Chapter 11 – Part 5 The Cardiovascular System

1. Chapter 11 – Part 5The Cardiovascular System

2. The following measurements are referred to collectively as vital signs in clinical settings: • Arterial pulse • Blood pressure • Respiratory rate • Body temperature • Vital signs are a fairly good indication of the efficiency of a person’s circulatory system Vital Signs

3. Pulse • Pulse – Pressure wave of blood • Is created from the alternating expansion and recoil of an artery that occurs with each beat of the left ventricle

4. Monitored at pressure points where pulse is easily palpated • Can feel a pulse where an artery lies close to the body surface • Are called pressure points because these same points are compressed to stop blood flow during hemorrhage Pressure Points

5. Normally pulse rate (pressure surges per minute) equals heart rate (beats per minute). • Pulse averages 70-76 beats per minute in a normal resting person. • Pulse is influenced by activity, postural changes, and emotions. Pulse

6. Place the tips of your first two or three fingers over one of the arteries designated as a pressure point. • Compress the artery firmly as you begin and then immediately ease up on your pressure slightly. How to Take a Pulse

7. Blood Pressure – The pressure the blood exerts against the inner walls of the blood vessels • It is the force that keeps blood circulating continuously even between heartbeats • Any system equipped with a pump that forces fluid through a network of closed tubes operates under pressure. • Understood to mean the pressure within the large systemic arteries near the heart Blood Pressure

8. Blood flows along a pressure gradient (from high to low) as it makes its circuit. • Pressure is highest in the large arteries and continues to drop throughout the pathway, reaching zero or negative pressure at the venae cavae • The high pressure in these arteries forces the blood to continually move into areas where the pressure is lower. Blood Pressure Gradient

9. Comparison of Blood Pressures in Different Vessels

10. The pressure differences between arteries and veins are apparent when the vessels are cut: • If a vein is cut - the blood flows evenly from the wound • If an artery is cut - rapid spurts of blood Blood Pressure Gradient

11. The continual flow of blood absolutely depends on the stretchiness (elasticity) of the large arteries and their ability to recoil and keep the pressure on the blood. • Garden hose example with hard walls: • When the water hose is turned on, the water spurts out under high pressure because the hose walls don’t expand. • When the faucet is suddenly turned off, the flow of water stops because the walls cannot recoil to keep pressure on the water. The pressure drops and the flow of water stops. Blood Pressure Gradient

12. Two arterial blood pressure measurements are usually made: • Systolic Pressure – Pressure in the arteries at the peak of ventricular contraction • Diastolic Pressure – Pressure in the arteries when the ventricles are relaxing • Blood pressures are reported in millimeters of mercury (mm Hg) Measuring Blood Pressure

13. Measuring Blood Pressure • A blood pressure of 120/80 indicates a: • Systolic pressure of 120 mm Hg • Diastolic pressure of 80 mm Hg

14. Measuring Arterial Blood Pressure

15. Arterial blood pressure is directly related to the two following factors. An increase in the following factors causes an increase in blood pressure. • Cardiac output (the amount of blood pumped out of the left ventricle per minute) • Peripheral resistance Blood Pressure: Effects of Factors

16. Peripheral Resistance – The amount of friction encountered by the blood as it flows through the blood vessels • It is increased by the constriction, or narrowing, of the blood vessels. • Increased blood volume or thickness (viscosity) increases peripheral resistance. Blood Pressure: Peripheral Resistance

17. Many factors can alter blood pressure. Some of the factors include: • Age • Weight • Time of day • Exercise • Body position • Emotional state • Various drugs Blood Pressure: Effects of Factors

18. Neural Factors: Autonomic Nervous System • Sympathetic nerves cause vasoconstriction, which increases blood pressure back to homeostatic levels • This hopefully increases venous return so circulation can continue. • During exercise: • There is a general vasoconstriction except in the skeletal muscles. • The vessels of the skeletal muscles dilate to increase the blood flow to the working muscles. Blood Pressure: Effects of Factors

19. Renal factors • Regulates blood pressure by altering blood volume • As blood volume decreases, blood pressure decreases. • As blood volume increases, blood pressure increases. Blood Pressure: Effects of Factors

20. Temperature • Heat has a vasodilation effect • Warm compresses are used to speed the circulation into an inflammed area • Cold has a vasoconstricting effect • Why cold compresses are recommended to prevent swelling of a bruised area Blood Pressure: Effects of Factors

21. Chemicals • Various substances can cause increases or decreases • Nicotine increases blood pressure by causing vasoconstriction • Alcohol causes vasodilation and decreases the blood pressure; often become flushed after drinking alcohol • Diet • A diet low in salt, saturated fats, and cholesterol helps to prevent high blood pressure Blood Pressure: Effects of Factors

22. Factors Determining Blood Pressure