Description of Heart
A hollow, cone shaped, 4 chambered, muscular organ, which weighs about 11 oz. and is about the size of a closed or clenched fist (about 5 inches long and 3.5 inches wide).
Location of Heart
In the mediastinum, placed obliquely (slanted) with 2/3 of it lying left of the midline right border lying or resting on the diaphragm.
Orientation of Heart
The pointed end of the heart is called the apex, which is directed inferiorly and to the left. The wide portion of the heart is called the base, it lies opposite to the apex, and therefore, it lies superior and to the right.
Apex of Heart
Pointed End of the Heart
Base of Heart
Wide portion of Heart
1. Outer layer of Heart. 2. Has a visceral layer Epicaridum), cavity and parietal layer.
1. Another name for Visceral Pericaridum. 2. Adheres tightly to the heart.
1. Serous fluid which fills the Pericaridal Cavity. 2. Only a few millimeters thick. 3. Important because it helps reduce friction between the 2 layers as the heart moves when beating
1. Middle Layer of Heart. 2. The muscle portion of the heart; (the cardiac muscle) 3. The thickest layer and forms the bulk of the heart 4. Is the layer responsible for the pumping action (Remember, cardiac muscle is striated like skeletal muscle but it is involuntary!)
1. The inner most layer of the heart. 3. A thin layer of endothelium that lies over a thin layer of connective tissue. 3. Not only covers the valves of the heart but it is continuous with the endothelial lining of blood vessels
Upper chambers of Heart
Singular name for upper chamber of Heart
Lower chambers of Heart
Wall or partition dividing a body space or cavity
The partition or wall that separates the right atrium from the left atrium
Separates the atria from the ventricles. This is a general term for separating the upper chambers from the lower chamber without regard to the side of the heart.
Right Atrio-ventricular Septum
Separates the right atrium from the right ventricle
Left Atrio-ventricular Septum
Separates the left atrium from the left ventricle
Wall or partition that it is located between the right and left ventricles.
Number of valves in Heart
Function of a Valve
1. To allow blood to flow in one direction. In other words, it prevents a backflow or regurgitation of blood. 2. They open and close when the heart contracts.
Tricuspid Valve / Right Atrio-ventricular valve
1. Located between the right atrium and the right ventricle
2. Gets its name because it has 3 cusps or flaps. 3. It allows the blood to flow from the right atrium to the right ventricle but not in the opposite direction.
Bicuspid valve / Mitral valve / Left Atrio-ventricular valve
1. Located between the left atrium and the left ventricle
2. gets its name because it has 2 cusps or flaps. 3. It allows blood to flow in one direction; from the left atrium to the left ventricle.
Pulmonary Semi-lunar valve
1. Found at the orifice (opening) of the pulmonary trunk
2. It allows blood to flow from the right ventricle into the pulmonary trunk which in turn will deliver blood to the lungs
Aortic Semi-lunar valve
1. Located at the orifice of the aorta. 2. permits blood to leave the left ventricle and flow into the aorta (ascending aorta).
1. Receives blood from: Superior Vena Cava, Inferior Vena Cava, Coronary Sinus 2. Systemic circulation, which includes coronary circulation, terminates in this chamber via these three veins.
Right Atrium Contains
1. Pectinate muscles which are muscular ridges located in the anterior wall. 2. Fossa Ovalis. (This is the remainder of the foramen (opening) ovalis in the fetal heart that normally closes soon after birth.)
muscular ridges located in the anterior wall of Right Atrium
An oval depression located in the septal wall of the right atrium (This is the remainder of the foramen (opening) ovalis in the fetal heart that normally closes soon after birth.)
Right and Left Ventricles Contain
1. Trabeculae carneae 2. Papillary muscles 3. Chordae tendineae
1. A series of ridges formed by irregular folds of the myocardium. 2. They are located in the anterior wall of the right ventricle.
Cone-shaped muscles located in the anterior wall of the ventricles that project up into the lumina (cavity) of the ventricle.
1. Fibrous cords that attach the undersurface of the tricuspid valve to papillary muscles. 2. Purpose is to keep the flaps of the valve taut
1. Deoxygenated blood leaves the _____________ of the heart via the pulmonary trunk. It will carry this blood to the lungs for re-oxygenation. 2. Pulmonary circulation originates from this chamber.
1. Receives oxygenated blood from the lungs through the 4 pulmonary veins. 2. There are two right pulmonary veins coming from the right lung and 2 left pulmonary veins coming from the left lung...giving us 4 pulmonary veins. 2. Pulmonary circulation terminates in this chamber.
1. Oxygenated blood leaves the _____________of the heart via the ascending aorta. 2. Systemic circulation begins in this chamber. 3. Also contains Trabeculae Carneae, Papillary Muscles and Chordae Tendineae
4 Tissues involved in the Heart's Conduction System
1. Sinoatrial Node (SA Node) 2. Atrioventricular Node (AV Node) 3. Bundle of His 4. Purkinje Fibers
Sinoatrial Node (SA Node)
Acts as the pacemaker of the heart; initiates a cardiac impulse which causes the contraction of both atria
Atrio-ventricular Node (AV Node)
Acts as receiving and transfer station for cardiac impulses; picks up the impulse from the SA node and delivers it to the bundle of his
Bundle of His
Acts as transport for cardiac impulses, carrying them down the interventricular septum to the Purkinje fibers
Emerges from the bundles of his. The electrical impulses shoot through these fibers until it reaches the apex of the heart causing both ventricles to contract
The two atria contract as the two ventricles relax, and the two atria relax when the two ventricles contract.
Contraction phase of the cardiac cycle
Relaxation phase of the cardiac cycle
Descripion of Cardiac Cycle
1. So each time the ventricles contract, blood leaves the right ventricle by the pulmonary trunk and travels to the lungs and blood leaves the left ventricle via the aorta and travels throughout the body. As the ventricles are contracting forcing the blood out of the heart, the atria are relaxing to allow them to fill up with blood .
2. The right atrium receives venous blood (via the SVC, IVC and coronary sinus) from all areas of the body except from the lungs. The left atrium is relaxing and receives oxygenated blood from the lungs via the 4 pulmonary veins