Science Starter What are the 3 parts of the circulatory system? Have you ever had your blood pressure measured? How do medical professionals measure blood pressure? You’ve probably heard that high blood pressure is harmful. Why do you think this is?

Today’s Agenda Science Starter Blood Circulation Blood Pressure Notes Pep Rally!

Blood Circulation https://www.youtube.com/watch?v=BEWjOCVEN7M

Unit 5: The Cardiovascular System 5 Unit 5: The Cardiovascular System 5.1 Structure and Function of Vessels

Pulse Pulse – pressure wave of blood (as heart pumps) Monitored at “pressure points” where pulse is easily palpated

Blood Pressure Measurements by health professionals are made on the pressure in large arteries (usually in arm) Systolic – pressure when ventricles (main pumping chambers) are contracted Diastolic – pressure when ventricles relax Pressure in blood vessels decreases as the distance away from the heart increases

Measuring Arterial Blood Pressure Figure 11.18

Comparison of Blood Pressures in Different Vessels Figure 11.17

Renal (kidney) factors Control of Blood Pressure Neural control Autonomic nervous system adjustments (sympathetic division) Renal (kidney) factors Regulation by altering blood volume Renin – hormonal control

Blood Pressure: Effects of Factors Temperature Heat has a vasodilation (lowering blood pressure) effect Cold has a vasoconstriction (raising blood pressure) effect Chemicals Various substances can cause increases or decreases Diet (lots of salt raises blood pressure)

Factors Determining Blood Pressure Figure 11.19

Variations in Blood Pressure Human normal range is variable Normal 140–110 mm Hg systolic 80–75 mm Hg diastolic Hypotension Low systolic (below 110 mm HG) Often associated with illness Hypertension High systolic (above 140 mm HG) Can be dangerous if it is chronic