Biology

• Adaptations of the villi

  Large surface area to volume ratio to increase rate of diffusion and rate of absorption

  Capillaries provide the villi with a good blood stream giving it a good concentration gradient for diffusion

  villi have a one cell think membrane for a short diffusion distance into the blood
• Coronary heart disease


  When the coronary arteries which supply blood to the heart muscle start to get blocked by the buildup of layers of fatty material, causing the lumen of the arteries to become narrower so that less blood and oxygen can reach the heart muscle
• Treatments for coronary heart disease


  1. Stents

  2. Statins
• Stent


  An expandable tube that can be placed inside the arteries to hold them open and ensure blood can keep flowing
• Stents advantages and disadvantage


  • The surgery is relatively quick and they're effective for a long time
  • There are risks such as inducing a heart attack, infection, or blood clot
• Statins


  Medications that alter the balance of cholesterol in the bloodstream by decreasing bad LDL cholesterol and increasing good HDL cholesterol, lowering the overall risk of coronary heart disease and other diseases
• Statins advantages and disadvantages


  • They have to be taken regularly for years
  • They can cause side effects such as headaches and kidney failure
• Faulty heart valves


  When the heart valves get damaged or weakened, either naturally over time or due to other factors, causing issues with blood flow
• Treatments for faulty heart valves

  1. Valve replacement with biological valves from another human or pig

  2. Valve replacement with man-made mechanical valves
• Heart valve replacements cons


  • Require surgery
  • Ongoing risk of blood clots
• Heart failure


  When the heart isn't able to pump blood around the body properly
• Treatments for heart failure

  1. Medications

  2. Heart transplant with a biological heart from a donor

  3. Artificial heart (temporary fix)
• Heart transplants cons


  • Donor heart may be rejected by the body's immune system
• Artificial hearts cons


  • Not as good as biological hearts, only a temporary fix
• Diffusion


  Net movement of particles from an area of high concentration to an area of low concentration. It is a passive process
• Factors affecting diffusion


  -temperature

  -surface area

  -concentration gradient
• Osmosis 


  Net movement of water molecules across a semi permeable membrane from an area of high water concentration to an area of low water concentration
• Active transports 


  Net movement of particles from an area of low concentration to an area of high concentration using energy from respiration