1. 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?

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

3. Blood Circulation

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

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

6. 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

7. Measuring Arterial Blood Pressure
Figure 11.18

8. Comparison of Blood Pressures in Different Vessels
Figure 11.17

9. 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

10. 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)

11. Factors Determining Blood Pressure
Figure 11.19

12. 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