Capillaries

Arteries 15 % of blood 

Capillaries 5 % of blood 

As blood travels outwards the arteries become smaller and smaller 

Until eventually the blood enters into what are known as Capillaries

Capillaries are location for

 Exchange of materials between blood and the cells of the body

Capillaries: Optimized exchange of materials between blood and cells

Capillaries are smallest in diameter and most numerous vessels in the body

Capillaries have the highest Total Cross Sectional Area

 Velocity Of Blood Flow

Factors Maintaining It: Cross Sectional Area

Velocity  = Cross Sectional Area and Blood Flow

Velocity is inversely proportional to cross sectional area

Velocity of blood flow is fastest in aorta and slowest in capillaries

Resistance and Blood Flow

Resistance: Hindrance to blood flow through a vessel

Factors maintaining Resistance

Blood Viscosity/Vessel Length/Vessel Radius

Vessel Radius: Smaller the radius greater the resistance 

Cross Sectional Area and Resistance

Large Cross Sectional Area  = Less Resistance 

Large Radius =  Less Resistance

Eg: Pulmonary Vascular Bed

Blood Flow = Pressure Gradient/Resistance

Blood Flow: Slowest In Capillaries

Regulation Of Blood Flow

Cardiac Output/Cross Sectional Area/ Resistance/Viscocity

Other Causes Regulation Of Blood Flow

Snapshot