Question

Respiration is controlled by
A. Medulla oblongata
B. Cerebellum
C. Hypothalamus
D. Cerebrum

Answer 1

Hint: It is the terminal part of the brain stem located between the pons and the spinal cord. It is a part of the central nervous system and forms in fetal development from the myelencephalon. The final differentiation is seen at week 20th gestation.

Complete answer: Medulla oblongata, also called the medulla, is a long stem-like structure present at the lowest part of the brainstem. It plays an important role in transmitting signals to and fro the spinal cord and the higher parts of the brain. It is responsible for performing involuntary bodily functions such as breathing, heart rate and blood pressure. Medulla oblongata controls the cardiac, respiratory, vomiting and vasomotor centres. It is categorised into two main parts, namely, the ventral medulla and the dorsal medulla. The medulla is composed of myelinated and unmyelinated nerve fibres, out of which the myelinated nerve fibres form a portion of the reticular formation. The neurons of the reticular formation transmit motor and sensory impulses which further regulate the nervous activity, heart rate, respiration etc. The medulla oblongata is developed during embryo development from myelencephalon which is a secondary vesicle formed from the hindbrain.
Therefore, the correct answer is option A.

Note: In case of damage to the middle portion of the medulla, a person may undergo partial paralysis of the opposite side of the body or tongue. This is known as ‘Medial medullary syndrome’.
In case of damage to the lateral medulla, a person may undergo ‘Lateral medullary syndrome’ and loose pain sensation, body coordination, gag reflex, temperature sensation etc.