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Chapter 44 - PowerPoint PPT Presentation


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Chapter 44. Regulating the Internal Environment. Homeostasis. Thermoregulation Osmoregulation Excretion. Homeostasis. All organisms must maintain a constant internal environment to function properly Temperature pH ion levels hormones. Negative Feedback. Body Temperature Regulation.

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slide1

Chapter 44

Regulating the Internal Environment

slide2

Homeostasis

  • Thermoregulation
  • Osmoregulation
  • Excretion
slide3

Homeostasis

  • All organisms must maintain a constant internal environment to function properly
    • Temperature
    • pH
    • ion levels
    • hormones
slide4

Negative Feedback

Body Temperature Regulation

slide5

Coping with Environmental Fluctuations

Regulating:

Endotherms are thermoregulators

Fundulus-osmoregulator

Conforming:

Ectotherms

Many inverts- nonregulator

slide6

Regulators & Conformers

Spider crab Libinia

slide8

Four physical processes account for heat gain or loss

  • Heat exchange by:
  • Conduction- transfer of heat between objects in direct contact with each other
  • Convection- heat is conducted away from an object of high temp to low temp
  • - Rate varies with different materials
  • Radiation- transfers heat between objects not in direct contact
  • - sun energy
  • Evaporation- change of liquid to vapor
  • - cooling
slide11

Advantages of Endothermy :

  • Maintains stable body temp
      • Cooling & heating the body
  • cooling and heating the body
  • high levels of aerobic metabolism
  • sustains vigorous activity for much longer than ectotherms
      • Long distance running
      • Flight
slide12

Disadvantages of Endothermy :

  • Greater food consumption to meet metabolic needs
  • Human metabolic mate at 200C & at rest
  • 1,300 to 1,800 kcal per day.
  • American alligator metabolic rate at 200C & at rest
  • 60 kcal per day at 200C.
slide13

Mechanisms for thermoregulation

  • Insulation
    • Fur
    • Hair
    • Feathers
    • Fat
    • Blubber
  • Evaporative cooling
    • sweating, panting, bathing
  • Shivering
  • Nonshivering thermogenesis & brown fat
  • Circulation adaptations
    • Countercurrent exchange
    • Vasodilatation (cooling)
    • Vasoconstriction (heat conservation)
  • Behavioral responses
slide14

Countercurrent heat exchangers

Goose leg

Dolphin flipper

slide16

Evaporative Cooling

Hippos bathing

slide19

Brown Fat & Non-shivering Thermogenesis

  • Brown fat- generates heat
  • important in neonates, small mammals in cold environments, and animals that hibernate
  • Located in neck and in inner scapula area
  • Non-shivering Thermogenesis
  • Larges amts of heat produced by oxidizing fatty acids in the mitochondria
slide21

Acclimatizationto New Env. Temps.

    • Endotherms (birds and mammals): grow a thicker fur coat in the winter and shedding it in the summer - and sometimes by varying the capacity for metabolic heat production seasonally.
    • Ectotherms compensate for changes in body temperature through adjustments in physiology and temperature tolerance.
    • For example, winter-acclimated catfish can only survive temperatures at high as 28oC, but summer-acclimated fish can survive temperatures to 36oC.
slide22

Some ectotherms that experience subzero body temperatures protect themselves by producing “antifreeze” compounds (cryoprotectants) that prevent ice formation in the cells.

    • In cold climates, cryoprotectants in the body fluids let overwintering ectotherms, such as some frogs and many arthropods and their eggs, withstand body temperatures considerably below zero.
    • Cyroprotectants are also found in some Arctic and Antarctic fishes, where temperatures can drop below the freezing point of unprotected body fluids (about -0.7oC).
slide23

Cells can often make rapid adjustments to temperature changes.

    • For example, marked increases in temperature or other sources of stress induce cells grown in culture to produce stress-induced proteins, including heat-shock proteins, within minutes.
    • These molecules help maintain the integrity of other proteins that would be denatured by severe heat.
    • These proteins are also produced in bacteria, yeast, and plants cells, as well as other animals.
    • These help prevent cell death when an organism is challenged by severe changes in the cellular environment.
slide24

Hibernation:long-term torpor as an adaptation to long-term winter cold and food shortage

  • Torpor in Ground Squirrels
    • Body temperature: 37oC
    • Metabolic rate: 85 kcal per day.
    • During the eight months the squirrel is in hibernation, its body temperature is only a few degrees above burrow temperature and its metabolic rate is very low.
slide26

Osmoregulation

Osmoregulation- the control of the concentration of body fluids.

Diffusion- movement of substance from an area of greater concentration to an area of lower concentration

Osmosis- diffusion of water through a semipermeable membrane

slide27

Adaptation to Marine Environment

  • Reducing salt
  • Seabird and marine iguana- nasal salt secreting gland
  • Sea snake- sublingual gland
  • Crocodile- lacrimal gland
  • Fish gills- chloride cells
  • Shark- rectal gland
slide29

Nitrogenous Waste Excretion

  • Ammonia- toxic
    • Excrete directly into water- jellies
    • Detoxifyurea
  • Urea- need lots of water to get rid of
  • Uric Acid- birds & reptiles
    • more costly to produce than urea, but needs less water to be removed
slide31

Balancing NaCl in Blood

  • Osmoconformer: isoosmotic
  • Osmoregulator: hyper-, hypo-, ureoosmotic
  • Euryhaline: wide tolerance range
  • Stenohaline: narrow tolerance range

Osmols- total solute concentration in moles of solute/liter of solution

slide32

Marine Fish: hypoosmotic

Less salt than external environment

H2O continually leaves body

continually drinks seawater

excretes salt through gills

produces small amts of dilute urine

slide33

Freshwater Fish: hyperosmotic

H2O continually enters body

does not drinks water

More salt than external environment

produces large amts of dilute urine

slide34

Shark and Coelacanth: ureoosmotic

Maintains high levels of urea and TMAO in blood

excretes salt through rectal gland

coelacanth

Rana cancrivora

slide35

Hagfish: ionosmotic

nonregulator

Seawater concentration = internal concentration

slide36

Osmolarity in Freshwater and Saltwater

Osmolarity- measure of total solutes(dissolved particles)

Ions FW m osmol/l SW m osmol/l

Na+ 1 470

Cl- 1 550

Ca++ variable 10

Total 10 1000

slide37

Habitat

Na+

Cl-

Urea

seawater

sw

478

558

hagfish (Myxine)

sw

537

542

lamprey

fw

120

96

Goldfish (Carassius)

fw

115

107

Toadfish (Opsanus)

sw

160

Crab-eating frog (Rana)

sw

252

227

350

Dogfish

sw

287

240

354

freshwater ray

fw

150

149

<1

coelacanth

sw

197

199

350

Concentration of Ions

slide38

Adaptations to Dry Environment

  • Many desert animals don’t drink water
  • Kangaroo rats lose so little water that they can recover 90% of the loss from metabolic water and gain the remaining 10% in their diet of seeds.
  • Also have long loop of Henle
slide40

Most excretory systems produce a filtrate by pressure-filtering body fluids into tubules.

slide41

Diverse excretory systems are variations on a tubular theme

  • Flatworms have an excretory system called protonephridia, consisting of a branching network of dead-end tubules.
    • The flame bulb draws water and solutes from the interstitial fluid, through the flame bulb, and into the tubule system.
slide42

Metanephridia consist of internal openings that collect body fluids from the coelom through a ciliated funnel, the nephrostome, and release the fluid through the nephridiopore.

    • Found in most annelids, each segment of a worm has a pair of metanephridia.
slide43

Insects and other terrestrial arthropods have organs called Malpighian tubules that remove nitrogenous wastes and also function in osmoregulation.

    • These open into the digestive system and dead-end at tips that are immersed in the hemolymph.