1. Relate Cause and Effect Why do some animals actively pump water over their gills

2. Interpret Visuals Contrast the structures of amphibian, reptilian, and mammalian lungs

3. 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.