Vascular shunt refers to the distrubution of blood around the body.
During Exercise the vascular system redistributes blood to areas with the greatest demand for oxygen away from areas with a lower demand for oxygen.
For example when exercising the blood is redistubuted to the muscles- away from the organs where the majority of the blood is at rest.
Only 15-20% of blood/cardiac output is supplied to the muscles. The remaining 80-85% supplies the bodies organs eg. Liver, kidney etc.
During lighter exercise increased blood supply goes to the skin in order lose heat. This decreased as intensity increases. 85% can be supplied to the working muscles as intensity increases. blood to the body organs is then decreased. Blood supply to brain is maintained.