'In a vein it's 2 or more cusps arranged to allow blood to flow in only one direction'
a valve
THE BODY HUMAN: In a vein its 2 or more cusps arranged to allow blood to flow in only one direction
In a vein it's 2 or more cusps arranged to allow blood to flow in only one direction
In a vein it's 2 or more cusps arranged to allow blood to flow in only one direction
THE BODY HUMAN
a valve
THE BODY HUMAN