Chapter 44 Reading Quiz

1. The four physical processes that account for heat gain or loss are conduction, ____, radiation, & ____.

2. “Summer torpor”, or the hot version of hibernation, is called _____.

3. In what form do we excrete nitrogenous waste?

4. What is the functional unit of the vertebrate kidney?

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

2. Describe the four physical processes that account for heat gain or loss.

1. Conduction transfer of thermal heatex: cold pool of water, hot rock

2. Convection transfer of heat by the movement of air or liquidex: wind (wind-chill factor)

3. Radiation emission of electromagnetic waves ex: the sun, polar bears’ fur

4. Evaporation the loss of heat from the surface of a liquidex: sweat

3. Differentiate how endotherms and ectotherms derive their body heat.

• Ectotherm warms its body mainly by absorbing heat from its surroundingsex: most invertebrates, fish, amphibians, reptiles

• Endotherm derives most or all of its heat from its own metabolismex: mammals, birds, some fish, many insects

4. List and describe the four general categories of adaptations that animals

make for thermoregulation.

1. Adjusting the rate of heat exchange between the animal and its surroundings- vasodilation/vasoconstriction- countercurrent heat exchanger

1. Cooling by evaporative heat loss2. Behavioral responses (basking, migration)3. Changing the rate of metabolic heat

production (increase in the cold)

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

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

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

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

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

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

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

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

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 stored1. Ammonia most aquatic animals, most lost

across the gills2. Urea 100,000X less toxic, produced by liver,

mammals, adult amphibians, marine fish, turtles3. Uric Acid can be excreted in pastelike form,

less soluble in water, egg layers; snails, insects, birds, many reptiles

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

15. List the four key functions of the excretory system.

1. Filtration – filters wastes from blood2. Reabsorption – absorbs selected

items from filtrate; glucose, salts, amino acids

3. Secretion – solutes are removed from the animal’s body fluids and added to the filtrate

4. Excretion – discarding of waste products

16. Describe the four diverse excretory systems.

1. Protonephridia: the Flame-Bulb System Platyhelmintes

2. Metanephridia Mollusks, Annelids3. Malpighian tubules Insects4. Vertebrate Kidneys vertebrate

animals

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

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

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

17. Briefly overview the mammalian kidney structure and function.

• Compact organs containing numerous tubules that are not segmentally arranged

• Function in both excretion & osmoregulation1. Blood enters each kidney via the renal vein2. Urine exits kidney through the ureter3. The ureters drain into the urinary bladder4. 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

18. List the five steps that outline how blood filtrate becomes urine.

1. Proximal tubule secretion & reabsorption, maintain constant pH, bicarbonate, potassium, salts, water

2. Descending limb of the loop of Henle water is passively reabsorbed

3. Ascending limb of the loop of Henle permeable to salt and not water, salt is reabsorbed

4. Distal tubule secretion & reabsorption, regulates K+ and H+ concentrations

5. Collecting duct resbsorption of salts and water

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

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

21. Describe several of the diverse adaptations of the vertebrate kidney that

have evolved in different habitats.

1. Desert mammals extremely long loops of Henle for more water absorption

2. Freshwater fish excrete excess water, conserve salts by efficient reabsorption

3. Amphibians accumulate salts and excrete dilute urine in water, on land reabsorb water

4. Marine bony fishes kidneys excrete very little urine, lots of salts

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