Transport and exchnage

• What do organsims need to exchange with their environments?

  • Oxygen and glucose- respiration
  • Co2 and urea- excrete waste products
• A mouse had a big surface area to volume ratio
• A hippo has a small surface area to volume ratio
• Why do Multicellular organsims need exchange surfaces?

  1. They have a large distance for diffusion
  2. Diffusion is too slow
  3. Low surface area to volume ratio
  4. High metabolic rate or demand for oxygen
• Features of exchange surfaces:

  • An increased surface area for diffusion
  • Thin walls
  • Good blood supply/ ventilation
• Goblet cells secrete mucus which traps microorganisms and dust particles
• Cilia waft mucus towards the throat to be swallowed to prevent lung infections
• Elastic fibres help with the process of breathing out as they recoil nd return away to its normal size
• Smooth muscle controle the airway diameter.

  • During exercise the air ways are wider to reduce resistance
• Cartilage rings provide support and stops airways collapsing when you breathe in and the pressure drops
• Ventilation in mammals

  • Breathe in and breathe out in mammals
  • Controlled by diaphragm and intercostal muscles
• Inspiration

  1. External intercostal musclee and diaphragm contract
  2. Ribcage move up and out and increases the volume of the thorax
  3. This decreases the pressure below atmospheric pressure
  4. Ait is forced int the lungs
  5. This requires energy so is an active process
• Expiration

  1. External intercostal muscles and diaphragm relax
  2. Ribcage moves down and in
  3. Air pressure increases above atmospheric pressure
  4. Air is forced out the lungs
  5. It's a passive process
  6. When forced internal intercostal muscles contract
• Tidal volume- volume of air breather in or out in each breathe
• Vital capicity- maximum volume of air breathed in or out
• Breathing rate- number of breaths a minute
• Oxygen uptake- rate organsim uses up oxygen
• Ventilation in fish is different as there is less oxygen in water than in air
• Fish countercurrent systems

  • Water enters through mouth an pass out through gills
  • Gill made of Gill filaments or labelled have a large surface area
  • Gill supported by Gill arch
  • Lqmqllqe have lots of capillaries and thin surface layer of cells
  • Counter current blood through Gill one way and water the other
  • Concentration of o2 in water is always higher than blood
• How are fish gils ventillated?

  • Fish open mouth, lowers buccal cavity and this increases buccal cavity vol but decreases pressure. Water is tucked in
  • Fish close mouth, buccal cavity floor is raised. This decreases volume and increases pressure
  • So water is forced out over gills
• • How are fish gils ventillated?
  • Fish open mouth, lowers buccal cavity and this increases buccal cavity vol but decreases pressure. Water is tucked in
  • Fish close mouth, buccal cavity floor is raised. This decreases volume and increases pressure
  • So water is forced out over gills
  • The operculum opens due to increased pressure allowing water to leave the gills