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Animal form and function


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Animal form and function

  1. 1. C H A P T E R 4 0Animal Form and Function
  2. 2. Size and Shapeo Anatomy – the biological formof the animalo Physiology – the biologicalfunction of an animalo Convergent Evolution – similarforms for animals in thesame environment,o Ex. Seals, penguins, tunas
  3. 3. Exchange with the Environmento The ears of a jackrabbit are extremelythin and largeo Provides the rabbit with aefficient way to dissipate heatfrom the blood vessels in theear to the airo Surface Area toVolume, higher ismore efficient
  4. 4. Organization of Body Planso Tissues – groups of cells with a similarappearance and common functiono Organs – made up of tissues, afunctional unito Organ System – made up ofo ex: Skin is an organ of theintegumentary system, whichhelps regulate body temperatureorgans that work together
  5. 5. Tissueso Epithelial Tissue – covers the outside of thebody, lines organs and cavities within the bodyo Closely Packed, allowing them to function as a barrieragainst mechanical injury, pathogens, and fluid losso Connective Tissue – holds other tissues andorgans in placeo Collagenous fibers – strong and flexibleo Reticular fibers – join connective tissue to other tissueso Elastic fibers – provide elasticity, allowing something toreturn to its original state
  6. 6. Signaling via Hormoneso A stimulus causes a cell to release ahormone into the blood streamo The signal travels everywhere throughthe bloodstreamo Cells that have a receptor for thathormone with generate a responseo Ex: When thyroid cells detect TSH, theyrelease another hormone, with promptscells to increase oxygen consumption andheat productiono Relatively slow, takes time to movethroughout the body
  7. 7. Signaling via Neuronso Nerve impulses go to a specific targetcell, rather than throughout the entirebodyo Travel along a path consisting of Axonso Four types of cells can receive nerveimpulses: other neurons, musclecells, endocrine cells, and exocrinecellso Extremely fast effect compared tohormones
  8. 8. Regulators and Conformerso Regulator – for a particular environmentalvariable, it uses internal mechanisms to controlinternal change if that variable fluctuates Ex: a river otter, which keeps its temperature constanto Conformer – allows its internal condition tochange in accordance with external changes Ex: large-mouthed bass, as the water warms or cools, sodoes the temperature of the large mouthed basso Animals may regulate some conditions and letothers conform to the enviorment
  9. 9. Homeostasiso Used to maintain a“steady state” or internalbalance regardless ofexternal environmento In humans, bodytemperature, bloodpH, and glucoseconcentration are eachmaintained at a constantlevelo A buffer is a weak acid orbase used to maintain theacidity (pH) ofa solution near a chosenvalue
  10. 10. Homeostasis (cont.)o Set point – aparticular value, seenas a targeto A stimulus detectedby a sensor will triggera responseo This response is aimedto return the variableto the set point
  11. 11. Feedback Controlo Negative feedback – dampens a stimulusshutting off the responseo Positive feedback – amplifies a stimulusincreasing the responseo ex:
  12. 12. The Circadian Rhythmo circadian rhythm – governs physiological changesthat occur roughly every 24 hourso Acclimatization – the set point changes gradually Ex, can offset the circadian rhythm slightly
  13. 13. Thermoregulationo Endothermic animals generate heat bymetabolism Includes many birds and mammalso Ectothermic animals gain heat from externalsources Includes most invertebrates, fishes, and amphibianso This means that endotherms are regulators fortemperature, whereas ectotherms areconformers for termperatureo Humans can dilate vessels to allow more bloodin and let heat radiate to the skin
  14. 14. Circulatory Adaptationso Vasodilation – widening of superficial bloodvesselso Used to cool down the animalo Vasoconstriction – reduces width to slow bloodflowo Used to keep the animal warmo Countercurrent exchange – the transfer of heator solutes between fluids flowing in oppositedirectionso Ex. As warm blood flows from the body‟s core and coldblood flows to the body‟s core, it maximizes heatexchange
  15. 15. Countercurrent Exchange
  16. 16. Quantifying Energy Useo Metabolic Rate – the sum of all the energy ananimal uses in a given unit of timeo kcalorie = 1000 calories or 4184 jouleso Fats: 9 Calories per gramo Carbohydrates and Proteins: 4.5 – 5 Calories per gram
  17. 17. Metabolic Rateo Smaller animals have higher metabolic rates pergram than larger animalso A mouse will use moreenergy per gram thanan elephant would
  18. 18. Energy Conservation Torpor – a physiological state of decreasedactivity and metabolism An adaptation that enables animals to save energy whileavoiding dangerous conditions Hibernation is a long term form of this that lets animals„skip‟ over winter Metabolic rates during torpor can be 20 timeslower than they would be otherwise
  19. 19. Works Citedo Pearson Educationo McGraw Hill Companies Inc.