Transport system Mrs jackie

The transport systems Made of the heart, blood vessels and blood. Superior vena cava Made of the heart, blood vessels and blood. Circulation through the heart Deoxygenated blood arrives from the lower and upper parts of the body and pours into the right atrium through the vena cava Inferior vena cava

Circulation The right atrium contracts and blood is pushed into the right ventricle through the atrioventricular valve or tricuspic valve The right ventricle contract increasing the pressure inside it and so he atrioventricular valve closes and the semilunar valve open and blood is pushed out of the heart through the pulmonary artery

Circulation Pulmonary vein Blood is carried in the pulmonary artery to the lungs, where gaseous exchange takes place and the blood becomes oxygenated The pulmonary vein carries the oxygenated blood into the left atrium, which contracts and pushes the blood into the into the left ventricle through the atrioventricular valve(aortic valve)

Blood Circulation The left ventricle contract and the pressure increases closing the atrioventricular valve and opening the Mitral valve Blood is pushed out the heart through the mitral valve into the aorta that take it to all pars of the body. The aorta branches into arteries that enter all body organs

Circulation Inside the organs the artery branches into arterioles and the arterioles into capillaries Capillaries are sites of exchange of substances. Capillaries merge into venules which merge into veins Veins merge into the vena cava that takes deoxygenated blood back to the right atrium.

Important facts of the circulatory system The left side of the heart is completely separated from the right side by a thick muscular wall called septum The right side contain deoxygenated blood the left side oxygenated blood The atria received blood from the body and the lungs The ventricles pump out blood to the body and lungs The atria is connected to veins, the ventricles to arteries Veins carry blood to the heart; arteries away from the heartç Veins carry deoxygenated blood except the pulmonary vein which takes oxygenated blood from the lungs to the left atrium Arteries carry oxygenated blood except the pulmonary artery which takes deoxygenated blood from the right ventricle to the lungs.

Important facts of the circulatory system Atria have very thin muscular walls because they need to pump blood only a short distance, which is to the two ventricles. Ventricles have thicker walls because they need to pump the blood to a longer distance. The left ventricle has more thicker walls than the right ventricle. This is because it send blood to the aorta The right ventricle has thinner walls because it sends blood only to the lungs, which are to a shorter distance away from the heart.

Important facts of the circulatory system Inside the heart the blood only moves from atria to ventricles. The atrioventricular valves prevent blood from returning back to the atria When the ventricles contract the atrioventricular valves close and blood is pushed into the main arteries; pulmonary arteries and aorta and leaves back. Arteries have much thicker walls than veins, because they carry blood pushed by the ventricles with a very large force The aorta has the thickest walls of all arteries because it receives blood from the left ventricle which contracts with a big force causing high pressure in the aorta.

Important facts of the circulatory system Between the main arteries and the ventricles, there are valves that prevent the blood from returning to the ventricles when the ventricles relax. Veins contain valves art certain intervals in the whole circulation, ensuring a one way traffic of blood. The coronary arteries branch from the aorta.

Initiation and regulation of heart beat Heart is said to be myogenic It initiates its beat intrinsically, which means that it does need a message from the brain to start its beat. If the heart is cut away from the body and immersed in the correct solution containing oxygen and all the needed salts and nutrients, it can keep beating for a very long time. This is because a tissue called sinoatrial node (SAN) or the pacemaker which spontaneously produces electric impulses, which spread into the two atria causing them to contract. The atrioventricular node (AVN) localized lower down in the wall between the right atrium and right ventricle fires impulses that travel through muscle fibers to the two ventricles causing contraction

Initiation and regulation of heart beat

Brain control of heart rate The pacemaker received two nerves from the brain Sympathetic nerve- release noradrenalin and causes an increase in heart rate Parasympathetic nerve- releases acetylcholine and lowers heart rate

Adrenaline The hormone adrenaline released by the adrenal gland situated above each kidney also increases the heart rate. It is called the flight or fight hormone, because it prepares the body for situations of stress by increasing the heart and breathing rate, and blood sugar levels.