Question

What is the role of brain in reflex action? What are the different types of reflexes?

Answer 1

The role of the brain in a reflex action is -

1. Reflex actions are sudden responses. It is an involuntary action that does not involve thinking. For example, when we touch a hot object, we withdraw our hands immediately without thinking.
2. The sensory nerves that detect heat are connected to the nerves that move the muscles of the hand.
3. Such a connection of detecting the signal from the nerves (input) and responding to it quickly (output) is known as a reflex arc.
4. Reflex arcs are formed in the spinal cord but the information is still sent to the brain.
5. The brain doesn’t have a significant response to it.

Different types Of Reflex Actions are -

1. Accommodation reflex: The most common reflex of eyes, that helps the pupils, lens, and vergence change their shape to accommodate sight when we look at distance objects and near objects. The change in shape is made by the ciliary muscles of the eyes.
2. Pupillary light reflex: If the light is flashed near one eye, the pupils of both eyes contract. Light is the stimulus, impulses reach the brain via the optic nerve, and the response is conveyed to the pupillary musculature by autonomic nerves that supply the eye. Reflexes are there to protect your body parts.
3. Acoustic Reflex: The word acoustic might ring a bell in your ears. Well yes, it is related to the contraction of the stapedius and tensor tympani muscles in the middle ear that respond to high decibel sounds.
4. Ankle jerk reflex: The jerking of the ankle is the common reflex action that is tested by doctors to check the reflex. This reflex helps maintain the balance and posture of a person, which allows maintaining the balance with little effort and conscious thought. The doctors test the knee jerk reflex by hitting the hammer on the knee. The absence of reflex may indicate receptor damage or peripheral nerve disease.
5. Biceps reflex: The jerking of the forearm when the biceps brachii tendon is struck with a tendon hammer leads to the biceps reflex. Biceps reflexes are also used to detect reduced reflexes. Absent reflexes are used as clues to locate neurological disease.
6. Blushing: This perhaps doesn’t need any introduction. Blushing refers to the reddening of the face caused by embarrassment, shame, or modesty. This is faced by a person because of psychological reasons.
7. Corneal reflex — Refers to the blinking of both eyes when the cornea of either eye is touched. This reflex is responsible to act when dust or foreign particles accidentally enter our eyes. The use of contact lenses may diminish or abolish the testing of this reflex.
8. Cough reflex — When dust enters our trachea or respiratory tract, the cough receptors produce a cough which in turn removes the foreign material from the tract before it reaches the lungs.
9. Sneeze: Irritation of nasal mucosa in the nose create a sneeze that helps get rid of the foreign particle in the nostrils.