the cardiovascular system. how do bruises form? capillaries have walls that are only one cell layer...

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)

Sphygmomanometer

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