Cerebral Circulation Overview

Cerebral Circulation Overview

• The cerebral circulation refers to the blood flow to and from the brain.
• It is a vital process that supplies oxygen and nutrients to the brain and removes waste products.

Blood Supply to the Brain

• The brain receives 15-20% of the total cardiac output, despite accounting for only 2% of the body's weight.
• The two main arteries that supply blood to the brain are:
  • Anterior cerebral artery (ACA)
  • Middle cerebral artery (MCA)
  • Posterior cerebral artery (PCA)
• These arteries branch into smaller arterioles and eventually into capillaries, where oxygen and nutrients are exchanged.

Cerebral Blood Flow Regulation

• Cerebral blood flow is regulated by:
  • Autoregulation: the brain's ability to maintain a constant blood flow despite changes in blood pressure.
  • Neurogenic regulation: the brain's ability to regulate blood flow in response to neural activity.
  • Metabolic regulation: the brain's ability to regulate blood flow in response to changes in oxygen and glucose levels.

Cerebral Vasculature

• The cerebral vasculature is composed of:
  • Arterioles: small arteries that branch into capillaries.
  • Capillaries: thin-walled vessels where oxygen and nutrients are exchanged.
  • Venules: small veins that merge into larger veins.
  • Cerebral veins: veins that drain blood from the brain.

Blood-Brain Barrier (BBB)

• The BBB is a specialized barrier that separates the brain from the bloodstream.
• It is composed of:
  • Endothelial cells
  • Basement membrane
  • Pericytes
  • Astrocytes
• The BBB regulates the passage of substances into and out of the brain.

Cerebral Circulation Disorders

• Disorders affecting cerebral circulation include:
  • Ischemic stroke: reduced blood flow to the brain.
  • Hemorrhagic stroke: bleeding in the brain.
  • Vasospasm: constriction of cerebral arteries.
  • Cerebral vasculitis: inflammation of cerebral blood vessels.

Cerebral Circulation Overview

• Cerebral circulation is the blood flow to and from the brain, supplying oxygen and nutrients and removing waste products.
• It is a vital process that accounts for 15-20% of the total cardiac output, despite the brain only making up 2% of the body's weight.

Blood Supply to the Brain

• The brain receives blood from two main arteries: anterior cerebral artery (ACA), middle cerebral artery (MCA), and posterior cerebral artery (PCA).
• These arteries branch into smaller arterioles and eventually into capillaries, where oxygen and nutrients are exchanged.

Cerebral Blood Flow Regulation

• Cerebral blood flow is regulated by autoregulation, which maintains a constant blood flow despite changes in blood pressure.
• Neurogenic regulation allows the brain to regulate blood flow in response to neural activity.
• Metabolic regulation allows the brain to regulate blood flow in response to changes in oxygen and glucose levels.

Cerebral Vasculature

• The cerebral vasculature is composed of arterioles, capillaries, venules, and cerebral veins.
• Arterioles are small arteries that branch into capillaries.
• Capillaries are thin-walled vessels where oxygen and nutrients are exchanged.
• Venules are small veins that merge into larger veins.
• Cerebral veins drain blood from the brain.

Blood-Brain Barrier (BBB)

• The BBB is a specialized barrier that separates the brain from the bloodstream.
• It is composed of endothelial cells, basement membrane, pericytes, and astrocytes.
• The BBB regulates the passage of substances into and out of the brain.

Cerebral Circulation Disorders

• Ischemic stroke occurs when there is a reduced blood flow to the brain.
• Hemorrhagic stroke occurs when there is bleeding in the brain.
• Vasospasm is the constriction of cerebral arteries.
• Cerebral vasculitis is the inflammation of cerebral blood vessels.