FUNCTION OF THE HEART Heart Sounds and Blood Pressure

Terms: Systole – Contraction of the myocardium Diastole – Relaxation of the myocardium Should already know: atria, ventricle, atrioventricular valve, aorta.

Process/Sounds of the Heart 1. Atrial systole (contraction) sends blood into the ventricles. 2. The ventricles fill which causes the atrioventricular valves to start closing. 3. Atrial diastole (relaxation). 4. Ventricular systole injects blood into the aorta or pulmonary artery. 5. AV-valves slam shut (“Lubb” sound)

Process/Sounds of the Heart 6. Back pressure in the aorta or pulmonary trunk builds up. 7. The aortic valve and pulmonary valve slam shut (“Dupp” sound) 8. Ventricular diastole.

Contraction Process

Listen to Heart Sounds Listen to your partner’s heart sounds. Should hear lubb-dubb, lubb-dubb. If a valve does not close all the way, it is called a murmur.

Regulation of Cardiac Output

BLOOD PRESSURE Section 13.5 Brainpop

Blood Pressure Facts The human heart creates enough pressure to squirt blood 30 ft.

Blood Pressure  Measurements by health professionals are made on the pressure in large arteries  Systolic – pressure at the peak of ventricular contraction  Diastolic – pressure when ventricles relax  Pressure in blood vessels decreases as the distance away from the heart increases

Measuring Arterial Blood Pressure

Slide 11.39a Blood Pressure: Effects of Factors Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Neural factors  Autonomic nervous system adjustments (sympathetic division)  Renal factors  Regulation by altering blood volume  Renin – hormonal control

Slide 11.39b Blood Pressure: Effects of Factors Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Temperature  Heat has a vasodilation effect  Cold has a vasoconstricting effect  Chemicals  Various substances can cause increases or decreases  Diet

Variations in Blood Pressure Slide Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  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