Lesson Overview

1
Lesson Overview

• 27.2 Respiration

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THINK ABOUT IT

• Humans can drown because our lungs cant extract
  the oxygen we need from water. Most fishes have
  the opposite problem out of water, their gills
  dont work.
• How are these different respiratory systems
  adapted to their different functions?

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Gas Diffusion and Membranes

• Animals have evolved respiratory structures
  that help movement of these gases by passive
  diffusion.
• Substances diffuse from an area of higher
  concentration to an area of lower concentration.
• Gases diffuse most efficiently across a thin,
  moist membrane that is permeable to those gases.
• The larger the surface area of that membrane,
  the more diffusion can take place.

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Requirements for Respiration

• Respiratory structures provide a large surface
  area of moist, selectively permeable membrane.
• Respiratory structures maintain a difference in
  concentrations of oxygen carbon dioxide
  promoting diffusion.
• Because respiratory surfaces are moist, an
  animals breath condenses into fog when the air
  outside is very dry.

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Gas Exchange

• What characteristics do the respiratory
  structures of all animals share?

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Gas Exchange

• What characteristics do the respiratory
  structures of all animals share?
• Respiratory structures provide a large surface
  area of moist, selectively permeable membrane.
• Respiratory structures maintain a difference in
  the relative concentrations of oxygen and carbon
  dioxide on either side of the respiratory
  membrane, promoting diffusion.

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Respiratory Surfaces of Aquatic Animals

• Many aquatic invertebrates most aquatic
  chordates exchange gases through gills.
• Gills are feathery structures that expose a
  large surface area of thin, selectively permeable
  membrane to water.
• Gill membranes is a network of tiny,
  thin-walled blood vessels called capillaries.

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Respiratory Surfaces of Aquatic Animals

• Many animals actively pump water over their
  gills as blood flows through inside.
• As water passes over the gills, gas exchange is
  completed within the gill capillaries.

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Respiratory Surfaces of Aquatic Animals

• Aquatic reptiles aquatic mammals, such as
  whales, breathe with lungs and must hold their
  breath underwater.
• Lungs are organs that exchange oxygen and carbon
  dioxide between blood and air.

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Respiratory Surfaces of Aquatic Animals

• Some aquatic invertebrates, such as cnidarians
  flatworms have thin-walled bodies rely on air
  diffusion through their outer body covering.
  (skin breathers)
• A few aquatic chordates, including lancelets,
  some amphibians, and even some sea snakes, rely
  on skin to breath ex.) lungless frog

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Respiratory Surfaces of Aquatic Animals

• How do aquatic animals breathe?

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Respiratory Surfaces of Aquatic Animals

• How do aquatic animals breathe?
• Many aquatic invertebrates and most aquatic
  chordates other than reptiles and mammals
  exchange gases through gills.
• Aquatic reptiles and aquatic mammals, such as
  whales, breathe with lungs and must hold their
  breath underwater.

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Respiratory Surfaces in Land Invertebrates

• Terrestrial invertebrates have a wide variety of
  respiratory structures.
• Some land invertebrates, such as earthwormsskin
  breather/ land snailsmantle cavity, which is
  lined with moist tissue and blood vessels.

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Respiratory Surfaces in Land Invertebrates

• Spiders respire using organs called book lungs,
  which are made of parallel, sheetlike layers of
  thin tissues containing blood vessels.

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Respiratory Surfaces in Land Invertebrates

• Most insects respire using a system of tracheal
  tubes that extends throughout the body.
• Air enters and leaves the system through
  openings in the body surface called spiracles.

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Lung Structure in Vertebrates

• Inhaling O2 air into the lungs.
• Inside the lungs, O2 diffuses into the blood
  through lung capillaries.
• Co2 diffuses out of capillaries into the lungs.
• Oxygen-poor air is then exhaled.

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Amphibian, Reptilian, and Mammalian Lungs

• The internal surface area of lungs increases
  from amphibians to reptiles to mammals.

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Amphibian, Reptilian, and Mammalian Lungs

• A typical amphibian lung is little more than a
  sac with ridges.

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Amphibian, Reptilian, and Mammalian Lungs

• Reptilian lungs are divided into chambers that
  increase the surface area for gas exchange.

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Amphibian, Reptilian, and Mammalian Lungs

• Mammalian lungs branch extensively and are
  filled with bubblelike structures called alveoli.

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Amphibian, Reptilian, and Mammalian Lungs

• Alveoli provide an enormous surface area for gas
  exchange, and enable mammals to take in the large
  amounts of oxygen required by their high
  metabolic rates.

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Bird Lungs

• In birds, the lungs are structured so that 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.
• This highly efficient gas exchange helps birds
  obtain the oxygen they need to power their flight
  muscles at high altitudes for long periods of
  time.

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Respiratory Surfaces of Terrestrial Animals

• What respiratory structures enable land animals
  to breathe?

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Respiratory Surfaces of Terrestrial Animals

• What respiratory structures enable land animals
  to breathe?
• Respiratory structures in terrestrial
  invertebrates include skin, mantle cavities, book
  lungs, and tracheal tubes.
• What respiratory structures enable land animals
  to breathe?
• But all terrestrial vertebratesreptiles, birds,
  mammals, and the land stages of most
  amphibiansbreathe with lungs.