Blood Flow Adjusts to Activity Through Vasoconstriction and Vasodilation
- The distribution of blood is regulated by the contraction or relaxation of smooth muscle in arteriole walls:
- Vasoconstriction: Circular muscles contract, narrowing the blood vessels and reducing blood flow to specific organs.
- Vasodilation: Circular muscles relax, widening the blood vessels and increasing blood flow to target tissues.
In some cases, shunt vessels bypass capillary networks to redirect blood quickly between arterioles and venules.
HintThese processes are regulated by the autonomic nervous system and hormones like adrenaline.
Blood Supply Prioritizes Muscles During Vigorous Exercise
- When engaging in intense physical activity, your body prioritizes oxygen delivery to muscles and energy conservation:
- Skeletal Muscles: Blood flow greatly increases to deliver oxygen and glucose for sustained contractions and ATP production.
- Digestive System: Blood flow decreases as digestion is temporarily paused.
- Kidneys: Reduced blood flow lowers the glomerular filtration rate, conserving energy.
- Brain: Blood supply increases slightly to ensure proper oxygen and glucose delivery for focus and coordination.
By prioritizing skeletal muscles, the body ensures optimal performance while maintaining essential brain functions.
Blood Supply Shifts to Support Rest During Wakeful Rest
- When the body is at rest but awake, blood distribution reflects maintenance priorities:
- Skeletal Muscles: Blood flow is moderate, supporting postural stability and light activities.
- Digestive System: Blood flow varies, increasing during digestion to support nutrient absorption and decreasing when the gut is inactive.
- Kidneys: Blood flow is at its maximum, maintaining waste filtration and fluid balance.
- Brain: A steady blood supply ensures cognitive function and neural activity.
