Vasomotor Control Centre (VCC)

Vasomotor Control Centre (VCC)

1. Located in the Medulla Oblongata in the brain regulates the redistibution of cardiac output by controlling the Vascular Shunt Mechanism

   • Chemo and baroreceptors stimulate VCC
   • VCC increases or decreases stimulation via the sympathetic nervous system to either vasodilate (widen) or vasoconstrict (narrow) the precapillary sphincters and arterioles supplying muscles and organs (Vascular Shunt Mechanism)

2. Vasomotor Control (VMC) Vascular Shunt Mechanism

   • Organs
     • Increased Sympathetic Stimulation
       • Vasoconstriction of arterioles and precapillary sphincters
         • Decreased blood flow to capillaries or non essential organs
   • Muscles
     • Decreases sympathetic stimulation
       • Vasodilation of arterioles and precapillary sphincters
         • Increased blood flow to capillaries or working muscles

3. O2 and CO2 are transported via the blood

   • O2
     • 97% in haemoglobin, in RBCs as oxyhaemoglobin (Hb02)
       • 3% within blood plasm
   • CO2
     • 70% combined with water in red blood cells as carbonic acid
       • 23% in haemoblobin as carbaminohaemoglobin
         • 7% dissolved in plasm

4. O2/CO2 - Transport and performance

   • Efficient O2 and CO2 transport aids participation in physical activity in that it is:
     • Prolongs duration of anaerobic and aerobic activity
     • Delays anaerobic threshold, which increases the possible intensity/work rate for the activity
     • Speeds up recovery during and after exercise

5. Smoking Impact on O2 transportation

   • Tobacco smoke contains carbon monoxide (CO). Haemoglobin (Hb) withing bred blood cells combines with CO in preference to O2. This reduces HbO2 association in the lungs and thus reduces maximal O2 uptake. Blood O2 transport/supply to the working muscles and lactate threshold are decreased
   • Net Effect
     • Decreases optimal performance especially in aerobic activities.