Chapter 44 Reading Quiz

2. Chapter 44 Reading Quiz • The four physical processes that account for heat gain or loss are conduction, ____, radiation, & ____. • “Summer torpor”, or the hot version of hibernation, is called _____. • In what form do we excrete nitrogenous waste? • What is the functional unit of the vertebrate kidney?

3. 1. Define thermoregulation. • The maintenance of body temperature within a range that enables cells to function efficiently  necessary for heat to be exchanged between animal and environment  every species has an optimal temperature range 

4. 2. Describe the four physical processes that account for heat gain or loss. • Conduction  transfer of thermal heat ex: cold pool of water, hot rock • Convection  transfer of heat by the movement of air or liquid ex: wind (wind-chill factor) • Radiation  emission of electromagnetic waves ex: the sun, polar bears’ fur 4. Evaporation  the loss of heat from the surface of a liquid ex: sweat 

6. 3. Differentiate how endotherms and ectotherms derive their body heat. • Ectotherm  warms its body mainly by absorbing heat from its surroundings ex: most invertebrates, fish, amphibians, reptiles • Endotherm  derives most or all of its heat from its own metabolism ex: mammals, birds, some fish, many insects 

8. 4. List and describe the four general categories of adaptations that animals make for thermoregulation. • Adjusting the rate of heat exchange between the animal and its surroundings - vasodilation/vasoconstriction - countercurrent heat exchanger • Cooling by evaporative heat loss • Behavioral responses (basking, migration) • Changing the rate of metabolic heat production (increase in the cold) 

10. 5. Describe how most invertebrates control their body temperature. • Very little control • Some use behavioral or physiological mechanisms • Bees and large moths are endothermic - can huddle together to keep warmth - countercurrent heat exchanger 

12. 6. Describe how most amphibians and reptiles control their body temperature. • Generally have low metabolic rates • Average body temperature can range 7 – 25 degrees Celsius • Behavioral adaptations (moving, “pushups”) • Usually adaptations are for heat gain • Some prevent heat loss  vasocontriction, shivering • Debate continues whether dinosaurs were endothermic 

13. 7. Describe how most fishes control their body temperature. • Usually temperatures are within 1 – 2 degrees Celsius of surrounding water • Metabolic heat from muscles is lost though gills to water • Endothermic fish  tuna, swordfish, great white shark; adaptations to circulatory system retain heat • Countercurrent heat exchanger 

15. 8. Describe the way most mammals and birds control their temperature, and some adaptations. • Mammals 36 – 38 Celsius • Birds 40 – 42 Celsius • Heat from metabolism • Heat production increased by: 1. contraction of muscles (moving or shivering) 2. Action of hormones that increase the metabolic rate and the production of heat instead of ATP (nonshivering thermogenesis) • Brown fat  tissue in the neck and between shoulders specialized for rapid heat production • Vasodilation/vasoconstriction • Fur, feathers, layer of fat (blubber), panting 

16. 9. Describe how feedback mechanisms are used in thermoregulation. • Complex homeostatic system • Nerve cells concentrated in the hypothalamus control thermoregulation • Contains a thermostat that responds to body temperature (high and low) • Activates mechanisms that promote heat gain or loss • Heat saving: vasoconstriction, raising fur, shivering • Body cooling: vasodilation, sweating, panting 

18. 10. Describe how animals respond to temperature ranges. • Acclimatization  a physiological response to adjusting to changes in the environment • May involve cellular adjustments - increase certain enzymes, variants of enzymes • When sudden changes occur, “stress-induced proteins” accumulate to keep the integrity of other proteins - include heat shock proteins 

19. 11. What is torpor? How does it conserve energy during environmental extremes? • Torpor  alternative physiological state in which metabolism decreases and the heart and respiratory system slow down • Hibernation  long-term torpor during which the body temperature is lowered as an adaptation to winter cold and less food • Estivation  “summer torpor” characterized by slow metabolism and inactivity • Instigated by seasonal changes and biological clock 

21. 12. Describe how water balance and waste disposal depend on transport epithelia. • Transport epithelia – a layer or layers of specialized epithelial cells that regulate solute movements • Maintaining water balance and getting rid of metabolic wastes requires transport of these between the animal and its surroundings • Joined by impermeable tight junctions, creates a selectively permeable membrane 

22. 13. How are an animal’s nitrogenous wastes correlated with its phylogeny and habitat? Describe the three main forms, and which animals excrete it. • Nitrogen is removed when macromolecules are broken down or converted • The waste product is ammonia (toxic) • Excreting ammonia takes no energy, but it cannot be stored • Ammonia  most aquatic animals, most lost across the gills • Urea  100,000X less toxic, produced by liver, mammals, adult amphibians, marine fish, turtles • Uric Acid  can be excreted in pastelike form, less soluble in water, egg layers; snails, insects, birds, many reptiles 

24. 14. Differentiate between osmoregulators and osmoconformers. How is water balance maintained in the ocean? In freshwater? On land? • Osmoconformer  an animal that is isoosmotic with its saltwater environment - does not actively adjust its internal osmolarity • Osmoregulator  an animal that is hypo- or hyperosmotic to the environment - must adjust its internal osmolarity - must either discharge excess water or take in water - energetically costly • Stenohaline vs euryhaline 

27. 15. List the four key functions of the excretory system. • Filtration – filters wastes from blood • Reabsorption – absorbs selected items from filtrate; glucose, salts, amino acids • Secretion – solutes are removed from the animal’s body fluids and added to the filtrate • Excretion – discarding of waste products 

29. 16. Describe the four diverse excretory systems. • Protonephridia: the Flame-Bulb System  Platyhelmintes • Metanephridia  Mollusks, Annelids • Malpighian tubules  Insects • Vertebrate Kidneys  vertebrate animals 

30. Protonephridia/Flame Bulb • A network of closed tubules lacking internal openings • Tubules branch throughout the body, the smallest capped with a “flame bulb” that draws water and solutes into tubule setup • Functions mainly in osmoregulation • Most metabolic wastes are diffused out of the body • Found in rotifers, some annelids, mollusk larvae, lancelets 

32. Metanephridia • Has internal openings that collect body fluids • Found in segmented worms, each segment has a pair enveloped by capillaries • Has excretory and osmoregulatory functions • As fluid moves along tubes, transport epithelium reabsorbs most solutes • Nitrogenous wastes disposed of in urine 

34. Malpighian tubules • Remove nitrogenous wastes from the hemolymph and function in osmoregulation • Transport epithelium lining secretes solutes (wastes) into tubules • Wastes are eliminated as nearly dry along with feces • Helps to conserve water 

36. 17. Briefly overview the mammalian kidney structure and function. • Compact organs containing numerous tubules that are not segmentally arranged • Function in both excretion & osmoregulation • Blood enters each kidney via the renal vein • Urine exits kidney through the ureter • The ureters drain into the urinary bladder • Urine leaves body through the urethra • 2 distinct regions: outer renal cortex and inner renal medulla • Nephron the functional unit of the kidney; consists of a single long tubule and a ball of capillaries called the glomerulus 

38. 18. List the five steps that outline how blood filtrate becomes urine. • Proximal tubule secretion & reabsorption, maintain constant pH, bicarbonate, potassium, salts, water • Descending limb of the loop of Henle water is passively reabsorbed • Ascending limb of the loop of Henle permeable to salt and not water, salt is reabsorbed • Distal tubule secretion & reabsorption, regulates K+ and H+ concentrations • Collecting duct resbsorption of salts and water 

40. 19. How is water conserved in the mammalian kidney? • The kidney can excrete urine 4x as concentrated as blood • The loop of Henle and the collecting duct maintain the osmolarity gradient that makes it possible to concentrate the urine • At its most concentrated (1200 osmolarity) it is isoosmotic with the surrounding interstitial fluid, but hyperosmotic to blood and all other interstitial fluids 

42. 20. Describe how the nervous system and hormonal feedback circuits help regulate kidney functions. (fig 21) • Antidiuretic hormone (ADH) is produced in the hypothalamus and secreted by the pituitary gland  enhances fluid retention • Release is triggered by osmoreceptor cells that detect an increase in osmolarity in blood (this promotes thirst) • Drinking reduces osmolarity, which inhibits ADH secretion, and the feedback loop is completed 

44. 21. Describe several of the diverse adaptations of the vertebrate kidney that have evolved in different habitats. • Desert mammals  extremely long loops of Henle for more water absorption • Freshwater fish  excrete excess water, conserve salts by efficient reabsorption • Amphibians  accumulate salts and excrete dilute urine in water, on land reabsorb water • Marine bony fishes  kidneys excrete very little urine, lots of salts 

46. 22. Discuss briefly how the various interacting regulatory systems maintain homeostasis. • Homeostasis depends on the interaction of numerous regulatory and organ systems • The regulation of body temperature has an impact on metabolic rate, blood pressure, tissue oxygenation, and body weight • Liver  largest and most functionally diverse organ - takes up glucose & stores excess as glycogen - synthesizes proteins for blood clotting & maintains osmotic balance in blood - detoxify chemicals and prepare metabolic wastes for disposal 