DASC20010 Lecture 18: 18

• School: University of Melbourne
• Department: Animal Science
• Course: DASC20010
• Professor: Peter Cakebread

Document Summary

Respiration= exchange of gases but in biochem is just intracellular. Slight negative pressure (4ml) to hold lungs against wall of thorax. Intra alveolar pressure changes by muscle where concentration of gases change because of volume changing. Diaphragm- when contracts, becomes flatter and makes more space for air. During birth of calf, close throat (larynx) and go to breathe out so thorax volume decreases and diaphragm can bulge opposite way and hold abdominal muscles which stretch. Both of these put extra pressure on the pelvic cavity which can help calf come out. Passive- lungs can collapse and become smaller so pressure is greater. Pleural pressure slightly less negative so lungs pressure becomes slightly more positive. Surface tension- water pull closer together so alveoli want to collapse passively. If gets bigger= less surface tension so easier to expand even more. Stops smaller ones getting smaller and bigger ones getting bigger. Whe(cid:374) pre(cid:373)ature, does(cid:374)"t ha(cid:448)e surfacta(cid:374)t so lu(cid:374)gs do(cid:374)"t (cid:449)ork.