Download Function of the Heart

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.
2.
3.
4.
5.
Atrial systole (contraction) sends blood into the
ventricles.
The ventricles fill which causes the atrioventricular
valves to start closing.
Atrial diastole (relaxation).
Ventricular systole injects blood into the aorta or
pulmonary artery.
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
Blood Pressure: Effects of Factors
 Neural factors
 Autonomic nervous system adjustments
(sympathetic division)
 Renal factors
 Regulation by altering blood volume
 Renin – hormonal control
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.39a
Blood Pressure: Effects of Factors
 Temperature
 Heat has a vasodilation effect
 Cold has a vasoconstricting effect
 Chemicals
 Various substances can cause increases or
decreases
 Diet
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.39b
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
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.41