ER 1

• Modification of inhaled air in the respiratory system

  1. Air enters through the nasal cavity

  2. Creates turbulence in air

  3. Large particles are caught on cilia and mucus

  4. Air is warmed and moistened

  5. Air passes through the pharynx

  6. Epiglottis allows air into the lungs

  7. Sound production in the larynx

  8. Cilia cleans air with mucus in the trachea

  9. Air enters lungs through two pathways in the bronchi

  10. Air reaches the alveoli through the bronchioles
• Pathway of an erythrocyte around the body

  1. Gas exchange in the lung's capillaries

  2. Oxygenated blood leaves the lungs

  3. Heart pumps oxygenated blood

  4. Delivery of oxygen to tissues

  5. Capillary gas exchange

  6. Deoxygenated blood returns to the heart

  7. Heart pumps deoxygenated blood to the lungs

  8. Deoxygenated blood enters the lungs
• Chemicals in cigarette smoke

  • Nicotine
  • Carbon monoxide
  • Irritant gases (e.g. Ammonia, Nitrogen Dioxide)
  • Tars
  • Carcinogens
• Nicotine


  A drug that causes physical and psychological dependance - stimulates the brain and some nerve endings to muscles and organs. Causes muscles to relax, decreases urine output, causes fatty acid concentrations in the blood to rise, causes platelets to stick together more readily promoting arteriosclerosis.
• Carbon monoxide


  Combines with haemoglobin in red blood cells and causes a reduction in the oxygen carrying capacity of the blood. This makes less oxygen available to the brain, heart and other muscles.
• Irritant gases


  Contribute to the destruction of lung tissue and the development of emphysema. Cause an increase in the production of mucus in the bronchial tubes and a decrease in the action of the cilia, accumulating mucus causes a smoker's cough and eventual destruction of the alveoli wall causing emphysema.
• Smaller babies at birth due to reduced oxygen and carbon monoxide combined with the baby's haemoglobin.
• Sequence of events in inhalation and exhalation

  Intercostal muscles contract and move ribs up and out to increase size of thoracic cavity, diaphragm contracts and moves downwards, volume of thoracic cavity increases and pressure decreases, air moves in from high pressure outside to low pressure inside lungs

  Intercostal muscles relax and move ribs down and in to decrease size of thoracic cavity, diaphragm relaxes and moves upwards, volume of thoracic cavity decreases and pressure increases, air moves out from high pressure inside lungs to low pressure outside
• Alveoli structure: Smallest structure at end of bronchioles, small air sacs, walls one cell thick, moist inner surface, round shape for large surface area, large capillary network
• Alveoli function: Simple squamous epithelium tissue creating a thin, delicate, moist membrane in direct contact with the blood supply for the rapid exchange of gases by diffusion
• Tar


  layer reduces gas exchange - forms a slick which damages the alveoli walls
• Efficient gas exchange surface

  Thin walls (alveoli one cell thick)

  Moist

  Large surface area

  Extensive blood supply

  Well ventilated
• Thin walls

  Alveoli are one cell thick (ss epithelium).

  This reduces the distance for oxygen to diffuse across onto the capillary and carbon dioxide to diffuse out of capillary into the alveoli.
• Moist

  Gases must dissolve in moisture before they diffuse
• Large surface area

  Increase the space over which gas exchange can occur. Alveoli are spherical, microscopic, and in clusters so they have a large surface area overall.
• Extensive blood supply

  Capillaries are alongside alveoli to allow less distance for diffusion. Blood low in oxygen and high in carbon dioxide is constantly being delivered which maximises the concentration gradient between alveoli and the capillaries.
• Well ventilated

  Breathing in air high in oxygen into the alveoli, oxygen will diffuse into the blood which has low oxygen, so diffusion is maximized. Breathing out removes air high in carbon dioxide so inside alveoli, the carbon dioxide level is lower than the carbon dioxide in the capillaries. This maximizes diffusion.
• Carcinogens


  Polycyclic aromatic hydrocarbons, others can be;

  complete carcinogens (cause cancers),

  tumor initiators (bring about the first stage of tumor formation),

  tumor promotes (complete the formation of a tumor after it has been begun by other substances)
• Other effects of smoking on our health

  Gingivitis and loss of teeth are more common in smokers.

  Chronic bronchitis and emphysema causes more rapid and strained breathing and resulting in stress. Less oxygen is available at times of activity and this requires the heart to work harder.

  Leucocytes (macrophages and lymphocytes) are reduces in number when exposed and become less activity

  In pregnancy - the chances of still birth and infant death are higher
• Other effects of smoking on our health


  
  

  • Gingivitis and loss of teeth are more common in smokers.
  • Chronic bronchitis and emphysema causes more rapid and strained breathing and resulting in stress. Less oxygen is available at times of activity and this requires the heart to work harder.
  • Leucocytes (macrophages and lymphocytes) are reduced in number when exposed and become less active
  • In pregnancy - the chances of still birth and infant death are higher