Neuroscience Study Questions - Blood Flow of Brain/Spinal Cord

What are the 3 components of the Blood Brain Barrier?

1. Endothelial tight junctions

2. Basement Membrane

3. Astrocyte food processes

Provide one example of a substance or compound that can easily diffuse across the BBB.

H₂O and CO₂

Provide one example of a substance or compound that can cannot cross the BBB.

Glucose

Define anastomosis

Interconnections between blood vessels and allows flow between them

Why does the COW meet the definition of Anastomosis

Due to its interconnections among the arteries in the COW this allows for blood flow to continue to move through the circuit even when one is injured or defected (corotid artery, basilar artery, and vertebral arteries)

What is the primary arterial supply to the anterior aspect of the circle of willis?

The internal carotid arteries

What is the primary arterial supply to the posterior aspect of the circle of willis?

The vertebral arteries

Name the arteries that comprise the anterior aspect of the COW

• ACA

• MCA

• Anterior Communicating Artery

• Internal carotid

• ½ of the posterior communicating artery

Name the arteries that comprise the Posterior aspect of the COW

• ½ of the posterior communicating artery

• PCA

• SCA

• Basil Artery

• AICA

• PICA

• Vertebral Artery

What portion of the cerebral hemispheres does the ACA supply?

The Mohawk of the cerebrum (midline/sagittal section)

What portion of the cerebral hemispheres does the MCA supply?

The lateral portion of the frontal, temporal, occipital and parietal lobe

What portion of the cerebral hemispheres does the PCA supply?

Primary occipital with some parietal and temporal lobe (ventral sides)

Define a watershed region

A watershed region is where an area of the brain is getting supplies from more than one areas (overlapping of arteries).

• Ex. ACA & PCA overlap, MCA & ACA overlap, and MCA & PCA overlap.

What are the two arteries that source arterial blood for the anterior spinal artery?

The two vertebral arteries (L & R)

What are the 3 types of cerebrovascular accidents?

Ischemic, Hemorrhagic, and Transient Ischemic Attack

What are the 3 subtypes of cerebrovascular accidents?

Embolic, Thrombotic, and Hemorrhagic

Two types of Ischemic strokes

Embolic and Thrombotic

Ischemic Stroke

Block of blood in artery (ex. plaque build-up restricting flow, or clot (more urgent)

Hemorrhagic

Burst of artery (more severe effects)

Vascular Syndromes: Transient Ischemic Attack (TIA)

• Mini stoke

• Short spouts of ischemia occurring that resolves on its own

• Strong predictor of full blown CVA

Structures Effected:

• Can occur anywhere

• Mostly small vessels

Vascular Syndromes: MCA

Most common

Structures Affected: Contralateral Affects

• Lateral portion of frontal parietal n.

  • Motor and speech homunculus

• Lateral Temporal lobe

• Basal Ganglia Structures (Parkinsonism)

• Face or arm effected

• Impaired speech

Vascular Syndromes: ACA

Structures Affected:

• Frontal & Parietal Lobes along midline

• Lower extremities in motor & sensory function (Unilateral)

Vascular Syndromes: PCA

Structures Affected: Contralateral

• Occipital Lobe

• Inferior Temoral Lobe

• Vision Changes

Vascular Syndromes: Vertebro-Basilar

• More Rare (not good outcomes)

  • Bad prognosis

Structures Affected:

• Pons, midbrain, cerebellum, medulla

Ischemic Breakdown - How many Cases

90% of CVA (fixed with drugs)

Ischemic Breakdown - Thrombotic (Thrombus)

Build up of plaque occurring locally

Ischemic Breakdown - Thrombotic (Thrombosis)

Thrombus dislodges and travels to brain

• Becomes an embolism

Ischemic Breakdown - Embolism

Caused by free flowing thrombus and clogs blood vessels

Hemorrhagic Stroke

Burst of blood vessel due to increased BP - Fast bust

• Fixed with neurosurgery or clots on its own.

What region of the cerebral hemispheres is supplied by the lenticulostriates

Comes off the MCA and supplies the basal ganglia

Why is the MCA the most common stoke space

Direct path from the heart

Circumventricular Organs: What are they and examples

Areas where our nervous tissues exits the BBB into NS.

Ex. Pineal gland, posterior lobe of the pituitary, choroid plexus, others.

Spinal Cord Circulation

Posterior Spinal Arteries

Anterior Spinal Arteries

• Strokes can happen here but it is rare

Maintenance of Appropriate Blood Flow

Brain makes up only 2% of the total body mass, but consumes ~25% of the body’s oxygen and 25% of its glucose

Blow Flow - Astrocytes

Induce local changes

• If using one part of brain, blood flow focuses here

• High Acuity = Burns 1000s of calories

• Astrocytes will direct flow to parts of brain used by reducing flow from other areas.