LIFESCI 2 Lecture Notes - Lecture 4: Perfusion, Hemoglobin, Partial Pressure
Document Summary
Respiratory gases are co2 and o2, only exchanged through diffusion, co2 out, o2 in. Increase diffusion by, increasing area, difference between p1 and p2, decrease. External gills- minimizes l with thin epithelial cells,membrane. Smaller bird lungs, able to live at higher altitudes. Avian respiratory system- unidirectional, little dead space, air sacs(not sites of exchange but hold inhaled air) Mammalian tidal breathing- bad half time have fresh air, [] of o2 in lungs less than air. 500 with 2000, bidirectional flow eliminates possibility of counter current exchange. Adaptations: big a, short diffusion path across alveolar cells, surfactant and mucus(surfactant- reduces surface tension(resistance to movement) makes breathing less costly. Insects spiracles open for gas, close for water loss. Spiracles --> tracheae --> tracheoles --> air capillaries air is better than water b/c oxygen content higher in air 200 ml/l vs water 10ml/l, But: in ectotherms, increased temp, increased oxygen need, less available in warmer.
