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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 heat
ex: cold pool of water, hot rock
2. Convection  transfer of heat by the movement
of air or liquid
ex: 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 liquid
ex: sweat 
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 
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 loss
2. 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, “stressinduced 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 stored
1. Ammonia  most aquatic animals, most lost
across the gills
2. Urea  100,000X less toxic, produced by liver,
mammals, adult amphibians, marine fish, turtles
3. 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 blood
2. 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, Annelids
3. Malpighian tubules  Insects
4. 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.
•
•
1.
2.
3.
4.
•
•
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 
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 