The Tell Tale Heart ( ANNOTATED )

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The sinoatrial node (SAN) is of a group of cells found high up in the right atrium close to its junction with the superior vena cava. 1,4,5 blood moves into this chamber through the mitral valve (aka left atrioventricular valve; aka bicuspid valve) during ventricular diastole; blood moves out of this chamber through the aortic valve during ventricular systole Before we dive into what those structures are, let’s briefly review the blood flow through the heart. heartbeat in terms of myogenic muscle contraction, the role of the pacemaker, nerves, the medulla of the brain and epinephrine (adrenaline). Leipsic J, Abbara S, Achenbach S et al. SCCT Guidelines for the Interpretation and Reporting of Coronary CT Angiography: A Report of the Society of Cardiovascular Computed Tomography Guidelines Committee. J Cardiovasc Comput Tomogr. 2014;8(5):342-58. doi:10.1016/j.jcct.2014.07.003 - Pubmed

At this point, you may want to use your colored pencils to mark these vessels so that you don't get them confused when you are searching for the other two openings that top of the heart. Relaxation phase: During the relaxation phase, all 4 chambers of the heart are in diastole as blood pours into the heart from the veins. The ventricles fill to about 75% capacity during this phase and will be completely filled only after the atria enter systole. The cardiac muscle cells of the ventricles repolarize during this phase to prepare for the next round of depolarization and contraction. During this phase, the AV valves open to allow blood to flow freely into the ventricles while the semilunar valves close to prevent the regurgitation of blood from the great arteries into the ventricles. valve is open unless pressure inside the ventricle pushes it closed; papillary muscles and chordae tendineae prevent the valves from flipping open during ventricular systole (prolapse)

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The structure of the heart consists of four muscular chambers – the right and left atria and the right and left ventricles – which are separated by valves and blood vessels, allowing for the circulation of blood throughout the body. Keep reading for more detailed A-level Biology revision! Summary

It is important to remember the key time when the valves open and when they close; the AV valve closes when the ventricular pressure exceeds the atrial pressure, indicated on Figure 2. The AV valve will only open again when the ventricular pressure is below the atrial pressure. When I had waited a long time, very patiently, without hearing him lie down, I resolved to open a little — a very, very little crevice in the lantern. So I opened it — you cannot imagine how stealthily, stealthily — until, at length a simple dim ray, like the thread of the spider, shot from out the crevice and fell full upon the vulture eye. Safety of handling butcher material: Anything that a butcher sells must have been passed as ‘fit for human consumption’, but may be carrying food-poisoning bacteria. We don’t wear gloves when preparing meat in a kitchen, so it is not necessary to wear gloves, but it is necessary to wash hands thoroughly after handling the material and before leaving the laboratory. The government has enacted the Specified Risk Materials (SRM) Regulations and these determine the parts of slaughtered animals which may be capable of transmitting spongiform encephalopathies and therefore must not be supplied. Only materials from cattle, sheep and goats are currently specified and only under certain circumstances. Thus anything that you can obtain through normal channels should not be SRM and could therefore be used. Do not store the material used for dissection in refrigerators used for food. The left ventricle is responsible for pumping blood to the whole body. Oxygenated blood is pumped to the whole body through the aorta. Which chamber receives deoxygenated blood from the body? The cardiac cycle is a series of physiological, mechanical and electrical events comprising one heartbeat. What are the different stages of the cardiac cycle?

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It was open — wide, wide open — and I grew furious as I gazed upon it. I saw it with perfect distinctness — all a dull blue, with a hideous veil over it that chilled the very marrow in my bones; but I could see nothing else of the old man's face or person: for I had directed the ray as if by instinct, precisely upon the damned spot.

The heart develops from the fusion of two endocardial cardiac tubes of endodermal origin into a primitive heart tube which then undergoes a complex series of dilatations, twisting, and septation in the first month which is covered in detail in the article development of the heart. Variant anatomy The auricle is the flap that covers the atrium, it looks like an ear. The pulmonary trunk is the located at the front of the heart and enters at an angle.

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The diagram of heart is beneficial for Class 10 and 12 and is frequently asked in the examinations. A detailed explanation of the heart along with a well-labelled diagram is given for reference. Well-Labelled Diagram of Heart The first part of the wave, called the P wave, is a small increase in voltage of about 0.1 mV that corresponds to the depolarization of the atria during atrial systole. The next part of the EKG wave is the QRS complex which features a small drop in voltage (Q) a large voltage peak (R) and another small drop in voltage (S). The QRS complex corresponds to the depolarization of the ventricles during ventricular systole. The atria also repolarize during the QRS complex, but have almost no effect on the EKG because they are so much smaller than the ventricles. The sino-atrial node (the pace maker) is a specialized bundle of thin, cardiac, muscular fibers buried in the right atrial wall, near the connection between the right auricle and the large veins The heart sits within a fluid-filled cavity called the pericardial cavity. The walls and lining of the pericardial cavity are a special membrane known as the pericardium. Pericardium is a type of serous membrane that produces serous fluid to lubricate the heart and prevent friction between the ever beating heart and its surrounding organs. Besides lubrication, the pericardium serves to hold the heart in position and maintain a hollow space for the heart to expand into when it is full. The pericardium has 2 layers—a visceral layer that covers the outside of the heart and a parietal layer that forms a sac around the outside of the pericardial cavity. Structure of the Heart Wall

I don't want to bother you much with what happened to me personally," he began, showing in this remark the weakness of many tellers of tales who seem so often unaware of what their audience would like best to hear; "yet to understand the effect of it on me you ought to know how I got out there, what I saw, how I went up that river to the place where I first met the poor chap. It was the farthest point of navigation and the culminating point of my experience. It seemed somehow to throw a kind of light on everything about me -- and into my thoughts. It was sombre enough, too -- and pitiful -- not extraordinary in any way -- not very clear either. No, not very clear. And yet it seemed to throw a kind of light Blood will then exit the right ventricle through the pulmonary valve and enter the lungs to be oxygenated. These steps make up one full contraction of your heart muscle. Your heart conduction system sends out thousands of signals per day to keep your heart beating. How does electrical conduction perform with the rest of your heart? As the pressure in the ventricle increases, (and becomes greater than that of the pulmonary artery and the aorta), the semilunar valves guarding the openings of these arteries open, and blood enters them. From the right ventricle, the deoxygenated blood enters the pulmonary artery. From the left ventricle, the oxygenated blood enters the dorsal aorta, to be taken to other body parts. Ventricular systole takes about 0.3 seconds.A normal healthy ECG trace shows what is known as the “PQRST shape” (Figure 5). Wave P is the stage that corresponds to atrial systole, excitation and contraction of the atria. Ventricular systole forms the “QRS” complex and the start of ventricular diastole corresponds to the “T” wave. Figure 5: The start is diastole where both the atria and ventricles are relaxed. The P wave shows the depolarisation of the atria and is followed by atrial systole (contraction). Atrial systole continues to the end of the QRS complex and the point where the atria relax. The QRS complex shows the relaxation of the ventricles and is followed by ventricular systole (contraction). The T wave represents a further depolarization (re- polarization) and marks the start of ventricular relaxation. The division of the heart into four cavities is indicated on its surface by grooves. The atria are separated from the ventricles by the coronary sulcus (atrioventricular groove); this contains the trunks of the nutrient vessels of the heart and is deficient in front, where it is crossed by the root of the pulmonary artery. The interatrial groove, separating the two atria, is scarcely marked on the posterior surface while anteriorly it is hidden by the pulmonary trunk and ascending aorta. The heart consists of two pumps that work together where both sides of the heart relax and contract with one another Atrial systole is where the atria within the heart contract and tops up the ventricles that are already filled with blood.