Why does too much salt cause hypertension?

RETAINS WATER. Human Body is 60% water by weight.Water is both in the cells(iNTRAVASCULA)and(EXTRAVASCULAR)outside the cells. Too much water is bad for the body as too little is Too much Sodium causes increased water in and out of the cells and that causes increase in Blood Pressure Most humans will simply excrete the excess Na,But20%of have genetic disposition that causes Na retention,that cause water retention.