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UH BIOL 1344 - Layers of the Heart
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BIOl 1344 Lecture 5 Outline of Last Lecture I. Determining blood typeII. Blood Clotting FactorsIII. Stages of Blood ClottingA. Intrinsic and Extrinsic pathwaysB. Intravascular clottingIV. Characteristics of the HeartV. Blood flow through the HeartOutline of Current Lecture VI. Layers of the HeartVII. Valves in the Heart and Conditions with Malfunctioning ValvesVIII. Coronary Arteries and Blood Pressure IX. Cardiac Muscle CellsCurrent LectureLayers of the heart:The epicardium is the visceral pericardium. Next comes the myocardium which is the muscular layer. This layer is responsible for muscular contraction and creating the force needed to pump blood out of the heart. The innermost layer is the endocardium, also known as the endotheliumwhich is a single layer of cells. The valves in the heart can become incompetent which mean that they do not properly close. This can cause back flow into the heart, or regurgitation. Valvular stenosis is a condition in which the valve opening is too narrow and more force is needed to pump blood through the opening. This causes this heart to become enlarged from working so hard and can result in a pain, chest tightness, or even a stroke. Aortic insufficiency is a condition in which the aortic valve is not working correctly and blood can flow back into the heart. This results in less blood going out to the body causing shortness of breath in the sufferer because the body is not receiving sufficient oxygen. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.There are four valves in the human heart. They are made of fibrous, collagen tissues and are non-conducting, non-contractile, and they electrically isolate. 1) Aortic Valve2) Tricuspid Valve 3) Bicuspid Valve4) Pulmonary Semilunar Valve The coronary arteries supply the heart with the blood. They move about 5 Liters of blood/minute or about 70 mL per beat with 70 beats/minutes. The anterior interventricular coronary feeds most of the left ventricle. The circumflex – backside of the heart. The posterior interventricular coronary – right ventricle. And the marginal coronary – lateral side of the heart. The systemic circuit which is the circuit in which blood flows from the heart to the body should maintain a blood pressure of 120/70 mmHg while the pulmonary circuit which is simply back and forth from the lungs to the heart should be about 25/8 mmHg. If the pulmonary circuit B. P. rises too much, the person has what is called pulmonary edema. This can happen at high altitudes. The human heart is a myogenic heart which means that the muscles are auto rhythmic, there is no nerve stimulus needed to maintain beating. Heart contractions begin at the apex which is the bottom of the heart and “wrings out” or causes a squeezing action to push the blood out of the top. A neurogenic heart requires nerve stimulus. 99% of the cardiac muscle cells are auto rhythmic cells which are contractile. They are excitable cells which generate force and action potential which causes muscle contraction. 1% of the cells are auto rhythmic cells which are excitable but are non-contractile. Instead they generate an electrical impulse. There are also pace maker cells. There are two types of these – sinoatrial node, and atrioventricular node which control nodal rhythm in the heart. These keep the heart rate at approximately 70 beats per minute (bpm). If the first pacemaker dies, the second will take over and maintain about 40-60 bpm. If the second dies, the papillary muscles will take overand maintain about 25 bpm. When muscle cells die, there is no regeneration. Instead scar tissuewill form and if enough cells die, this causes a heart


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UH BIOL 1344 - Layers of the Heart

Type: Lecture Note
Pages: 2
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