1. THE HEART

2. The Heart
Surrounded by fluid-filled membrane called the pericardium to prevent friction
Two pumps divided by a septum that are synchronized
Right side = receive deoxygenated blood, pumps to lungs
Left side = receives oxygenated blood from lungs and pumps to body

3. Chambers of the heart
Four chambers, composed of 2 thin atria (sin. atrium) two thick ventricles
Ventricles are more muscular to pump blood to distant tissues
left ventricle has thickest walls, it must force blood throughout body

5. How blood moves through the heart
Deoxygenated blood moves through veins into the superior & inferior vena cava 
right atrium  both atria contract 
right ventricle  both ventricles contract 
pulmonary arteries  to lungs (oxygenated) 
pulmonary veins  left atrium
left ventricle  aorta  to body

7. Heart Valves valves prevent blood from flowing wrong way in the heart
Atrioventricular valves  separate atria from ventricles
Semilunar valves  separate ventricles from arteries (half-moon shaped)

9. Special Arteries Aorta  largest artery
Pulmonary arteries carry blood away from the heart (only one that carries deoxygenated blood)
Coronary arteries  supply heart muscle with oxygen/nutrients (moves away from the heart, back to the heart)
Blocked coronary artery causes angina (heart pains) due to lack of oxygen

10. Coronary Bypass Surgery
During operation, heart-lung machine takes over
Vein in leg is removed
Vein is attached from aorta past blockage
Another option: bypass with mammary artery
Bypass increases blood flow to the area served by the coronary artery

11. Heart Circulation

12. Heart Beats
heart undergo over 3 billion contraction cycles in a lifetime
heart made of myogenic muscle, can contract without stimulation
Rhythmic contractions due to two different bundles of nerves
SA node (sinoatrial node), also called pacemaker, starts & keeps heartbeat regular
AV node (atrioventricular node) causes ventricles to contract
AV node passes impulses to 2 large nerve fibres called Purkinje fibres, that branch & carry impulses throughout ventricles

13. Contraction Of The Heart & Action Of The Nerve Nodes

16. Electrocardiogram (ECG) measures changes in electrical potential across heart, & can detect contraction pulses
P wave represents contraction of atria
QRS wave is ventricular contraction
T wave signals the ventricles have recovered
ECGs are useful in diagnosing heart abnormalities.
Pg. 260

17. Cardiac Cycle Consists of two parts:
Systole = contraction of the heart muscle, blood is forced out
Diastole = relaxation of the heart muscle, chambers fill with blood
Atria contract while ventricles relax.
Valves in heart open & close during cardiac cycle.

18. Heart Sounds
Sound of the heart is valves opening & closing produces a characteristic "lub-dub" sound
Atria fill, muscular walls contract, increasing pressure, forcing AV valves to open filling ventricles
Ventricles fill with fluid, they contract
Lub is the closure of the AV valves
Dub is the closing of the SL valves.

19. The Cardiac Cycle

20. Hypertension
Hypertension, high blood pressure (the silent killer), occurs when blood pressure is consistently above 140/90.
Causes in most cases are unknown, although stress, obesity, high salt intake, and smoking can add to a genetic predisposition