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

2. Positive or Negative... what’s YOUR 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  Positive Pressure Breathing (Most other lunged animals) Thoracic cavity enlarges by: Action of the rib muscles, yes…. But mostly due to: Contraction of the diaphragm. Both lower pressure In the lungs to below Atmospheric Pressure. 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…)

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

4. 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 CO 2 levels rise  pH lowers  Tempo of breathing increases Remember! Gases diffuse down their concentration gradient!!  Loading & Unloading of O 2 & CO 2 Blood arriving in lungs has a lower Po 2 and higher Pco 2 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 O 2 molecule COOPERATIVITY: binding of first subunit changes the shape of the rest of them and increases their affinities. Bohr Shift- O 2 has lower affinity at lower pH

5. CO 2 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 CO 2 into the bicarbonate. CO 2 + H 2 O  Carbonic Acid Carbonic Acid dissociates into Bicarb + H + Reverses in Lungs