Lecture 3

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Lecture 3
2015-04-23 23:01:08
Lecture 3: Circulation & Gas Exchange
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  1. Partial Pressure
    the pressure exerted by a articular gas in a mixture of gases
  2. Describe Tracheal System
    • consists of tiny branching tubes that penetrate the body
    • Respiratory and circulatory systems are separate
    • Instead of taking oxygen in and transporting it to cells that need it, they have a series of tubes/canals that brings the air to the cell
  3. Gas diffusion increases with _____ and decreases with ______
    • increases with surface area
    • decreases with distance
  4. Gills have large ____ and small _____
    large area, small distance
  5. Requirements of gills
    circulate water to exchange gases
  6. In water the solubility of gases
    is lower than it is in air
  7. Why is countercurrent exchange used in fishes/underwater?
    to maximize efficiency of extracting oxygen
  8. Co-Current Exchange
    • flow in same direction
    • as they most left-right, start to equilibrate
    • but only 50% of ink/gas is extracted
  9. Countercurrent Exchange
    • flows in opposite directions
    • 100% of ink/gas is extracted this way
    • much more efficient
  10. Lungs are
    an infolding of the body surface
  11. Circulatory system of birds
    • they never stop breathing
    • unidirectional flow of air: clean and dirty air do not mix
  12. How does a mammal breathe?
    • inhale air, rib cage expands
    • exhale air, rib cage gets smaller
  13. What kind of breathing do mammals have?
    discontinuous breathing (unlike birds)
  14. Open circulatory system
    circulatory fluid bathes all the cells, taken up by heart and pumped throughout body
  15. Closed circulatory system
    fluid never leaves the body, travels from one organ to the next
  16. What is the advantage of a closed circulatory system over an open one?
    • this system has pressure, which allows heart to be able to overcome gravity
    • pumps to head and forces blood to come back from feet
  17. Single Circulation vs. Double circulation
    • single— blood only passes through heart once
    • double— two pumps, blood goes out of heart, goes up to lungs, comes back, pressurized by heart again, and travels at high pressure throughout the rest of the body
  18. Amphibians are special because they have (advantage)
    • 3 chambered heart instead of 2
    • advantageous because it allows them to divert blood where need when they are underwater
  19. Purpose of valves in the heart?
    • help keep the blood where it should be
    • due to amount of pressure generated, don’t want blood to travel backwards anywhere you don’t want it
  20. How does the heart work?
    by contracting/squeezing itself
  21. Cardiac output (and what it depends on)
    • volume of blood pumped into the system circulation per minute
    • Depends on both heart rate and stroke volume
  22. Heart rate
    number of bets per minute, aka pulse
  23. Stroke Volume
    amount of blood pumped into a single contraction
  24. If stroke volume is lower than usual and you need same amount of cardiac output, what happens?
    heart rate is increased
  25. Pacemaker is regulated by?
    sympathetic (speeds up) and parasympathetic (slows down) divisions
  26. 3 types of blood vessels
    • Arteries
    • Veins
    • Capillaries
  27. Structural difference between arteries and veins
    arteries have a lot of muscle surrounding them, whereas veins do not have that much muscle around them
  28. What are capillaries?
    smallest blood vessels that connect arterioles and venules
  29. How are arteries and veins different?
    Arteries carry blood away from heart, veins bring blood back to heart
  30. Area vs. Speed vs. Pressure in Capillaries
    • Huge surface area
    • Speed is very slow - same amount of blood is being distributed into many capillaries, needs to be slow to equilibrate
    • Pressure decreases gradually as area decreases
  31. at lower pH, hemoglobin ________
    releases more oxygen
  32. What happens when hemoglobin picks up CO2
    • reacts with water, acidifies the blood
    • (the more CO2, the more acidic the blood becomes)
  33. What is the Bohr shift?
    • when CO2 produced during cellular respiration lowers blood pH and decreases affinity of hemoglobin for O2
    • so hemoglobin retains less O2 at lower pH
  34. Why/how do fetus’ steal oxygen from their mothers?
    Because fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin does
  35. How does the body measure how much CO2 is in our body?
    by looking at the pH
  36. Describe process of acclimatization when there is low oxygen present?
    • Low oxygen, high CO2, pH drops
    • pH sensors in blood/fluids detect that
    • trigger a response (breathe more deeply to bring in more O2 and release more CO2 until pH returns to normal)
  37. What does the hemoglobin dissociation curve show?
    how much oxygen hemoglobin can carry at a particular partial pressure concentration
  38. The partial pressure of oxygen is maximal in ____ and minimal in ______
    lungs, tissues at rest