The heart and blood vessels make up the cardiovascular (circulatory) system.. The heart pumps blood to the lungs to collect oxygen and then returns the oxygenated blood to the body. The blood that flows through this system brings oxygen and nutrients to the tissues of the body and removes waste products (such as carbon dioxide) from those tissues.
The heart, a muscular hollow organ, is located in the middle part of the chest. The heart has two sides right and left.
The right and left sides of the heart each have:
Atrium: the upper chamber where blood is collected and expelled into the lower chamber
Ventricle: the lower chamber that expels blood from the heart.
To allow blood to flow in only one direction, each chamber of the heart has an inlet valve and an outlet valve.
Each stopcock is made up of flaps ( cusps or faucets), which open and close like a swinging door. The mitral stopcock has two cusps. The other faucets (tricuspid, aortic and pulmonary) have three. The large flux faucets (mitral or tricuspid) have attachments conforming of papillary muscles and cords of towel, which help the faucets from opening toward the patio. When a papillary muscle is damaged (for illustration, following a heart attack), the stopcock can cock backwards and begin to blunder (regurgitation). Still, the blood inflow through the stopcock is dropped, If the opening of the stopcock is narrowed (stenosis). The same stopcock can have both leakage and narrowing.
Heartbeats are evidence that the heart is pumping. Doctors often say that a heartbeat makes a “lub-dub” sound. When doctors listen to the heartbeat with a stethoscope, the first sound they hear (the lub-dub) is the closing of the mitral and tricuspid valves. The second heart sound (the dub) corresponds to the closure of the aortic and pulmonary valves. Each heartbeat has two phases:
Systole: During systole, the ventricles contract and eject blood out of the heart, while the atria relax and begin to fill again.
Diastole During diastole, the ventricles relax and fill with blood.The atria then contract, forcing more blood into the ventricles.
The principal function of the heart is to pump blood.
The right side of the heart pumps blood to the lungs, where it’s amended with oxygen and sanctified of carbon dioxide.
The left side of the heart pumps blood to the rest of the body where oxygen and nutrients are supplied to the apkins and waste products ( similar as carbon dioxide) are transferred to the blood for junking by other organs ( similar as the lungs and feathers)
The blood follows the following circuit Blood from the body, depleted of oxygen and loaded with carbon dioxide, flows through the two largest modes (the superior vena cava and the inferior vena cava, inclusively called the vena cava) to the right patio. When the right ventricle relaxes, blood from the right patio flows into the right ventricle through the tricuspid stopcock. When the right ventricle is nearly full, the right patio contracts, expelling further blood into the right ventricle, which in turn contracts. This compression closes the tricuspid stopcock and expels the blood through the pulmonary stopcock into the pulmonary highways that supply the lung. Formerly in the lungs, the blood flows into the small capillaries that compass the pulmonary alveoli. There it absorbs oxygen and releases carbon dioxide, which is also exhaled.
Blood from the lungs, now rich in oxygen, flows into the left patio through the pulmonary modes. When the left ventricle relaxes, blood from the left patio flows through the mitral stopcock into the left ventricle. When the left ventricle is nearly full, the left patio contracts, expelling further blood into the left ventricle, which in turn contracts. (In the senior, the left ventricle doesn’t fill as well before the left patio contracts, making left atrial compression particularly important. The compression of the left ventricle closes the mitral stopcock and pushes blood through the aortic stopcock into the aorta, the largest roadway in the body. The blood carries oxygen to the entire body except for the lungs.
The pulmonary rotation is the circuit that runs through the right heart, lungs and left patio.
The systemic rotation is the circuit that runs through the left side of the heart, utmost of the body, and the right patio.
Blood supply to the heart
Like all other tissues in the body, the heart muscle must receive oxygen-rich blood and its waste products must be removed by the blood. The right and left coronary arteries, which branch off the aorta as it leaves the heart, supply the heart muscle with oxygen-rich blood. The right coronary artery divides into two branches, the marginal artery and the posterior interventricular artery, located at the posterior aspect of the heart. The left coronary artery (typically called the left main coronary artery) divides into two branches, the circumflex artery and the anterior interventricular artery. The cardiac veins collect blood containing waste products from the heart muscle and drain it into a large vein on the posterior surface of the heart, called the coronary sinus, which returns the blood to the right atrium.
Regulation of the heart
The compression of the heart’s muscle filaments is largely systematized and controlled. Metrical electrical impulses ( discharges) travel through the heart in a precise manner along distinct pathways and at a controlled rate. The impulses appear from the natural trendsetter (the sinus knot or sino-atrial knot, a small mass of towel in the wall of the right patio), which generates a bitsy electrical current.
Heart rate, or palpitation, is the number of times your heart beats in a nanosecond. The heart rate increases when the body needs further oxygen (for illustration, during physical exertion). The heart rate decreases when the body needs lower oxygen (for illustration, during rest).
The rate at which the sinoatrial knot transmits its impulses (and therefore governs the heart rate) is determined by two opposing corridor of the autonomic nervous system one to speed up the heart rate (the sympathetic nervous system) and one to decelerate it down (the parasympathetic system).
The sympathetic system operates through a network of jitters called the sympathetic supersystem and through the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline), which are buried by the adrenal glands and whim-whams consummations.
The parasympathetic system operates through a single whim-whams, the vagus whim-whams, which releases a neurotransmitter, acetylcholine.