Question

Which of the following statements is not true?
A. Regulation of blood vessel diameter originates from the vasomotor centre of the pons
B. Baroreceptors may stimulate the vasomotor center
C. Chemoreceptors are particularly sensitive to blood levels
D. Cerebral cortex can play a role in regulating blood pressure

Answer 1

Medulla oblongata is the lower part of the brain that controls the breathing, heart functions and also blood vessel functions. Changes in blood pressure regulated by baroreceptors. Chemoreceptor helps to transfer impulse. Cerebral cortex regulates voluntary actions.

Complete answer:
The actions on blood vessels which can alter its diameter are called vasomotor. It performs the vasodilator action and vasoconstrictor action. These actions are controlled by the medulla oblongata that is the lower part of the brain. The regulation of breathing, heart and blood vessel function, digestion, sneezing, and swallowing is done by medulla oblongata. The center portion of the medulla oblongata is known as vasomotor center. It works together with cardiovascular & respiratory centers. It regulates the blood pressure.
Baro-receptors located in carotid sinus sense pressure changes by responding to change in the tension of the arterial wall. It also responds fast to changes in blood pressure.
Chemo-receptors are present in the neurons which help to provide various body responses.
The outer layer of the neural tissue of the cerebrum is the cerebral cortex. It performs various voluntary actions such as languages, speech, and multiple brain functions.
From the above information we have found that regulation of blood vessel diameter originating from the vasomotor centre of the pons is the wrong statement.

Hence, the correct answer is option (A).

Note: The sympathetic nerve fibers secrete the neurotransmitters such as norepinephrine. These neurotransmitters activate the alpha-adrenergic receptors to promote vasoconstriction. Beta-adrenergic receptors help to mediate the relaxation of the muscle cells which results in vasodilation. The chemicals such as nitric oxide and prostacyclin are vasodilators of the smooth muscle.