cardiovascular disease and circulatory system

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  • the circulatory system
    • heart
      • left ventricle has thicker muscular walls than the right ventricle
      • ventricles have thicker walls that atria
      • atrioventricular values link the atria to the ventricles and stop back flow
      • semi-lunar values link the ventricles to pulmonary artery and aorta, and stop blood black flow
      • the cord attach the atrioventricular valves to the ventricles
      • if theres a higher pressure behind a valve , its forced open.
    • blood vessels
      • artery
        • thick walled, muscular and have elastic tissue in order to cope with high pressure cause by heart beat
        • endothelium is folded, allowing artery to expand
      • veins
        • wider than arteries. very little elastic or muscle tissue. contain valves to stop back flow.
      • capillaries
        • metabolic exchange occurs.there are networks of capillaries in tissue which increase surface area for exchange. they are one cell thick.
    • cardiac cycle
      • 1- ventricular diastole, atria systole
        • ventricles are relaxed. atria contracted, decreasing volume of chamber. slight increase in ventrical pressure and chamber pressure.
      • 2- ventricular systole, atrial diastole
        • atria relax. ventricles contract increasing their pressure. forces AV valves shut to prevent back flow. pressure in the ventricle is higher than in the aorta and pulmonary artery which opens SL valves
      • 3- ventricular diastole , atrial diastole
        • both relaxed. atria fill again due to high pressure in the vena cava and pulmonary artery. pressure in ventricles reduces, AV valves open which allows blood flow into the ventricles from the atria. the atria contract and process begins again
    • cardiovascular disease
      • atheroma
        • 1.damage occurs to endothelium resulting in inflammatory response
        • 2. white blood cells and lipids from the blood clump together under the endothelium to form fatty streaks
        • 3. over time more WBC , lipids and connective tissues build up and harden to form a fibrous plaque.
        • 4. plaque partially blocks the lumen of the artery and restricts blood flow which causes blood pressure to increase
        • hardening of the arteries is acalled atherosclerosis
      • thrombosis
        • atheromas develop in artery wall which can cause a rupture triggering thombosis
        • a blood clot forms at the site of rupture which can cause a complete blockage of the artery.
        • heart attack, stroke and deep vein thrombosis are three forms of CVD that can be caused by blood clots
      • blood clot
        • 1. thromboplastin  released from damaged blood vessel
        • 2. triggers the conversion of prothrombin into thrombin
        • 3. thrombin then catalyses the conversion of fibrinogen to fibrin
        • 4.fibrin fibres tangle together and form a mesh which platelets and red blood cells get trapped- this forms the blood clot

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