Here are some facts about systemic circulation,
Systemic circulation is the portion of the cardiovascular system which carries oxygenated blood away from the heart, to the body, and returns deoxygenated blood back to the heart. The term is contrasted with pulmonary circulation.
In the systemic circulation, arteries bring oxygenated blood to the tissues. As blood circulates through the body, oxygen diffuses from the blood into cells surrounding the capillaries, and carbon dioxide diffuses into the blood from the capillary cells. Veins bring deoxygenated blood back to the heart.
Arteries
Oxygenated blood enters the systemic circulation when leaving the left ventricle, through the hi aortic semilunar valve. The first part of the systemic circulation is the artery aorta, a massive and thick-walled artery. The aorta arches and gives off major arteries to the upper body before piercing the diaphragm in order to supply the lower parts of the body with its various branches.
Capillaries
Blood passes from arteries to arterioles and finally to capillaries, which are the thinnest and most numerous of the blood vessels. These capillaries help to join tissue with arterioles for transportation of nutrition to the cells, which absorb oxygen and nutrients in the blood. Peripheral tissues do not fully deoxygenate the blood, so venous blood does have oxygen, but in a lower concentration than in arterial blood. In addition, carbon dioxide and wastes are added. The capillaries can only fit one cell at a time.
Venules
The deoxygenated blood is then collected by venules, from where it flows first into veins, and then into the inferior and superior venae cavae, which return it to the right heart, completing the systemic cycle. The blood is then re-oxygenated through the pulmonary circulation before returning again to the systemic circulation.
Veins
The relatively deoxygenated blood collects in the venous system which coalesces into two major veins: the superior vena cava (roughly speaking from areas above the heart) and the inferior vena cava (roughly speaking from areas below the heart). These two great vessels exit the systemic circulation by emptying into the right atrium of the heart. The coronary sinus empties the heart's veins themselves into the right atrium.
Advantages
Because the systemic circulation is powered by the left ventricle (which is very muscular), one advantage of this form of circulation - as opposed to open circulation, or the gill system that fish use to breathe - is that there is simultaneous high-pressure oxygenated blood delivered to all parts of the body.
Summary
From the lungs, the blood goes back to the heart through the pulmonary veins. The oxygenated blood now enters the left atrium. The blood then goes down into the left ventricle through the mitral valve. This valve also closes as the left ventricle starts to pump blood to all parts of the body through the aortic semi-lunar valve to the aorta. The aorta is where the oxygenated blood passes on its way to the head, arms, hands, chest, and down to the waist, legs, and feet. At the different body parts, blood delivers nutrients and oxygen, picks up waste materials and flows back to the heart again. The movement of the blood from the left part of the heart to the various parts of the body and back to the heart is commonly called as the systemic circulation.
Showing posts with label anatomy of human heart. Show all posts
Showing posts with label anatomy of human heart. Show all posts
Wednesday, June 16, 2010
The Anatomy of Human Heart
Here are some facts about human heart.
The heart is basically a hollow muscular pump, which pushes the blood through out the body via the blood vessels. A normal sized healthy heart is roughly the same size as a fist. It is located between the lungs and slightly to the left of center. The heart is an involuntary muscle that has approximately seventy to ninety contractions per minute during a restful state. It begins to pump early in the life of a fetus and will continue unceasingly until death.
A hollow organ, the heart’s walls are made up by three distinct layers. They are as follows:
1. Endocardium (en-do-kar’de-um) this is a very smooth layer of cells that form the interior membrane of the heart. The endocardium tissue is also the type of tissue that makes up the valves of the heart.
2. Myocardium (mi-o-kar’de-um) is the actual muscle tissue of the heart and is by far the thickest layer.
3. Pericardium (per-I-kar’de-um) is the outermost layer of the heart and is also the tissue that serves as the lining of the pericardial sac.
The main portion of the heart is split into two different sides with an actual partition called the septum. Each side of the heart works as a separate pump and have two chambers apiece or as a whole, the heart has four distinct chambers.
1. Right atrium is the thin-walled area that receives the venous or “used” blood returning to the body by the veins.
2. Right ventricle is the “pump” area of the heart’s right side. The atrium dumps the blood into the ventricle where it is then pumped out the pulmonary arteries and to the lungs.
3. Left atrium receives the oxygenated blood returning from the lungs.
4. Left ventricle has the thickest walls of all. It is from this chamber the blood is pumped out of the heart, into the aorta and out to the rest of the body.
Since blood flow needs to be a one-way affair, there are valves at the entrance and exit of each ventricle. The entrance valves are called atrioventricular (a-tre-o-ven-trik’u-lar) and the exit valves are semilunar (sem-e-lu’nar). Each of the actual valves has it’s own specific name though.
1. Tricuspid valve is the one located at the entrance of the right ventricle. It prevents the blood from washing back into the right atrium. It gets its name from the three “cusps” or flaps that make up the valve.
2. Pulmonary semilunar valve is located between the right ventricle and the pulmonary artery.
3. Mitral valve is made of very heavy cusps and is located at the entrance of the left ventricle. This is a powerful valve that closes as the left ventricle begins each of its contractions to ensure the oxygenated blood doesn’t re-enter the left atrium.
4. Aortic valve is located, as its name would imply, between the left ventricle’s exit and the aorta itself.
Even though the heart is split up into two distinct halves, these two must work together to function properly.
When the heart starts to contract, it begins in the upper (atrium), thin-walled chambers and causes the blood to be squeezed out into the lower (ventricle) chambers. As the upper chamber finishes its squeeze, the lower chamber begins its work. The active action of these two chambers working together is called systole (sis’to-le). Each of these active periods will be followed by a short resting period known as diastole (di-as’to-le) although the heart never actually stops.
As the walls of the atrium complete their contraction, the ventricle begins its active stage. As the ventricle has been contracting the atrium has been filling up with blood so the entire process begins anew.
The sound of a normal heartbeat has often been described as “lubb” and “dupp”. The “lubb” period is the longer and deeper sounding of the two and is made as the ventricle is in its systole period. It is thought the sound is a result of the thick muscled walls of the ventricle contracting and the atrioventricular valves slamming shut. The “dupp” sound is shorter and has a distinctively sharper pitch. It occurs during the ventricle’s diastole period and is made as the semilunar valves close.
When these valves are not functioning normally there is a “swooshing” sound that can be heard. These are caused by the blood backwashing into the various chambers of the heart and are one of the possibilities when health care professionals are speaking of “murmurs.”
If a spinal or some other type of injury occurs and the nerves to voluntary muscles are cut, that muscle ceases to work and the area becomes paralyzed. Amazingly, if the nerves to the heart are cut it will continue to beat. The reason for this is that even though the heart is controlled by the nervous system, the heart’s muscles can actually contract rhythmically on its own. Unfortunately the nervous system is required for the heart to beat rapidly enough to maintain proper blood flow. If the nerves were to be cut, the heart’s rate could drop below 40 beats per minute and even if activity is increased, the heart’s rate would not.
The human heart is a fascinating organ that many, if given the chance, would love to exam. For most this possibility will never become a reality but for the really curious, there is an adequate substitute. This substitute is the heart of the common cow and can usually be obtained by visiting a local meat market and asking for one.
The heart is basically a hollow muscular pump, which pushes the blood through out the body via the blood vessels. A normal sized healthy heart is roughly the same size as a fist. It is located between the lungs and slightly to the left of center. The heart is an involuntary muscle that has approximately seventy to ninety contractions per minute during a restful state. It begins to pump early in the life of a fetus and will continue unceasingly until death.
A hollow organ, the heart’s walls are made up by three distinct layers. They are as follows:
1. Endocardium (en-do-kar’de-um) this is a very smooth layer of cells that form the interior membrane of the heart. The endocardium tissue is also the type of tissue that makes up the valves of the heart.
2. Myocardium (mi-o-kar’de-um) is the actual muscle tissue of the heart and is by far the thickest layer.
3. Pericardium (per-I-kar’de-um) is the outermost layer of the heart and is also the tissue that serves as the lining of the pericardial sac.
The main portion of the heart is split into two different sides with an actual partition called the septum. Each side of the heart works as a separate pump and have two chambers apiece or as a whole, the heart has four distinct chambers.
1. Right atrium is the thin-walled area that receives the venous or “used” blood returning to the body by the veins.
2. Right ventricle is the “pump” area of the heart’s right side. The atrium dumps the blood into the ventricle where it is then pumped out the pulmonary arteries and to the lungs.
3. Left atrium receives the oxygenated blood returning from the lungs.
4. Left ventricle has the thickest walls of all. It is from this chamber the blood is pumped out of the heart, into the aorta and out to the rest of the body.
Since blood flow needs to be a one-way affair, there are valves at the entrance and exit of each ventricle. The entrance valves are called atrioventricular (a-tre-o-ven-trik’u-lar) and the exit valves are semilunar (sem-e-lu’nar). Each of the actual valves has it’s own specific name though.
1. Tricuspid valve is the one located at the entrance of the right ventricle. It prevents the blood from washing back into the right atrium. It gets its name from the three “cusps” or flaps that make up the valve.
2. Pulmonary semilunar valve is located between the right ventricle and the pulmonary artery.
3. Mitral valve is made of very heavy cusps and is located at the entrance of the left ventricle. This is a powerful valve that closes as the left ventricle begins each of its contractions to ensure the oxygenated blood doesn’t re-enter the left atrium.
4. Aortic valve is located, as its name would imply, between the left ventricle’s exit and the aorta itself.
Even though the heart is split up into two distinct halves, these two must work together to function properly.
When the heart starts to contract, it begins in the upper (atrium), thin-walled chambers and causes the blood to be squeezed out into the lower (ventricle) chambers. As the upper chamber finishes its squeeze, the lower chamber begins its work. The active action of these two chambers working together is called systole (sis’to-le). Each of these active periods will be followed by a short resting period known as diastole (di-as’to-le) although the heart never actually stops.
As the walls of the atrium complete their contraction, the ventricle begins its active stage. As the ventricle has been contracting the atrium has been filling up with blood so the entire process begins anew.
The sound of a normal heartbeat has often been described as “lubb” and “dupp”. The “lubb” period is the longer and deeper sounding of the two and is made as the ventricle is in its systole period. It is thought the sound is a result of the thick muscled walls of the ventricle contracting and the atrioventricular valves slamming shut. The “dupp” sound is shorter and has a distinctively sharper pitch. It occurs during the ventricle’s diastole period and is made as the semilunar valves close.
When these valves are not functioning normally there is a “swooshing” sound that can be heard. These are caused by the blood backwashing into the various chambers of the heart and are one of the possibilities when health care professionals are speaking of “murmurs.”
If a spinal or some other type of injury occurs and the nerves to voluntary muscles are cut, that muscle ceases to work and the area becomes paralyzed. Amazingly, if the nerves to the heart are cut it will continue to beat. The reason for this is that even though the heart is controlled by the nervous system, the heart’s muscles can actually contract rhythmically on its own. Unfortunately the nervous system is required for the heart to beat rapidly enough to maintain proper blood flow. If the nerves were to be cut, the heart’s rate could drop below 40 beats per minute and even if activity is increased, the heart’s rate would not.
The human heart is a fascinating organ that many, if given the chance, would love to exam. For most this possibility will never become a reality but for the really curious, there is an adequate substitute. This substitute is the heart of the common cow and can usually be obtained by visiting a local meat market and asking for one.
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