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AS PE - The structure and Function of the Heart
Transcript of AS PE - The structure and Function of the Heart
The heart is a muscular pump and beat continuously over 100000 times a day.
Together with blood vessels and the blood, the heart provides the tissues and cells with essential for life itself -oxygen and nutrients. Location and size. Lies behind
the sternum and ribs which offer protection. Size of a clenched fist.
Although trained athletes often experience cardiac hypertrophy (an enlargement of the heart). Structure The ventricles are more muscular (thicker) than the atria.
Atria are low pressure chambers. Having only to pump blood directly to the ventricles, the muscular walls are thinner compared to the ventricles. The function of the ventricles is to pump blood all round the body. The heart can also be divided into left and right halves, due to a muscular partition called the septum. Septum Position of the heart in the Thoracic cavity Superior Venea Cave Coronary Artery Right Atrium Right Ventricle Left Atrium Left Ventricle The Heart as a dual-action Pump Left Side: Circulating oxygen rich blood throughout the entire body.
Systemic Circulation. Separation from left and right essential, since each side has a different role: Right Side: Pumping oxygen-poor blood to the lungs for re-oxygenation. Pulmonary Circulation. The major vessels act as entry and exit points for blood to enter and exit the heart.
They are all situated towards the top of the heart. The thick muscular wall of the heart is called myocardium and is composed of cardiac muscle fibres.
The myocardium is responsible for contraction and ejection of blood from the heart. To Ensure smooth passage of blood through the heart, a number of valves exist.
Valves make sure;
blood flows in one direction
prevent backflow of blood
Two Semilunar valves (SL)
Right SL - Pulmonary Valve.
Left SL - Aortic Valve. Four one-Way Valves Two Artioventricular Valves (AV) separate the Atria from the ventricles.
Right AV - Tricuspid Valve.
Left AV - Biscuspid or (Mitral) Valve. Similarly the right ventricle only pumps blood to the lungs, whereas the left ventricle pumps blood around the whole body and consequently the left ventricle has a thicker muscular wall than the right one. Covering the exterior of the heart are coronary arteries. These feed the heart muscle with blood. (since it is a muscle it still requires fuel to keep pumping continuously. Blockages of these arteries result in a number of cardiovascular diseases such as;
Hypertension, angina pectoralis and mycardial infractions (heart attacks). Coronary veins - alongside the coronary arteries, drain deoxygenated blood directly back in the the right atrium via the coronary sinus Blood Flow through the heart
(the journey through it) 6. Semilunar valves ensure the unidirectional flow of blood, preventing backflow into the heart. 1. Blood low in oxygen enters the RA via the Venae Cavae. 1. At the same time oxygen rich blood enters the LA via the pulmonary Veins. 2. The septum (thick muscular wall that runs through the middle of the heart) enables the two pumps to function separately - thus enabling the heart to be dual-purpose 3. Blood eventually start to enter the right and left ventricles 4. In doing so, it passes the atrioventicular (AV) valves. (Which are?)(What are the purposes of these valves?) 5. When ventricles contract, blood on the right side of the heart is forced through the semilunar pulmonary Valve into the pulmonary artery, from where it travels to the lungs. 5. Meanwhile , blood from the left ventricle enters the aorta via the semilunar aortic valve. The Aorta branches into many different arteries, which then transport the blood around the whole body. Right Atrium The human Heart Animation.