving the message from coordinators, the effectors perform action. This action is called response. Usually, nervous coordination produces immediate but short living responses while chemical coordination produces slow but long living responses. Example- Pulling our hand away from something very hot. The movement of the flower of sunflower towards light are the examples of responses.
