Ch. 18.3 Pathway of Blood Through Heart

Coronary arteries

- Both left and right coronary arteries arise from base of aorta and supply arterial blood to heart - Both encircle heart in coronary sulcus - Branching of coronary arteries varies among individuals - Arteries contain many anastomoses (junctions) • Provide additional routes for blood delivery • Cannot compensate for coronary artery occlusion - Heart receives 1/20th of body's blood supply

Coronary veins

- Collect blood from capillary beds - Coronary sinus empties into right atrium; formed by merging cardiac veins • Great cardiac vein of anterior interventricular sulcus • Middle cardiac vein in posterior interventricular sulcus • Small cardiac vein from inferior margin - Several anterior cardiac veins empty directly into right atrium anteriorly

Left side of the heart

- Four pulmonary veins --> - Left atrium --> - Mitral valve --> - Left ventricle --> - Aortic semilunar valve --> - Aorta --> - Systemic circulation

Coronary circulation

- Functional blood supply to heart muscle itself - Shortest circulation in body - Delivered when heart is relaxed - Left ventricle receives most of coronary blood supply

Myocardial infarction (heart attack: Homeostatic Imbalance)

- Prolonged coronary blockage - Areas of cell death are repaired with noncontractile scar tissue

Right side of the heart

- Superior vena cava (SVC), inferior vena cava (IVC), and coronary sinus --> - Right atrium --> - Tricuspid valve --> - Right ventricle --> - Pulmonary semilunar valve--> - Pulmonary trunk --> - Pulmonary arteries --> - Lungs

Angina pectoris (Homeostatic Imbalance)

- Thoracic pain caused by fleeting deficiency in blood delivery to myocardium - Cells are weakened

Equal volumes

_______ of blood are pumped to pulmonary and systemic circuits

Systemic circuit

________ is long, high-friction circulation

Pulmonary circuit

________ is short, low-pressure circulation

Anatomy of ventricles reflects differences Left ventricle

________ walls are 3 X's thicker than right • Pumps with greater pressure

Coronary sinus

empties into right atrium; formed by merging cardiac veins • Great cardiac vein of anterior interventricular sulcus • Middle cardiac vein in posterior interventricular sulcus • Small cardiac vein from inferior margin

Small cardiac vein

from inferior margin

Middle cardiac vein

in posterior interventricular sulcus

Great cardiac vein

of anterior interventricular sulcus

Anterior cardiac veins

several ________ empty directly into right atrium anteriorly

Left coronary artery

supplies interventricular septum, anterior ventricular walls, left atrium, and posterior wall of left ventricle has two branches: • Anterior interventricular artery • Circumflex artery

Right coronary artery

supplies right atrium and most of right ventricle; has two branches: • Right marginal artery • Posterior interventricular artery