1 / 65

Ch. 44: REGULATING THE INTERNAL ENVIRONMENT

Ch. 44: REGULATING THE INTERNAL ENVIRONMENT. Introduction A.Homeostasis:. Thermoregulation = Regulation of Body Temperature Osmoregulation = Regulation of solute and water balance Excretion = Control of Nitrogen containing waste . Regulators v. Conformers:.

megan
Download Presentation

Ch. 44: REGULATING THE INTERNAL ENVIRONMENT

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Ch. 44: REGULATING THE INTERNAL ENVIRONMENT

  2. Introduction • A.Homeostasis: • Thermoregulation = Regulation of Body • Temperature • Osmoregulation = Regulation of solute • and water balance • Excretion = Control of Nitrogen containing • waste • Regulators v. Conformers: • Regulators: Maintain constant internal • environment • Conformers: Allow for internal environment • to change over a range of external • conditions.

  3. Thermoregulation: Regulation of Body Temp. • Q10 Effect: The rate at which an enzyme- • mediated chemical reactions increases for • every 10° C temperature increase. Ex. Rate of glycogen hydrolysis in a frog is 2.5 time greater at 30° C than 20° C. It’s Q10 for that reaction is 2.5. • Temperature has a great effect on an animal’s • ability to do work. • Four physical processes account for heat gain • or loss: • Conduction: direct transfer of thermal • motion (heat) between molecules of objects • in direct contact with each other, as when • an animal sits on a pool of cold water or on • a hot rock.

  4. Convection: is the transfer of heat by the • movement of air or liquid past a surface. • Radiation: is the emission of electro- • magnetic waves by all objects warmer than • absolute zero, including an animal’s body, • the environment, and the sun. • Ex. Transfer of heat from animal’s body.

  5. Evaporation: Loss of heat from liquid to • gas.

  6. Sources of Body Heat: • 1.Ectotherms: determined by the • surrounding environment. • 2.Endotherms: determined by metabolic • rates.

  7. Advantages of endothermy: • High level of cellular respiration; allows for • endotherms to perform vigorous activities • much longer than ectotherms. • Stable body temperature allows for an • endotherm to live in fluctuating temps, that • are characteristics of terrestrial landscape. • However, endothermy requires much more energy intake than ectothermy. Example: 20°C, a human at rest has a metabolic rate of 1,300 to 1,800 kcal/day and an American alligator, has a metabolic rate of only about 60 kcal per day at 20°C.

  8. Thermoregulation involves physiological and • behavioral adjustments that balance heat gain • and loss. Four categories of adpations that help animals thermoregulate: • Adjusting the rate of heat exchange • between the animal and its surroundings: • Insulation (hair, fur, feathers, fat) • reduces the flow of heat between an • animal and its environment. • Adaptations of the circulatory system: • Vasodilation: an increase in the • diameter superficial blood vessels, • increasing the transfer of body heat to a • cool environment by radiation, conduction, • and convection.

  9. Vasoconstriction: Reduces blood flow and heat transfer by decreasing the diameter of superficial vessels.

  10. Countercurrent heat exchanger: special arrangement of blood vessels that help trap heat in the body core; helps reduce heat loss in many endotherms. Heat from the body core in the arteries are transferred to the veins.

  11. Cooling by evaporative heat loss: • evaporation at skin and by breathing; as • water evaporates, it also removes the heat. • -Panting • -Sweating • -Bathing • Behavioral responses: Sun basking, lying • in shade, hibernation, and migration, etc. • Changing the rate of metabolic heat • production: greatly increase heat • production when exposed to cold (will be • discussed further in the next section) • -Applies only to endotherms

  12. Endothermy: Mammals and Birds • Body temp range: mammals = 36-38° C • birds = 39-42° C • 2.Must counteract the constant heat loss to • the environment by: • a.High metabolic rate • b.Shivering to produce heat • c.Certain hormones can cause mitochondria • to increase their metabolic activity and • produce heat instead of ATP. This is • called NST (Nonshivering • Thermogenesis). It takes place • throughout the body, and also in a • specialized region called “brown fat.”

  13. Insulation: Hair, feathers, fat • Vasodilation/Vasoconstriction • Panting • Sweating/Spreading saliva on body • surfaces • Ectothermy: Amphibians and Reptile • Body temp range: 7° to 25° C. • Behavioral adaptations: Moving to shade • or sunny spots. • Galapagos Island Iguana: vasoconstrict • their superficial blood vessels to conserve • body heat. • 4.Large Endothermic Reptiles: Female • pythons, incubating eggs, increase their • metabolic rates by shivering, generating • heat (Dinosaurs endothermic??).

  14. Ectothermy: Fishes • Conformers: within 1-2° C of their • surroundings. • Specialized endothermic fishes: powerful • swimmers like bluefin tuna, swordfish, and • great white sharks, have circulatory • adaptations that retain metabolic heat in • the body.

  15. -Endothermy in great white sharks: countercurrent heat exchanger in its swimming muscles.

  16. Ectothermy: Invertebrates • Aquatic Invertebrates: conformers • Terrestrial Invertebrates are actually endo- • thermic as they can elevate body temp by • moving their powerful flight muscles. -Bees and moths (Ex. Hawk moth) -Countercurrent heat exchanger at the thorax -Honeybee social behavior: huddle and shiver together in cold weather

  17. Feedback Mechanisms in Thermoregulation: • Nerve cells that regulate thermoregulation • is concentrated in the hypothalamus.

  18. The hypothalamus is like a thermostat, • responding to changes in body temperature • above and below a set point by activating • mechanisms that promote heat loss or gain.

  19. Adjusting to Changing Temperature: • Many animals adjust to a new range of • environmental temperatures over a period • of days or weeks. This is called • acclimatization. • Acclimatization in birds and mammals: • Adjust the amount of insulation (thicker • coat of fur in the winter, etc), adjust the • metabolic heat production. • Acclimatization in ectotherms: process of • compensating for changes in body • temperature through adjustments in • physiology and temperature tolerance. • Ex. Winter-acclimated catfish can only survive • temps as high as 28°C, but summer-acclimated • fish can survive temps to 36°C.

  20. -Acclimation in ectotherms often include • adjustments at the cellular level: • Variant enzymes are produced that have the same function, but has a different optimal temperature. • Membranes can also change the proportions of saturated and unsat. lipids they contain, which helps keep membranes fluid at different temps. • Antifreeze chemical: prevents ice from forming in cells. Ex. Cryoprotectants • Stress-Induced proteins (i.e., heat- shock proteins): help maintain the integrity of other proteins that would otherwise be destroyed by heat.

  21. Torpor conserves energy during • environmental extremes. • Torpor: a physiological state in which • activity is low and metabolism decreases. • Hibernation: long-term torpor • a.Body temp declines • b.Low metabolic rate •  Allows for survival on limited supplies of • energy • Belding squirrel: hibernates for 8 months; body temp during hibernation is near freezing; arouses for a few hours every week or two.

  22. Body temp and metabolism during Hibernation of Belding’s ground squirrel:

  23. Estivation: Summer torpor; slow • metabolism and inactivity during high • temps and when water is scarce. • Daily torpor: Small endotherms; occurs • at night or during the day (during hours • when they cannot feed).

  24. Water Balance and Waste Disposal • Osmoregulation: management of water • content and solute composition. • Water balance and waste depends on • transport epithelia. • Transport epithelium: layers of epithelial • cells that move specific solutes in controlled • amounts in particular directions. • An animal’s nitrogenous wastes are • correlated with is phylogeny and habitat. • -Nitrogenous waste is produced when macro- • molecules are broken down for energy. • -Nitrogen is removed in the form of • ammonia.

  25. Ammonia: small and very toxic molecule • created when macromolecules are broken • down. • Can only be tolerated at low • concentrations  requires access to lots • of water. • Ammonia release is common in aquatic • species. • Released easily by diffusion to the • surrounding water. -Marine invertebrates: Diffuses across the entire body surface. -Fish: lost as ammonium ions (NH4+) across the epithelium of gills, while the kidneys extract minor amounts of nitrogenous wastes.

  26. Urea: Made in the liver by combining • ammonia with carbon dioxide and excreted • by the kidneys. • Low toxicity  allows for animals to • store and transport urea safetly at high • concentrations. • Disadvantage: Requires energy to • convert ammonia into urea. • Uric Acid: Land snails, insects, birds, and • reptiles excrete uric acid. • Insoluble in water and can be excreted • as a semisolid paste with very little water • loss (advantage). • Disadvantage: Requires a considerable • amount of ATP to synthesize it from • ammonia.

  27. Osmoregulation: • Osmoconformers: internal osmolarity is • the same as that of its environment. • Osmoconformers often live in water that • has a very stable composition. • Osmoregulator: animals that must • control their internal osmolarity. • Most animals are stenohalines (animals • that cannot tolerate substantial changes in • external osmolarity. • Euryhalines are animals that can survive • large fluctuations of external osmolarity. • Example: Salmon migrate back and forth • between fresh and salt water.

  28. Maintaining water balance in the sea: • Most marine invertebrates are osmo- • conformers. • Marine fishes (Class Osteichthyes) • constantly lose water through their skin • and gills. • -gain water through food, and drinking • large volumes of water (with salt disposed • by active transport out of the gills) • -very little urine is produced • Cartilagenous fish, like sharks (Class • Chondrichthyes) do not have large water • loss due to high concentrations of urea in • their body fluids, along with trimethylamine • oxide (TMAO), which protects proteins from • the urea; body is hyperosmotic to seawater.

  29. Maintaining osmotic balance in freshwater: • Since freshwater fish are hypotonic to their • surroundings, they are constantly gaining • water by osmosis. • Freshwater fish excrete large amounts of • very dilute urine and regain lost salts in • food. • Paramecium have • a contractile • vacuole to • pump water out:

  30. Salmon must adjust to different environ- • ments as they migrate from freshwater to • saltwater. • Ocean: Salmon drink seawater and excrete • salt from their gills. • Freshwater: Salmon cease drinking, begin • to produce lots of dilute urine and their • gills take in salt from water.

  31. Freshwater fish are hypertonic to their environment. Saltwater fish are hypotonic to their environment.

  32. Special Problems of Living in Temporary • Waters: Anhydrobiosis (“life without water”) • Example: Tardigrades, or water bears • -Tiny invertebrates • -Active, hydrated state (85%) • -Inactive, dehydrate state (2%); can • survive in this state for decades Active State Inactive State

  33. Maintaining Water Balance On Land: • 1.Loss of water = Largest problem for • terrestrial organisms • Adaptations: • -Waxy cuticle • -Skin • -Drinking water and eating moist food

  34. Excretory Systems A. An Overview: • Urine is produced in two steps: • a. Body fluid is collected – Filtration • b. Reabsorbtion • Filtrate: water and • small solutes, such • as salts, sugars, • amino acids, and • nitrogenous wastes • After filtration, the filtrate is modified in the excretory tubule as valuable substances from the filtrate are reabsorbed.

  35. Diverse excretory systems: 1. Protonephridia: Flame-Bulb System • Network of dead-end tubules lacking • internal openings. • b.Tubes branch throughout body, capped by • a flame bulb. • Cilia draws water and solutes • into flame bulb. • Urine is moved • outwards through • the nephridiopores. • Urine = dilute • Most metabolic • waste diffuses out • across the body surface • or into body cavity and out through mouth

  36. Metanephridia: tubular excretory system • -Internal openings that collect body fluid • -Ciliated funnel, the nephrostome, which • collects fluids from coelom • -Each body segment contains a pair of • metanephridia

  37. Malpighian Tubules: In insects and • terrestrial arthropods • -Remove nitrogenous wastes and • osmoregulate • -Tubes open to digestive tract and the • tips are immersed in the hemolymph

  38. -Epithelial lining the tubules secrete solutes and nitrogen wastes -Water follows the solutes into tubule -Most solutes are pumped back into the hemolymph -Water follows the solutes, and nitrogen waste (uric acid) is eliminated as dry matter (conserves water!)

  39. Vertebrate Kidneys: • -Functions: osmoregulation and excretion • -Compact, hightly organized tubules • -Associated with capillaries and ducts • -Mammals have a pair of kidneys: • Bean shape • Supplied with blood by the renal artery and a renal vein • Urine exits each kidney through a duct called the ureter • Each ureter drains into the bladder • Urine is expelled through a tube called the urethra

  40. Female and Male urinary tracts

  41. C.Structure and Function of the Nephron and their Associated Structures: 1.Two distinct regions of the kidney: a. Renal Cortex b. Renal Medulla

  42. 2.Nephron = the functional unit of the kidney 3.A nephron is a long tubule and a ball of capillaries called the glomerulus 4.Bowman’s capsule: the end of the tubule that surrounds the glomerulus. 5.Average human kidney has a million nephrons, with a total tubule length of 80 km.

  43. Filtration of blood: • -Blood pressure forces fluid from blood in • the glomerulus into the lumen of • Bowman’s capsule • -Specialized cells called podocytes are • permeable to solutes and water • -Filtrate: salts, glucose, and vitamins; & • nitrogenous wastes • Pathway of the Filtrate - Passes through 3 • regions of the nephron: Proximal tubules  Loop of Henle  Distal Tube (empties into collecting duct)

  44. 8.Two types of nephrons: -Cortical (reduced or no loop of henle) -Juxtamedullary well-developed loop of henle; goes into renal medulla)

More Related