"The Description of the Human Body The Description of the Human Body () is an unfinished treatise written in 1647 by René Descartes (1596-1650). Descartes felt knowing oneself was particularly useful. This for him included medical knowledge. He hoped to cure and prevent disease, even to slow down aging. René Descartes believed the soul caused conscious thought. The body caused automatic functions like the beating of the heart and digestion he felt. The body was necessary for voluntary movement as well as the will. However, he believed the power to move the body was wrongly imagined to come from the"
"atrium via one of the four [[pulmonary vein]]s. Blood flows nearly continuously back into the atrium, which acts as the receiving chamber, and from here through an opening into the left ventricle. Most blood flows passively into the heart while both the atria and ventricles are relaxed, but toward the end of the [[diastole|ventricular relaxation period]], the left atrium will contract, pumping blood into the ventricle. The heart also requires nutrients and oxygen found in blood like other muscles, and is supplied via [[coronary circulation|coronary arteries]]. The [[skin|integumentary system]] is made up of three layers: the outermost [[epidermis (skin)|epidermis]], the"
"right atrium and the right ventricle, separated by a valve, the tricuspid valve. The right atrium receives blood almost continuously from the body's two major veins, the superior and inferior venae cavae. A small amount of blood from the coronary circulation also drains into the right atrium via the coronary sinus, which is immediately above and to the middle of the opening of the inferior vena cava. In the wall of the right atrium is an oval-shaped depression known as the fossa ovalis, which is a remnant of an opening in the fetal heart known as the foramen ovale. Most"
"combines from capillaries around the gastrointestinal tract where the blood absorbs the various products of digestion; rather than leading directly back to the heart, the hepatic portal vein branches into a second capillary system in the liver. The heart pumps oxygenated blood to the body and deoxygenated blood to the lungs. In the human heart there is one atrium and one ventricle for each circulation, and with both a systemic and a pulmonary circulation there are four chambers in total: left atrium, left ventricle, right atrium and right ventricle. The right atrium is the upper chamber of the right side"
"the smooth walled part of the right atrium, the ""sinus venarum"" derived from the sinus venosus. The sinus venarum is the adult remnant of the sinus venous and it surrounds the openings of the venae cavae and the coronary sinus. High in the upper part of the left atrium is a muscular ear-shaped pouch – the left atrial appendage. This appears to ""function as a decompression chamber during left ventricular systole and during other periods when left atrial pressure is high"". The sinoatrial (SA) node is located in posterior aspect of the right atrium, next to the superior vena cava."
"is found at the bottom of the right atrium in the atrioventricular septum—the boundary between the right atrium and the left ventricle. The septum is part of the cardiac skeleton, tissue within the heart that the electrical signal cannot pass through, which forces the signal to pass through the atrioventricular node only. The signal then travels along the bundle of His to left and right bundle branches through to the ventricles of the heart. In the ventricles the signal is carried by specialized tissue called the Purkinje fibers which then transmit the electric charge to the heart muscle. The normal"
"atria to increase and forcing additional blood flow into the ventricles. This beginning of the atrial systole is known as the ""atrial kick""—see Wiggers diagram. The atrial kick ""does not"" supply the larger amount of flow (during the cardiac cycle) as about 80 per cent of the collected blood volume flows into the ventricles during the active suction period. At the beginning of the cardiac cycle, all four chambers of the heart—two atria and two ventricles—are in relaxation and dilation, or diastole. The atria are filling with separate blood volumes returning to the right atrium (from the vena cavae) and"
"depending on what is counted as a chamber. The atrium and ventricle are sometimes considered ""true chambers"", while the others are considered ""accessory chambers"". Primitive fish have a four-chambered heart, but the chambers are arranged sequentially so that this primitive heart is quite unlike the four-chambered hearts of mammals and birds. The first chamber is the sinus venosus, which collects deoxygenated blood from the body through the hepatic and cardinal veins. From here, blood flows into the atrium and then to the powerful muscular ventricle where the main pumping action will take place. The fourth and final chamber is the"
"simultaneously into the two bottom chambers, or ventricles. Blood first enters the heart at the right atrium, which then empties blood into the right ventricle, which pumps the blood into the lungs through the pulmonary artery to get oxygen. From the lungs, the blood enters the left atrium through the pulmonary vein; the left atrium empties into the left ventricle, which pumps the blood into the aorta and from there reaches the rest of the body. Because the left ventricle is responsible for getting blood to the entire body through the aorta, it is usually the biggest and strongest chamber"
"although this description is disputed, as the heart is likely to be slightly larger. Well-trained athletes can have much larger hearts due to the effects of exercise on the heart muscle, similar to the response of skeletal muscle. The heart has four chambers, two upper atria, the receiving chambers, and two lower ventricles, the discharging chambers. The atria open into the ventricles via the atrioventricular valves, present in the atrioventricular septum. This distinction is visible also on the surface of the heart as the coronary sulcus. There is an ear-shaped structure in the upper right atrium called the right atrial"
"the third chamber, the ventricle, before it reaches the conus anteriosus, which itself is connected to the ventral aorta. This is considered a primitive arrangement, and many vertebrates have condensed the atrium with the sinus venosus and the ventricle with the conus anteriosus. With the advent of lungs came a partitioning of the atrium into two parts divided by a septum. Among frogs, the oxygenated and deoxygenated blood are mixed in the ventricle before being pumped out to the body's organs; in turtles, the ventricle is almost entirely divided by a septum, but retains an opening through which some mixing"
"primitive atrium descends the septum primum, which grows towards the endocardial cushions within the atrial canal. Right before the septum primum fuses with the endocardial cushions there's a temporary space called the foramen primum. Once they fuse a new opening forms in the middle of the septum primum called the ostium secundum or ""foramen secundum"". To the right of the septum primum and also coming down from the roof of the primitive atrium, descends a semilunar-shaped partition called the septum secundum. The free edges of the septum secundum produce an orifice called ""foramen ovale"", which closes after birth when the"
"in the left atrium. This in turn increases the oxygen concentration of blood in the left ventricle, the aorta, the coronary circulation and the circulation of the developing brain. Following birth and separation from the placenta, the oxygen content in the inferior vena cava falls. With the onset of breathing, the left atrium receives oxygen-rich blood from the lungs via the pulmonary veins. As blood flow to the lungs increases, the amount of blood flow entering the left atrium increases. When the pressure in the left atrium exceeds the pressure in the right atrium, the foramen ovale begins to close"
"Primary interatrial foramen In the developing heart, the atria are initially open to each other, with the opening known as the primary interatrial foramen or ostium primum (or interatrial foramen primum). The foramen lies beneath the edge of septum primum and the endocardial cushions. It progressively decreases in size as the septum grows downwards, and disappears with the formation of the atrial septum. The foramen lies beneath the edge of septum primum and the endocardial cushions. It progressively decreases in size as the septum grows downwards, and disappears with the formation of the atrial septum. The septum primum, a which"
"symptoms of heart failure. The heart is a biological pump designed to move blood through the brain and body. It has four chambers: two ""upper"" chambers, the atria (single:atrium), and two ""lower"" chambers (the ventricles). Anatomically, the atria sit more posterior to the ventricles, but for ease of understanding, are often drawn ""above"" them. The atria are separated from the ventricles beneath by the atrioventricular valves, which open to allow blood into the ventricles and close when ventricular pressure exceeds atrial pressure. Blood is transferred into the ventricles in 2 steps: in the first step, as the ventricle relaxes from"
"body section posterior to that bearing the legs and head (the prosoma or cephalothorax). Abdomen The abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The region occupied by the abdomen is termed the abdominal cavity. In arthropods it is the posterior tagma of the body; it follows the thorax or cephalothorax. The abdomen stretches from the thorax at the thoracic diaphragm to the pelvis at the pelvic brim. The pelvic brim stretches from the lumbosacral joint (the intervertebral disc between"
"into the right atrium to form the sinus venarum. Sinus venosus The sinus venosus is a large quadrangular cavity which precedes the atrium on the venous side of the chordate heart. In mammals, it exists distinctly only in the embryonic heart (where it is found between the two venae cavae); however, the sinus venosus persists in the adult. In the adult, it is incorporated into the wall of the right atrium to form a smooth part called the sinus venarum, also known as the venarum sinus, which is separated from the rest of the atrium by a ridge of fibres"
"of the person whose heart it is. There are four chambers in a heart: an atrium (upper) and a ventricle (lower) on both the left and right sides. In mammals and birds, blood from the body goes to the right side of the heart first. Blood enters the upper right atrium, is pumped down to the right ventricle and from there to the lungs via the pulmonary artery. Blood going to the lungs is called the pulmonary circulation. When the blood returns to the heart from the lungs via the pulmonary vein, it goes to the left side of the"
"Abdomen The abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The region occupied by the abdomen is termed the abdominal cavity. In arthropods it is the posterior tagma of the body; it follows the thorax or cephalothorax. The abdomen stretches from the thorax at the thoracic diaphragm to the pelvis at the pelvic brim. The pelvic brim stretches from the lumbosacral joint (the intervertebral disc between L5 and S1) to the pubic symphysis and is the edge of the pelvic"
"appendage, or auricle, and another in the upper left atrium, the left atrial appendage. The right atrium and the right ventricle together are sometimes referred to as the ""right heart"". Similarly, the left atrium and the left ventricle together are sometimes referred to as the ""left heart"". The ventricles are separated from each other by the interventricular septum, visible on the surface of the heart as the anterior longitudinal sulcus and the posterior interventricular sulcus. The cardiac skeleton is made of dense connective tissue and this gives structure to the heart. It forms the atrioventricular septum which separates the atria"
"Atrium (architecture) In architecture, an atrium (plural: atria or atriums) is a large open air or skylight covered space surrounded by a building. Atria were a common feature in Ancient Roman dwellings, providing light and ventilation to the interior. Modern atria, as developed in the late 19th and 20th centuries, are often several stories high and having a glazed roof or large windows, and often located immediately beyond the main entrance doors (in the lobby). Atria are a popular design feature because they give their buildings a ""feeling of space and light."" The atrium has become a key feature of"
"the right atrium. The inferior vena cava drains the blood from below the diaphragm and empties into the back part of the atrium below the opening for the superior vena cava. Immediately above and to the middle of the opening of the inferior vena cava is the opening of the thin-walled coronary sinus. Additionally, the coronary sinus returns deoxygenated blood from the myocardium to the right atrium. The blood collects in the right atrium. When the right atrium contracts, the blood is pumped through the tricuspid valve into the right ventricle. As the right ventricle contracts, the tricuspid valve closes"
"Interatrial septum The interatrial septum is the wall of tissue that separates the right and left atria of the heart. The intratrial septum is a that lies between the left atrium and right atrium of the human heart. The interatrial septum forms during the first and second months of fetal development. Formation of the septum occurs in several stages. The first is the development of the septum primum, a crescent-shaped piece of tissue forming the initial divider between the right and left atria. Because of its crescent shape, the septum primum does not fully occlude the space between left and"
"Heart The heart is a muscular organ in most animals, which pumps blood through the blood vessels of the circulatory system. Blood provides the body with oxygen and nutrients, as well as assists in the removal of metabolic wastes. In humans, the heart is located between the lungs, in the middle compartment of the chest. In humans, other mammals, and birds, the heart is divided into four chambers: upper left and right atria; and lower left and right ventricles. Commonly the right atrium and ventricle are referred together as the ""right heart"" and their left counterparts as the ""left heart""."
"the lungs (congestive heart failure causing pulmonary edema). The constant pressure overload of the left atrium will cause the left atrium to increase in size. As the left atrium increases in size, it becomes more prone to develop atrial fibrillation (AF). When atrial fibrillation develops, the atrial kick is lost (since it is due to the normal atrial contraction). In individuals with severe mitral stenosis, the left ventricular filling is dependent on the atrial kick. The loss of the atrial kick due to atrial fibrillation ( i.e. blood cannot flow into the left ventricle thus accumulating in the left atrium"
"at about two weeks, a primitive atrium begins to be formed. It begins as one chamber which over the following two weeks becomes divided by the septum primum into the left atrium and the right atrium. The interatrial septum has an opening in the right atrium, the foramen ovale which provides access to the left atrium; this connects the two chambers, which is essential for fetal blood circulation. At birth, when the first breath is taken fetal blood flow is reversed to travel through the lungs. The foramen ovale is no longer needed and it closes to leave a depression"
"right atrium, at the upper right front portion of the heart. It is also known as the cranial vena cava in other animals. No valve divides the superior vena cava from the right atrium. As a result, the (right) atrial and (right) ventricular contractions are conducted up into the internal jugular vein and, through the sternocleidomastoid muscle, can be seen as the jugular venous pressure. Superior vena cava obstruction refers to a partial or complete obstruction of the superior vena cava, typically in the context of cancer such as a cancer of the lung, metastatic cancer, or lymphoma. Obstruction can"
"the hole (foramen ovale) between the right and left atrium normally found within the heart during fetal development; the creation of a hole between the atrium may also be acquired. There are two types of ASD: Ostium secundum and ASD Primium. The failure of the hole between the right and left atrium to close shortly after birth is the cause behind ASD primium. During fetal development blood will pass from the umbilical cord and flow into the left atrium through a hole between the two atria. Once a baby is born and the lungs begin to fill with air, the"
"Thorax The thorax or chest (from the Greek θώραξ ""thorax"" ""breastplate, cuirass, corslet"" via ) is a part of the anatomy of humans and various other animals located between the neck and the abdomen. The thorax includes the thoracic cavity and the thoracic wall. It contains organs including the heart, lungs, and thymus gland, as well as muscles and various other internal structures. Many diseases may affect the chest, and one of the most common symptoms is chest pain. In humans and other hominids, the thorax is the chest region of the body between the neck and the abdomen, along"
"atrium, and the sinus venosus. Initially, all venous blood flows into the sinus venosus, and is propelled from tail to head to the truncus arteriosus. This will divide to form the aorta and pulmonary artery; the bulbus cordis will develop into the right (primitive) ventricle; the primitive ventricle will form the left ventricle; the primitive atrium will become the front parts of the left and right atria and their appendages, and the sinus venosus will develop into the posterior part of the right atrium, the sinoatrial node and the coronary sinus. Cardiac looping begins to shape the heart as one"
"passage between the two atrial chambers consists of a long oblique slit through which blood flows from the right atrium to the left. Initially, a single pulmonary vein develops in the form of a bulge in the back wall of the left atrium. This vein will connect with the veins of the developing lung buds. As development proceeds the pulmonary vein and its branches are incorporated into the left atrium and they both form the smooth wall of the atrium. The embryonic left atrium remains as the trabecular left atrial appendage, and the embryonic right atrium remains as the right"
"Crista terminalis The crista terminalis represents the junction between the sinus venosus and the heart in the developing embryo. In the development of the human heart, the right horn and transverse portion of the sinus venosus ultimately become incorporated with and forms a part of the adult right atrium where it is known as the ""sinus venarum"". The line of union between the right atrium and the right atrial appendage is present on the interior of the atrium in the form of a vertical crest, known as the crista terminalis (in older texts the ""crista terminalis of His)"". The crista"
"in the hotel above the gardens of: Delta, Cascades, Garden-Conservatories, and Magnolia. As of 2016, the Burj Al Arab hotel in Dubai, has the world's tallest atrium at . The Luxor Hotel, in Las Vegas, Nevada, has the largest atrium in the world (by volume) at . Atrium (architecture) In architecture, an atrium (plural: atria or atriums) is a large open air or skylight covered space surrounded by a building. Atria were a common feature in Ancient Roman dwellings, providing light and ventilation to the interior. Modern atria, as developed in the late 19th and 20th centuries, are often several"