Blood Suply Of The CNS/Neurovascular Coupling

Question 1

What is neuromuscular coupling

Answer 1

Neuronal activity evokes localised changes in blood flow

Question 2

How much cardiac output and oxygen consumption does the brain use

Answer 2

15% CO
25% oxygen consumption

Question 3

List the cerebral blood vessels

Answer 3

Anterior cerebral artery
Middle cerebral artery
Posterior cerebral artery
Basilar artery

Question 4

….. vessels give off branches that ……

Answer 4

Pail vessels give off branches that penetrate the brain cortex

Question 5

Plial cells-> ……->…..

Answer 5

Cortical arterioles
Cortical capillary network

Question 6

Vascular density is associated with ……

Answer 6

the metabolic demands of different regions

Question 7

Gray matter vs white matter metabolic needs

Answer 7

Gray matter hasrhigher metabolic demands than white matter

Question 8

What vessels regulate blood flow

Answer 8

Pre-capillary arterioles and capillary pericytes regulate blood flow

Question 9

Describe the mechanisms of neuromuscular coupling

Answer 9

1. Neuron-Astrocyte-vessel signalling
   -K+; COX-2 products; P450 products
2. Interneurons
   -vasoactive intestinal peptide; nitric oxide
3. Metabolic factors
   -lactate, CO2, hypoxia, adenosine

Question 10

Neuron to astrocyte signalling

Answer 10

Neuron (synaptic bouton and spine) -> astrocyte network -> blood vessel

Question 11

Astrocyte to vessel signalling (K ions)

Answer 11

Modest elevations in K+ dilate cortical arterioles
ES induced dilation of an arterioles in a brain slice is prevented by inhibition of Kir channels

Question 12

Astrocyte to vessel signalling (arachidonic acid metabolites)

Answer 12

Ca2+ dependent phospholipase A2 activation causes accumulation of arachidonic acid
Vasodilation: EETs and prostaglandin E2

Question 13

Vasoactive NTs are

Answer 13

Interneurons
Direct activation of a single Interneurons is sufficient to increase the diameter of a neighbouring micro vessel
VIP or NOS positive Interneurons

Question 14

Potential mechanism underlying neuromuscular coupling?

Answer 14

Local accumulation of metabolic factors
Adenosine produced during ATP catabolism and lactate produced during brain activation could be important mediators.
However time-course NVC argues against this
Metallics factors are likely to affect blood vessels during hypoxia or ischemia

Question 15

Brain imaging techniques for monitoring brain function rely on

Answer 15

Detecting small changes in blood flow to visualise active areas of the brain

Question 16

3 examples of functional brain imaging techniques

Answer 16

Positron Emission Tomography (PET)
Single-photon emission computerised tomography (SPECT)
Functional magnetic resonance imagine (fMRI)

Question 17

Describe fMRI

Answer 17

Best approach to analysing brain at work
Based on the fact that oxyHb has a different magnetic resonance signal than deoxy-Hb or the surrounding brain tissue
Within seconds after onset of localised brain activity there is an increase in cerebral blood flow (NVC). The increase s larger than the increase in oxygen consumption
Results in a local increase in oxyHB and a drop in deoxyHB which alters the magnetic resonance signal and forms the basis of the fMRI signal