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6.2 The Blood System. The Heart . Transport system consists of the heart and associated blood vessels Heart pumps blood to pulmonary circuit (lungs) for gas exchange The heart consists of 4 chambers 2 atria which are on the top (right and left)
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The Heart • Transport system consists of the heart and associated blood vessels • Heart pumps blood to pulmonary circuit (lungs) for gas exchange • The heart consists of 4 chambers • 2 atria which are on the top (right and left) • 2 ventricles which are on the b (right and left)
Flow of Blood Heart • Blood enters right atrium from vena cava • Goes through the Tricuspid valve • Move to the right ventricle • Pumped through the pulmonary valve (pulmonary artery) • To the lungs (gas exchange)(pulmonary veins) • To the left atrium • Through the Bicuspid valve • To the left ventricle • Through the aortic valve and out of the heart
Two Circulatory Paths • Systemic: blood flows from the heart to the body (out the aorta and back through the vena cava) • Pulmonary: blood flows from the heart to the lungs (out through the pulmonary artery to the lungs and back to the heart through the pulmonary vein)
Coronary Arteries • Located outside of the heart and supply the heart cells with nutrients and clear metabolic waste products • Can become blocked which can lead to a heart attack
Actions of the Heart • Atria receive blood from body (right) and from the lungs (left) • Ventricles are more powerful: pump blood a greater distance • When AV valves are closed (atrioventricular) then the semilunar valves are open and vica versa • Valves control the direction of blood flow
Control of the Heart • Myogenic muscle contraction - Signal for heartbeat comes from the heart not the brain • - Signal originates in the Sinoatrial Node (SA) signal is then sent to the AV node • - SA is a specialized set of cardiac cells that generate an electric impulse • - The implusespreads across the atria at a speed of approx 1m per sec., causing the atria to contract
Influences to heart rate • Heart beat set by SA node • Nervous system can influence heart rate by impulses delivered by medulla oblongata • Increase or decrease if there is a need for oxygen • Endocrine system also influences heart rate • Increase or decrease by releasing adrenalin
Arteries • Largest circulatory vessels • Take blood away from the heart • Have high pressure • Aorta is the largest artery in the body • Most carry oxygenated blood except the pulmonary artery
Veins • Bring blood back to the heart • Carry most deoxygenated blood (except the pulmonary vein) • Superior and inferior vena cava (top and bottom) bring blood back to the heart
Capillaries • Most numerous of all blood vessels • Contain only endothelium • One cell thick • Carry out exchange of materials between blood and body cells
Blood flow through arteries, veins and capillaries Heart arteries arterioles capillaries venules veins heart
Cell fragments called… A straw-coloured liquid called… Plasma Composition of Blood Red Blood Cells White Blood Cells Carries dissolved substances: CO2 Other wastes Hormones Food molecules Carry oxygen Fight Infection Help with blood clotting