BIOL 111 Lecture Notes - Lecture 17: Gas Exchange, Osmotic Concentration, Hagfish

• School: McGill University
• Department: Biology (Sci)
• Course: BIOL 111
• Professor: Rajinder Dhindsa

Document Summary

Biol 111-lecture 17-fishes precious: respiration, pharyngeal slits=gill slits. -respiration in vertebrates (gills: bars between the slits=gill arches. -bony fish have 4 pairs of gill arches, & gill cover (operculum: gill filament structure. -water & blood flow in opposing directions (countercurrent mechanism: gas exchange (countercurrent) -concentration gradients are maintained along the length of the exchange area. -high efficiency: circulatory system of fishes, gills dorsal aorta arterial blood distributed to the body venous blood collected from the body heart aorta, closed system. *arteries (away from heart) arterioles capillaries venules (to heart) veins. Systemic circuit=heart body heart (in us, not in fish: fish heart. -one way valves maintains blood flow: characteristics of vertebrates, axial skeleton. -ventral heart: organs suspended in coelom, fish diversity, agnathans ( jawless fishes ) -osmotic concentration same as seawater, don"t regulate the ionic concentration. -adults can be parasitic on other fishes: characteristics of fishes. -not present in early fishes & present-day agnathans.