BIOl 152 1st Edition Lecture 18Outline of Last Lecture I. Bulk vascular systemII. Vertebrate vascular systemIII. Heart contractionsIV. Blood compositionOutline of Current Lecture I. Gas Exchange SurfacesII. Mammalian lungsIII. HomeostasisIV. Exceptions to the excretory systemCurrent LectureI. Gas exchange surfacesAquatic vertebrates such as fish, use gills as a means of gas exchange. The gills increase the surface area and therefore help the fish obtain a sufficient amount of oxygen. The gills are an external structure, meaning that they are on the surface of the organism. The countercurrent exchange system enhances the flow of oxygen and maintains a concentration gradient. Insects, millipedes, and centipedes contain a structure called the trachea, which are internal branching tubes with a small opening to the outside. Amphibians, reptiles and mammals contain lungs, which are an internal organ with an opening to the outside. The lungs and trachea are terrestrial adaptations, to limit water loss and to not dry out.II. Mammalian lungsThe lungs in mammals increase the surface area and the thin walls of the alveoli and capillaries enhance the diffusion of gasses into the air sacs. The hemoglobin, or blood pigment, reversibly binds to oxygen at high partial pressures and releases the oxygen to areas of low oxygen partial pressure.III. HomeostasisHomeostasis is the maintenance of a constant internal environment in an organism, and is essential for proper function of the cell, tissues and organs. Homeostasis is maintained These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.through the processes of osmoregulation and excretion. Osmoregulation refers to the regulation of water concentrations and the excretion includes urine and feces.IV. Exceptions to the excretory systemThere are some animals that do not release waste by the excretory system and have other systems that help them release waste. The Protonephridium, or flatworm have no blood vessels and instead have specialized cells that filter fluid. Insects have malpighian tubules that are entirely
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