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Period 6 Chapter 42b

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  1. 1. HBS Project <ul><ul><li>The Respiratory System and Gas Exchange </li></ul></ul>Melia Ungson, Kioma Palkhivala, Aviva Prager, Carina Coffey
  2. 2. Gas Exchange <ul><li>Gas exchange is the uptake of molecular oxygen from the environment and the discharge of carbon dioxide to the environment. </li></ul><ul><li>After oxygen is diffused across the respiratory surface, the molecules travel throughout an organism via the transport system. </li></ul><ul><ul><li>cellular respiration and ATP production </li></ul></ul><ul><ul><ul><li>It involves: </li></ul></ul></ul><ul><ul><ul><ul><li>Respiratory Medium - water or air </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Respiratory Surface - Skin, trachea, gills, lungs </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Must be a thin, moist, large surface area </li></ul></ul></ul></ul></ul>
  3. 3. Gas Exchange - In Aquatic Animals <ul><li>Respiratory Surface: Gills </li></ul><ul><li>Respiratory Medium: Water </li></ul><ul><li>Advantages: easily stays moist </li></ul><ul><li>Disadvantages: water has a low oxygen concentration </li></ul><ul><ul><li>Must use ventilation —increasing the flow of the respiratory medium over the respiratory surface </li></ul></ul>
  4. 4. Countercurrent Exchange <ul><ul><ul><li>Enhances gas exchange </li></ul></ul></ul><ul><ul><ul><ul><li>Blood flows in opposite direction as the water moving past the gills </li></ul></ul></ul></ul><ul><ul><ul><ul><li>It is of adaptive value because it is a very efficient process that greatly reduces the energy cost of ventilation alone and yields more oxygen because diffusion across the membrane is always favored </li></ul></ul></ul></ul>
  5. 5. In Insects and Terrestrial Animals <ul><li>Respiratory Medium: Air </li></ul><ul><li>Advantages: </li></ul><ul><ul><li>Much higher concentration of oxygen </li></ul></ul><ul><ul><li>Less ventilation required </li></ul></ul><ul><ul><li>More energy efficient </li></ul></ul><ul><li>Disadvantages: </li></ul><ul><ul><li>Respiratory surface constantly loses water by evaporation </li></ul></ul><ul><ul><ul><li>Respiratory surface is folded into the body to reduce loss of water in terrestrial animals </li></ul></ul></ul>
  6. 6. Tracheal System: In Insects <ul><li>Air tubes branch throughout the body and the largest tracheal tubes opening to the outside </li></ul><ul><li>Gas is exchanged by diffusion across epithelium lining ends of system </li></ul><ul><ul><li>Open circulatory system not involved </li></ul></ul>
  7. 7. Lungs- In Many Terrestrial Animals <ul><li>Size and complexity correlated with metabolic rate </li></ul><ul><li>Restricted to one location </li></ul><ul><ul><li>Circulatory system must be involved with gas exchange </li></ul></ul><ul><ul><ul><li>Have a dense net of capillaries under epithelium that transports gases between lungs and rest of the body </li></ul></ul></ul>
  8. 8. Mammalian Respiratory System
  9. 9. Mammalian Respiratory System- Continued <ul><ul><li>Alveoli are the air sacks at the tips of bronchioles </li></ul></ul><ul><ul><li>Capillaries cover each alveolus and gas diffuses across epithelia </li></ul></ul><ul><ul><ul><li>Oxygen diffuses across the alveoli epithelia into the surrounding capillaries </li></ul></ul></ul><ul><ul><ul><li>Carbon Dioxide diffuses the opposite direction, from capillaries into the alveoli </li></ul></ul></ul>
  10. 10. Lung Ventilation – Breathing <ul><li>Alternate inhalation and exhalation of air </li></ul><ul><ul><li>Amphibian </li></ul></ul><ul><ul><ul><li>Positive pressure breathing </li></ul></ul></ul><ul><ul><ul><ul><li>Pushes air down trachea </li></ul></ul></ul></ul>
  11. 11. Breathing in Mammals <ul><li>Negative pressure breathing </li></ul><ul><ul><li>Pulls air down trachea </li></ul></ul><ul><ul><ul><li>(Inhalation) - Diaphragm contracts, lung volume increases </li></ul></ul></ul><ul><ul><ul><li>Gas flows from a region of higher pressure to a region of lower pressure, so air rushes into the body and down to the alveoli </li></ul></ul></ul><ul><ul><ul><li>( Exhalation) – Diaphragm relaxes, decreasing lung volume and increasing pressure inside alveoli </li></ul></ul></ul><ul><ul><ul><li>Forces air out of the lungs and out of the body </li></ul></ul></ul>
  12. 12. Breathing in Mammals- Continued <ul><li>Tidal Volume – volume of air inhaled and exhaled with each breath </li></ul><ul><li>Vital Capacity – maximum tidal volume during forced breathing </li></ul><ul><li>Residual Volume – the air remaining in the lungs after exhaling as much as possible </li></ul><ul><ul><ul><li>Lungs do not empty and refill completely with each breath so inhaled air mixes with residual air </li></ul></ul></ul>
  13. 13. Breathing of Birds <ul><li>Parabronchi – tiny channels that air flows through in only one direction (instead of dead-ended alveoli) </li></ul><ul><li>Air sacs in addition to lungs to keep air flowing through lungs </li></ul><ul><li>Completely renews air in lungs with every exhalation </li></ul><ul><ul><li>Maximum lung oxygen concentration is higher </li></ul></ul><ul><ul><ul><li>High altitude (migration over mountains) </li></ul></ul></ul>
  14. 14. Control of Breathing – Humans <ul><li>Breathing Control Centers- </li></ul><ul><ul><li>Pons </li></ul></ul><ul><ul><ul><li>Moderate medulla’s basic rhythm, smoothing out transitions between exhalations and inhalations </li></ul></ul></ul><ul><ul><li>Medulla Oblongata </li></ul></ul><ul><ul><ul><li>Sets basic breathing rhythm </li></ul></ul></ul><ul><ul><ul><li>Responds to pH changes determined by amount of carbon dioxide in blood (and cerebrospinal fluid surrounding brain) </li></ul></ul></ul><ul><ul><ul><li>Sends impulses to diaphragm and rib muscles, stimulating contraction, which causes inhalation </li></ul></ul></ul>
  15. 15. Control of Breathing in Humans- Continued <ul><li>Carotid arteries </li></ul><ul><ul><li>Signal medulla to increase breathing when oxygen levels severely low </li></ul></ul><ul><ul><li>Detect changes in blood pH and send nerve impulses to medulla </li></ul></ul><ul><li>Aorta </li></ul><ul><ul><li>Sends alarm signals to control centers when oxygen level is too low </li></ul></ul><ul><ul><li>Sends impulses to medulla when blood pH change is detected </li></ul></ul><ul><li>Diaphragm </li></ul><ul><ul><li>Contracts/relaxes to draw in or push out air </li></ul></ul>
  16. 16. Partial Pressure Gradients <ul><li>Partial Pressure – differences in quantity of a gas </li></ul><ul><li>Gasses diffuse from a region of higher partial pressure to lower partial pressure </li></ul><ul><ul><ul><li>Blood arriving at lungs from pulmonary arteries has lower Po2 and a higher Pco2 than air in alveoli </li></ul></ul></ul><ul><ul><ul><li>Po2 of blood is raised and Pco2 lowered </li></ul></ul></ul><ul><ul><ul><li>Blood returns to heart to be pumped through systemic circuit </li></ul></ul></ul>
  17. 17. Respiratory Pigments <ul><li>proteins that bind to and transport oxygen and circulate with the blood – increase amount of oxygen that can be carried in blood </li></ul><ul><ul><li>This is crucial because oxygen has a low solubility in water and blood </li></ul></ul>
  18. 18. Oxygen Transport <ul><li>Hemocyanin </li></ul><ul><ul><li>In arthopods and mainly mollusks </li></ul></ul><ul><ul><li>Uses copper to bind oxygen, results in bluish blood </li></ul></ul><ul><li>Hemoglobin </li></ul><ul><ul><li>In erythrocytes of most vertebrates and many invertebrates </li></ul></ul><ul><ul><li>Has 4 subunits with iron atom at center to bind oxygen </li></ul></ul>
  19. 19. Oxygen Transport- Continued <ul><ul><li>Dissociation Curves </li></ul></ul><ul><ul><ul><li>Hemoglobin Dissociation with Po2 – a small drop in Po2 causes a large increase in the amount of oxygen unloaded (in active tissues) – oxygen saturation in hemoglobin is greater than that of resting tissues, so oxygen still leaves hemoglobin if tissues are not active, just at a lesser rate </li></ul></ul></ul>
  20. 20. <ul><li>Hemoglobin Dissociation with pH – drop in pH lowers affinity of hemoglobin for oxygen – Bohr Shift – which increases oxygen released, which supports cellular respiration </li></ul>More Oxygen Transport
  21. 21. Carbon Dioxide Transport <ul><li>Hemoglobin – transports carbon dioxide as well as oxygen </li></ul><ul><ul><li>Aides in buffering – preventing harmful changes in blood pH </li></ul></ul><ul><ul><ul><li>Carbon dioxide produced by body tissues diffuses into plasma and interstitial fluid </li></ul></ul></ul><ul><ul><ul><li>Most of the carbon dioxide diffuses into red blood cells, small percent stays in plasma as dissolved carbon dioxide </li></ul></ul></ul><ul><ul><ul><li>Some of CO2 in blood transported by hemoglobin </li></ul></ul></ul><ul><ul><ul><li>Most CO2 reacts with water in red blood cells to form carbonic acid (H2CO3)‏ </li></ul></ul></ul>
  22. 22. Carbon Dioxide Transport- Continued <ul><ul><ul><li>Carbonic acid dissociates into bicarbonate ion and hydrogen ion </li></ul></ul></ul><ul><ul><ul><li>Hemoglobin binds most of the hydrogen ion, preventing acidic pH change in blood (and Bohr Shift)‏ </li></ul></ul></ul><ul><ul><ul><li>Most of the bicarbonate ion diffuses into red blood cells from plasma, combines with released hydrogen ions reforming carbonic acid </li></ul></ul></ul><ul><ul><ul><li>Converted back into carbon dioxide and water </li></ul></ul></ul><ul><ul><ul><li>Carbon dioxide unloaded from hemoglobin and diffused into interstitial fluid </li></ul></ul></ul><ul><ul><ul><li>Diffuses into alveolar space, exhaled out of body </li></ul></ul></ul><ul><ul><ul><li>Reduction of carbon dioxide concentration in plasma stimulates break down of carbonic acid into carbon dioxide and water in red blood cells </li></ul></ul></ul>
  23. 23. Evolutionary Adaptations in Animals <ul><li>Endurance Runners (Pronghorn) </li></ul><ul><li>Diving Mammals (Weddell Seal) </li></ul><ul><ul><ul><li>Higher concentration of myoglobin – oxygen storing protein -- in muscles </li></ul></ul></ul>
  24. 24. Questions?
  25. 25. Ready to Start Your Quiz? Good Luck!