(Terrestrial) RESPIRATION: When AIR is the respiratory Medium…. Benefits over water: Higher O2 content Better diffusion rates Less of a need to ventilate Biggest obstacle to overcome: NEED A MOIST MEMBRANE!!! Insects (the main category of terrestrial invertebrates) have “TRACHEA”: Highly branched air tubes which extend to nearly every cell Air is taken in through small pore on their sides called “SPIRACLES” http://www.youtube.com/watch?v=quwhcgkVO3c LUNGS! Terrestrial Vertebrates (of course) have _________ There are 2 main strategies for breathing: POSITIVE & NEGATIVE PRESSURE

Positive or Negative ...what’s YOUR pressure? Positive Pressure Breathing Example: Air is forced down into the lungs by use of a mouth pouch Negative Pressure Breathing (Most other lunged animals) Thoracic cavity enlarges by: Action of the rib muscles, yes…. Both lower pressure In the lungs to below Atmospheric Pressure. But mostly due to: Contraction of the diaphragm. Tidal Volume- Amount of air an animal breaths in a normal breath Vital Capacity- Maximum air volume during forced breathing (There will always be some Residual Volume: the amount still remaining…)

Bird Respiration: Kenny G. You ain’t got nuthin’!! …a very complex system!! Besides lungs, they have 8-9 air sacs in their abdomen: Serve as bellows to a continuous movement of air Air channels continuously through “Para bronchi” Animate!

Control of Breathing: a lot is just in your head… Breathing Control Centers of the Medulla Oblongata & Pons: Send impulses to rib muscles & diaphragm Monitor blood & spinal fluid pH: As CO2 levels rise  pH lowers  Tempo of breathing increases Loading & Unloading of O2 & CO2 Remember! Gases diffuse down their concentration gradient!! Blood arriving in lungs has a lower Po2 and higher Pco2 than the air in the alvioli OXYGEN: Carried by hemoglobin (Iron containing pigment) What’s Hemoglobin again? Protein with a 4 subunits: alpha & beta Each subunit binds one O2 molecule COOPERATIVITY: binding of first subunit changes the shape of the rest of them and increases their affinities. Bohr Shift- O2 has lower affinity at lower pH

CO2 Transport: a little more tricky Transported in 3 ways: 1. 7% is dissolved in plasma. 2. 23% bound to amino groups of hemoglobin. 3. A full 70% as a bicarbonate ion. In erythrocytes, CARBONIC ANHYDRASE converts CO2 into the bicarbonate. CO2 + H2O  Carbonic Acid Carbonic Acid dissociates into Bicarb + H+ Reverses in Lungs