Билингвальный урок в презентации Сердечно-сосудистая система

The Cardiovascular System The Cardiovascular System A closed system of the heart and blood vessels The heart pumps blood Blood vessels allow blood to circulate to all parts of the body The function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products The Heart Location Thorax between the lungs Pointed apex directed toward left hip About the size of your fist The Heart: Coverings Pericardium – a double serous membraneVisceral pericardium - Next to heartParietal pericardium - Outside layerSerous fluid fills the space between the layers of pericardium The Heart Wall: 3 layers Epicardium Outside layer This layer is the parietal pericardium Connective tissue layer Myocardium Middle layer Mostly cardiac muscle Endocardium Inner layer Endothelium External Heart Anatomy Figure 11.2a The Heart: Chambers Right and left side act as separate pumps Four chambers Atria Receiving chambers Right atrium Left atrium Ventricles Discharging chambers Right ventricle Left ventricle Figure 11.2c Blood Circulation Figure 11.3 The Heart: Valves Allow blood to flow in only one directionFour valvesAtrioventricular valves – between atria and ventriclesBicuspid valve (left)Tricuspid valve (right) Semilunar valves between ventricle and arteryPulmonary semilunar valveAortic semilunar valve The Heart: Valves Valves open as blood is pumped throughHeld in place by chordae tendineae (“heart strings”)Close to prevent backflow Operation of Heart Valves Figure 11.4 The Heart: Associated Great Vessels Aorta - leaves left ventricle Pulmonary arteries - leave right ventricle Vena cava - enters right atrium Pulmonary veins (four) - enter left atrium Coronary Circulation Blood in the heart chambers does not nourish the myocardium The heart has its own nourishing circulatory system Coronary arteries Cardiac veins Blood empties into the right atrium via the coronary sinus The Heart: Conduction System Intrinsic conduction system (nodal system) Heart muscle cells contract, without nerve impulses, in a regular, continuous way Special tissue sets the pace Sinoatrial node (SA) - Pacemaker Atrioventricular node (AV) Atrioventricular bundle Bundle branches Purkinje fibers The Heart’s Cardiac Cycle Atria contract simultaneously Atria relax, then ventricles contract Systole = contraction Diastole = relaxation Heart Contractions Contraction is initiated by the sinoatrial node Sequential stimulation occurs at other autorhythmic cells Filling of Heart Chambers – the Cardiac Cycle Figure 11.6 The Heart: Cardiac Cycle Cardiac cycle – events of one complete heart beatMid-to-late diastole – blood flows into ventriclesVentricular systole – blood pressure builds before ventricle contracts, pushing out bloodEarly diastole – atria finish re-filling, ventricular pressure is low The Heart: Cardiac Output Cardiac output (CO) Amount of blood pumped by each side of the heart in one minute CO = (heart rate [HR]) x (stroke volume [SV]) Stroke volume Volume of blood pumped by each ventricle in one contraction Cardiac Output Regulation Figure 11.7 Regulation of Heart Rate Stroke volume usually remains relatively constantStarling’s law of the heart – the more that the cardiac muscle is stretched, the stronger the contractionChanging heart rate is the most common way to change cardiac output Regulation of Heart Rate Increased heart rate Sympathetic nervous system Activated in a Crisis Low blood pressure Hormones Epinephrine Thyroxine Exercise Decreased blood volume Regulation of Heart Rate Decreased heart rate Parasympathetic nervous system High blood pressure or blood volume Decreased venous return Blood Vessels: The Vascular System Taking blood to the tissues and back Arteries Arterioles Capillaries Venules Veins Figure 11.8a The Vascular System Figure 11.8b Blood Vessels: Anatomy Three layers (tunics) Tunic intima: Endothelium Tunic media Smooth muscle Controlled by sympathetic nervous system Tunic externa Mostly fibrous connective tissue Differences Between Blood Vessel Types Walls of arteries are the thickestLumens of veins are largerSkeletal muscle “milks” blood in veins toward the heartWalls of capillaries are only one cell layer thick to allow for exchanges between blood and tissue Movement of Blood Through Vessels Most arterial blood is pumped by the heart Veins use the milking action of muscles to help move blood Figure 11.9 Capillary Beds Capillary beds consist of two types of vesselsVascular shunt – directly connects an arteriole to a venule Figure 11.10 Capillary Beds True capillaries – exchange vesselsOxygen and nutrients cross to cellsCarbon dioxide and metabolic waste products cross into blood Figure 11.10 Diffusion at Capillary Beds Figure 11.20 Major Arteries of Systemic Circulation Figure 11.11 Major Veins of Systemic Circulation Figure 11.12 Arterial Supply of the Brain Figure 11.13 Hepatic Portal Circulation Figure 11.14 Circulation to the Fetus Figure 11.15 Pulse Pulse – pressure wave of bloodMonitored at “pressure points” where pulse is easily palpated Figure 11.16 Blood Pressure Measurements by health professionals are made on the pressure in large arteriesSystolic – pressure at the peak of ventricular contractionDiastolic – pressure when ventricles relaxPressure in blood vessels decreases as the distance away from the heart increases Measuring Arterial Blood Pressure Figure 11.18 Blood Pressure: Effects of Factors Neural factorsAutonomic nervous system adjustments (sympathetic division)Renal factorsRegulation by altering blood volumeRenin – hormonal control Blood Pressure: Effects of Factors Temperature Heat has a vasodilation effect Cold has a vasoconstricting effect Chemicals Various substances can cause increases or decreases Diet Variations in Blood Pressure Human normal range is variableNormal140–110 mm Hg systolic80–75 mm Hg diastolicHypotensionLow systolic (below 110 mm HG)Often associated with illnessHypertensionHigh systolic (above 140 mm HG)Can be dangerous if it is chronic Capillary Exchange Substances exchanged due to concentration gradients Oxygen and nutrients leave the blood Carbon dioxide and other wastes leave the cells Capillary Exchange: Mechanisms Direct diffusion across plasma membranes Endocytosis or exocytosis Some capillaries have gaps (intercellular clefts) Plasma membrane not joined by tight junctions Fenestrations of some capillaries Fenestrations = pores Developmental Aspects of the Cardiovascular System A simple “tube heart” develops in the embryo and pumps by the fourth weekThe heart becomes a four-chambered organ by the end of seven weeksFew structural changes occur after the seventh week