a-short-review-of-histology

Valves:

Structurally, valves are formed from folds in the tunica intima
The small amount of connective tissue which is usually found in the tunica intima is enhanced by additional dense connective tissue which gives some structural strength to the valves
Functionally, valves control the direction of blood flow in the cardiovascular system
In the heart, valves separate the chambers from each other and from the great arterial vessels
Because of the very high pressures that are generated in the heart chambers, the valves have supporting structures which act like guy ropes to prevent them being turned inside out (like an umbrella in a high wind)
The cusps of the valves in the heart fit tightly together
If they do not, either through a congenital defect or as result of damage, it is a serious clinical condition as it effects the efficiency of the heart as a pump
In peripheral veins, particularly in the limbs, the valves are regularly placed to direct the flow of blood towards the heart
Valves in peripheral veins are bicuspid
Not all veins have valves:

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