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The Respiratory System

The Respiratory System - The Respiratory System Robert...

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The Respiratory System Robert Boyle (1627 – 1691) : Best known for Boyle’s Law, showed that both animals and flames died in a vacuum indicating that air contained something that is required both to maintain life and to keep a candle burning Joseph Priestly (1733 – 1804) : Examined the ability of gases to support life, finding that most gases cannot support it. o Mice survived when placed in gas produced by heating mercuric oxide o Mice lived longer if plant material was present in the container. Antoine Lavosier (1743 -1794) : Experimented with Priestly’s ‘life-supporting’gas o Named the gas “Oxygen” o Discovered that animals and burning coal consume O 2 releasing CO 2 and heat o Demonstrated that the amount of heat produced relative to O 2 uptake is about the same for animals and burning coal Respiration Major function of respiration is gas exchange o Uptake of molecular 0 2 from environment o Discharge of CO 2 into environment Animals require continuous supply of O 2 Reservoirs of Oxygen: o Atmosphere is a major one: 21% O 2 o Bodies of water also contained dissolved O 2 O 2 is not very soluble in water Respiratory Surface The site of O 2 /CO 2 exchange ALL respiratory surfaces are moist o Cells must be bathed in H 2 O to maintain plasma membrane o O 2 and CO 2 must dissolve in water before exchange can take place Large surface area is needed for gas exchange o Different solutions to this problem evolved depending on the size and habitat of the animals that need them. Small or long, thin animals can use the ENTIRE surface area of the organism for respiration O 2 diffuses very slowly through water (about 3 million times slower than through air) Cells MUST be within about 1mm of the respiratory surface In larger animals, the body surface does not have enough area to support all of the cells. Specialized respiratory surfaces have evolved In many animals a circulatory system serves as a transport between cells and a specialized respiratory system. However, not all animals with specialized respiratory surfaces transport O 2 and CO 2 via a circulatory system . Tracheal System: Insects In Insects, a tracheal system has evolved that does not rely on a circulatory system for exchange. It consists of tubes that branch throughout the body The Largest part of the tubes, the Trachea , branch throughout the body; The finest branches extend to the surface of virtually every cell. In larger insects, rhythmic body movements compress and expand the tubes thus ventilating the system.
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Coupled Respiratory/Circulatory Systems A 2-step exchange process: o 1.) Exchange between respiratory medium and circulatory system o 2.) Exchange between circulatory system and interstitial fluid bathing cells Aquatic Animals Advantage of a water medium is that the respiratory systems stay moist Disadvantages of water mediums are that O 2 concentration is relatively low, so
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The Respiratory System - The Respiratory System Robert...

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