The Cardiovascular System

{The Heart}Chapter 13

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… 1st: atria contract simultaneously while

ventricles are relaxing 2nd: 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

seconds 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 (1st 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

OverviewSuperior & inferior vena cava right atrium

right AV valve (tricuspid) right ventricle pulmonary semilunar valve pulmonary artery (& branches) lungs (drop off CO2, pick up O2) pulmonary veins left atrium left AV valve (bicuspid, mitral) left ventricle aortic semilunar valve aorta body (drop off O2, pick up CO2)

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

deO2 blood Pulmonary veins & umbilical veins carry O2 blood

You must know… The flow of blood through the heart

4 chambers 5 vessels 4 valves (all names)