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Anatomy 1.6
the Heart
| Question | Answer |
|---|---|
| How much does the heart weigh? | approximately 11 ounces |
| How big is the heart? | approximately 5 inches long and 3.5 inches wide |
| Where is the heart located? | The heart is located in the mediastinum and sits obliquely with 2/3 lying left of the midline. |
| What does the right border of the heart rest on? | the diaphragm |
| How many layers does the heart consist of? | three: pericardium, myocardium, and the endocardium |
| The pericardium is what kind of membrane? | The pericardium a serous membrane, which means it has two layers separated by a cavity. The two layers are the parietal pericardium and the epicardium or visceral pericardium, separated by the pericardial cavity full of serous fluid (pericardial fluid). |
| What function does the pericardial cavity serve? | This cavity is very thin, only a few milliliters thick, but it has the important responsibility of reducing friction between the two pericardial layers when the heart is beating. |
| Pericardium | This is the outer most layer of the heart and it is a serous membrane. |
| Myocardium | This is the middle layer of the heart. It is the muscle portion of the heart (cardiac muscle) and is responsible for the pumping action. |
| Endocardium | This is the inner most layer of the heart. It is a thin layer of endothelium that lies over a thick layer of connective tissue an the valves of the heart. |
| Which layer of the heart is the thickest? | The myocardium, or middle layer. |
| Cardiac muscle | striated and involuntary |
| How many chambers are there in the heart? | 4 chambers: upper chambers (the right atrium and the left atrium), lower chambers (right ventricles and left ventricles) |
| Septum | A wall or partition dividing a body space or cavity. |
| Interatrial Septum | This is the partition or wall that divides the right atrium from the left atrium. |
| Atrio-ventricular Septum | This is the partition or wall which separates the atria from the ventricles. This can be broken down into the right atrio-ventricular septum and the left atrio-ventricular septum. |
| Interventricular Septum | This is the wall or partition that separates the right ventricle from the left ventricle. |
| How many valves does the heart have? | 4 valves: tricuspid valve, bicuspid valve, pulmonary semi-lunar valve, aortic semi-lunar valve |
| What is the function of a heart valve? | The valves of the heart ensure that blood flows in one direction, preventing backflow. They open and close when the heart contracts and relaxes. |
| Tricuspid Valve or Right Atrio-Ventricular Valve | Located on the right between atrium and ventricle, this valve has 3 cusps or flaps, allowing blood to flow from right atrium to right ventricle but not in the opposite direction. |
| Bicuspid Valve, Mitral Valve or Left Atrio-Ventricular Valve | Located on the left between the atrium and ventricle, this valve has 2 cusps or flaps, allowing blood to only flow from the left atrium to the left ventricle. |
| Pulmonary Semi-Lunar Valve | Located at the orifice of the pulmonary trunk, it allows blood to flow from the right ventricle into the pulmonary trunk which will deliver the blood to the lungs. |
| Aortic Semi-Lunar Valve | Located at the orifice of the aorta, this valve allows blood to flow from the left ventricle and flow into the ascending aorta. |
| What are the veins in the Right Atrium? | The superior vena cava (SVC), the inferior vena cava (IVC), and the coronary sinus. |
| Superior Vena Cava | This vein in the right atrium returns blood from all areas above the diaphragm. |
| Inferior Vena Cava | This vein in the right atrium returns blood from areas inferior to the diaphragm. |
| Coronary Sinus | This vein in the right atrium is located in the posterior wall and returns blood from the coronary circulation. |
| Systemic Circulation | This includes coronary circulation and terminates in the right atrium by way of the three veins: superior vena cava, inferior vena cava, and the coronary sinus. |
| What does the Right Atrium contain? | the pectinate muscles and the fossa ovalis |
| Pectinate Muscles | These are muscular ridges located in the anterior wall of the right atrium. They run parallel to each other and resemble the teeth of a comb. |
| Fossa Ovalis | An oval depression located in the septal wall of the right atrium. This is the remainder of the foreamen (opening) ovalis in the fetal heart that closes shortly after birth. |
| What does the Right Ventricle contain? | the trabeculae carneae, the papillary muscles, and the chordae tendineae |
| Trabeculae Carneae | a series of ridges formed by irregular folds of the myocardium, located in the anterior wall of the right and left ventricles |
| Papillary Muscles | cone shaped muscles located in the anterior wall of the left and right ventricles that project up into the lumina (cavity) of the ventricle. |
| Chordae Tendineae | fibrous cords that attach to the under-surface of the tricuspid and bicuspid valves to the papillary muscles. |
| What chamber does pulmonary circulation originate from? | the right ventricle |
| What kind of blood leaves the Right Ventricle through the pulmonary trunk. | deoxygenated blood leaves the right ventricle through the pulmonary trunk. It carries the blood to the lungs for re-oxygenation. |
| What is the purpose of the chordae tendineae? | to keep the flaps or cusps of the tricuspid valve taut so blood flows in one direction only. |
| Left Atrium | the superior left chamber of the heart. it |
| What kind of blood does the Left Atrium receive? | It receives oxygenated blood from the lungs through the four pulmonary veins: two pulmonary veins from each lung. |
| Where does pulmonary circulation terminate? | in the Left Atrium chamber. |
| What does the Left Ventricle mimic? | the Right Ventricle |
| What do the Left and Right Ventricles both house? | the trabeculae carneae, papillary muscles and cordae tendineae. |
| How does the heart beat? | by an intrinsic regulating system of four specialized cardiac muscle fibers which generate electrical impulses and distribute them throughout the cardiac muscle. |
| Autorhythmic fibers | self-excitable - example being the cardiac muscle fibers which generate their own electrical impulses. |
| What are the four tissues in the conduction system? | Sinoatrial Node (SA Node), Atrioventricular Node (AV Node), Bundle of His, Purkinje Fibers |
| Sinoarterial Node (SA Node) | This tissue is part of the conduction system, acts as a pacemaker of the heart, initiates a cardiac impulse which causes the contraction of both atria. |
| Atrioventricular Node (AV Node) | This tissue is part of the conduction system, acts as a receiving and transfer station for cardiac impulses, picking up the impulse from SA Node and delivering it to the Bundle of His. |
| Bundle of His | This tissue is part of the conduction system, acts as transport for cardiac impulses, carrying them down the interventricular septum to the Purkinje fibers. |
| Purkinje Fibers | This tissue is part of the conduction system, emerging from the Bundle of His. Electrical impulses course through these fibers until they reach the apex of the heart causing ventricles to contract. |
| Systole | The contraction phase of the cardiac cycle |
| Diastole | The relaxation phase of the cardiac cycle |
| In what pattern do the chambers of the heart contract and relax? | As the two atria contract, the two ventricles relax, and as the two ventricles contract, the two atria relax. |
| What happens when the ventricles contract? | Blood leaves the right ventricle by way of the pulmonary trunk and travels to the lungs, simultaneously blood leaves the left ventricle via the aorta and travels throughout the body. Meanwhile, the atria are relaxing to allow blood in. |
| How does the right atrium receive venous blood? | Deoxygenated blood enters the right atrium via the SV, IVC & the coronary sinus, from all areas of the body except the lungs. |
| While the right atrium receives venous blood, what happens to the left atrium? | The left atrium relaxes as receives oxygenated or arterial blood from the lungs via the 4 pulmonary veins. |
Created by:
kellyrb
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