Question

The amount of blood received by the brain every minute is
A. 2500 ml
B. 1000 ml
C. 750 ml
D. 450 ml

Answer 1

Hint: The brain-like all other organs, requires a constant supply of oxygen and nutrients which are supplied by the blood. The brain derives its arterial supply from the paired carotid and vertebral arteries.

Complete answer: The brain is the central functioning organ that oversees all other bodily functions. Like all cells and organs in our body, the brain requires oxygen to function. About 40% of the entire oxygen consumed is sent to the brain. The brain receives this oxygen via the blood carried through special blood vessels. The brain receives blood via two systems, namely the carotid arteries and the vertebral basilar system. The carotid artery joins the heart, through the side of the neck and enters the brain anteriorly and the vertebral basilar system joins the brain posteriorly via the vertebral column. The carotid and vertebral arteries begin extracranially, and course through the neck and base of the skull to reach the cranial cavity. The internal carotid arteries and their branches supply the anterior 2/3 of the cerebral hemispheres, including its deep white matter and the basal ganglia. The vertebral arteries and basilar artery, with their branches, supply the remaining posterior and medial regions of the hemispheres, most of the diencephalon, the brainstem, cerebellum, and cervical spinal cord. The carotid and vertebral-basilar circulations are interconnected with each other by the circle of Willis. Every minute, about 600-700 ml of blood flow through the carotid arteries and their branches while about 100-200 ml flow through the vertebral-basilar system. Therefore, as an average, we can assume the brain receives around 700 – 800 ml of blood every minute via both the systems.
Therefore, the correct option is C.

Note: Even though both the carotid and the vertebral basilar system are connected the supply of blood is individually regulated. This is to ensure that even under conditions where one supply system has blocked the brain still keeps receiving blood and oxygen. Prolonged periods of oxygen deprivation cause cells in the brain to die and ultimately Brain death.