Chapter 29

Chapter 29 - Chapter 29: Respiration Impacts & Issues...

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Chapter 29: Respiration
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In the US, about 3,000 teenagers take up smoking every day Just one cigarette immobilizes cilia that line airways of the lungs for hours, preventing them from sweeping away airborne pathogens and pollutants Nicotine has many side effects, including constriction of blood vessels and raising BP Smoking ↑ the risk of deadly lung cancers Secondhand smoke causes about 3,000 lung cancer deaths each year Impacts & Issues
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Why Exchange Gases? Gas exchange supports cellular respiration In vertebrates – O 2 -rich air inhaled and O 2 deposited in blood – O 2 transported to body cells by blood – Blood transports CO 2 from tissues to lungs – CO 2 released from lungs (and body) during exhalation
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Common Features of Animal Respiratory Systems All animal respiratory systems share 3 features (1) Respiratory surface must be moist so gases can diffuse across cell membranes (2) Cells lining respiratory surface are thin to optimizes gas diffusion (3) The respiratory surface area must be large to allow for adequate gas exchange
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Some Animals in Moist Environments Lack Specialized Respiratory Structures Gases diffuse short distances in smaller animals to reach cells Gas exchange optimized by long, flat bodies with greater surface area Examples: roundworms and flatworms
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Some Animals in Moist Environments Lack Specialized Respiratory Structures Low energy demands translate into larger animals that rely on their moist body surface for gas exchange Larger size possible because less O 2 needed by cells Example: Jellyfish
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Some Animals in Moist Environments Lack Specialized Respiratory Structures Some animals bring the environment close to all their cells Allows greater exposure of cells to O 2 Example: Sponges
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Some Animals in Moist Environments Lack Specialized Respiratory Structures Other animals combine large skin surface area with well-developed circulation for delivery to cells – Skin has many capillaries that carry O 2 to internal body tissues – This arrangement sustains a favorable O 2 concentration gradient between skin and blood Example: Earthworm
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Respiratory Systems Facilitate Gas Exchange Respiratory systems more effectively exchange gases between the environment and an animal’s body Respiratory systems alternate bulk flow of air/water and diffusion of gases Bulk Flow: describes when fluids or gases move through spaces from high pressure to low pressure
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Respiratory Systems Facilitate Gas Exchange In mammals Air moves past respiratory surface by bulk flow (down pressure gradient) – O 2 and CO 2 are exchanged by diffusion Gases transported to/from tissues by bulk flow Gases exchanged with tissues (cells) by diffusion
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Oxygenated blood Deoxygenated blood CO 2 O 2 CO 2 O 2 CO 2 CO 2 CO 2 CO 2 CO 2 alveoli (air sacs) left atrium right atrium right ventricle left ventricle O 2
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Chapter 29 - Chapter 29: Respiration Impacts & Issues...

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