Presentation on theme: "CONTROLLING THE INTERNAL ENVIRONMENT"— Presentation transcript:
1CONTROLLING THE INTERNAL ENVIRONMENT This presentation will probably involve audience discussion, which will create action items. Us PowerPoint to keep track of these action items during your presentationIn Slide Show, click on the right mouse buttonSelect “Meeting Minder”Select the “Action Items” tabType in action items as they come upClick OK to dismiss this boxThis will automatically create an Action Item slide at the end of your presentation with your points entered.CONTROLLING THE INTERNAL ENVIRONMENTVolunteer State Community CollegeNancy G. MorrisCampbell: Chapter 44
2Control the Internal Environment Most animals can survive environmental fluctuations more extreme than any individual cell could tolerate…because mechanisms of homeostasis maintain internal environments within ranges tolerable to body cells.
3Mechanisms of homeostasis: Adaptation to the thermal environment: thermoregulationAdaptation to the osmotic environment: osmoregulationStrategies for the elimination of waste products of protein catabolism: excretion
4Regulation of Body Temperature Metabolism & membrane properties are very sensitive to changes in an animal’s internal temperature.Each animal lives in, and is adapted to, an optimal temperature range in which it can maintain a constant internal temperature when external temperatures fluctuate.Maintaining the body temperature within a range that permits cells to function efficiently is known as thermoregulation.
54 physical processes account for heat gain or loss: 1) Conduction2) Convection3) Radiation4) EvaporationEvaporation & convection are the most variable causes of heat loss.
64 physical processes account for heat gain or loss: Conduction is the direct transfer of heat (thermal motion) between molecules of the environment & body surface.Heat is always conducted from a body of higher temperature to one of lower temperature.Water is 50 to 100 times more efficient than air in conducting heat.On a hot day, an animal in cold water cools more rapidly than one on land.
74 physical processes account for heat gain or loss: Convection is the transfer of heat by movement of air or liquid past a body surface.For example, breezes contribute to heat loss from an animal with dry skin.
84 physical processes account for heat gain or loss: Radiation is the emission of electromagnetic waves produced by all objects warmer than absolute zero.It can transfer heat between objects not in direct contact.For example, an animal can be warmed by the heat radiating from the sun.
94 physical processes account for heat gain or loss: Evaporation is the loss of heat from a liquid’s surface that is losing some molecules as gas.Production of sweat greatly increases evaporative coolingCan only occur if surrounding air is not saturated with water molecules.
10Major source of heat?Ectotherms derive body heat mainly from their surroundingsInvertebrates, fishes, reptiles, amphibiansEndotherms derive heat mainly from metabolic activityMammals, birds, some fishes, numerous insects
11Thermoregulation: Involves physiological and behavioral adjustments. Heat loss is reduced by presence of hair, feathers, and fat just below the skin.The amount of blood flowing to the skin can be changed to regulate heat exchange: vasodilation and vasoconstriction.Evaporative heat loss: panting, sweating, bathing increases evaporative cooling across the skin.
12Behavioral ResponsesIn winter, many animals bask in the sun or on warm rocks.In summer, many animals burrow or move to damp areas.Some animals migrate to more suitable climates.
13Metabolic heat production Occurs only in birds and mammalsIncreased muscle activity and shivering can greatly increase metabolic heat produced.
14Water Balance & Waste Disposal The majority of cell in most animals (all but sponges and cnidarians) are not exposed to the external environment, but are bathed by an extracellular fluid.Animals with an open circulatory system have an extracellular compartment containing hemolymph which bathes the cells.Animals with a closed circulatory system have two extracellular compartments – interstitial fluid and blood plasma.
15Nitrogenous WastesThe metabolism of proteins and nucleic acids produces ammonia, a small & very toxic waste product.Some animals excrete the ammonia directly, while other convert it to urea or uric acid, which are less toxic, but require ATP to produce.
16Nitrogenous Wastes: Ammonia: water soluble and permeates membranes easily.produced by aquatic animals.In soft-bodied invertebrates, ammonia diffuses across the body surface and into the surrounding water.In fishes, ammonia is excreted as ammonium ions across gill epithelium.
17Nitrogenous Wastes: Urea Terrestrial animals can not excrete ammonia because it requires large amounts of water and is so toxic it must be eliminated quickly.Mammals & adult amphibiansCan be concentrated because it is 100,000 times LESS toxic than ammonia.Reduces water loss for terrestrial animals.Liver combines CO2 with amine groups to produce urea. Filtered out by kidneys.
18Nitrogenous Wastes: Uric Acid Land snails, insects, birds, and many reptiles.Much less water soluble than urea or ammonia; can be excreted as a precipitate after reabsorption of water from urine.Eliminated through cloaca in paste form (mixed with feces) in birds & reptiles.Because it precipitates out, it can be stored as a solid in the egg without toxic build up.
20Osmotic gain and water loss: Animal cells can not survive a net gain or a loss of water.Osmosis – diffusion of waterOccurs when two solutions separated by a membrane differ in osmolarity (total solute concentration)In other words, there is a concentration difference.
21Osmotic gain & water loss: Recall that when two solutions of differing osmolarities are separated by a semipermeable membrane, water flows from hypo to hyperosmotic.
22Osmoregulators expend energy Osmoregulators expend energy to control their internal osmolarity.Water may enter a terrestrial organism through food, drinking, oxidative phosphorylation; water may exit through excretion and evaporation.Aquatic organisms are not affected by evaporation but face a major osmotic problem: water may enter (in fresh water) or leave (in marine water) the body.
23Excretion process by which metabolic wastes are eliminated urine, sweat, CO2, nitrogen are primary wastes3 excretory functions:Nitrogen ExcretionOsmotic RegulationWater Balance
24Nitrogen Excretionnitrogenous waste results from deamination of amino acids during protein catabolismpackaged as urea by liverfiltered out by kidneys
25(regulation of salt, ions, solutes) ExcretionOSMOTIC REGULATION(regulation of salt, ions, solutes)fluid and electrolytehomeostasisWATER BALANCE(maintenance)
27What goes where?Approximately 2,300 mL H2O absorbed per day by the small intestineApproximately 300 mL per day lost from the lungsApproximately 1500 mL per day lost from the kidneysApproximately 500 mL per day lost from the skin
28Water sources: Principle source is diet. Oxidation of nutrient molecules during aerobic respiration. Why?
29Form follows function (again): Excretory structures vary based on the type of osmotic environment in which the animal lives.TERRESTRIAL ANIMALS need to conserve water so …Reptiles & birds excrete nitrogenous wastes as crystalline uric acid.Mammals excrete urea that must be dissolved in water (urine).
32Survey of the phyla: PROTONEPHRIDIUM platyhelminthes & nematodes flame-bulb systemwastes either diffuse out of body or are excreted into the gastrovascular cavitycilia keeps fluid moving though the tubules
34Survey of the phyla: METANEPHRIDIUM annelids coelom is fluid-filled each tubule possesses a nephrostome, collecting tubule, and a nephridioporenephrostome drains the metamere just anterior to the one in which the metanephridium is locatedcilia keeps fluid moving though the tubules
36Survey of the phyla: Malphigian tubules – arthropods outfoldings of the digestive system.tubules secrete nitrogenous wastes and salts from the hemolymph; water follows the solutes by osmosis.most of the water and salts are reabsorbed across the epithelium in the rectum.dry product called frass is eliminated.
48URINE FORMATION: 1) Filtration: Filtrate is forced out of glomerulus & received by Bowman’s capsule.Approximately 180 liters per day or 4.5 x the amount of fluid in the body is forced out into glomerulus.= filters 125 mL per minute
49URINE FORMATION: 2) Reabsorption: Occurs simultaneously with secretion.Mostly salts, H2O, solutes, vitamins are transported back to peritubular capillaries via active transport.124 mL of the 125 mL filtered out during filtration will be reabsorbed here.
50URINE FORMATION: 3) Secretion: Filtrate is passed through the renal tubule.Walls of the tubule are a single cellular layer of cubodial epithelium specialized for active transport.Molecules remaining in the plasma are selectively removed (penicillin) from the peritubular capillaries & secreted into the filtrate.
51URINE FORMATION:Na+ Pump – sodium ions are actively pumped across the membrane and Cl- follow passively by electrostatic attraction.Active transport is a “high energy” requirement – higher on a gram for gram basis than the heart beat.
52URINE FORMATION: 4) Excretion: Remaining fluids leave the nephron and pass into the renal pelvis (funnel of the ureter) and travel to bladder until released through the urethra.