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The Cardiovascular System

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Presentation on theme: "The Cardiovascular System"— Presentation transcript:

1 The Cardiovascular System

2 Physiology of Circulation

3 Compare and Contrast – Arteries & Veins

4 Arteries - Characteristics
Thicker tunica media – smooth muscle layer Smaller lumen Elastic – stretch and recoil as blood is pumped through High pressure Carry blood away from heart

5 Veins - Characteristics
Thin tunica media (smooth muscle layer) Larger lumen Rely on other structures to help return blood to heart Valves Skeletal muscle Pressure changes in thoracic cavity

6 Arterial Pulse Pulse: the alternating expansion and recoil of artery as the left ventricle contracts Usually equals pulse rate Normal pulse rate: bpm Pressure points: pulse points compressed to stop blood flow

7 Blood Pressure Pressure blood exerts against the inner walls of the blood vessels Blood flows from aorta  arteries arterioles  capillaries  venules  veins  vena cava Pressure is strongest at the aorta, and zero at the vena cava

8 You Decide: Which was cut in the man – an artery or vein? How do you know?

9 Measuring Blood Pressure
Systolic pressure: pressure in arteries at the peak of ventricular contraction Diastolic pressure: pressure when ventricles relax normal BP: 120 (systolic)/80 (diastolic)

10 Factors affecting blood pressure
Peripheral resistance Friction encountered as blood flows through vessels Age, weight, time of day, exercise, body position, emotional state, drugs Neural factors Sympathetic system causes vasoconstriction of vessels which increases blood pressure Renal factors (kidneys) Alter blood volume As BP increases above normal, kidneys excrete more water into urine

11 Factors Continued Temperature Chemicals Diet
Cold causes vasoconstriction, heat is a vasodilator Chemicals Nicotine causes vasoconstriction (increases bp), alcohol causes vasodilation (decreases bp) Diet Low salt, saturated fats and cholesterol help prevent hypertension (high bp)

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