The Cardiovascular System The Cardiovascular System {The Heart} Chapter 13

Cardiovascular System Cardiovascular System a/k/a Circulatory System Heart Pumps blood Blood Fluid of system Blood vessels Pathway of tubules for blood Veins (venules): capillaries  heart  Vena cava = largest veins Arteries (arterioles): heart  capillaries  Aorta = largest artery

Terminology Cardiology: study of the structure, function, & diseases of the heart Electrocardiogram (ECG): recording of electrical changes that accompany heart beat Cardiac cycle: one heart beat Systole: contraction of heart muscle Diastole: relaxation of heart muscle Stroke volume: the amount of blood pumped out per beat Septum: divider

About the heart… Located in the mediastinum between lungs 2/3 to the left of midline Approx. the size of a fist Apex (tip) points downward Heart muscle = myocardium

Tissues of the heart Membranes (serous fluid in between layers) Parietal pericardium: makes up a tough, fibrous cavity that the heart sits in Visceral pericardium: covers surface of the heart **Inflammation of the pericardial membranes = pericarditis Muscle Epicardium: covers the exterior surface of the heart Myocardium: bulk of heart muscle Endocardium: lines the interior cavities of the heart

Cardiopulmonary Resuscitation (CPR) Rhythmic compression of the heart Coupled with artificial respiration it can be life saving Works because the heart is sandwiched between 2 firm surfaces Anteriorly, the sternum Posteriorly, the body of the vertebrae

Conditions/Disorders/Diseases Angina pectoris: chest pain (usually precursor to heart attack) Myocardial infarction: heart attack; caused by insufficient blood flow to myocardium; therefore tissue dies Heart murmur: valve disorder; causes backflow of blood Palpitation: irregular heart beat Phlebitis: Inflammation of a vein Hypertension: high blood pressure Cardiovascular Disease

5 types of circulation Systemic: blood pumping to body (system) Pulmonary: blood pumping to the lungs Coronary: blood pumping to the heart itself Fetal: circulation of blood to and from the placenta Hepatic: blood going through liver to be filtered and detoxified

Electricity of the Heart Sinoatrial (SA) node: the heart’s natural pacemaker; initiates action potentials; located in atrial wall Atrioventricular (AV) node: the heart’s “back up” pacemaker Bundle of His & Purkinje fibers carry impulse throughout heart

When SA node initiates… 1 st: atria contract simultaneously while ventricles are relaxing 2 nd : atria relax while ventricles simultaneously contract **This simultaneous contraction and relaxation results in a lubb-dupp sound

The lubb-dupp of your heart… Results from closing of heart valves Lubb = quiet; systole of atria; diastole of ventricles (AV valves closing) Dupp= loud; systole of ventricles; diastole of atria (semilunar valves closing) 1 heart beat (cardiac cycle) takes about 0.8 secondscardiac cycle Average resting heart rate = 75 bpm (beats per minute) Average stroke volume = 70mL

Components of heart Chambers Upper Right atrium Left atrium Lower Right ventricle Left ventricle Vessels Pulmonary Pulmonary artery  Right & left branches Pulmonary veins  2 right & 2 left branches Systemic Superior vena cava Inferior vena cava aorta

Valves of the heart Function: to prevent backflow of blood Held in place by papillary muscle (in base of chamber) & chordae tendineae Lessens chance of oxygenated & deoxygenated blood mixing Right AV valve (tricuspid): b/w right atrium & ventricle Left AV valve (bicuspid/mitral): b/w left atrium & ventricle Pulmonary semilunar valve: b/w right ventricle & pulmonary artery Aortic semilunar valve: b/w left ventricle & aorta

Blood Flow Through Heart {Pulmonary Circulation} Superior vena cava (from upper body) & inferior vena cava (from lower body) carry deoxygenated blood  right atrium When right atrium fills, it contracts and forces blood through the right AV valve (tricuspid)  right ventricle When right ventricle fills, it contracts and forces blood through the pulmonary semilunar valve  pulmonary artery (trunk) The trunk of the pulmonary artery divides into right and left pulmonary branches  right and left lungs In lungs: oxygen and carbon dioxide are exchanged

Blood Flow Through Heart {Systemic Circulation} Pulmonary veins carry oxygenated blood  left atrium When the left atrium fills, it contracts and forces blood through the left AV valve (bicuspid, mitral)  left ventricle When the left ventricle fills, it contracts and forces blood through the aortic semilunar valve  aorta (ascending, arch, & descending) Aorta  entire body

Blood Flow Through Heart {Coronary Circulation} Aorta Ascending (1 st inch) Coronary vessels branch off here Go back to myocardium Arch (curve) 3 branches: services left arm, head & neck, and right arm Descending (remainder) Thoracic aorta Abdominal aorta  iliac arteries in legs

Overview Superior & inferior vena cava  right atrium  right AV valve (tricuspid)  right ventricle  pulmonary semilunar valve  pulmonary artery (& branches)  lungs (drop off CO 2, pick up O 2 )  pulmonary veins  left atrium  left AV valve (bicuspid, mitral)  left ventricle  aortic semilunar valve  aorta  body (drop off O 2, pick up CO 2 )

The Double Pump Although we describe the flow of blood as linear, it is truly a double pump Both atria contract together Both ventricles contract together Myocardium in the right side of the heart is thinner as it is pumping to the nearby lungs Myocardium in the left side of the heart is thicker as it is pumping all over the body

Exceptions to the rule… Most of the time Veins carry deoxygenated blood (dark reddish purple blood) Arteries carry oxygenated blood (bright red blood) However, Pulmonary arteries & umbilical arteries carry deO 2 blood Pulmonary veins & umbilical veins carry O 2 blood

You must know… The flow of blood through the heart 4 chambers 5 vessels 4 valves (all names)