The Cardiovascular System

How do bruises form?• Capillaries have walls that are only one cell layer thick - so

they are very fragile • If you get hit on your arm with a baseball…

o The capillaries get ruptured by the impacto The blood contained within them gets released into the

spaces between tissueso This produces the discoloration and possible swelling

known as a bruise

Blood PressureDiastole:• When atria are relaxed (i.e. filled with blood)

Systole:• Atria push blood into ventricles• Ventricles contract and push blood into arteries• When AV valves shut – LUBB• Ventricles relax – DUBB

Written as: DIASTOLIC pressure (mm Hg) SYSTOLIC pressure (mm Hg)

How do we take Blood Pressure?

• Need to use a stethoscope • Normal systolic should be 120 mm Hg• Normal diastole should be 80 mm Hg

To measure:• Tighten the cuff…as soon as you release you

should hear a lubb sound – measure pressure (systolic – should be 120 mm Hg)

• Then deflate until sound disappears – check pressure (diastole – should be 80mm Hg)

 

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