Body processes

Cerebral Blood Volume – Function, Task & Diseases

Cerebral blood volume

Cerebral blood volume is the volume of blood in the skull that supplies oxygen and nutrients to the brain and meninges . Cerebral blood volume is closely related to cerebral blood flow . Severe changes in blood volume can increase intracranial pressure or result in an insufficient supply of oxygen.

What is cerebral blood volume?

The blood volume corresponds to the total amount of blood in the human body. There are different blood volumes depending on the localization. For example, cerebral blood volume is the total amount of blood in the neurocranium (skull). The blood at this location serves to supply the brain and the meninges (meninges).

The supply of blood is also a supply of nutrients. In addition, the blood supply ensures the oxygen supply on which every tissue of the human body is absolutely dependent. Oxygen binds to the hemoglobin in human blood and is thus transported together with the hemoglobin to the smallest vessels. The bond breaks depending on parameters such as pH . In this way, the oxygen is released again and can be absorbed by the individual tissues . These processes make the blood a transport medium for vital substances.

The cerebral blood volume is correspondingly important for the central nervous system and especially the brain. If there is a persistent lack of oxygen, body tissues die. In connection with a vital organ like the brain, this has correspondingly serious consequences.

function & task

The human skull always has a similar anatomy. For example, there is an average of 1500 grams of brain matter in the human skull, which in turn consists of gray and white matter . In addition to an average of 75 milliliters of liquor (brain water), there are also around 100 to 130 milliliters of blood in the brain. This blood is the cerebral blood and makes up the cerebral blood volume.

The cerebral blood is divided into different vessels. Around 15 percent of the total cerebral volume is carried by the arteries there. About 40 percent, on the other hand, are carried by the cerebral veins . On average, the remaining 45 percent of the total cerebral volume is located in the tissue of the brain and in the capillaries .

Cerebral blood volume is associated with specific tissue values. Values ​​of around 3.5 milliliters per 100 grams apply to the gray matter of the brain. The white matter has values ​​of around 1.75 milliliters per 100 grams. This means that the white matter contains only about half of the blood volume that is in of the gray matter. The white matter consists of portions of the central nervous system that contain axons of neurons .

The cerebral blood volume is closely related to the concept of cerebral blood flow. For example, science assumes that the blood flow in the brain is around 15 to 20 percent of the cardiac output . This cardiac output is in turn about 5l/min. This results in a blood flow of around 1000 milliliters per minute for the blood flow in the brain with a mass of around 1.5 kilograms.

The cerebral blood flow depends not only on the cerebral blood volume but also on the mean blood pressure of the arteries, the intracranial pressure and the vascular resistance of the cerebral vessels .

Diseases & Ailments

Any changes in cerebral blood volume can be associated with serious symptoms and are therefore of high clinical relevance. Above all, the significant increase in cerebral blood volume has serious consequences. Such an increase in the amount of blood in the cranium can be caused by a hematoma , for example . A second possibility is an acute hemorrhage within the brain. Once this change violates the Monro-Kellie Doctrine, the increase in cerebral blood volume can sometimes cause life-threatening increases in intracranial pressure.

The Monro-Kellie doctrine dates back to the 19th century and refers to the sum of all components in the cranium. According to the doctrine, the proportions of brain tissue, blood, and CSF must remain constant for intracranial pressure to remain constant. The total intracranial volume is limited to 1600 milliliters. If there is an increase beyond this volume limit, the intracranial pressure increases accordingly.

For this reason, increases in cerebral blood volume can produce intracranial pressure signs that indicate an increase in intracranial pressure . When the intracranial pressure increases, the individual parts of the brain sometimes become trapped. Depending on the affected part of the brain, irreversible consequences can arise.

Not only an increase in cerebral blood volume, but also a significant reduction can have serious consequences. Such a reduction occurs, for example, in the context of a stroke . If the brain no longer receives enough blood, it will become partially or even completely insufficiently supplied with blood. This insufficient blood flow can result in an undersupply of nutrients and oxygen. The insufficient supply of oxygen in particular is devastating for the tissue of the brain and causes individual nerve cells to die off. If blood circulation and with it the oxygen supply to the brain is no longer guaranteed over a longer period of time, brain death occurs.

Although major changes in cerebral blood volume can have the consequences described and thus represent serious disease phenomena, minor fluctuations in cerebral blood volume do not necessarily cause symptoms.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.