10 26 07 - Respiratory System I-2

10 26 07 - Respiratory System I-2 - *Respiratory System I*...

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*Respiratory System I* Cutaneous respiration Amphibians; may provide 50-100% of oxygen demands - blood vessels in skin lie close enough to surface to allow gas exchange - requires a high ratio of surface to volume to be useful - animals must occupy high humidity environments Gas exchange – principles - O 2 and CO 2 move in opposite directions, down their diffusion gradients All tissues need a supply of O 2 and a way to eliminate CO 2 The site of external respiration is the respiratory membrane - thin – to minimize diffusion time - highly vascular – to maximize the amount of surface area General Structure of the shark gill apparatus: Embryonically, the endodermal pouches, and ectodermal clefts unite producing gill slits The bars of tissue remaining in between are the gill arches , each containing a skeletal element (visceral cranium) - Running perpendicular to the skeletal element is an interbranchial septa with skeletal gill rays running parallel - Gill rays allow attachment of branchial muscles, allowing movememt of the septa - primary gill lamellae face toward the gill slit
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10 26 07 - Respiratory System I-2 - *Respiratory System I*...

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