Cerebral Meninges, CSF & the Blood-Brain Barrier

These flashcards cover key concepts and details regarding the structure and function of the meninges, cerebrospinal fluid, and the blood-brain barrier, as discussed in the lecture.

What are the three main layers of the meninges?

Dura, Arachnoid, Pia.

What is the structure of the Dura mater?

It is adjacent to the skull and has two layers: periosteal and meningeal.

What layer of the meninges is described as spider web-like?

Arachnoid.

What does the Pia mater closely attach to?

The basement lamina of the brain.

What is located within the Dura and Arachnoid layers?

Blood vessels.

What is an epidural hemorrhage?

Bleeding outside the dura, usually arterial.

What is a subdural hemorrhage?

Bleeding between the dura and arachnoid from bridging veins.

What causes subarachnoid hemorrhage?

Bleeding in the arachnoid space, often from ruptured aneurysm.

What is the MRI appearance of an epidural hematoma?

Lens-shaped appearance.

What symptom is associated with epidural hematoma?

A lucid interval followed by sudden unconsciousness.

How does a subdural hematoma appear on MRI?

Spread out appearance.

What are the symptoms of subdural hematoma?

Confusion, headache, vomiting, with a delayed onset.

What is the falx cerebri?

A sagittal sheet of dura that divides the two cerebral hemispheres.

What is the tentorium cerebelli?

A transverse sheet of dura that separates the cerebrum from the cerebellum.

What is the tentorial incisure?

The gap between the two sides of the tentorium where the brainstem passes through.

What fills the cerebral ventricles?

Cerebrospinal fluid (CSF).

Where is cerebrospinal fluid primarily formed?

By the choroid plexus in the brain ventricles.

What cells are responsible for forming the blood-CSF barrier?

Ependymal cells.

How is cerebrospinal fluid formed?

Ultrafiltrate of blood passes through fenestrated choroid capillaries into the sub-ependymal layer.

What is the normal production rate of cerebrospinal fluid?

Approximately 500mL/day.

What causes CSF pressure variations?

Coughing or internal compression of jugular veins.

What is hydrocephalus?

Accumulation of CSF in the ventricular system due to obstruction of normal circulation.

How can hydrocephalus be detected?

Translucent skull due to the absence of brain matter to block light.

What are the two main types of cells in brain tissue?

Neurons and glia.

What is the role of glial cells in the brain?

Support neurons, supply nutrients, destroy pathogens, and insulate neurons.

What distinguishes oligodendrocytes from astrocytes?

Oligodendrocytes form myelin sheaths, while astrocytes support and regulate the neuron environment.

What is the primary role of astrocytes?

Surround and hold neurons in place, supply nutrients, and maintain chemical balance.

What is the glia limitans?

A layer of joined astrocyte endfeet covering the outer surface of the brain.

What structure prevents proteins from exiting cerebral capillaries?

Tight junctions between endothelial cells.

What is the blood-brain barrier (BBB)?

A barrier formed by tight junctions in capillaries that restricts macromolecule passage to the CNS.

What is a consequence of the BBB breaking down in conditions like meningitis?

Increased penetration of antibiotics like penicillin into brain tissue.

What effect does brain tumor pathology have on the BBB?

Endothelial cells in rapidly growing tumors lack tight junctions, affecting hydration and visibility on MRI.

What types of transport exist for amino acids across the blood-brain barrier?

Three specific transport systems: acidic, neutral, and basic.

What is typically found in healthy cerebrospinal fluid?

Clear, colorless, mainly water (99%), very little protein, and no cells.

How does blood pCO2 affect cerebrospinal fluid pH?

Small changes in blood pCO2 cause appreciable changes in CSF pH.

What is the typical glucose concentration of CSF compared to blood plasma?

About 60% of the glucose concentration found in plasma.

What is the normal pressure range for CSF?

4.4-7.3 mmHg (0.6-0.9 kPa).

What is the role of arachnoid granulations?

They allow CSF to be drained into the superior sagittal sinus.

What is the function of ependymal cells in cerebrospinal fluid production?

They regulate the flow of CSF and form a lining for the ventricles.