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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Ch.37 Respiration
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Essential knowledge 4.B.2:
• Cooperative interactions within organisms promote efficiency in the use of energy and matter.
– a. Organisms have areas or compartments that perform a subset of functions related to energy and matter, and these parts contribute to the whole.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Essential knowledge 4.A.4:
• Organisms exhibit complex properties due to interactions between their constituent parts.
– a. Interactions and coordination between organs provide essential biological activities.
– b. Interactions and coordination between systems provide essential biological activities.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Essential knowledge 2.D.2:
• Homeostatic mechanisms reflect both common ancestry and divergence due to adaptation in different environments.
• a. Continuity of homeostatic mechanisms reflects common ancestry, while changes may occur in response to different environmental conditions.
• b. Organisms have various mechanisms for obtaining nutrients and eliminating wastes.
• c. Homeostatic control systems in species of microbes, plants and animals support common ancestry.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Essential knowledge 2.A.3:
• Organisms must exchange matter with the environment to grow, reproduce and maintain organization.
– a. Molecules and atoms from the environment are necessary to build new molecules.
– b. Surface area-to-volume ratios affect a biological system’s ability to obtain necessary resources or eliminate waste products.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Ch.37 Gas Exchange
• Respiration involves three events
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– External respiration - gas exchange occurs between air and blood (O2 from air to blood; CO2 from blood into air) within the lungs and oxygen is carried to other parts of the body by circulatory system
– Internal respiration - gas exchange occurs between blood and tissue fluid (O2 from blood to tissue fluid; CO2 from tissue fluid into blood). Bodies’ cells exchange gases (O2 taken in; CO2 released) with tissue fluid. Blood carries carbon dioxide from cell to lungs
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• Gas exchange occurs across specialized respiratory surfaces
• Gas exchange supplies oxygen for cellular respiration and disposes of carbon dioxide
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Animals require large, thin, moist respiratory surfaces for the adequate diffusion of respiratory gases between their cells and the respiratory medium, either air or water
•
• (1)This means that respiratory surfaces must be kept moist for oxygen and carbon dioxide to diffuse through the cell’s plasma membrane
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• (2)Respiratory surfaces must be extensive enough (large surface area) to take up enough oxygen and get rid of carbon dioxide for the entire body
•
• (3)These delicate moist tissues of respiratory surfaces need to be protected
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Gas Exchange
• Hydras and planarians
– Small animals with large surface area
– Most of their cells exchange gases directly with the environment
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Types of respiratory systems
• Skin
• Gills
• Tracheal system
• Lungs
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Skin
• Skin - animals such as earthworms have no specialized gas exchange surfaces
• Oxygen diffuses into capillaries beneath the skin
• They must live in damp places or in water to keep respiratory surfaces moist
•
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Gills in Aquatic Animals
• Gills are featherlike outfoldings (evaginations) of the outer or inner body surface specialized for gas exchange, and occur in aquatic animals
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• Gills have finely subdivided surfaces to provide adequate surface area and contain a rich blood supply for transport (vascularization)
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• The feathery gills projecting from a salmon
– Are an example of a specialized exchange system found in animals
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• In some invertebrates
– The gills have a simple shape and are distributed over much of the body
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• Many segmented worms have flaplike gills
– That extend from each segment of their body
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• The gills of clams, crayfish, and many other animals
– Are restricted to a local body region
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• Oxygen makes up 0.45% of seawater, but 21% of air
• This means that aquatic animals have a greater problem obtaining enough oxygen than do terrestrial animals and expend much more energy doing so (25% compared to1-2% of their energy)
• Diffusion is also 1000X slower in water than in air (water is 1000X more dense than air)
•
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• The effectiveness of gas exchange in some gills, including those of fishes is increased by ventilation and countercurrent flow of blood and water
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Counter-current exchange
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• This maintains a favorable gradient between blood and the water at every point of exchange, this maximizes the amount of oxygen the blood removes from the water
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Respiratory systems
• Land animals have two advantages: air contains more oxygen than an equal volume of water and air is lighter and easier to move.
• Terrestrial animals expend much less energy than an aquatic animal in gas exchange
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• Most terrestrial animals have respiratory surfaces that are infoldings (invaginations) of the body surface
• This protects the respiratory surface and keeps it moist
•
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Land Environments: Tracheae
• Insects and other terrestrial arthropods
– A respiratory system consists of branched tracheae
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– Tracheae branch until end in tracheoles (surface area) that are in direct contact with body cells so they do not require circulatory system to transport gases
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• The tracheal tubes supply O2 directly to body cells and are filled with fluid for gas exchange
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Lungs
• Spiders, land snails, and most terrestrial vertebrates have internal lungs
• Lungs are invaginated
• Lungs are restricted to one part of the body, so a circulatory system is needed to transport gases from lungs to the rest of the body
•
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Land Environments: Lungs of Vertebrates
• Terrestrial vertebrates have evolved lungs
–Lungs of amphibians
• Possess a short tracheae which divides into two bronchi that open into lungs
• Many also breathe to some extent through skin
–Reptiles
• Inner lining of lungs is more finely divided in reptiles than in amphibians
–Lungs of birds and mammals are elaborately subdivided
• All terrestrial vertebrates, except birds, use a tidal ventilation system
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How an Amphibian Breathes
• An amphibian such as a frog
– Ventilates its lungs by positive pressure breathing, which forces air down the trachea
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How a Mammal Breathes
• Mammals ventilate their lungs by negative pressure breathing, which pulls air into the lungs
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Ventilation in Terrestrial Vertebrates
• Inspiration (inhalation) in mammals
• Create negative pressure in lungs
–The rib cage is elevated (rib muscles contract)
–The diaphragm lowers (contracts)
–Thoracic pressure decreases (volume increases) to less than atmospheric pressure
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Ventilation in Terrestrial Vertebrates
• Expiration (exhalation) in mammals
• Create positive pressure in lungs
– The rib cage is lowered
– The diaphragm rises
– Thoracic pressure increases,(thoracic cavity volume decreases) to more than atmospheric pressure
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How a Bird Breathes
• Besides lungs, bird have eight or nine air sacs
– That function as bellows that keep air flowing through the lungs
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•
• Every exhalation completely renews the air in the lungs
• Lungs do not have alveoli, but contain tiny parallel tubes called parabronchi
• Air flows one direction and blood flows in the opposite direction acting as counter-current exchange
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Human Respiratory System
• As air moves through upper respiratory system
– It is filtered to free it of debris
– Warmed, and
– Humidified
• When air reaches lungs
– It is at body temperature, and
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Human Respiratory System
• Air passes from pharynx through glottis
• Larynx and trachea
– Permanently held open by cartilage rings
– Facilitates movement of air
• When food is swallowed
– The larynx rises, and
– The glottis is closed by the epiglottis
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Human Respiratory System
• Trachea divides
– Forms two primary bronchi
– Bronchi enter the right and left lungs
• Bronchi branch until there are a great number of tiny bronchioles
– Each bronchiole terminates in an elongated space enclosed by alveoli which greatly increase the surface area of the respiratory surface
• Alveoli are air sacs lined with a thin layer of epithelial cells which form the respiratory surface
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Ventilation
• Humans breathe using a tidal mechanism
– Volume of thoracic cavity and lungs is increased by muscle contractions that lower the diaphragm and raise the ribs
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Control of Breathing in Humans
• The main breathing control centers
– Are located in two regions of the brain, the medulla oblongata and the pons
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• The centers in the medulla regulate the rate and depth of breathing in response to pH changes (H+) in the blood and cerebrospinal fluid
• The medulla adjusts breathing rate and depth to match metabolic demands
• CO2 reacts with H2O to form carbonic acid, which lowers the pH of the blood
•
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• By monitoring pH, the medulla regulates CO2 levels in the blood
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• Sensors in the aorta and carotid arteries
– Monitor O2 and CO2 concentrations in the blood
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Respiratory Pigments
• Respiratory pigments are proteins that transport oxygen and greatly increase the amount of oxygen that blood can carry
• O2 is not very soluble in water, so blood transports very little dissolved O2
•
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• Hemoglobin is composed of four polypeptide chains, each polypeptide chain contains a heme group which contains an iron atom.
•
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• Like all respiratory pigments
– Hemoglobin must reversibly bind O2, loading O2 in the lungs and unloading it in other parts of the body
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Gas Exchange and Transport
• Oxygen diffuses into pulmonary capillaries
– Most combines with hemoglobin in red blood cells to form oxyhemoglobin
• CO2 diffuses out of pulmonary capillaries
– Most carbon dioxide is transported in the form of bicarbonate ion
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• Loading and unloading of O2
– Depend on cooperation between the subunits of the hemoglobin molecule
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Carbon Dioxide Transport
• Hemoglobin also helps transport CO2 and assists in buffering the pH of the blood
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• Carbon dioxide from respiring cells
– Diffuses into the blood plasma and then into erythrocytes and is ultimately released in the lungs
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CO2 transport
• Some CO2 dissolves in the plasma, but most enters the red blood cells
• Some CO2 binds to hemoglobin, but most reacts with H2O to form carbonic acid (H2CO3)
• Carbonic acid forms more easily in RBC’s with the help of the enzyme carbonic anhydrase
• H2CO3 dissociates to become (H+) hydrogen ion and (HCO3
-) bicarbonate ion
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• Bicarbonate ions buffer the blood pH by combining with H+ ions and removing them from the blood, or by releasing H+ ions when needed
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Respiration and Health
• Upper Respiratory Tract Infections
– Strep Throat
• Streptococcus pyogenes
– Sinusitis
• Infection of sinuses
– Tonsillitis
• Infection of tonsils
– Laryngitis
• Infection of larynx
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Respiration and Health
• Lower Respiratory Tract Infections
– Acute bronchitis
• Infection of primary and secondary bronchi
– Pneumonia
• Viral or bacterial infection of the lungs where bronchi and alveoli fill with fluid
– Pulmonary tuberculosis
•
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Disorders
• Pulmonary fibrosis
– Fibrous connective tissue builds up in the lungs
• Chronic bronchitis
– Airways inflamed and filled with mucus
• Emphysema
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Disorders
• Asthma
– Airways are unusually sensitive to specific irritants
• When exposed to the irritants, the smooth muscles in the bronchioles undergo spasms
• Lung Cancer
–