Brain blood flow and exercise

Question 1

Brain is only 2-3% of body mass, yet demands ?% of total CO?

Answer 1

20%

• stroke caused by over or under perfusion

Question 2

What is the relationship between aerobic fitness and brain blood flow?

Answer 2

Positive correlation
- Habitual exercise offsets the natural age-related decline in brain blood flow.

Question 3

What reduces brain size?

Answer 3

• Ageing
• Inactivity

Question 4

How to measure brain blood flow in a dynamic context?

Answer 4

Transcranial Doppler - measure blood velocity as an index of flow

Question 5

What does Near-infared Spectroscopy (NIRS) do?

Answer 5

Measures the balance of oxygen supply and oxygen demand directly at a capillary level in the cerebral cortical tissue.

Gives us a measure of brain activation – neurovascular coupling

Question 6

What 5 factors influence regulation of brain blood flow?

Answer 6

-Metabolism (nerve cell activity)
-Blood pressure (perfusion pressure)
-Neurogenic (Cerebral SNA)
-Chemical (Arterial PCO2)
-Cardiac Output (CO)

Question 7

Is brain blood flow more responsive to O2 or CO2?

Answer 7

CO2 - BBF highly sensitive to changes in arterial partial pressure of carbon dioxide (PaCO2).

e.g., when you hold your breath, CO2 build up makes you breathe, not lack of O2

Question 8

Brain blood flow increases with exercise intensity up until a certain point, then it decreases, what is this point?

Answer 8

Anaerobic threshold