What is the role of the brain in reflex action?

The reflexes which involve only the spinal cord are called spinal reflexes. The spinal reflexes are produced in the spinal cord, but the message of reflex action taken also reaches the brain where the thinking process occurs. Some reflex arcs involve the brain, rather than the spinal cord only. They are called cerebral reflexes. Closing of eyes when exposed to flash of light and salivation at the sight of tempting food are the examples of cerebral reflexes.

What reflexes are shown by our eyes to the changes in light intensity?

As the person enters a dark room from a brightly lit one, the pupil dilates to allow more light to enter the eye. On the contrary, when the person is exposed to light on leaving a dark room, the pupil constricts and the eyelids close partially to allow less light to enter into the eye.

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Reflex Action

A reflex action is a quick involuntary action in response to an external or internal stimulus, generally without the involvement of the brain.

E.g. A tap on the knee results in a spontaneous withdrawal i.e. a knee-jerk. Similarly, when we touch a hot object, we spontaneously withdraw our hand.

Reflex action is of two types:

(1) Unconditioned reflex - Inborn and inherited. E.g. sneezing and coughing.

(2) Conditioned reflex - Learned reflexes. E.g. cycling and salivation on smelling one's favourite food.

1.0Significance of Reflex Action

Act as an alarm which indicates about some unnatural incidents that are going to happen.

Quick and sudden reflexes protect us from the dangers and injuries.

Reflex Arc: A reflex arc is the shortest route that can be taken by an impulse from receptor to an effector.

The basic components of reflex arc are a receptor, a sensory neuron, a centre, a motor neuron and an effector.

2.0Components of reflex arc are

(1) Receptor: The dendrite of sensory neuron receives stimulus and initiates a nerve impulse.

(2) Sensory neuron: The nerve impulse passes from the dendrites to the axon terminal branches of the sensory neuron in the spinal cord.

(3) Centre: It is the region in the spinal cord or brain where the incoming sensory impulse generates an outgoing motor impulse. Relay neurons are found in the brain and spinal cord and allow sensory and motor neurons to communicate.

(4) Motor neuron: It transmits the impulse generated by the sensory neuron in the centre to the effector organ of the body that will respond, such as a muscle or gland.

(5) Effector: It is the organ of the body that responds to motor nerve impulse.

	Reflex action		Walking
1.	Reflex action is the immediate and involuntary action.	1.	Walking is a voluntary action which is under our control.
2.	It is regulated by the spinal cord.	2.	It is controlled by brain.
3.	It occurs in a fraction of seconds.	3.	It takes longer time.

3.0Also Read

Excretion and Excretory Organs	Ecology	Aquatic Habitats
Excretory System in Human	Food Chain and Food Web	Movement of Animals
Vertebrate Nervous System	Adaptations and Their Habitats	Life Process

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Reflex Action

A reflex action is a quick involuntary action in response to an external or internal stimulus, generally without the involvement of the brain.

E.g. A tap on the knee results in a spontaneous withdrawal i.e. a knee-jerk. Similarly, when we touch a hot object, we spontaneously withdraw our hand.

Reflex action is of two types:

(1) Unconditioned reflex - Inborn and inherited. E.g. sneezing and coughing.

(2) Conditioned reflex - Learned reflexes. E.g. cycling and salivation on smelling one's favourite food.

1.0Significance of Reflex Action

Act as an alarm which indicates about some unnatural incidents that are going to happen.

Quick and sudden reflexes protect us from the dangers and injuries.

Reflex Arc: A reflex arc is the shortest route that can be taken by an impulse from receptor to an effector.

The basic components of reflex arc are a receptor, a sensory neuron, a centre, a motor neuron and an effector.

2.0Components of reflex arc are

(1) Receptor: The dendrite of sensory neuron receives stimulus and initiates a nerve impulse.

(2) Sensory neuron: The nerve impulse passes from the dendrites to the axon terminal branches of the sensory neuron in the spinal cord.

(3) Centre: It is the region in the spinal cord or brain where the incoming sensory impulse generates an outgoing motor impulse. Relay neurons are found in the brain and spinal cord and allow sensory and motor neurons to communicate.

(4) Motor neuron: It transmits the impulse generated by the sensory neuron in the centre to the effector organ of the body that will respond, such as a muscle or gland.

(5) Effector: It is the organ of the body that responds to motor nerve impulse.

	Reflex action		Walking
1.	Reflex action is the immediate and involuntary action.	1.	Walking is a voluntary action which is under our control.
2.	It is regulated by the spinal cord.	2.	It is controlled by brain.
3.	It occurs in a fraction of seconds.	3.	It takes longer time.

3.0Also Read

Excretion and Excretory Organs	Ecology	Aquatic Habitats
Excretory System in Human	Food Chain and Food Web	Movement of Animals
Vertebrate Nervous System	Adaptations and Their Habitats	Life Process

Frequently Asked Questions

What is the role of the brain in reflex action?

What reflexes are shown by our eyes to the changes in light intensity?

Frequently Asked Questions

What is the role of the brain in reflex action?

What reflexes are shown by our eyes to the changes in light intensity?

Join ALLEN!

Reflex Action

1.0Significance of Reflex Action

2.0Components of reflex arc are

3.0Also Read

Table of Contents

Join ALLEN!

Reflex Action

1.0Significance of Reflex Action

2.0Components of reflex arc are

3.0Also Read

Table of Contents