... pressure is inverse with the size of a vessels, i.e. the lumens, meaning that the smaller the lumen the greater the resistance to flow and so the higher the pressure, however, the blood pressure in the capillaries is very low, but the it has the smallest lumens of blood vessels in the body, so this contradicts the latter principle, because smaller lumens means higher pressure !
And I'd also like to understand the changes in velocity in the blood vessels and why ?