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Ch 22- Respiration- The Exchange of Gases

Ch 22- Respiration- The Exchange of Gases. Lungs Negative pressure breathing Partial pressure Pharynx Respiration Respiratory surface Trachea Tracheae Tracheoles Ventilation Vital capacity Vocal cords. Alveoli Breathing control centers Bronchi Bronchioles Countercurrent exchange

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Ch 22- Respiration- The Exchange of Gases

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  1. Ch 22- Respiration- The Exchange of Gases Lungs Negative pressure breathing Partial pressure Pharynx Respiration Respiratory surface Trachea Tracheae Tracheoles Ventilation Vital capacity Vocal cords • Alveoli • Breathing control centers • Bronchi • Bronchioles • Countercurrent exchange • Diaphragm • Emphysema • Gas exchange • Gills • Hemoglobin • Hyperventilating • Larynx

  2. Gas exchange • Gas exchange- interchange of O2 and CO2 between an animal and it’s environment • Mechanisms: • Breathing • Gases transported by circulatory system to body • Tissues take up O2 and release CO2 to the blood • Animals exchange gases through moist body surfaces • Respiratory surfaces- must be wet to function properly, thin for O2 and CO2 to diffuse easily

  3. Respiratory Surfaces • Entire outer skin- ex: earthworm • Gills- for exchange in water • Opening and closing of mouth and gills allows for increase in gas exchange efficiency (ventilation) • Countercurrent flow of water enhances O2 transfer (80% can be removed!!!)

  4. Countercurrent exchange

  5. Respiratory Surfaces • Tracheal system- branching air tubes in body (tracheae) opens to outside, narrowest-tracheoles- extend to nearly every cell in body • * terrestrial animals spend less E on getting O2 because air is lighter and has more O2) • Lungs- most terrestrial vertebrates

  6. Human respiratory system

  7. Human respiratory system • Air enters through nostrils- warmed, humidified and sampled • Pharynx- throat • Larynx- voice box- air rushing over cords creates sound • Trachea- windpipe- has rings of cartilage to maintain open shape • Bronchi- 2 tubes, 1 to each lung • Bronchiole- get thinner and finer branching within lung • Alveoli- air sacs, end of branching, covered in capillaries, where gas exchange takes place • Cilia and mucous throughout system- clean air • Diaphragm- muscle at bottom of chest cavity, facilitates breathing

  8. Breathing • Alternating inhaling and exhaling • Diaphragm contracts, rib cage expands= air rushes in • Diaphragm relaxes, rib cage lowers= air’s pushed out • Negative pressure breathing- muscle contraction causes lower pressure inside than outside and air rushes in • Vital capacity- max volume of air we can breathe in & out

  9. Breathing

  10. Controlling Breathing • Pons and medulla oblongata – breathing control center • Nerve signals sent to contract diaphragm and raise ribs by contraction of muscles • Medulla monitors CO2 levels and regulates breathing in response, also monitors blood pH, cerebrospinal fluid and O2 levels in large arteries and when O2 levels in blood are severely decreased • pH decreases when CO2 increases

  11. Hyperventilation • Shows how control center works • Purge blood of CO2 so there is a temporary signal to stop breathing (b/c of low CO2 levels)

  12. Circulation of gases • O2 rich blood in lungs goes to heart to be pumped to body • O2 poor blood in body goes to heart to be pumped to lungs to pick up O2 • Gas exchange occurs by diffusion • Hemoglobin- O2 carrier in RBC’s • 1 hemoglobin can carry 4 O2 molecules • Fig 22.11A and B in text • CO2 forms H2CO3 (carbonic acid) in RBC’s  it breaks to HCO3- (bicarbonate ion) and H+ (which hemoglobin takes up so that blood doesn’t become acidic) • In lungs- reaction is reversed HCO3- binds with H+ then H2CO3 is converted to CO2 and H2O which is diffused into alveoli

  13. CO2 transport in the blood

  14. Gas exchange in fetus • Uses placenta for exchange from mothers blood from lungs • Fetal hemoglobin-special type that has higher affinity for O2 • At birth – increase in fetus’s CO2 level triggers breathing control center to start breathing

  15. Problems in respiratory system • Asthma- bronchi become inflamed due to allergic reaction • Bronchitis- inflammation of bronchi due to pathogens (ex: bacteria) • Smoking!!- cilia and mucous trap particles and sweep them out before reaching alveoli • Macrophages also engulf particles and microorganisms • Smoking destroys cilia and macrophages- allowing toxins to reach alveoli • Fig 22.7A- lung cancer • Emphysema- alveoli become brittle and rupture, decreases gas exchange (not enough oxygen)

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