The Heart and the Cardiac Cycle PDF

The Heart and the Cardiac Cycle Review! Blood flows through the body in two pathways. Pulmonary - blood circulates to and from the lungs Systemic - blood circulates throughout the rest of the body tissues. Pulmonary Systemic (+ coronary)  The Heart Right side...

The Heart and the Cardiac Cycle Review! Blood flows through the body in two pathways. Pulmonary - blood circulates to and from the lungs Systemic - blood circulates throughout the rest of the body tissues. Pulmonary Systemic (+ coronary)  The Heart Right side = blood goes to the pulmonary system Left side = blood goes to the systemic system Septum = separates these sides Atria = holds blood Ventricle = pumps blood Atrioventricular valves = prevent backflow into atria Semilunar valves = prevents backflow into ventricles Label your diagram - Fig 1 p 495 in your textbook  Outer Heart Anatomy Coronary Arteries Coronary Veins Pericardium  Heart – Superior view *Tricuspid valve (AV valve between the right atrium and right ventricle) *Bicuspid/Mitral Valve (AV valve between the left atrium and left ventricle) Papillary muscles Attach via the Chordae tendinae to the AV Valve and prevent the valve from inverting (getting pushed inside out) during systole Chordae tendinae Tendon-resembling fibrous cords connecting the papillary muscles to the AV Valve The Flow of Blood through the Heart Blue is deoxygenated (from body tissues, then heart to the lungs) (inferior and superior vena cava -> r. atrium -> r. ventricle -> pulmonary arteries) Red is oxygenated (from lungs to heart then body tissues) (pulmonary veins ->left atrium -> l. ventricle->aorta) Fun Facts! Average heart rate is 60-100 beats per minute A resting heart can pump 5L/min of blood With exercise, the heart can pump 25L/min One cycle of contraction and relaxation takes ~ 0.8s. The Cardiac Cycle and Blood Pressure Diastole – relaxation of heart – atria fill with blood – Atrioventricular (AV) valves open, and blood begins to fill the relaxed ventricles Systole – contraction of atria then ventricles – blood goes out of heart Systolic/Diastolic Blood Pressure – measure of the pressure in arteries during these events. Measured using a sphygmomanometer (blood pressure cuff) – Average blood pressure is 120/80 mmHg Diastole: Atria and Ventricles are relaxed; atria fill with blood Systole: Atria and Ventricles contract, blood leaves the heart.  Heart Sounds Lubb DUBB (or Guh-Gung ☺ ) – Lubb = AV valves close after atria contract – DUBB = semilunar valves close after ventricles contract Heard with – Stethoscope Blood leaking due to faulty valves = heart murmur – Inefficient blood flow 🡪 increased heart rate  Heart Sounds and Defects https://www.youtube.com/watch?v=iTfxS7hjLrM Heart Sounds 45 sec The Heart’s Tempo Regulation of Heart Rhythm The heart muscle consists of myogenic muscle Has the unique ability to contract and relax without external stimulation Normal Rhythm of a Heartbeat - Medical Animation Regulation of Heart Rhythm The heartbeat initiates in the sinoatrial (SA) node Specialized bundle of nerves and muscle tissue in the right atrium This is the “pacemaker” of the heart Leads to atrial systole (contraction) Regulation of Heart Rhythm The signal then travels to the atrioventricular (AV) node and on to the Purkinje fibres that radiate into the ventricles These signals cause ventricular systole (contraction) Purkinje fibres What Makes Your Heart Beat  Electrocardiogram (ECG) Measures the electrical impulses from the heart Waves of an ECG are identified as: QRS complex: Ventricle contracts SA node sends signal for atrium to contract T wave: Ventricle recovers P wave: Atria contract AV node sends signal to ventricle to contract Electrocardiograph “lub” “dub” Abnormal ECGs Tachycardia: HR is faster than normal (>100 beats/min) Bradycardia: HR is slower than normal (