Cardiovascular System

• Two divisions: pulmonary & systemic

• Pulmonary Division

–Blood flows from heart to alveolar capillaries and back to heart

• Systemic Division

– Blood flows from heart to all tissue capillaries (except alveolar capillaries) and back to heart

• Heart

– Location: mediastinum

– Size: about that of a fist

• Pericardium: protective sac surrounding the heart

• Layers of the heart wall

– endocardium

– myocardium

– epicardium (same as the visceral pericardium)

• Chambers of the heart

– Receiving chambers: atria (singular: atrium)

– Pumping chambers: ventricles

• Right ventricle: pump for the pulmonary circulation

• Left ventricle: pump for the systemic circulation

• “Great Vessels” of the Heart

– Aorta

– Pulmonary Trunk

• Heart valves: ensure one-way flow of blood through heart

– Semilunar valves

• pulmonary semilunar

• aortic semilunar

– Atrio-ventricular (AV) valves

• tricuspid

• bicuspid (mitral)

Ø Associated with papillary muscles and chordae tendineae

• Skeleton of the Heart

– Set of 4 fibrous rings near base of heart

– Provides rigidity to prevent the dilation of valves

– Provides a point of attachment for valves

– Electrically isolates the atria from the ventricles.

• The A-V bundle (“bundle of His”) is the only electrical connection between the atria and the ventricles

• Path of Blood Flow Through the Heart (see diagram from lecture)

• Heart Sounds

– 1^st sound (“lub”)

• closing of the AV valves

– 2^nd sound (“dup”)

• closing of the semilunar valves

• Blood Vessels

–Arteries

–Arterioles

–Capillaries

–Venules

–Veins

• All blood vessels are lined with endothelium

• Arteries

– Carry blood away from the heart

– Subject to the highest blood pressure

– Located deep

– Structure of Arteries

• Tunica interna

• Tunica media

• Tunica externa

• Types of arteries

– Elastic arteries

• Contain elastic fibers in the tunica media and interna

• Largest arteries

• Arterioles

• < 1mm in diameter

• Endothelium and smooth muscle

• Metarterioles regulate flow of blood into capillaries

• Help regulate blood pressure

• Capillaries

• Sites of exchange

Øexchange between blood and tissue cells in systemic caps

Øexchange between blood and air in pulmonary caps

• Very permeable

– Veins

• Return blood back towards heart

• Smallest veins: venules

• Veins have 3 layers like arteries

• Differences between arteries and veins

– thinner

– larger diameter

– located both deep and superficial

– veins have valves

Distribution of Blood

• Coronary Circulation

– Blood flow to and from the myocardial capillaries

• Some vessels of the coronary circuit

– Right coronary artery

– Left coronary artery

• circumflex

• anterior interventricular (also: LAD)

– Coronary sinus

• Hepatic Portal Circulation

• Features of fetal heart

– Foramen ovale

– Ductus arteriosus

• Other features of fetal circulation

– Umbilical arteries and veins

– Ductus venosus

• Changes in fetal circulation after birth

– foramen ovale closes

– ductus arteriosus closes

· Coronary Artery Disease

– Degenerative changes in coronary arteries

– Often associated with arterial plaques