Reflex Actions and Reflex Arc
Any sudden, immediate, involuntary, and mechanical response to a stimulus that is done without the will of the body is called reflex action. Mostly these reactions are controlled by the spinal cord and thus called spinal reflex action; however, some reflex actions are also controlled by the brain and are called cerebral reflex action.
Examples of Reflex Action
- Our pupil contract when bright light falls on them.
- We tend to close our eyes when something is about to come in contact with it.
- We start to sneeze and cough when something enters our nose or throat.
- We tend to withdraw our hand or leg when suddenly anything hot/cold or sharp/pointy objects come in contact.
- Our mouth starts watering when we see something tasty.
Advantages of Reflex Action
- This process helps to protect our body in response to any harmful stimuli without wasting time in thought processing.
- Saves our brains from overloading.
- Helps in the survival of those animals which lack an efficient thought process.
Reflex Arc
The pathway that is taken by a nerve impulse and its response in a reflex action is called the reflex arc. The process involves the following steps;
Stimulus ⇢ Receptor organ ⇢ Sensory neurons ⇢ CNS (mostly spinal cord) ⇢ Motor neuron ⇢ Effector organ ⇢ Response
Components of a reflex arc are:
- Receptor: It is present in the sense organs of the body (like skin, eye, nose, etc.) that receive the stimulus.
- Sensory (afferent) neurons: The nerve fibers that are responsible for the transmission of the stimulus to the spinal cord (CNS).
- Integration center/ modulator: The spinal cord (CNS) acts as the immediate processor of the information and transmits the response to the motor neuron with the help of relay neurons.
- Motor (efferent) neurons: It transmits the response from the spinal cord to the effector organ of the body which will act on it.
- Effector: The organ that executes the response sent by the spinal cord.
Example: In the diagram above the hand came in contact with a hot pan. The receptors present in the skin receive the stimulus i.e. heat. The sensory neuron carries the information of the stimulus to the spinal cord where it is immediately processed and a response is transmitted by the relay neurons to the motor neurons. The motor neuron carries the response to the effector muscle that will remove the hand immediately from the hot pan. This whole process takes just a fraction of a second to take place.
NCERT Notes Class 10 Control and Coordination
NCERT Class 10 Science Notes Chapter 6: Control and Coordination in the living organism mean the ability to control and coordinate different body functions to complement each other. Separately control means the ability of our body to have power of regulation over any mechanism whereas coordination means the process by which all the different parts of the body work together to produce the desired outcome. You will find the NCERT Control and Coordination Notes for Chapter 6 Class 10 Notes here.
Table of Content
- Control and Coordination in Animals
- Nervous System
- Human Nervous System
- The Central Nervous System
- Reflex Actions and Reflex Arc
- Endocrine Gland
- Control and Coordination in Plants
- Plant Hormones
- FAQs on Control and Coordination