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  • The Heart
    • Heart Valves
      • Cuspid
        • Lie between the atria and the ventricles
        • When blood is flowing from atrium to ventricle the valve is pushed open
          • It lies flat against the heart wall
        • As the ventricles contract blood is forces into the cusps which closes the valve
          • Cusps are small membrane-like flaps
        • The valve tendons keep the cusps firmly in position
          • Papillae are the points where the valve tendons are attached to
      • Semi-lunar
        • Aorta and pulmonary artery
        • Blood forces the valves open
        • When open it lies flat against the artery
        • Blood can’t flow back because the valve pockets fill with blood
    • Types of circulatory systems
      • Closed circulatory
        • Most animals have closed systems
        • Blood remains inside tunes until it returns to the heart
        • Movement of blood is easily controlled
      • Double circulation
        • We have two circulatory systems in our bodies
          • Pulmonary
            • From the heart to the lungs and back to the heart
          • Systemic
            • From the heart to the body and back to the heart
    • The external structure of the heart
      • Position
        • Middle of the thorax
        • Between the lungs
        • Slightly to the left
          • Left lung is smaller than right
        • Bottom of the heart is pointy
          • Apex
      • A double membrane known as the pericardium surrounds the heart
        • Fluid between membranes
          • Reduces friction
            • When the heart contracts and relaxes
      • Made up of cardiac muscle
      • Coronary blood vessels supply blood to the heart
        • A blockage here can result in a heart attack
    • Blood Vessels
      • Arteries
        • Carry blood away from the heart
          • Almost all blood in arteries in oxygenated
            • The exception being the pulmonary artery
        • Structure
          • 1. Lumen
          • 2. Endothelium
          • 3. Muscle and elastic fibre layer
          • 4. Fibrous outer layer
        • The bulging of the artery is what we feel as a pulse
        • High pressure
        • Arteriole
          • Branch of an artery
      • Capillaries
        • The thinnest vessel
          • Red blood cells travel in single file
        • Single layer of endothelium
          • Easy diffusion
        • Slow down the rate of flow of blood
      • Veins
        • Carry blood to the heart
          • All blood is deoxygenated except for the pulmonary vein
        • Low pressure
          • Structure
            • 1. Lumen
            • 2. Muscle and elastic fibre layer
              • Thinner than in arteries
            • 3. Fibrous outer layer
        • Venule
          • A branch of a vein
    • Blood
      • Composition
        • Liquid plasma
          • 55%
            • 95% Water
            • Clear/yellowish
            • Carries
              • Vitamins
              • Blood cells
              • Proteins
              • Blood-clotting factors
              • Minerals
              • Hormones
              • Enzymes
              • Antibodies
        • Red blood cells (erythrocytes)
          • 40-50%
            • Biconcave
            • Disc shaped
            • Contains a pigment called haemoglobin
              • Carries oxygen and carbon dioxide
        • White blood cells (leucocytes)
          • 1%
            • Large cells with nuclei that have unusual shapes
            • Kills foreign cells
            • Get rid of dead or drying blood
        • Platelets
          • >1%
            • Cell fragments that lack a nucleus
              • Clot blood
                • Forming scabs
              • Fight infection
      • Functions
        • Blood carries substances
        • Blood plays an important role in fighting disease and infection
        • Blood helps to control and regulate body temperature
      • Substances carried
        • Water
          • Carried from intestines to the rest of the body
        • Food
          • Specifically
            • Sugars
            • Amino acids
            • Fats
          • Carried from the small intestine to the liver then the rest of the body
        • Waste products
          • Called urea
          • From all parts of the body to the kidneys
        • Oxygen
          • From the lungs to the rest of the body
        • Carbon dioxide
          • From the rest of the body to the lungs
        • Hormones
          • From hormone-secreting glands to the various target organs
    • The internal structure of the heart
      • Upper chambers
        • Atria
      • Lower chambers
        • Ventricles
      • Double pump
        • Separated by a muscular wall
          • Known as the septum
      • = right
        • Deoxygenated
      • = left
        • Oxygenated
      • Valves
        • Between atria and ventricle
          • Atrioventricular (AV)
            • Tricuspid
              • Left
            • Bicuspid
              • Right
        • Semi-lunar
          • Base of the two major arteries
            • Carry blood away
      • Major blood vessels
        • Venae cavae
          • Superior and inferior
        • Pulmonary veins
        • Pulmonary artery
        • Aorta
    • Cardiac Cycle
      • Enters right atrium via the vena cava
        • Flows into the right atrium via the tricuspid AV valve
          • Flows into the lungs via the pulmonary artery which is accessed by the pulmonary valve
            • From the lungs blood flows back to heart in the pulmonary veins and enters the left atrium
              • Blood flows down into the left ventricle via the bicuspid AV valve
                • Blood is pushed out the left ventricle into the aorta via the aortic valve
                  • Cycle repeats
      • The cycle
        • Atrial systole (0.1sec)
          • Atria contract
          • AV valved are open
        • Ventricular systole (0.3sec)
          • Ventricles contract
          • AV valves closed
          • Semi-lunar valves open
        • General diastole (0.4sec)
          • Heart relaxes
          • AV valves open
            • So that blood trickles into the ventricles
          • Semi-lunar valves closed
      • Control
        • Natural pacemaker
          • Sinoatrial node
            • Connected to the brain by the
              • Sympathetic nerve
                • Tells the heart to slow down
              • Parasympathetic nerve
                • Tells your heart to beat faster
                • Stimulated by adrenaline (epinephrine)

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