Circulatory System

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  • Created by: Abc312
  • Created on: 12-05-18 20:04
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  • Circulatory System
    • The Heart
      • Pumps blood around the body in a double circulatory system
      • Flow of blood
        • From the body (deoxygenated)
          • Through the vena cava
            • Into the right atrium
              • The atria contract
                • Pushing blood into the right ventricle
                  • The  ventricles contract
                    • Forcing blood  through the pulmonary artery
                      • The blood goes to the lungs
                        • Gas exchange happens
                          • Oxygenated blood flows into the heart
                            • Through the pulmonary vein
                              • Into the left atrium
                                • The atria contract
                                  • Pushing blood into the left ventricle
                                    • The ventricles contact
                                      • The blood is pushed out of the aorta
                                        • It flows around the body
        • Both sides happens the same time
      • The heart needs its own flow of oxygenated blood
        • The coronary arteries branch off the aorta and surround the heart.
      • The natural resting heart rate is controlled by cells in the right atrium
        • They produce a small electrical impulse which causes them to contract
        • If the natural pacemaker cells don't work then an artificial pacemaker is fitted
          • It fits under the skin and has a wire going to the heart and produces an electric current
    • Blood Vessels
      • Arteries
        • The heart pumps blood at high pressure.
          • This means artery walls have to be strong and elastic
        • Walls are thick compared to the lumen
        • Thick layers of muscle to make them strong
        • Have elastic fibres to allows them to stretch and spring back
      • Veins
        • Capillaries join up to form veins
        • The blood is now at a lower pressure
          • This means the walls are not as thick as in arteries
        • Bigger lumen than arteries
          • Help the blood flow better despite the lower pressure
        • Have valves to help blood flow in the right direction
      • Capillaries
        • Arteries branch  into capillaries
        • They are tiny - too small to see
        • They carry blood really close to every cell in the body to exchange substances
          • They supply oxygen and food and take away waste like CO2
        • Have permeable walls for easier diffusion
        • Walls are only one cell thick
          • Increases the rate of diffusion
            • Because of a shorter distance to diffuse
        • Have a very small lumen
    • Blood
      • Plasma
        • The liquid that carries everything.
          • Red blood cells
          • White blood cells
            • And the antibodies and antitoxins that they make
          • Platelets
          • Nutrients
            • Like glucose and amino acids that are soluble products of digestion and taken to body cells
          • Carbon dioxide
          • Urea
          • Hormones
          • Proteins
      • Red blood cells
        • Carry oxygen from the lungs to all body cells
        • Shaped as a biconcave disc
          • Gives a large surface area for absorbing oxygen
        • Have no nucleus
          • Gives more space to carry oxygen
        • Contain a red pigment called haemoglobin
          • When it binds to oxygen it becomes oxyhaemoglobin
      • White  blood cells
        • Defend against infection
        • Some change shape to swallow pathogens
          • Phagocytocis
        • Some produce antibodies and antitoxins
        • They do have a nucleus
      • Platelets
        • Small fragments of cells
        • Have no nucleus
        • Help blood to clot at a wound
        • If you don't have enough platelets you can bleed and bruise too much,
    • Cardiovascular disease
      • Coronary Heart Disease
        • Layers of fatty material build up inside the coronary arteries
          • This narrows them
        • It causes reduced blood flow through the arteries
          • Causing a lack of oxygen for the heart muscle
      • Stents
        • Tubes that go inside arteries
          • They keep them open
            • Means blood can pass through
        • Positives
          • Reduce the risk of a heart attack
          • Effective for a long time
          • Recovery time is relatively quick
        • Negatives
          • Could be complications during surgery
          • Risk of infection from surgery
          • Could develop a blood clot near the stent - called thrombosis
      • Statins
        • Cholesterol is an essential lipid that you need to function
        • Too much of certain bad cholesterol can cause problems
          • It can lead to fatty deposits forming inside arteries
        • Statins reduce cholesterol -slowing down  the rate of fatty deposits developing
        • Positives
          • Reduce the risk of strokes, heart disease and heart attacks
          • Can increase the amount of good cholesterol
        • Negatives
          • Long-term drug that you need to take regularly
            • Could forget to take them
          • Can cause negative side effects
            • Headaches or more serious like kidney failure, liver damage and memory loss.
          • Takes time for the effects to kick in.
      • ArtificialHeart
        • If a person has heart failure donor organs can be used
          • However this can sometimes be hard to find or not suitable for the patient so an artificial heart can be used
        • They are mechanical devices that pump blood.
        • They are usually only used temporarily
          • To allow someones heart to rest and heal or while waiting for a transplant
        • Positives
          • Less likely to be rejected than a donor heart
            • Because they are made from metal or plastic so the body doesn't attack them like they would a donor heart.
        • Negatives
          • Surgerycan lead to bleeding and infection
          • They don't work as well as natural ones.
            • Parts could fail or wear out.
          • Blood doesn't flow through artificial hearts as smoothly
            • This means the patient has to take drug thinners
              • This can cause more problems
      • Heart Valves
        • Heart valves can be weakened by heart attacks, infection or old age
          • It could become stiff not letting it open fully
          • May become leaky allowing blood to flow in both directions
        • Replacing a valve is a lot less drastic than a whole heart transplant
          • Surgery is still risky though
        • Valves can be:
          • Mechanical- man made
          • Biological- From another human or animal
      • ArtificialBlood
        • Even if a person loses a lot of blood the heart can still pump red blood cells with oxygen if the volume of blood can be topped up
        • It is a blood substitute
          • Used to replace the lost volume of blood
        • It can keep people alive even if they lose two thirds of their blood.

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