Biology and Anatomy & Physiology Helps: The Heart (Biology and Anatomy and Physiology Helps: Book 4)
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However, arguably the most important substance it circulates is oxygen. Oxygen is required for animal cells to perform cellular respiration. Without oxygen, cells cannot break down food to produce ATP, the cellular currency of energy.
Soon, none of their energy-dependent processes can function. Without its energy-dependent processes, a cell dies. Neural tissues, including the brain, are particularly sensitive to oxygen deprivation.
Anatomy and Physiology of the Human Heart
Neural tissues maintain a special cellular chemistry which must be constantly maintained through the consumption of lots and lots of energy. If ATP production stops, neural cells can begin to die within minutes. For this reason, the body has taken many special measures to protect the heart. It is located below the strongest part of the ribcage and cushioned between the lungs. It is also surrounded by a protective membrane called the pericardium, which is filled with additional cushioning fluid.
Here we will review its essential components, and how and why blood passes through them. The heart has three layers of tissue , each of which serve a slightly different purpose. These are:. The heart has four chambers, which are designed to pump blood from the body to the lungs and back again with extremely high efficiency. You may be wondering how the heart ensures that blood flows in the right direction between these chambers and blood vessels.
Heart valves are just that — biological valves that only allow blood to flow through the heart in one direction, ensuring that all the blood gets to where it needs to be.
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Here is a list of the most important valves in the heart, and an explanation of why they are important:. Many people have minor irregularities with these valves, such as mitral valve prolapse, which make their hearts less efficient or more prone to experiencing problems. People with minor valve issues can often lead a normal, healthy life.
However, total failure of any of these valves can be catastrophic for the heart and for blood flow. The sinoatrial node is another very important part of the heart. It is a group of cells in the wall of the right atrium of the heart — and it is what keeps the heart pumping! The cells in the sinoatrial node produce small electrical impulses in a regular rhythm. These impulses are what drive the contractions of the four chambers of the heart. However, healthy people have a natural pacemaker built right into the heart!
Heart Definition The heart is a muscular organ that pumps blood throughout the body. Function of the Heart The heart pumps blood through our immense and complicated circulatory systems at high pressure. Layers of the Heart Wall The heart has three layers of tissue , each of which serve a slightly different purpose. These are: The Epicardium. The epicardium is also sometimes considered a part of the protective pericardial membrane around the heart. It helps to keep the heart lubricated and protected. The Myocardium.
The myocardium is the muscle of the heart. It is responsible for pumping blood throughout the body.
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The Endocardium. The endocardium is a thin, protective layer on the inside of the heart. It is made of smooth, slippery endothelial cells, which prevent blood from sticking to the inside of the heart and forming deadly blood clots. Chambers of the Heart The heart has four chambers, which are designed to pump blood from the body to the lungs and back again with extremely high efficiency. The right and left atria are the smaller chambers of the heart, and they have thinner, less muscular walls.
The Right Ventricle. The ventricles are larger chambers with stronger, thicker walls. They are responsible for pumping blood to the organs at high pressures. There are two ventricles because there are two circuits blood needs to be pumped through — the pulmonary circuit, where blood receives oxygen from the lungs, and the body circuit, where oxygen-filled blood travels to the rest of the body.
BIOL 121: Anatomy & Physiology I
Maintaining these two separate circuits with two separate ventricles is much more efficient than simply pumping blood to the lungs and allowing it to flow to the rest of the body from there. With two ventricles, the heart can generate twice the force, and deliver oxygen to our cells much faster. The right ventricle is the one attacked to the pulmonary circuit. It pumps blood through the pulmonary artery and to the lungs, where the blood fills with oxygen, at high pressure.
The blood then returns to… The left atrium receives oxygenated blood from the pulmonary veins. It pumps this blood into the left ventricle, which… The left ventricle pumps blood throughout the rest of the body. In most people, this whole circulatory path only takes about a minute to complete! Valves of the Heart You may be wondering how the heart ensures that blood flows in the right direction between these chambers and blood vessels.
Here is a list of the most important valves in the heart, and an explanation of why they are important: The Tricuspid Valve. As you might guess by the name, it ensures that blood only flows from the atrium to the ventricle — not the other way around.
Heart - Wikipedia
These atrioventricular valves have to stand up to very high pressures to ensure that no blood gets through, as the ventricle contracts quite powerfully to squeeze blood out. The tricuspid valve is the valve that ensures that blood in the right ventricle goes into the pulmonary artery and reaches the lungs, instead of being pushed back into the right atrium.
The Pulmonary Valve. The pulmonary valve is what is called a semilunar valve.
enter Semilunar valves are found in arteries leaving the heart. Without properly functioning semilunar valves, blood can flow back into the ventricle instead of going to the rest of the body. This drastically decreases the efficiency with which the heart can move oxygenated blood through the body. The pulmonary valve lies in between the pulmonary artery and the left ventricle, where it ensures that blood pumped into the pulmonary artery continues to the lungs instead of returning to the heart.
The Mitral Valve. The mitral valve is the other atrioventricular valve. Some species have a partial separation of the ventricle to reduce the mixing of oxygenated coming back from the lungs and deoxygenated blood coming in from the body. Two sided or two chambered hearts permit pumping at higher pressures and the addition of the pulmonary loop permits blood to go to the lungs at lower pressure yet still go to the systemic loop at higher pressures.
The relationship of the heart and circulatory system to major visceral organs. Below: the structure of the heart. Establishment of the four-chambered heart, along with the pulmonary and systemic circuits, completely separates oxygenated from deoxygenated blood. This allows higher the metabolic rates needed by warm-blooded birds and mammals. The human heart, as seen in Figure 11, is a two-sided, four-chambered structure with muscular walls.