Regulation of the body

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  1. a regulator
    uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation
  2. a conformer
    allows its internal condition to vary with certain external changes
  3. Organisms use what to maintain a “steady state” or internal balance regardless of external environment
    • homeostasis
    • In humans, body temperature, blood pH, and glucose concentration are each maintained at a constant level
  4. set point
    • Mechanisms of homeostasis moderate changes in the internal environment
    • For a given variable, fluctuations above or below a set point serve as a stimulus; these are detected by a sensor and trigger a response (in nervous system)
  5. how does a mammal (otter) maintain its body temp in a cold environment (compared to a fish)
    • fish's body temp will match environment
    • mammal burns calories to maintain its temp
  6. The dynamic equilibrium of homeostasis is maintained by what?
    • negative feedback which helps to return a variable to either a normal range or a set point
    • Most homeostatic control systems function by negative feedback, where buildup of the end product shuts the system off
  7. positive feedback
    loops occur in animals, but do not usually contribute to homeostasis
  8. Set points and normal ranges can change with what?
    age or show cyclic variation
  9. acclimatization
    homeostasis can adjust to changes in external environment
  10. thermoregulation
    is the process by which animals maintain an internal temperature within a tolerable range
  11. endothermic
    animals generate heat by metabolism; birds and mammals are endotherms
  12. ectothermic
    animals gain heat from external sources; ectotherms include most invertebrates, fishes, amphibians, and non-avian reptiles
  13. In general, who tolerates greater variation in internal temperature
  14. The body temperature of a poikilotherm does what?
    varies with its environment
  15. a hometherm does what?
    is relatively constant compared to a poikilotherm
  16. endotherms are?
    • are active at a greater range of external temperatures
    • Endothermy is more energetically expensive than ectothermy
  17. what are the 4 physical processes organisms use to exchange heat?
    Organisms exchange heat by four physical processes: conduction, convection, radiation, and evaporation
  18. Heat regulation in mammals often involves the what system?
    • integumentary system
    • skin, hair, and nails
  19. what 5 adaptations help animals thermoregulate?
    • Five general adaptations help animals thermoregulate:
    • –Insulation
    • –Circulatory adaptations
    • –Cooling by evaporative heat loss
    • –Behavioral responses
    • –Adjusting metabolic heat production
  20. insulation
    is a major thermoregulatory adaptation in mammals and birds
  21. skin, feathers, fur and blubber reduce what?
    Skin, feathers, fur, and blubber reduce heat flow between an animal and its environment
  22. feathers were used for thermoregulation before they were used for flight
  23. vasodilation
    • blood flow in the skin increases, facilitating heat loss
    • Many endotherms and some ectotherms can alter the amount of blood flowing between the body core and the skin
  24. vasoconstriction
    blood flow in the skin decreases, lowering heat loss
  25. Alcohol is a what?
    • vasodilator
    • –Blood vessels on the surface are dilated
    • –Apparent warmth caused by this
    • –Actual effect is to cool the body
  26. countercurrent exchange
    • The arrangement of blood vessels in many marine mammals and birds allows for countercurrent exchange
    • Countercurrent heat exchangers transfer heat between fluids flowing in opposite directions
    • Countercurrent heat exchangers are an important mechanism for reducing heat loss
  27. evaporative loss
    • Many types of animals lose heat through evaporation of water in sweat
    • Panting increases the cooling effect in birds and many mammals
    • Sweating or bathing moistens the skin, helping to cool an animal down
  28. behavioral responses
    • Both endotherms and ectotherms use behavioral responses to control body temperature
    • Some terrestrial invertebrates have postures that minimize or maximize absorption of solar heat
  29. migration
    cyclic movement often timed with the seasons
  30. endotherm behavior (grey whale)
    • Gray whales
    • –Summer in the Arctic
    • –Migrate to the Baja Peninsula for calving
  31. Birds and mammals can vary their what to acclimatize to seasonal temperature changes
  32. When temperatures are subzero, some ectotherms produce what kind of compounds to prevent ice formation in their cells
  33. Surface Area to Volume ratio for endotherms
    • – increases as the square of the animal’s length
    • – increases as the cube of the animal’s length
  34. what region of the brain controls thermoregulation
  35. The hypothalamus triggers what?
    • heat loss or heat generating mechanisms
    • Fever is the result of a change to the set point for a biological thermostat
  36. hypothalamic thermoregulation
  37. Metabolic rate
    is the amount of energy an animal uses in a unit of time
  38. Basal metabolic rate (BMR)
    is the metabolic rate of an endotherm at rest at a “comfortable” temperature
  39. Standard metabolic rate (SMR)
    • is the metabolic rate of an ectotherm at rest at a specific temperature
    • (BMR and SMR)Both rates assume a nongrowing, fasting, and nonstressed animal
    • Ectotherms have much lower metabolic rates than endotherms of a comparable size
  40. Torpor
    • is a physiological state in which activity is low and metabolism decreases
    • Torpor enables animals to save energy while avoiding difficult and dangerous conditions
  41. hibernation
    • is long-term torpor that is an adaptation to winter cold and food scarcity
    • –Glucose is obtained from gluconeogenesis during hibernation

Card Set Information

Regulation of the body
2013-04-10 16:50:51
Life 103

test 3
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