BIOL 111 Lecture Notes - Lecture 20: Vomeronasal Organ, Reabsorption, Control Volume

• School: McGill University
• Department: Biology (Sci)
• Course: BIOL 111
• Professor: Rudiger Krahe

Document Summary

How to fully survive away from water: more efficient heart, amniotic egg, better excretory system. Reptiles are fully terrestrial: more efficient heart, must conserve water, produce a special nitrogenous waste (uric acid, skin is waterproofed by keratin, breathe via lungs only, reproduce & develop on land, amniotic egg, internal fertilization. Reptilian hearts are more separated than those of amphibians. Birds and mammals have completely separate pulmonary and systematic systems. Phylogeny tree of heart evolution: egg surrounded by extra-embryonic membranes external shell. Egg: leathery or brittle (caco3 ): mechanical support, permeable to gases (o2 & co2 ): gas exchange, fairly impermeable to water, not present in therian mammals. Consequences of using terrestrial eggs internal fertilization: sperm cannot penetrate egg shell, shell & albumen are added to the fertilized egg in the female"s oviduct, non-toxic nitrogen waste product is required, which is uric acid. Nitrogenous wastes: ammonia (nh3) very soluble in water very toxic.