Relate Cause and Effect Why do some animals actively pump water over their gills Interpret Visuals Contrast the structures of amphibian, reptilian, and mammalian lungs Explain Describe the events that occur when a mammal respires including the path of air through the lungs.

Ch 27 Animal Systems I 27.2 Respiration

Gas Diffusion and Membranes Gases diffuse most efficiently across a thin, moist membrane that is permeable to those gases Larger the surface area membrane, the more diffusion that can occur.

Requirements for Respiration Large surface area of moist, selectively permeable membrane Difference in relative concentrations of oxygen and carbon dioxide on either side of the respiratory membrane.

Respiratory Surfaces of Aquatic Animals Some aquatic invertebrates and a few chordates rely on diffusion of oxygen and carbon dioxide through their outer body covering.

Respiratory Surfaces of Aquatic Animals Many aquatic invertebrates and most aquatic chordates exchange gases through gills Gills Feathery structures that expose a large surface area of thin, selectively permeable membrane to water Capillaries Network of tiny, thin-walled blood vessels.

Respiratory Surfaces of Aquatic Animals May actively pump water over their gills as blood flows through inside Gas exchange occurs as water passes over the gills.

Respiratory Surfaces of Aquatic Animals Lungs Organs that exchange oxygen and carbon dioxide between blood and air Aquatic reptiles and aquatic mammals, must hold their breath underwater.

Respiratory Surfaces in Land Invertebrates Wide variety of respiratory structures Respire across their skin Mantle cavity Book lungs Tracheal tubes.

Book Lungs Which are made of parallel, sheetlike layers of thin tissues containing blood vessels.

Tracheal Tubes Air enters and leaves the system through openings in the body surface called spiracles Most invertebrates.

Lung Structure in Vertebrates Lung structure in terrestrial vertebrates varies Processes of inhaling and exhaling are similar

Inhaling brings oxygen-rich air through the trachea (airway) into the lungs Oxygen diffuses into the blood through lung capillaries Carbon dioxide diffuses out of capillaries into the lungs Oxygen-poor air is then exhaled.

Amphibian, Reptilian, and Mammalian Lungs Typical amphibian lung is little more than a sac with ridges.

Amphibian, Reptilian, and Mammalian Lungs Reptilian lungs are divided into chambers Increase the surface area for gas exchange.

Amphibian, Reptilian, and Mammalian Lungs Mammalian lungs branch extensively Filled with Alveoli.

Alveoli Provide enormous surface area for gas exchange Enable mammals to take in the large amounts of oxygen required by their high metabolic rates.

Bird Lungs Air flows mostly in only one direction, so no stale air gets trapped in the system Gas exchange surfaces are continuously in contact with fresh air Highly efficient Enables flight, at high altitude for extended time.