Humans

• Alveoli adaptations

  Increased SA for gaseous exchange Elastic fibers to expand/ stretch and recoil are thin- so short diffusion distance moisture allows gases to disolve during exchange
• How does oxygen move from the alveolus to blood

  Diffusion out of the epithelial alveolus into the endothelium of capillary into the blood
• Intercostal muscles during in/exhalation

  Inhalation: -Internal intercostal relax -External intercostal contract Exhalation: -Internal intercostal contract -External intercostal relax
• Inspiration Mechanism

  Inspiration: Ribs- up and out Diaphragm- down (contracts) -Internal intercostal relaxes -External intercostal contracts -Thorax volume increases -Pressure decreses -Lungs Inflate- air rushes in down a pressure gradient
• Exhalation mechanism

  -Ribs- down and in -Diaphragm- up (relax) -Internal intercostal- contract -External intercostal- relax -Thorax volume decreases -Pressure increases -Lungs deflate - air rushes out down a pressure gradient
• Pulminary ventilation equation + definitions

  PV = Tidal volume x ventilation rate -PV- dm3/ min -Tidal volume- volume of air in each breath- dm3 -Ventilation rate- number of breaths per min /min -Forced expiration volume (FEV)- macimum air breathed out in a second -Forced vital capacity (FVC)- maximu volume of air forcefully breathed out after a deep breath
• Positive Cooperativity

  -first o2 molecule binds -changes quaternary shape of haemoglobin portein -so this allows 2nd binding site to uncover

  -next o2 binds more easily

  -Fourth o2 binds but is more difficult as molecule is almost fully satuatred with o2
• Describe how heomoglobin loads and unloads oxygen in the blood

  1- oxygen loads onto haemoglobin at high partial pressure

  2- in the lungs haemoglobin has high affinity for oxygen

  3 tissues have low partial pressure of oxygen as it has been used in respiration

  4- in tissues haemoglobin has a lower affinity for oxygen

  5- haemoglobin unloads oxugen at low partial pressures
• Transport - Loading and unloading of O2

  In the lungs:

  -Co2 is constantly removed -the pH is slightly raised -so higher pH changes Hb shape -so it loads more easily (Hb affinity for o2 increased)

  In respiring tissues:

  -Co2 is being porduced in the cells -Th pH is lowered -Shape of Hb is changed -So Hb releases o2 more easily (lower affinity)

  -This triggers Hb to release O2 in respiring tissues
• Ileum adaptations for absorption

  Microvilli give large surface area for diffusion - more transpoprt protiens thin walled - so short diffusion pathway and faster diffusion muscular to maintain conc gradient by mixing material to be absorbed + break apart bolus Good blood supply from many capillaries