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RESPIRATION What is the goal of respiration? Exchange gas between an organism & the environment RESPIRATION Gas exchange between air, blood, tissues 1. Evolution of Organismal Respiration 2. Structures of the Human System 3. Breathing 1. Inhalation 2. Exhalation 3. Bulk flow vs. Diffusion 4. Control 3.5 Gas Exchange in Water • What gases are being exchanged? • In order for the diffusion to occur, gases must be dissolved in liquid • How do fish increase their exchange efficiency? – Structures – Counter-current exchange 3.6 Adaptations for Land • Oxygen is plentiful BUT… – Exchange surface must be moist … why? – Problem of drying out • Organisms want… – Large SA for efficient exchange – Low respiration loss of water – Problem – large SA increases water loss • Evolved adaptations: – Internal exchange surface/organs – External barrier to retain moisture • Secrete surface waxes/lipids … can block exchange so… – Specialized openings, can be controlled • Spiracles, stomates, etc. Respiratory surfaces and gas exchange • Respiratory surface – Size of organism – Habitat – Metabolic demands • Unicellular organisms – Entire surface area for diffusion • Simple invertebrates – Sponges, cnidarians, flatworms – diffusion Grasshoppers Avian breathing Air sacs act as bellows to keep air flowing through the lungs. http://www.sci.sdsu.edu/mu ltimedia/birdlungs/ HUMAN RESPIRATORY STRUCTURES • Nose/mouth: filters, moistens, warms • • • • Pharynx Larynx Trachea – mucus, cilia 2 lungs – 2 bronchi – Bronchioles – Alveoli • Site of exchange • Thin walls, lots-o-capillaries • Large # S.A. • A thin layer of mucus is produced on the lining of the tubes of the respiratory system This thin layer traps particles of dust or smoke These tubes are lined with CILIA that sweep away particles • These tubes are made of cartilage and are surrounded by smooth muscle CILIA ALVEOLI • Small structures at the end of each bronchiole • Occur in clusters • Place where gas exchange occurs – Oxygen into blood, carbon dioxide into lung – Each is surrounded by capillaries • 300 million alveoli are in each healthy lung – Provides a large surface area for gas exchange • Oxygen dissolves in the moisture – It can then diffuse into the capillaries – CO2 diffuses in the opposite direction – Coated in surfactant HEMOGLOBIN binds with so much oxygen that it increases the oxygen carrying- capacity of the blood more than 60 times RECAP • Name the structures of the respiratory system • Where does gas exchange occur? • http://www.airinfonow.org/html/lungattack/l ungplay.htm • Next: What is the difference between respiration and breathing? Breathing • Breathing is the movement of air into and out of the lungs • Lungs sit in two sacs = pleural membranes • At the bottom of the chest cavity is the diaphragm • Between ribs are intercostal muscles Force that drives breathing is air pressure – No muscles are directly connected to the lungs Volume If you have a container of gas, how will the pressure change if you make the container smaller? Make it larger? • When you inhale, the diaphragm contracts and expands the volume of the chest cavity • Because the chest cavity is tightly sealed, this creates a partial vacuum inside the cavity • Air rushes into the lungs as a result Inhaling Exhaling • Exhaling is a passive event • Diaphragm relaxes and lungs return to normal size, placing pressure on the lungs – Air rushes out of the lungs 78% Nitrogen 21% Oxygen 0.03% Carbon Dioxide Partial Pressure: “Concentration of Gas” 1) Volume: If you have a container of gas, how will the pressure change if you make the container smaller? Make it larger? – Bulk Flow ~ Breathing 2) Total atmospheric pressure = 760mmHg – Oxygen is 21% of this, therefore = 159mmHg • O2 air > O2 alveoli > O2 blood > O2 cells • 159mmHg 100mmHg 40mmHg 40mmHg (exchange to 100mmHg) – Diffusion RECAP • What causes breathing? • What muscles are involved with breathing? – Are they attached to the lungs? • What controls your breathing? Breathing Control • Breathing is voluntary to a point, then it becomes involuntary • Nervous system will take over – Sensory receptors in major blood vessels detect amount of carbon dioxide in blood • b/c pH will change – Message goes to medulla oblongata in the brain – If the level of carbon dioxide gets too high, the diaphragm will contract Hb + 4O2 “HbO” Oxygen in Blood • 98.5% is bound to Hb • 1.5% dissolved in plasma Carbon Dioxide in Blood • 60% dissolves in H2O (as H2CO3) • 30% binds to Hb • 10% dissolves in plasma Carbon Monoxide • Hb affinity 200 X’s stronger • irreversible REGULATION of pH • Normal plasma pH = 7.4 (Range: 7.35 - 7.45) CO2 + H20 H2CO3 H+ + HCO3Waste product of metabolism Always Present Converted to Waste product Buffer Products on of metabolism LEFT by Carbonic Anhydrase ____________________________________________________________________________________________________ Expelled by Adjusted in kidney Lung Or Rxts w/Bicarb. R. Or Rxts w/H+ on L. The exchange • http://www.airinfonow.org/html/lungattack/lungplay. htm • • • • What can go wrong? http://www.hisdbenefits.org/hisd/living/animations/ List of animations for respiratory disorders http://in.truveo.com/Human-AtlasEmphysema/id/1459776665 • Similar animations, better quality Breathing Quiz: Is it inhalation or exhalation? • Diaphragm Contracts • Intercostal Muscles relax • Chest Cavity increases in size • Pressure in cavity decreases • Air rushes out of lungs • Diaphragm relaxes • Intercostal muscles contract • Volume of chest cavity decreased • Pressure inside greater • Air rushes in and inflates lungs
