Alveoli Features & Breathing

Alveoli Features & Breathing

1. Alveoli features

   • Diffusion distance
     • Single layer of cells - rapid gas exchange
   • Increased surface area
     • Great number of alveoli
   • Dense network of capillaries
     • Supply of blood with low O2 & high CO2 concentration
   • Secretion of fluid
     • Allows gases to dissolve & prevent sides of alveoli sticking
   • Cilia
     • fine 'hairs' on cell surface
     • Beat in a co-ordinated way to carry mucus ( with trapped microbes & dust) away from the lungs
   • Goblet cell
     • Produces sticky mucus & releases it onto the cell surface

2. Breathing

   • At rest
     • CO2 level & blood pH are kept at safe level
   • During exercise
     • more air must be breathed in & out as muscle have to work harder
     • Deeper more rapid breathing
       • More CO2 lost from lungs
     • Deeper more rapid heartbeat
       • More blood pumped to tissues to carry CO2 away