[amalia (OP)]

Justin sent us a really interesting question:
Being a cyclist, when I am cycling, what are all my different organs doing? What is my gallbladder doing while I am pushing up a hill at 90% power for example? Just sitting there wondering what to do next?
Do you know the answer?

[chris]

It depends upon the organ!

Your heart is pretty critical and will augment activity to meet the rising metabolic demands of the tissues. Your kidneys receive about 20% of blood flow and operate constantly to regulate blood biochemistry; this won't change. The liver maintains blood glucose during prolonged exercise through gluconeogenesis, sources for which include glycogen, proteins and glycerols from fats; the brain remains highly active throughout, consuming about 15% of cardiac output, and the lungs augment their activity to promote gas exchange. The intestinal system, though, becomes relatively quiescent during bouts of exercise. Muscle tone drops, gastric and intestinal secretions slow, and peristalsis is reduced. Simultaneously, mesenteric blood flow drops. As part of this system, the gall bladder also relaxes and stores - rather than actively expels - bile, since this is not needed during exercise.

Does that answer the question?