BIO 126 Lecture Notes - Lecture 6: Countercurrent Exchange, Rib Cage, Pharynx
13 Apr 2016
School
Department
Course
Professor
Document Summary
Gills- specialized extensions of tissue that project into water. Constant movement required to ensure contact w/ oxygen rich fresh water. Gills of bony ish located between oral & opercular cavities. Moves water into mouth & out of ish through gill cover. Countercurrent exchange- water and blood low in opposite directions. Frogs: positive pressure breathing- air to lungs by creating a positive pressure in buceal cavity. Reptiles: negative pressure breathing- ribcage expands by muscular contraction, creating lower pressure inside the lungs. Packed w/ alveoli- the site of gas exchange. This is the last thing to develop in- utero. Why preterm labor can cause the baby"s lung to collapse. Pharynx larynx trachea bronchi bronchioles alveoli. Air channeled through tiny air vessels called parabronci. Cycle 1: inhale air to trachea posterior air sac lungs. Cycle 2: air from lungs anterior air sacs exhaled through trachea. Crosscurrent low- blood lows 90 degrees to air low.
