Location and function (13.0) Location: to the left of the midline in the Thoracic Cavity –Between the lungs and above the diaphragm Function: Pump blood throughout the entire body.

Heart Anatomy (13.1) Heart - slightly larger in size than a clenched fist, self- adjusting pump, slightly larger in men, 4 chambers, 3 layered wall. Arteries – thick-walled, contractibility, bright red blood that spurts, carry oxygenated blood away from the heart TO tissues of the body (except for pulmonary artery which carries de-oxygenated blood from the heart to the lungs) Veins – larger lumen, carry de-oxygenated blood to heart, dark red/maroon blood that flows Capillaries – single cell thick, location of gas exchange at tissues Arterioles – connect arteries to capillaries Venules – connect capillaries to vein

Blood Vessels (13.8) Arteries – strong elastic vessels –Thicker muscle – more powerful Veins – thinner vessels with more diameter (lumen) –Uses “trap door” to prevent blood from being pulled down by gravity.

Blood Vessels (13.8)

Pulmonary vs. Systemic (13.12) Circuit of blood through the heart. Circuit of blood through the whole body.

Heart (outside)

Heart (13.3) Four Chambers: Each side consists of an atrium (pl. atria) and a ventricle receiving dischargingAtrium is the receiving area that pumps blood into the ventricle, the discharging chamber

Heart (inside) (13.4) Semilunar Valves Bicuspid Valve

Heart Circulation (13.4) Right Atrium: receives deoxygenated blood from the superior and inferior vena cava and coronary veins – then pumps blood into the right ventricle. Right Ventricle: delivers de-oxygenated blood to the lungs via the pulmonary arteries. Left Atrium: receives blood from the pulmonary veins - then pumps blood to left ventricle *It’s walls are slightly thicker than rt. Atrium Left Ventricle: delivers oxygen rich blood to the entire body via the aorta. *It’s walls are twice as thick as the right ventricle because it does more work.

Blood Flow through Heart (13.4)

Heart Pumping Action (13.4) Click for animation Trace A Drop of Blood (13.4) Quia

Cardiac Cycle (13.5) Cardiac Cycle = “events of one complete heart beat” –Atria  Ventricle  Arteries The heart beat is often referred to by using the sounds LUBB, DUBB. Lubb = closing of AV (tri/bicuspid) valves Dubb = closing of the SL (pulm/aortic) valves

Cardiac Cycle Cont.. (13.5) The two atria contract at the same time, then they relax while the two ventricles simultaneously contract. The contraction phase = systole The relaxation phase = diastole At a normal heart rate, one cardiac cycle last for 0.8 seconds!

Cardiac Cycle Cont.. (13.5) Atrial diastole (relaxation) = atria fills with blood Atrial systole (contraction) = atria pumps blood into the ventricles Ventricular diastole = blood flows into ventricles Ventricular systole = blood pressure pushes blood out the arteries

The Normal Conduction System (13.5/7) The action potential is sent on a direct pathway.. –SA node  AV node  Bundle of His (AV bundle)  Bundle Branches  Purkinje fibers Sino Atrial (SA) node: “Pace Maker” – controls the electrical signals sent through the heart causing contractions to occur.

The electrocardiogram (EKG or ECG) is a graphic display of the electrical events of the cardiac cycle. What is an Electrocardiogram? (13.6) Each event has a distinctive waveform, the study of which can lead to greater insight into a patient’s cardiac output.

Wave Interpretation (13.6) P Wave = atrial systole PQ Wave = signal arrives at AV node slowing down a bit to allow ventricles to fill with blood Q Wave = signal moves to Bundle of His and divides into the bundles and Purkinje fibers R Wave = systole of left ventricle S Wave = systole of right ventricle T Wave = ventricular diastole

Cardiac Output Cardiac Output = volume (amount) of blood pumped per minute (rate) –Product of Heart Rate (beats/ min.) X Stroke Volume (vol./ beat) –At rest: 75 bpm X 70 ml/b = 5,250 mL/min. = 5.25 L/ min. –During exercise: 100 bpm X 110 ml/b = 11,000 mL/min = L/ min. –Extreme exercise: 120 bpm X 125 ml/b = 15,000 mL/ min. = L/ min.

Heart disorders (13.11) Arrhythmia – abnormal heartbeats –Tachycardia – heart beats > 100bpm –Bradycardia – heart beats < 60bmp Myocardial infarction (Heart attack) = Circulation Problem –occurs when blood stops delivering oxygen to the heart and it becomes damaged. Cardiac Arrest – Electrical problem –Pumping ceases with no contraction.

Heart Disorders/Diseases

Heart Rate = Pulse Pulse –Pressure wave of blood Monitored at “pressure points” in arteries where pulse is easily palpated Pulse averages 70–76 beats per minute at rest

Blood Pressure (13.10) Measurement of the force of blood traveling through your arteries. –Systolic—pressure at the peak of ventricular contraction –Diastolic—pressure when ventricles relax –Write systolic pressure first and diastolic last (120/80 mm Hg) Pressure in blood vessels decreases as distance from the heart increases

Measuring Arterial Blood Pressure