BLOOD PRESSURE What is blood pressure Blood Pressure

BLOOD PRESSURE

What is blood pressure? • Blood Pressure is the force per unit area on the wall of a blood vessel • Measured in terms of mm. Hg • Measured in largest arteries near the heart

What all plays a role in blood pressure?

Resistance • Exactly what it sounds like, the resistance of blood flow • Makes blood flow difficult • Seen well away from the heart

Viscosity • Thickness of the blood • Greater viscosity, harder to move • Lower viscosity, the easier the flow

Total Vessel Length • The longer the blood vessel, the more resistance • The more resistance, the higher the blood pressure • Adding weight adds miles to your total blood vessel length

Blood Vessel Diameter • This is what changes most often…the other three stay relatively constant • Friction – the outside wall causes friction on blood passing close to the outside, slowing it down • Laminar flow versus turbulent flow

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Systemic Blood Pressure • Systemic blood flow just means that blood flows through a patter like a circuit • It is a circular pattern • Think back to our picture of the heart. Where would pressure in the blood flow pattern be highest? Lowest?

Systolic vs. Diastolic Pressure • Systolic pressure is the pressure when the heart is pumping • Diastolic pressure is the pressure in the vessels when the heart is relaxed • The difference between the two is called pulse pressure • Numbers at a Dr. ’s office is systolic over diastolic pressures

Normal Blood Pressure • A normal blood pressure is 120/80 mm. Hg • During the lab tomorrow, we will be measuring blood pressures of specific ages of people. We will label them normal or as having hypertension • Hypertension is too much pressure within your blood vessels

Return to Sender • How the blood gets back to the heart • These structures return blood to the heart, and are located within the venous system • Respiratory Pump – Abdominal pressure from breathing in squeezes veins causing a return to the heart • Muscular Pump – Most important pump in return of blood. Muscles surrounding veins contract and relax “milking” blood back to the heart.