The Heart & Circulation Lab Activity #7.1 The Heart & Circulation

Most simply stated, the major function of the cardiovascular system is TRANSPORTATION.

Substances carried in the blood include… Oxygen Carbon Dioxide Nutrients Cell wastes Hormones

The Heart Size of a fist Weighs less than a pound Apex directed toward left hip, and rest on diaphragm Bulk of mass between 2nd and 6th rib About 2/3 of heart is left of median

Interesting facts… The heart beats 100,000 times a day Approximately 35 million times a year 2.5 billion times during the average life span Your 6 quarts (1.5 gallons) of blood pumped through your body 1,000 times per day That’s 6000 quarts (1,500 gallons) of fluid that your heart pumps every day

Pericardium Double sac of serous membrane around the heart Visceral pericardium (epicardium) Next to heart Actually part of heart wall Parietal pericardium Outside layer Anchors heart to surrounding structure Serous fluid fills the space between the layers of pericardium; eliminates friction

Heart Wall Three layers Epicardium Outside layer AKA visceral pericardium Connective tissue layer

Heart Wall Three layers Myocardium Middle layer Mostly cardiac muscle Layer that contracts

Heart Wall Three layers Endocardium Inner layer Thin sheet of Endothelium (simple squamous membrane)

Four Chambers of the Heart Atria – on top Receiving chambers Atrium is singular! Auricle is lateral “pouching” of each atrium Ventricles – on bottom Discharging chambers Left ventricle has thickest wall because it pumps blood to rest of body! Lined with endocardium to help blood flow smoothly through

Heart Supporting Structures Superior Vena Cava: carries oxygen-poor blood from body to heart (right atrium) Inferior Vena Cava: carries oxygen-poor blood from body to heart (right atrium)

Heart Supporting Structures Pulmonary trunk: carries oxygen-poor blood from heart (right ventricle) to pulmonary arteries Pulmonary arteries: carries oxygen-poor blood from pulmonary trunk to lungs Only artery to carry O2 poor blood!

Heart Supporting Structures Pulmonary Veins: carries oxygen-rich blood from lungs to heart (left atrium) Only vein to carry O2 rich blood! Aorta: carries oxygen-rich blood from heart (left ventricle) to body Largest artery in body

The heart does 2 types of circulation… Pulmonary Circulation Leaves from right side of heart Delivers CO2 waste to lungs, and picks up O2 to take back to heart Returns to left side of heart Systemic Circulation Leaves from left side of heart Delivers O2 and nutrients to body, and picks up CO2 to take back Returns to right side of heart

The Valves The heart is equipped with four valves… Allow blood to flow in only ONE direction through the heart chambers Have cusps (flaps) that open & close

The Valves Have CHORDAE TENDINEAE (“heart strings”) which hold the cusps in place Prevent backflow of blood

Atrioventricular (AV) Valves Located between the atrial and ventricular chambers Left AV Valve: Bicuspid (Mitral) valve 2 cusps Right AV Valve: Tricuspid valve 3 cusps OPEN during heart relaxation and CLOSED when ventricles contracting

FYI: Why the special name for the bicuspid valve? Early anatomists thought that the bicuspid (mitral) valve looked like a bishop’s miter (their funny hat)

Semilunar Valves Guards the bases of the two large arteries leaving the ventricular chambers Pulmonary Semilunar Valve (right) Aortic Semilunar Valve (left) Both have THREE cusps CLOSED during heart relaxation and OPEN when ventricles contracting http://www.youtube.com/watch?v=WXwYYsi6z7Q

Blood Supply to Heart The blood supply that oxygenates and nourishes the heart itself (myocardium) is provided by the right & left CORONARY ARTERIES, which branch from the base of the AORTA and encircle the heart in the ATRIOVENTRICULAR GROOVE.

Coronary arteries branch off from the base of the aorta Right Coronary Artery breaks into… Posterior interventricular (on back side of heart) Marginal Left Coronary Artery breaks into… Anterior interventricular Circumflex

Blood Supply to Heart The heart (myocardium) is drained by several CARDIAC VEINS, which empty into the CORONARY SINUS, which in turn, empties into the RIGHT ATRIUM.

Cardiac Veins include… Great cardiac vein Anterior cardiac vein Small cardiac vein Middle cardiac vein (on posterior side of heart)

Labeling The Heart A: Aortic Arch (Aorta) B: Superior Vena Cava C: (Right) Pulmonary Veins D: Right Atrium E: Tricuspid Valve AB: Right Ventricle AC: Inferior Vena Cava

Labeling The Heart AD: (Left) Pulmonary Artery AE: Left Atrium BC: Bicuspid (Mitral) Valve BD: Aortic Semilunar Valve BE: Left Ventricle CD: Aorta

Labeling The Heart Let’s Also Label… Pulmonary Trunk Pulmonary Semilunar Valve Septum Apex