Circulatory System PDF

Size: 9 ounce or 30 gram. Partition: Right and left Chamber : Each side has two chambers. Network: The heart has its own circulation network, consisting of arteries and veins. Regulation: Four valves regulate blood flow through your heart:  The tricuspid valve regulates blood flow between the...

Size: 9 ounce or 30 gram. Partition: Right and left Chamber : Each side has two chambers. Network: The heart has its own circulation network, consisting of arteries and veins. Regulation: Four valves regulate blood flow through your heart:  The tricuspid valve regulates blood flow between the right atrium and right ventricle. The pulmonary valve controls blood flow from the right ventricle into the pulmonary arteries, which carry blood to your lungs to pick up oxygen. The mitral valve lets oxygen-rich blood from your lungs pass from the left atrium into the left ventricle. The aortic valve opens the way for oxygen-rich blood to pass from the left ventricle into the aorta, your body's largest artery, where it is delivered to the rest of the body. Heart  Atrium (Auricle)  Auricle: Two upper chambers are called auricels  Flow of blood: When the blood enters the right auricle, a valve closes after right auricle is full. Then, through a kind of trapdoor valve, blood is released from the right auricle into the right ventricle. When the right ventricle is full, and its outlet valve opens. When inundated with blood the left auricle propels its contents into the left ventricle. A valve closes between the left auricle and ventricle, and the heart pumps.  Electrical impulses from heart muscle (the myocardium) cause heart to beat (contract). This electrical signal begins in the sinoatrial (SA) node, located at the top of the right atrium. The SA node is sometimes called the heart's "natural pacemaker." When an electrical impulse is released from this natural pacemaker, it causes the atria to contract. The signal then passes through the atrioventricular (AV) node. The AV node checks the signal and sends it through the muscle fibers of the ventricles, causing them to contract. Pulmonary Circulation  Before a component of blood is pumped out of the heart to the body, it has to acquire oxygen from the lungs which is critical for every cell in the body to function. Blood from the head and arms enter the heart through the right auricle from the upper ( superior) vena cava. Blood from the trunk and legs enter the heart from the lower ( inferior) vena cava. The blood flow restricted by a valve is channeled to the right ventricle. It is then conveyed to the lungs via the pulmonary (pertaining to the lungs) artery (it is called an artery because it leads away from the heart) to obtain oxygen. Having obtained oxygen in the lungs, blood is brought back to the left auricle through two pulmonary veins. (They are called veins because they lead to the heart). After that it is pumped through the aorta to be dispersed to all segments of the body  Coronary Circulation  Blood is supplied to the heart by its own vascular system, called coronary circulation.  The aorta (the main blood supplier to the body) branches off into two main coronary blood vessels (also called arteries) These coronary arteries branch off into smaller arteries, which supply oxygen-rich blood to the entire heart muscle.  The right coronary artery supplies blood mainly to the right side of the heart.  The right side of the heart is smaller because it pumps blood only to the lungs. The left coronary artery, which branches into the left anterior descending artery and the circumflex artery, supplies blood to the left side of the heart. The left side of the heart is larger and more muscular because it pumps blood to the rest of the body. Arteries (Aorta/Arterioles) The coronary arteries have been called the arteries of sudden death since a blood clot in their tubes can lead to a fatal heart attack. The aorta is the largest artery emerging from the left ventricle. The aorta branches off into over 250 different named arteries dispersed throughout each part of the body- to name a few places, wrist, hand, testes, muscles of the neck, spinal cord, brain, stomach, scalp, and middle ear walls. Ventricle  The lower chamber of the heart has two ventricles , the right ventricle and the left ventricle. The left ventricle pumps blood to the entire body. It has an opening that blood flows through to the aorta (the central artery where blood circulation originates throughout the body).  Blood Pressure (Heartbeat)  On average, without strenuous exercise, the heart beats 72 times a minute for adults.  Electrical waves pulsate through the heart causing the opening and closing of valves and muscular contractions of the ventricles.  Each heartbeat has two main phases. Both auricles (atria) contract at the same time, forcing and squeezing out blood into the ventricles. This period of contraction is called systole.  Then both ventricles contract (while the auricles relaxes and refill with blood) forcing and squeezing blood into the aorta. This period of relaxation is called diastole. Because the heart pumps blood continually into the aorta,the mean pressure in the aorta is high, averaging about 100 mm Hg. Also, because heart pumping is pulsatile, the arterial pressure alternates between a systolic pressure level of 120mm Hg and a diastolic pressure level of 80 mm Hg. As the blood flows through the systemic circulation, its mean pressure falls progressively to about 0 mm Hg by the time it reaches the termination of the venae cavae where they empty into the right atrium of the heart. The pressure in the systemic capillaries varies from as high as 35 mm Hg near the arteriolar ends to as low as 10 mm Hg near the venous ends. In the pulmonary arteries, the pressure is pulsatile, just as in the aorta, but the pressure level is far less: pulmonary artery systolic pressure averages about 25 mm Hg and diastolic pressure 8 mm Hg, with a mean pulmonary arterial pressure of only 16 mm Hg. The mean pulmonary capillary pressure averages only 7 mm Hg. Blood Vessels  Blood vessels are part of a closed extensive network of narrow elastic passageways whose main function is to circulate blood to all the far out places of the body. If all the blood vessels of a human being joined its length will be 63000 miles which can encircle the earth by 2.5 times.  Capillaries  Capillaries are minute blood vessels that allow oxygen and nutrients to traverse through their walls to all the body cells. The walls of the capillaries act as a semipermeable (authorizing passage only of certain molecules) membrane for the interchange of various substances between the blood and tissue fluid. They carry blood between the smallest arteries (arterioles ) and the smallest veins (venules ). Capillaries are so small Veins (Venae Cavae/Venules)  The two venae cavae are the largest veins in the body and are the veins which carry the deoxygenated blood to the right side of the heart.The tissues of the veins are thinner, less flexible, and less muscular than the arteries. Like the arteries there are also over 250 different named veins dispersed throughout each part of the body - to name a few places, eyeball, lung, ankle, eyelid, foot, toe, and nose. Veins are blood vessels in which blood flows toward the heart conveying deoxygenated blood (blood that has given up most of its oxygen).