BIO271H1 Lecture Notes - Lecture 7: Internal Intercostal Muscles, Negative Feedback, Paracrine Signalling
Document Summary
Respiratory organs are typically thin with a large sa and must be kept moist. Two animal lineages that colonized terrestrial habitats: arthropods. System is almost identical to their water-breathing cousins. Extensive, branched tracheal system where air filled tubes are open to the outside via spiracles. Tracheae branch to form tracheoles (end of the tube and filled with hemolymph, so most gases dissolve in it) Tracheole is invaginated into the muscle tissue in the myofibers themselves. Oxygen has a high diffusion coefficient in air. Contraction of abdominal muscles or movements of the thorax. Tidal: air flows in and out of the same spiracles. Unidirectional: enter anterior spiracles and exit. They leave some of their spiracles open which forces the air through while they are flying: discontinuous gas exchange. Po2 decreases: this part triggers phase 2. Co2 is being produced, but it can be converted into bicarbonate and stored in the hemolymph of the tracheoles.
