Biology B4 - Organising animals & Plants (Heart)

• Stents

  -Metal mesh inserted into artery

  -Balloon inflates opening stent

  -Not as invasive as a bypass

  -Can cause clots
• Bypass surgery

  -Works on badly blocked arteries where stents not possible

  -General anaesthetic

  -Long recovery time

  -Replaces/bypasses block with vein so normally need a new bypass in 10-15 years
• Pacemaker


  -Controls heartbeak if natural pacemaker goes wrong

  -Extends life

  -Can cause blood clots
• Statins


  -Drugs that reduce cholesterol levels in blood

  -Can cause side effects

  -Need to remember to take them
• Mechanical artificial valves


  -Last 20-30 years

  -Increased risk of blood clots
• Biological valves


  -Last 12-15 years

  -Low risk of clots
• Blood vessels - Arteries


  -Away from heart

  1. thick walls of muscle (to withstand pressure)
  2. elastic tissue (to maintain shape & withstand high blood pressure)
• Blood vessels - Veins


  -Towards heart

  1. less elastic & smaller muscle layer (blood under low pressure)
  2. have valves (prevent backflow of blood)
• Blood vessels - Capillaries

  1.One cell thick (short diffusion pathway)
• Composition of blood


  Dissolved gases

  • O2 in red blood cells
  • CO2 in plasma
  • Urea (from breakdown of amino acids)

  Nutrients

  • Glucose
  • Amino acids
  • Lipids
• Components of the blood - Red blood cells


  Function

  • carry oxygen

  Adaptions

  • contain haemoglobin (to carry oxygen)
  • biconcave shape disc (increase SA to volume in the cell)
  • no nucleus to increase amount of haemoglobin
• Components of the blood - White blood cells


  Function

  • fight off diseases (immune system)

  Adaptions

  • can engulf pathogens (diseases)
  • can produce antibodies
  • produce antitoxins
• Components of the blood - Platelets


  Function

  • Clot blood

  Adaptions

  • produces proteins
• Components of the blood - Plasma


  Function

  • carries blood
  • carries dissolved substances