Chapter 42

  1. exchange ultimately occurs at the _______ level; in ___________ organisms exchange occurs directly with the ________ _________
    cellular; unicellular; external environment
  2. two solutions to the slowness of difussion:
    1) a body size/shape that keeps cells in direct contact w/ environment (sponges, cnidarians, flatworms) or 2) circulatory system that moves fluid between cell's immediate surroundings (found in all other animals)
  3. open circulatory system
    circulatory fluid (hemolymph) also serves as the interstitial fluid and bathes the organs directly; arthropods and mollusks; lower hydrostatic pressure = less costly
  4. closed circulatory system
    blood is confined to vessels and is distinct from interstitial fluid; annelids, cephalopods, and vertebrates; benefit = high blood pressure (effective delivery of O2 & nutrients
  5. arteries
    carry blood from the heart TOWARD the capillaries
  6. veins
    return blood to the heart FROM capillaries; except the portal vein, which carries blood between pairs of capillary beds
  7. atria
    muscular chamber of the heart that RECEIVES blood
  8. ventricle
    muscular chamber of the heart that pumps out blood
  9. single circulation
    a heart with TWO chambers each of which the blood only passes through once; foudn in bony fishes, rays, sharks; swimming helps accelerate pace of circulation
  10. double circulation
    pumps for 2 distinct circuts serve different tissues but combined in the heart; found in amphibians, reptiles, mammals
  11. pulmonary circuit
    the right side of the heart carries oxygen-depleted blood away from the heart, to the capillary beds in the lungs ONLY, and returns oxygenated blood back to the heart
  12. pulmocutaneous circuit
    found in amphibians, where deoxygenated blood is carried to the capillary beds in both the lungs AND skin
  13. systemic circuit
    contraction of the left side of the heart carries oxygenated blood away from the heart to the body, and returns deoxygenated blood back to the heart
  14. cardiac cycle
    one complete sequence of pumping and filling; contraction = systole, relaxtion = diastole
  15. cardiac output
    the volume of blood each ventricle pumps per minute; determined by heart rate (number of beats per minute) and stroke volume (amount of blood pumped by a ventricle in a single contraction)
  16. blood _____ as it moves from arteries to arterioles to capillaries because:
    SLOWS; there are MANY capillaries, therefore the overall area of campillary beds is much greater than anywhere else in the circulatory system
  17. endothelin
    a peptide that induces vasoconstriction
  18. exchange of substances takes place:
    across endothelial walls of capillaries
  19. blood pressure...
    drives fluid out of capillaries
  20. blood proteins (albumin)...
    create osmotic pressure differences between inside the capillary and the outside interstitial fluid; tends to pull fluid back into the capillaries
  21. edema
    swelling resulting from the excessive accumulation of fluid in tissues
  22. lymph nodes
    organs along a lymph vessel that filter the lymph and house cells that attack viruses/bacteria; play important role in body's defenses
  23. partial pressure
    the pressure exerted by a particular gas in a mixture of gasses; Po2 = 160 mm Hg (partial pressure of O2; is much less at sea level)
  24. alveoli
    air sacs clustered at the tips of the tiniest bronchioles; where GAS EXCHANGE occurs; maximum partial pressure of oxygen is a always LESS in the alveoli than in the atmosphere
  25. sufacants
    specialized secretions (containing a mixture of phospholipids and proteins) that relieve the surgace tension in the fluid that coats the surface of the alveoli; in their absence alveoli collapse
  26. tidal volume
    volume of air inhaled and exhaled with each breath; during maximum in/exhalation it's called the vital capacity, and amounts to about 3.4-4.8 L
  27. breathing control centers
    networks of neurons that control breathing, located in the medulla oblongata [establish breathing rhythm] and pons [regulate medulla onlongata's tempo] (brainstem)
  28. respiratory pigments
    molecule consisting of a protein and metal (metalloproteins)that binds to O2 and transport the majority of oxygen by circulating with blood (hemolymph) and are often contained within specialized cells; reduces cardiac output
  29. hemoglobin
    vertebrate respiratory pigment that consists of 4 polypeptide chains that each contain a cofactor called a heme group with an iron atom at its center; e/a iron atom binds to 1 molecule of O2, meaning 1 hemoglobin carries 4 O2's
  30. Bohr shift
    when low pH decreases hemoglobins affinity for O2; thus when CO2 production is greatest, hemoglobin releases MORE O2 which can be used to support cellular respiration
Card Set
Chapter 42
Midterm II