Blood Vessels, BBB, and CSF in CNS: Structure and Function

What is the primary function of vascularization in the brain?

To provide nutrients and oxygen while removing waste.

How does the metabolic rate of brain grey matter compare to white matter?

The metabolic rate of brain grey matter is about four times that of white matter.

What is the blood-brain barrier (BBB) and what is its primary role?

The BBB is an endothelial barrier that restricts the entry of water-soluble compounds into the brain.

What type of cells induce the formation of the blood-brain barrier?

Astrocytes.

Describe the structure of the blood-brain barrier.

It consists of non-fenestrated endothelial cells bound by tight junctions and surrounded by a basement membrane.

In which areas of the brain does the blood-brain barrier not exist?

In circumventricular organs that monitor systemic metabolic changes, such as portions of the hypothalamus, pituitary, and pineal gland.

What is the role of cerebrospinal fluid (CSF) in the brain?

CSF provides nutrients, removes waste, and facilitates communication between brain regions.

What is the flow path of cerebrospinal fluid in the brain?

From lateral ventricles to the third ventricle, through the mesencephalic aqueduct to the fourth ventricle, and then to the surface of the brain.

Where is cerebrospinal fluid generated?

By the choroid plexus.

What structures make up the choroid plexus?

Vascular tufts with supportive connective tissue (tela choroidea) and choroidal epithelium.

How does the osmolality of cerebrospinal fluid compare to plasma?

The osmolality of CSF approximates that of plasma.

What is the significance of potassium (K+) levels in cerebrospinal fluid?

K+ is actively transported out of CSF, resulting in levels that are only 40% of plasma concentrations, which maximizes efficiency of K+ leak channels.

What role does glucose play in cerebrospinal fluid?

A small amount of glucose is transported into CSF, contributing to neuronal ATP production.

What is the blood-CSF barrier?

It is created by the tight junctions of the choroidal epithelium and the fenestrated endothelium of the tela choroidea.

What is the function of cilia on ependymal cells?

Cilia drive the circulation of cerebrospinal fluid.

What is the subarachnoid space and what does it contain?

The subarachnoid space is between the arachnoid membrane and pia mater, filled with cerebrospinal fluid.

What is the dura mater?

A tough fibrous connective tissue covering that protects the brain and spinal cord.

What is the role of arachnoid villi in cerebrospinal fluid circulation?

Arachnoid villi extend into the dorsal sagittal sinus, permitting resorption of CSF into the venous circulation.

What happens if there is decreased resorption of cerebrospinal fluid?

It can lead to hydrocephalus.

How can inflammatory or metabolic changes in the CNS affect cerebrospinal fluid?

They can alter CSF composition, making CSF analysis a valuable diagnostic tool.

What is the significance of CSF analysis in diagnosing CNS issues?

CSF analysis provides a survey of the entire central nervous system, helping to establish the nature of problems.

How do inflammatory cells interact with cerebrospinal fluid?

Inflammatory cells can exit post-capillary venules and may join CSF in the subarachnoid space.

What is the primary means by which leaked vascular fluid rejoin the systemic circulation in the CNS?

Resorption of plasma proteins into the CSF in the subarachnoid space.

What is the composition of the pia mater?

The pia mater is intimately associated with the surface of the brain and spinal cord.

What is the function of the tela choroidea?

It provides nutritive support to the choroidal epithelium, which is responsible for CSF production.