gas exchange + smoking

• Alveoli

  An exchange surface found in the lungs of mammals, adapted for the efficient exchange of oxygen and carbon dioxide
• Alveoli


  • Wall-adapted for the efficient exchange of oxygen and carbon dioxide
  • Millions of little air sacs where gas exchange takes place
• Factors affecting the rate of diffusion

  • Distance
  • Concentration gradient
  • Surface area
• Gases are exchanged in the lungs by diffusion
• Gas exchange in mammals

  1. Blood arriving at the alveoli has high CO2 and low O2

  2. O2 diffuses out of the air in the alveoli and into the blood

  3. CO2 diffuses in the opposite direction to be breathed out
• Alveoli

  • Moist lining for dissolving gases
  • Good blood supply to maintain concentration gradients of O2 and CO2
  • Very thin walls to minimise distance gases have to move
  • Enormous surface area (about 75 m² in humans)
• Inhaling gases

  1. Diaphragm moves down and contracts

  2. Increased volume in lungs

  3. Pressure decreases

  4. Intercostal muscles contract
• Alveoli are surrounded by blood capillaries which allow more oxygen to pass into the blood
• EXHALING

  1. Ribcage relaxes

  2. Pressure increases

  3. Air is pushed out of the lungs

  4. Intercostal muscles contract
• Diaphragm

  A dome-shaped flat sheet of muscle under the lungs that contracts and relaxes
• Trachea


  • Also known as the windpipe, it is a tube that runs from the mouth down the throat towards the lungs, with rings of cartilage
  • It splits into a left and right bronchus, each leading to a lung
• Air flow through the respiratory system

  1. Trachea

  2. Bronchus

  3. Bronchioles

  4. Alveoli
• Alveoli


  Tiny air sacs at the end of the bronchioles where oxygen moves out into the blood and CO2 moves out
• Intercostal muscles

  • Muscles that run between the ribs and form the chest wall, they contract and relax
• Nicotine


  Causes the blood vessels to become narrower, which increases blood pressure
• Narrower blood vessels


  Less red blood cells carrying oxygen will be able to travel to the heart
• Narrower blood vessels

  Increases heart rate and causes high blood pressure
• Nicotine can cause heart attack
• Tar

  Forms a sticky layer inside the lungs
• Tar

  • Can cause emphysema and cancer
  • It is a black brown sticky substance that coats aliated cells, making it hard to breathe
• Carbon monoxide

  Poisonous gas that reduces the amount of oxygen that red blood cells carry
• Reduced oxygen in red blood cells


  Increases the risks of heart disease and strokes
• Tobacco smoke


  Goblet cells in lining of trachea, bronchi and bronchioles produce sticky mucus to trap dirt and pathogens
• Cilia


  Hair-like projections that move the mucus out of the lungs
• Chemicals in tobacco smoke and tar


  Destroy cilia, causing mucus to build up in the small airways and making it harder for the smoker to breathe
• Coronary Heart Diseaseoccurs when arteries that carry blood to the heart muscle are narrowed by plaque or blocked by clots. Chemicals in cigarette smoke cause the blood to thicken and form clots inside veins and arteries.
• When tobacco smoke is inhaled, the tar can form a sticky layer on the inside of the lungs. This damages the lungs and may lead to lung cancer, emphysema, or other lung problems
• Coronary Heart Disease

  • no O2 +glucose reaches the heart cells