The Y axis is MR (kcal/day)
What is the total metabolic rate of the mouse?
What is the total metabolic rate of the horse?
What is the mass specific metabolic rate of the mouse?
What is the mass specific metabolic rate of the horse?
How many rabbits by weight = 1 horse
How many kcal/day of food will these rabbits will consume to maintain
their metabolic rate?
Although all these rabbits weigh the same as one horse, they will consume
____________ times more food (kcal/day) than one horse. (2 points)
The following question is taken from Animal
Physiology -- Biology 462, University of Washington. Metabolism II -- Body
Size, Endothermy vs. Ectothermy, R. B.Huey
Typical values for vertebrates, where MR is in ml O2/hour, W in grams.
b = slope, a = Y intercept of exponential equation MR = a * Wb
b time (hr) for a 1 g animal to use 10 ml O2
passerine bird (42ºC) 7.5 .72
placental mammal(37ºC) 3.8 .75
average = 4.5
lizard (37ºC) .42
frog (ranid) (25ºC) .29 .75
fish (25ºC) .20
beetles (22-25ºC) .23 .86
average = 0.4
- Exercise 1: Fill in the "?" values in the table using the allometric
values given (e.g., solve for t)
- If W=1, then MR = 10 ml O2 / hr = a*1b*t, 10 = a*1*t
- Exercise 2: calculate the times for a 100 g animal of each taxon to use 10 ml O2.
- (If M=100, then MR = 10 ml O2 / hr = a*100b*t)
- What is the equation for this line? [MR = a * Wb, where MR is the metabolic rate in Kcal/day, and W is the body mass in kg]
- What is the equation for this line?
- What is the TOTAL metabolic rate of a mammal that weighs 1500 g.
- Another question from Animal Physiology -- Biology 462, University of Washington. Metabolism II -- Body
Size, Endothermy vs. Ectothermy, Raymond B.Huey
- Researchers had found that a daily dose of 500 mg acrylamide (for life!) induces cancer in rats.
- The California Attorney General was alarmed by this finding and wanted to force warning labels on French fries
and potato chips, because cooking of these starches produces acrylamide. However, a newspaper article discounted this as a
problem because the author felt that (based on the rat data) a human would need to eat 35,000 mg of acrylamide per day to induce cancer.
That’s about 180 pounds of French fries per day!
- The newspaper reporter’s estimate of 35,000 mg/day was obviously based on scaling by weight. If a rat weighs 1
kg, and a human weighs 70 kg, then 70 * 500 = 35,000 mg.
- Compute the daily safe dose if risk scales not with mass but with
total metabolic rate
- Metabolic rate for mammals: MR = 3.8 W75
- Compute the total MR for the 1 kg rat and the 70 kg human
- How many times greater is the human's MR versus the rat?
- This suggests a safe daily dose of __? (hint: your answer
should be more than 500, but less than 35,000 mg/day)
- If instead of the total metabolic rate, what if the safe dose depended on clearance time from the body, where clearance time
might (hypothetically) scale with the mass specific metabolic rate and not with body mass.
- Mass specific MR for mammals: MR/W = 3.8 W-0.25
- Compute the total MR for the 1 kg rat and the 70 kg human
- How many times greater is the rat's MR/W versus the human?
- This suggests a safe daily dose for humans of __? (hint:
your answer should be less than 500 mg/day)
- What if dosage depends on both body mass and mass
specific metabolic rate.
- First, if the optimal dose for a 100 kg adult is 100 mg, what is the optimal dose for a 10 kg child based on body mass alone?
- If the total metabolic rate of a 10 kg child is half that of a 100 kg adult, what is the proper dose based on MR alone?
- If the mass-specific metabolic rate (MR/W) of a 10 kg child is twice as high as that of a 100 kg adult, indicating the child would be
metabolizing the drug twice as fast as the adult rendering it ineffective, what is the proper drug dosage for this child based on both
weight and MR/W?
Chapter 9 Thermal Relations
Some of these questions have been taken from other Animal Physiology pages. All questions require answers that fully explain the conditions, causes, and results.
- Are ectotherms/poikilotherms 'cold-blooded'?
- Do ectotherms/poikilotherms have constant or variable body temperatures?
- What is the difference between a heterothermic endotherm and a
- What is the difference between temperature and heat?
- Why are ecologists and other biologists concerned about the affects of global warming (Fig. 9.2, Box 9.1)
- Discuss and characterize the four major avenues by which an animal
exchanges heat with its environment (Fig. 9.3).
- Water at 10 degrees C feels colder than air at the same temperature. Why?
- Be able to calculate surface area to volume ratios for cubes and spheres.
- How does surface area change as volume changes?
- Why is surface area to volume important for thermal regulation?
- What is the relationship between conduction and convection in relation to
- How do jackrabbits regulate and control heat loss (Fig. 9.5)?
- What do HWA Figs. 9.8a and b indicate about the body temperature of
lizards? Why is it important that both 9.8a and b are presented?
- What is a Q10? How is it calculated? Why is it physiologically important?
- .Given the Q10 and the metabolic rate at a particular temperature be able to construct a graph similar to HWA Fig. 9.10.
- Be able to calculate the Q10 from figures such as HWA 9.10, 9.11.
- Does a given animal have a single Q10 for all physiological activities and across temperature ranges? Why would it be advantageous to have a
temperature sensitive Q10?
- What is being shown in HWA Fig. 9.11? Why is temperature acclimation
important to this species?
- What is the difference between the acute response to declining
temperature by an ectotherm and the acclimation response (Fig. 9.12).
- What is the difference between an acclimation response (Fig. 9.12) and an
adaptive response (Fig. 9.18) by fishes to different water temperatures?
- What does HWA Fig. 9.18 demonstrate about enzyme-substrate affinity in different species of fish that normally live at different water temperatures?
- How are extremely low temperatures physiologically detrimental to animals?
- What is the major difference in response to cold by ectotherms and endotherms?
- What are nucleating agents? How do they function?
- What are cryoprotectants? How do they function?
- What are the two functions of cryoprotectants to protect against cold temperatures?
- Nucleating agents can both increase freeze damage and decrease it. What are nucleating agents in general and how might they act to decrease freeze damage?
- Explain how some invertebrates and lower vertebrates survive freezing.
- Describe the cellular and extracellular processes that enable a frozen wood frog to survive freezing.
- What is the difference between freeze tolerance and freeze avoidance?
Which of these two adaptations would an animal use if it needed to be active in cold weather?
- Would you expect an animal from an intertidal area to have a greater or lower thermal tolerance range (area) than a benthic animal? Why?
- How do endotherms regulate their body temperature inside the thermal neutral zone?
- How do endotherms regulate their body temperature below the thermal neutral zone?
- How do endotherms regulate their body temperature above the thermal neutral zone?
- Explain HWA Fig. 9.26a carefully. What is Tlc (lower critical temperature)? What happens to metabolic rate as ambient temperature drops below Tlc?
- In HWA 9.26b, why doesn't metabolic rate change when Ta goes from 38 to 8 degrees (or 8 to 38 degrees)?
- Why does the graph line of MR versus Tair in Fig. 9.27a intersect the X axis at Ta = Tb?
- What is the relationship between conductance and insulation? Why? Explain figure 9.27c.
- What mechanisms contribute to thermoregulation within the thermoneutral zone?
- What mechanisms contribute to thermoregulation at temperatures above the upper critical temperature? Why does the overall metabolic rate increase above the UCT?
- What mechanisms contribute to thermoregulation at temperatures below the lower critical temperature?
- Compare, contrast, and explain the responses to changing temperature of a sloth, a lemming, and a white fox (HWA Fig. 9.39).
- How do birds minimize heat loss?
- How does huddling behavior help male emperor penguins survive the long periods they must go without food while they incubate eggs?
- Describe the roles of counter-current exchange systems in establishing regional heterothermy.
- What is the main mechanism that marine mammals rely on to stay warm in cold water?
- What is a rete mirabile. How does it function?
- Draw and label a picture showing how a countercurrent system in the limb of an arctic mammal works.
- How is circulation in heat exchangers modified to retain heat?
- How is circulation in heat exchangers modified to dissipate heat?
- How does evaporation work as a cooling mechanism? What are some of its costs?
- Why is using evaporative cooling a dangerous strategy for most desert animals?
- How does panting work as a cooling mechanism? What are some of its costs? How can costs be reduced?
- How do birds lower their body temperature?
- Explain and illustrate how nasal countercurrent systems work.
- Why is it important for the brain to remain cooler than an overheated body? How is this done?
- How do gazelles keep their brains at a lower body temperature when they are active (be able to draw and explain Fig. 9.35)?
- Explain the mammalian physiological specialization to different climates shown in Fig. 9.39. Explain the relationship between the width of the thermal
neutral zone and conductance in tropical versus arctic mammals.
- Why do small animals hibernate? What is the definition of hibernation?
- What are the major physiological changes that occur during hibernation?
- Explain what is illustrated in Figure Fig. 9.42. What is physiological significance of the distance between the homeothermic and hypothermia lines?
- Why do hummingbirds undergo daily torpor? What physiological changes occur?
- Explain how the arrangement of arteries and veins contributes to maintaining constant body temperatures in poikilotherm animals.
- Explain how fish maintain body temperatures above ambient water temperatures.
- Discuss 'endothermy' in large fish such as tuna. How is it made possible? Why it needed? Use illustrations to elucidate your answer.
- How do tuna manage to keep their power swimming muscles at an elevated temperature?
- Sphinx moths require muscle temperatures = 35 degrees C for hovering flight. They can never the less achieve hovering flight when ambient
temperatures = 10 degrees C. How do they manage this?
- Define, explain the importance to thermal physiology, and give an example f the following
- Core body temperature
- Heat balance
- iBehavioral thermoregulation
- Thermal compensation through acclimation
- Thermal compensation through adaptation
- Antarctic fish
- Nucleating agents
- Freeze avoidance species
- Freeze tolerant species
- Antifreeze molecule
- Lethal temperature
- Define, explain the importance to thermal physiology, and give an example of the following
- Thermal neutral zone
- Lower critical temperature
- Upper critical temperature
- Brown adipose tissue
- Countercurrent heat exchanger
- Gular flutter
- Non-shivering thermogenesis
- Shivering thermogenesis
- Regional heterothermy
- lCarotid rete mirabile
- Thermal Map
- Daily torpor
- Swim muscle rete mirabile
- How are the nervous system and endocrine systems similar? How do they differ?
- Describe a simple reflex circuit.
- Define: nerve, neuron, axon, and synapse.
- Be familiar with the generalized structure of a 'typical' neuron, as shown in fig. 12.2 or 12.4.
Be able to label the parts and explain their function.
- What is the significance of the giant axon of the squid to neural research?
- What generates the resting potential in a nerve cell?
- What happens to the membrane potential of the squid axon when the axoplasm is removed? Explain why.
- What are the relative concentrations of Na+, Cl-, K+, and
non-permeating anions inside and outside a neuron? (Fig. 12.12a)
- Why is the resting potential of a neuron about -70 mV?
- Be able to use a simplified version of the Goldman equation as discussed in lecture to calculate the membrane potential. The following example is given in the text and on
the class webpage.
- [K] out = 20 mM
- [K] in = 400 mM
- PK=10 and PNa=1
- Given the equation, compute the membrane potential
- What is the role of the Na+/K+ pump in neuron function? How does it work?
- What is the difference between pump (Na+/K+), ligand-gated (Na+
and K+) and leak channels (K+)?
- Why are both a pump (Na+/K+)
and leak channels (Na+ and K+) required to maintain the resting membrane potential?
- Define the terms polarize, depolarize, repolarize, and hyperpolarize in relation to membrane potential.
- How are voltage gated channels important to the propagation of an action potential?
- Draw a picture showing the change in voltage potential in the generation of a single action potential. Fully label the graph
and the different parts of the action potential curve and the different parts of the action potential curve.
- Given an unlabeled version of a figure such as 12.14a, label the axes and the different parts of the action potential curve. Be able to explain what is causing the different membrane potentials.
- Be able to fully explain Fig. 12.15. Discuss what is going on the K leak channel, voltage gated Na channel and
voltage gated K channel in the resting, rising, falling, and recovery phases
and how this relates to the membrane potential at each of these four phases.
- Explain the rising and falling phases of the action potential in terms of: sodium and
potassium ions, sodium and potassium channels, and the sodium/potassium pump.
- What causes polarization? Depolarization? Repolarization? Hyperpolarization?
- What meant by the statement that the action potential is an “all or none” phenomenon? Explain.
- Draw a typical action potential on a graph of voltage vs. Time, label the axes, and draw a
line to the points where significant changes are going on within the Na+
gate, K+ gate and changes in ion flows.
- Be able to draw an action potential over time, and explain how different relative ion permeabilities affect the different voltage changes.
- Describe the changes that occur in the membrane and its voltage once threshold is achieved.
- What is occurring to the Na+ and K+ voltage gated channels during the rising and overshoot phase?
- What is occuring to the Na+ and K+ voltage gated channels during the falling phase?
- What is occuring to the K+ voltage gated channels during the undershoot phase?
- What is an absolute and relative refractory period and what’s responsible for each?
- What are the roles of the Na+ and K+ voltage gated channels in depolarization, repolarization, and hyperpolarization?
- When are the Na+ voltage gated channels open? closed? inactivated? What is the result of each state?
- How is the action potential propagated along the axon?
- Why do action potentials not reverse direction?
- What are the Na+ and K+ voltage gated channels doing behind the
action potential, at the action potential, and ahead of the action potential on the axon? (Fig. 12.25)
- Explain the significance of the refractory periods in insuring that the action potential
travels down the axon in only one direction.
- Explain how an action potential propagates along an axon without decrementing.
- What determines the speed of an action potential?
- What is the advantage of having large diameter axons? The disadvantage?
- How does myelination affect the propagation of an action potential?
- What is saltatory conduction? How does it work?
- For a given conduction velocity, be able to calculate the time it takes to travel a
certain distance. From the time and the distance, calculate the conduction velocity.
- For Fig. 12.26 graphing the relation between conduction velocity and axon diameter, be able to determine the velocity for a given size axon, the size of the axon for a
given velocity, and calculate the equation for any of the lines as an exponential equation. Be able to use the equation for values that are not on the graph.
- Define and explain the importance to nervous system/neuron function of the following. Use diagrams as appropriate in your answers to help explain your written response
- Absolute refractory period
- All or none response
- Axon hillock
- Cell body
- Central Nervous System
- Chemical synapse
- Conduction with decrement
- Conduction without decrement
- Excitable cell
- Gated ion channel
- Giant axon
- Glial cells
- Goldmann equation
- Graded potential
- leak channel
- Nodes of Ranvier
- Post synaptic potential
- Post synaptic receptor
- Relative refractory period
- Resting membrane potential
- Saltatory conduction
- Schwann cell
- Signal integration
- Sodium Potassium pump
- Synaptic cleft
- Synaptic vesicle
- Threshold potential
- Voltage gated channels
- Sodium voltage gated channel
- Potassium voltage gated channel
- Calcium voltage gated channel
Chapter 13 SYNAPSES
- What is an electrical synapse? How do they function? Where do they
occur in mammals?
- Explain how a signal is transmitted across a chemical synapse. Explain
what happens in the presynaptic and postsynaptic cells.
- Compare and contrast electrical synapses with chemical synapses,
including advantages and disadvantages for each.
- What is a neurotransmitter?
- How does the action potential cause a neuron to release neurotransmitters?
- Explain how ion-gated calcium channels are involved in signal
transmission at the synapse.
- What is the difference between an ionotropic receptor and a metabotropic
- What occurs in the postsynaptic cell when a neurotransmitter binds to an
- What occurs in the postsynaptic cell when a neurotransmitter binds to a
- Explain what is meant by the statement "Metabotropic receptors act
via second messengers."
- Why don't postsynaptic membranes continue to
depolarize after the neurotransmitter binds to
- Discuss what causes an excitatory postsynaptic potential. How does this
affect the postsynaptic cell?
- Discuss what causes an inhibitory postsynaptic potential. How does this
affect the postsynaptic cell?
- Explain the steps involved in the summing of graded responses to
generate an action potential.
- What is the difference between temporal summation and spatial
summation in the post synaptic cell?
- Explain why it is the receptor and not the
neurotransmitter that determines whether the postsynaptic membrane
produces an EPSP or an IPSP.
- Figure 13.9 shows a 'Summary of events in chemical synaptic transmission at the vertebrate neuromuscular junction.' Eight steps
are shown from the depolarization of the axon terminal (1) to the
re-synthesis of acetylcholine (8). Explain what is occurring at
each step (including the cause and the effect).
- Explain how temporal summation or spatial summation triggers a response in
the postsynaptic cell.
- What is the function of acetylcholinesterase?
- What is the difference between flaccid paralysis and spastic
- How do curare, nicotine, and botulism affect the function of acetylcholine?
- How does nitric oxide affect smooth muscle?
Chapter 14 Biological Clocks
- What is an endogenous rhythm?
- Explain what happens to human biological clocks when there are no
external cues as shown in Figure 14.12.
- Give some examples of processes that show circadian rhythms (Table 14.3).
- Explain what is illustrated in figure 14.13 and why it demonstrates circadian rhythms in the chaffinch? What is the cause of the difference between
14.13a and 14.13b?
- Discuss the difference between a trained and untrained rhythm, as shown for the flying squirrel in Fig. 14.14.
- What is a free-running endogenous rhythm?
- What is a zeitgeber?
- What is the role of the superchasmatic nuclei in maintaining circadian rhythms?
- What is the role of the pineal gland in maintaining circadian rhythms?
- Explain the cellular mechanisms of circadian timekeeping as shown in Fig 14.15a
- How does the oscillation in clock and cycle protein production affect transcription of the per and cry genes?
- What is the evidence that the superchiamatic nuclei are involved in maintaining circadian rhythms (see Fig. 14.16)?
Chapter 19 Muscles
- Why does skeletal muscle appear to be striated?
- What proteins are involved in generation of force by all muscles? What is their function?
- Study and be sure you understand figure 19.1c and d. What is a vertebrate skeletal (striated)
muscle made up of?
- Describe the structure of a sarcomere. Where are sarcomeres found?
- Describe the basic structure and shape of the thick filaments and the thin filaments. See Figure
191e and f.
- What are the two binding sites on a myosin head? What is their function in producing a power stroke?
- Describe the interaction between actin, myosin, ADP, and ATP in causing a sarcomere to shorten.
- What causes the thin and thick filaments to slide past one another? What molecule provides the energy
that allows the myosin to swivel and pull on the thin filament to which it binds?
- Be able to explain each of the 6 stages shown in Figure 19.5, 'Molecular interactions that underlie
muscle contraction.' Be able to answer questions such as, but not limited to
- What happens when ATP binds to the myosin head?
- What happens when the ATP dissociates to ADP + Pi?
- What happens when the Pi is released from the myosin?
- What happens when the ADP is released from the myosin?
- What 2 additional proteins other than actin make up thin myofilaments and how are these three
proteins arranged in a thin myofilament?
- Explain the roles of Calcium, tropomyosin and troponin in the process of muscle contraction.
- Describe the contraction of a muscle fiber, from arrival of the neural action potential to fiber
relaxation. Use illustrations to elucidate your answers.
- Explain how an action potential arriving at the presynaptic terminal of a motor neuron triggers
contraction of a postsynaptic muscle fiber.
- How is an impulse conducted across a neuromuscular junction?
- Explain the roles of acetylcholine and ligand-gated Sodium channels in the process of muscle
- Explain the roles of acetylcholine, calcium, motor neurons, neuromuscular junction, sarcoplasmic
reticulum, and T-tubules in the process of muscle contraction.
- Explain how the muscle fiber action potential is spread to reach all of the fibrils within the fiber.
- How does an action potential of a neuron trigger the release of Calcium in the muscle cell?
- How does muscle relax following contraction?
- Why doesn't a muscle continue to contract once the calcium is released?
- What occurs during the latent period of muscle contraction? The contraction period? The relaxation
period? (Fig. 19.9)
- Describe the summation process shown in figure 19.11. What is occurring in each of the 5 episodes in
- Differentiate between muscle twitch, wave summation, unfused tetanus, and fused tetanus.
- Describe and explain what is shown in Figure 19.12. When and why is muscle tension maximized 2.0-2.25
microns? Why is it less at shorter and greater lengths?
- Describe the basic differences between the three kinds of vertebrate twitch.
- What is the difference between slow twitch (slow oxidative) and fast twitch A (fast oxidative
glycolytic) muscle fibers?
- What is the difference between fast twitch A (fast oxidative glycolytic) and Fast twitch B (fast
glycolytic) muscle fibers?
- How do motor units regulate the force of muscle contraction?
- How does smooth muscle differ from skeletal muscle?
Define and explain the importance to muscle contraction of the following. Use
diagrams as appropriate in your answers to help explain your written response
- Antagonistic muscle
- Cardiac muscle
- Creatine phosphate
- Isometric contraction
- Isotonic contraction
- Ligand-gated channel
- Muscle fiber
- Muscle fibril
- Oxygen debt
- Rigor mortis
- Sarcoplasmic reticulum
- Skeletal muscle
- Sliding filament model
- Smooth muscle
- Transverse tubule
Chapter 22 RESPIRATION 1
Some of these questions have been taken from other Animal Physiology pages. All questions require answers that fully explain
the conditions, causes, and results.
- What are the functions of respiration?
- What is the difference between organismal respiration and cellular respiration?
- What are the percentages of oxygen, nitrogen, and carbon dioxide in dry air?
- What is the percentage of water vapor in the atmosphere?
- A gas mixture contains 0.2 mol of N2, 0.4 mol of O2, and 0.1 mol of CO2. For this mixture,
what is the percent of each of the three gases? If the mixture is at STP, what
is the partial pressure (in mm) of each gas
- How does the solubility of oxygen in water compare with the solubility of carbon dioxide in water?
- Henry's Law states that the quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility
coefficient (its physical or chemical attraction for water), at a given temperature.
- Henry's Law: The volume of a gas (Vx) dissolved in a liter of water is Vx = (pX)*(SC) where pX is the partial pressure in atmospheres and SC
is the solubility coefficient
- At one atmosphere and 37 degrees Celsius, the solubility coefficient for oxygen is 0.024 ml O2/ml H2O.
- How much oxygen can dissolve in a liter of water at 37 degrees Celsius if the partial pressure of oxygen is 85 mm Hg?
- What factors are responsible for rates of diffusion from gas to water? Explain why carbon dioxide will diffuse more rapidly than oxygen from air to
water, if both are at the same partial pressure.
- How does temperature affect gas solubility? What effects might this have on organisms?
- How does salinity affect gas solubility? What effects might this have on organisms?
- How does the difference in diffusion rate of a gas in air versus that of a gas in water affect the structure of respiratory organs (i.e., lungs versus gills)?
- Many air-breathing aquatic insects have a "diffusion lung"
(Figure 22.3). Explain why
an insect that takes down a bubble of normal air survive much longer than an
insect that takes down a bubble of pure oxygen. In both cases the water is
in equilibrium with the atmosphere above it. Explain what happens if
it takes a bubble of normal air down into water that lacks oxygen.
- Explain figure 22.5 (turtle egg incubation). What does the graph show happened after day 50? Why? What does the graph show happened on day 60? How
did this affect the eggs?
- Box 22.1: Why is the larval anchovy able to survive without gills or circulatory system?
- Box 22.1: What is the relationship between rates of diffusion and allometric change as the anchovy matures?
- Why do larger animals need circulatory systems, while smaller animals do not?
- Box 22.2: Many subterranean mammals such as moles have low metabolic rates to cope with the low oxygen availability in their tunnels. How are
prairie dogs able to obtain enough oxygen to sustain high metabolic rates in their burrows?
- Why do larger animals need to supplement diffusion with convective flow to meet their gas exchange needs?
- What is the difference between external respiration and internal
respiration? Discuss the roles of convection and diffusion in each. (see Figure
- Why is the movement from the lungs to the mitochondria an example of an
oxygen cascade? (see Fig. 22.8)
- Explain what figure 22.8b shows with regard to the movement of oxygen
from the air to the mitochondria.
- What are some of the advantages of obtaining oxygen from air versus
water? What is the main disadvantage?
- Define, explain the importance to respiratory physiology, and give an
example of the following
- Dalton's Law
- Partial pressure of
- Organismal respiration
- Cellular respiration
- External respiration
- Internal respiration
- Solubility coefficient
- Solubility of carbon
- Solubility of oxygen
- Bulk flow
- Unidirectional flow
- Tidal flow
- Oxygen cascade
Chapter 23 - RESPIRATION 2
Some of these questions have been taken other Animal Physiology pages. All questions require answers
that fully explain the conditions, causes, and results.
- Discuss the relationship between surface area and volume as it relates to diffusion.
- Why can small organisms rely solely on diffusion for gas exchange?
- Why do small animals that rely solely on diffusion for respiration tend to be flattened in shape?
- What types of organisms tend to rely on cutaneous gas exchange?
- Compare air and water as media for respiratory gas exchange.
- How do viscosity and density affect the cost of ventilation in water breathing versus air breathing animals?
- List and explain the three primary properties of air and water that make respiration in water more difficult than respiration in air.
- Why do most terrestrial organisms use bi-directional flow for respiration, while most aquatic organisms use unidirectional flow?
- How do the physical properties of air and water dictate the form of the structures animals use for gas exchange?
- Why is it that organisms that use water as their respiratory medium are almost never 'warm-blooded?'
- Compare and contrast cocurrent, countercurrent, and crosscurrent arrangements of flow between the respiratory medium and blood.
- Draw a figure (similar to 22.4a) that shows how cocurrent (parallel) exchange occurs. Do the same for countercurrent flow (22.4b). Explain the different results.
- What does figure 22.7 indicate about respiratory surfaces within a group of vertebrates? Why?
- What does figure 22.7 indicate about respiratory surfaces between groups of vertebrates? Why?
- What is the general relationship between respiratory surface area and metabolic rate?
- What is the most surprising group of vertebrates plotted in figure 22.7? Explain.
- Describe the gills of fish and the mechanisms by which water is pumped across the respiratory exchange surface of fish. What is the arrangement between blood flow
and the flow of water?
- Explain the structural features and mechanisms of fish gills that maximize the extraction of oxygen from water (see fig. 22.10)
- Explain how the fact that blood and water flow in opposite directions in the gill of a fish enhances the exchange of oxygen between the water and the blood.
- Why is it important that water be moved over the surface of a gill?
- What are the general similarities and differences between the structure of gills and lungs?
- Why is it that lungs do not make good gills and gills do not make good lungs?
- Describe and discuss the breathing cycle in teleost (bony) fish. (Figure 22.11)
- Compare and contrast ram and opercular ventilation in fish.
- Compare and contrast the difficulties experienced by aquatic and terrestrial animals in
obtaining oxygen. Give an example of the solutions to these problems employed by a terrestrial and aquatic animal.
- How do viscosity and density affect the cost of ventilation in water breathing versus air breathing animals?
- What is a positive (buccal force) pressure pumps? Which terrestrial vertebrates use it? Explain briefly it functions.
- Explain why in Figure 22.15 (the development of external respiration in the bullfrog) the carbon dioxide excretion curves for skin and lungs differ from the oxygen
uptake curves for skin and lungs.
- How does the structure of the mammalian lung differ from the reptile lung? Explain why.
- Discuss the mechanics of inhalation and expiration in mammals.
- Define the following: Tidal volume, Inspiratory reserve volume, Expiratory reserve volume, Residual volume, Dead Space.
- If a mammal's tidal volume is 2 L, its tracheal volume is 80 mL, its anatomical dead space volume is 350 mL, and its breathing frequency is 9 breaths/minute, what is
the rate of gas exchange in the alveoli?
- Describe how mammals ventilate their lungs (inhalation and exhalation).
- Describe the anatomy of the bird respiratory system and the bird lung
- What are the unique adaptations of the bird respiratory system that make it work so
- How is it that the PO2 in the lung of a bird is greater than the PO2 in the lung of a
mammal (at same elevation)? (make sure to explain your answer)
- Compare and contrast parabronchii and alveoli.
- Describe how air is transported through the lungs of a typical bird (Fig. 22.22).
Explain what happens with each inspiration and expiration to move air through the respiratory system.
- What advantages do birds seem to gain over mammals by the design of their respiratory system?
- Describe and illustrate the tracheal system of insects.
- What are tracheae? What are spiracles?
- Explain the basic design of the gas exchange system in insects. Is the circulatory
system involved? Why or why not?
- Outline the differences among the three most sophisticated lungs found in modern
animals: the mammalian lung, the avian lung, and the insect tracheal system.
- What are the physiological problems if mammals attempted to breathe water (why do we
drown and fish don't?)
- Define, explain the importance to respiratory physiology, and give an example of the following
- Surface area/Volume
- Unidirectional flow
- Tidal flow
- Cocurrent flow
- Countercurrent flow
- Crosscurrent flow
- Countercurrent blood flow in fish gills
- Buccal pumping
- Opercular pumping
- Ram ventilation
- Cutaneous respiration
- Dead space
- Tidal ventilation
- Tidal volume
- Tracheal system
Chapter 23 GAS TRANSPORT
in CO2 transport in the tissues? In the lungs?
- One could say that a respiratory pigment with relatively low O2 affinity is potentially disadvantageous for loading, but advantageous for unloading.
Explain both parts of this statement.
- Outline the ways in which mammalian hemoglobin simultaneously plays important roles in O2 transport, CO2 transport, and control of blood pH..
- The hemoglobin in mammalian blood is usually thought of simply increasing
the amount of oxygen that can be carried by each liter of blood. In a lecture on hemoglobin, a respiratory physiologist made the following statement: "The
presence of hemoglobin in the blood also makes possible the rapid uptake of
oxygen by the blood as it flows through the lungs." Explain the lecturer's point.
- What are the two principal reasons for enclosing oxygen carrying proteins in blood cells?
- What is the functional significance of the typical sigmoid shape (Fig. 24.4) of the hemoglobin-oxygen dissociation curve? What is the advantage of
the shape of the curve at oxygen partial pressures > 80 mm Hg; < 40 mm Hg.
- Using Fig 24.5, show how much more oxygen is released to tissues doing exercise versus tissues at rest.
- For Fig. 24.6, how much of a drop in O2 partial pressure is required to cause unloading of 5 vol % O2 if the initial concentration is 20 ml O2 /100 ml?
10 ml O2 /100 ml? Show how you calculated this.
- What is the significance of Figure 24.7? Why does the curve for myoglobin have a hyperbolic shape and the curve for hemoglobin a sigmoid shape? Why is
the curve for myoglobin to the left of the curve for hemoglobin? What is the physiological significance of this for oxygen transport?
- Discuss the interaction between hemoglobin and myoglobin. Illustrate your answer with a graph (e.g., Fig 24.7) showing oxygen dissociation. Use actual
numbers from the graph to show how it works.
- What is P50, and how is it related to the oxygen affinity of a respiratory pigment?
- Draw a hemoglobin-oxygen dissociation curve. What label should be given along the X-axis; the Y-axis? Circle the region of the graph that would be
representative of the conditions in a mammalian alveolus of a lung; in a tissue capillary bed. What is the P50 for your graph?
- From a single oxygen-hemoglobin (i.e., no Bohr effect) dissociation curve, be able to determine and/or explain what the saturation will be for a given
oxygen pressure; the oxygen pressure for a given saturation; the P50; the oxygen pressure and saturation in the respiratory organs; the oxygen pressure
and saturation in the deep tissues; the change in oxygen pressure and saturation going from the respiratory organs to the deep tissues; and the
change in oxygen pressure and saturation going from deep tissues to the respiratory organs.
- What is the Bohr Effect?
- Explain why higher temperatures tend to shift the Hb-O2 dissociation curve to the right.
- How does blood pH influence the Hb-O2 dissociation curve?
- Draw a single oxygen-hemoglobin (i.e., no Bohr effect) dissociation curve for a mammal with correctly labeled X and Y axes (e.g., a figure similar to
Fig. 24.5). Blood leaving the lungs carries 20 ml O2 / 100 ml. From this curve, calculate the amount of oxygen that 100 ml of blood will unload to the
respiring tissue. Show your work or no credit. Now do same for a graph showing the Bohr Effect (i.e., with two oxygen dissociation curves, (Fig. 24.10).
- Fully explain a figure showing the Bohr Effect (e.g., Fig. 24.10). Include information about what each of the two curves represent, what causes them to
differ from each other, what is the advantage of each, and give an example of where each of the two is operating. Discuss an actual example with approximate
real values of saturation %'s and oxygen pressures to demonstrate the adaptive advantage of this system.
- Examine and be sure you understand the graph Figure 24.10. Explain in words what is shown on the y-axis. What is shown on the x-axis? Discuss what
each of the two curves represent, what causes them to differ from each other, what is the advantage of each, and give an example of where each of the two is
operating. Discuss an actual example with approximate real values of saturation %'s and oxygen pressures to demonstrate the adaptive advantage of
Figs. 24.11 shows hemoglobin saturation curves for pH and CO2
partial pressures. What causes these different pH
and CO2 values. What is the advantage of
the curves shifting to the left or right (see ig. 24.12)?
- Figs. 24.14 shows hemoglobin saturation curves for various
What is the advantage of the curves shifting to the left or
right ? Would you expect to see all of these curves in a
- How does DPG affect the P50 of the blood (e.g. Fig.24.15 and 24.16)? What is the biochemical mechanism?
- How and why do humans at high elevations change their DPG levels?
- How and why do humans with anemia change their DPG levels?
- What is the difference between adult and fetal hemoglobin?
Why is this advantageous?
- Fig. 24.20 shows what happens to the hemoglobin when water
fleas are transferred to low
O2 water. Explain what kind of physiological
changes (acute, chronic, and/or evolutionary) have occurred?
What physiological advantages do these changes cause?
- Discuss how and where carbon dioxide is transported in the blood.
- What are the chemical reactions that allow increased ability of the blood to transport higher amounts of carbon dioxide at higher partial pressures (Fig
- Explain what is being shown in Figure 24.22a, i.e. the Haldane Effect.
- Explain Fig. 24.22b. What is the physiological significance of the Haldane Effect for humans who are exercising?
- What is the role of carbonic anhydrase in the deep tissues? In the lungs?
- Why is the enzyme carbonic anhydrase so critical for respiratory exchange in the circulatory system?
- What is the role of
- Define, explain the importance to respiratory physiology, and give an example of the following
- Respiratory pigment
- Bohr Effect
- DPG (bisphosphoglycerate)
- Haldane effect
- Carbonic anhydrase
CHAPTER 25 Circulation
- What functions does the
circulatory system perform?
- Know the path of
circulation from the veins through the heart to the arteries. Be able to
label all the features shown in Fig. 25.1.
- What is occurring during
systole? During diastole?
- How and why does ventricular pressure differ on the left and right sides of the heart?
- Explain what is occurring during the five phases of the heart cycle shown in Figure 25.2.
- Atriole systole
- Isovolumetric contraction
- Ventricular ejection
- Isovolumetric relaxation
- Ventricular filling
- How do atriole systole and ventricular relaxation add to the end diastolic volume? Which is more important?
- At what stage do the atrio-ventricular valves close? What causes this?
- At what stage do the atrio-ventricular valves open? What causes this?
- At what stage do the pulmonary and aortic valves close? What causes this?
- At what stage do the pulmonary and aortic valves open? What causes this?
- Why isn't blood ejected during isovolumetric contraction?
- You should know that Cardiac output = (Heart Rate)*(Stroke Volume)
- If a normal cardiac output is 6 liters/minute (when the person is at rest), use your resting
heart rate to find out the stroke volume.
- From the blood capacity,beat volume, and pulse rate, be able to determine the amount of oxygen being
transported by the circulatory system. For example, use the capacity = 20 ml O2 / 100 ml blood, pulse rate = 60 beats per minute, and the stroke
volume = 70 ml
- What causes the heart sounds heard with a stethoscope?
- What happens when heart muscles depolarize? Repolarize?
- How is heartbeat regulated in mammals?
- What is the pacemaker? How does it control heart rate?
- Why to the ventricles contract after the atria?
- Briefly discuss the processes occurring during the wave of depolarization of the contraction cycle of the heart (Fig. 25.4b).
- Explain what is shown in the electrocardiogram of a normal human heart (Fig. 25.6).
- What does the P wave signify? The QRS complex? The T wave?
- What is the Frank-Starling Law of the heart? What is its significance?
- How do positional effects affect blood pressure (Figure 25.7)?
- Discuss and explain blood pressure at your feet, heart, and head when you are standing up and when you are lying down.
- Compare and contrast blood pressure in a human and a giraffe.
- What animal phyla lack circulatory systems? How do they respire?
- Compare and contrast an open and closed circulatory system.
- Compare and contrast arteries, veins, and capillaries. ?
- Illustrate and describe the circulatory system of a typical bird or mammal (Fig. 25.10).
- Illustrate and describe the general path of flow of blood through the circulatory system of a mammal.
- How does the heart of a bird or a mammal differ from that of a typical reptile? What are the
advantages of this arrangement?
- How does cross sectional area affect flow rate?
- Discuss and explain the changes in cross-sectional area from the arteries to the capillaries to the veins (Figure 25.12a).
- Why does blood pressure decrease from the arteries to the capillaries? Explain Figure 25.12b.
- Discuss and illustrate what happens as blood flows through capillaries (Fig. 25.13).
- Explain the roles of hydrostatic pressure and osmomotic in the capillaries (Fig. 25.13).
- What happens to hydrostatic pressure as blood flows through the capillaries. What cause the changes?
- What happens to osmotic pressure as blood flows through the capillaries. What cause the changes?
- What happens to excess fluid that leaves the capillaries and remains in the interstitial fluids?
- What is the blood pressure in the venous system? What two mechanisms move blood pressure back to the heart?
- How does the circulatory system of cephalopods differ from that of other mollusks? Why?
- Illustrate and describe the anatomical arrangement of the heart of a teleost fish or shark (e.g., Fig. 25.14).
- Illustrate and describe the circulatory system of a teleost fish (e.g., Fig. 25.14). Discuss the
oxygen and blood pressure changes that occur in the circuit. How is blood pumped to complete the circuit?
- Describe the basic anatomy and pattern of blood flow of the amphibian heart. How does it differ from the fish heart?
- Does deoxygenated and oxygenated blood mix together in the undivided ventricle of amphibians? Why?
- Compare and contrast a typical reptilian heart and the heart of a mammal (or bird). Explain the
significance of the differences.
Define, explain the importance to the physiology of circulation, and give an example of the following
- Cardiac cycle
- Isovolumetric contraction
- Ventricular ejection
- Cardiac output
- Stroke volume
- Heart murmur
- Sinoatrial node
- Atrioventricular node
- Starling's Law of the Heart
- Interstitial fluid
- Closed circulatory system.
- Open circulatory system.
- Pulmonary circulation
- Systemic circulation
- Colloidal osmotic pressure of the capillaries
- Hydrostatic pressure of the capillaries
- Lymphatic system
CHAPTER 25 Diving Mammals
- Which tissues need the most energy during diving?
- Which tissues need the most O2 ?
- Compare the blood oxygen stores of terrestrial and marine mammals. How do they differ in carrying capacity? Blood volume?
- Compare and discuss the reasons for the different total as well as the individual lung, blood, and myoglobin oxygen stores of humans, shallow diving mammals, and deep diving mammals. (see Figure 25.6)
- How is oxygen supply maximized in diving mammals? Where is it stored?
- Compare oxygen storage in a marine mammal and a human.
- Outline the pros and cons of carrying lots of air during a dive.
- How does the circulatory system respond to extended dives by whales and seals?
- How does the pattern of circulation pattern in a marine mammal during a deep dive? Why?
- How can the muscles of marine mammals function if there is no oxygen available for them to contract?
- Why is it important to reduce the heart rate during a dive?
- What is produced by anaerobic metabolism in animals? What potential problems does this cause? How is this minimized?
- Discuss oxygen levels in the blood and muscles during the course of a deep dive (Fig. 25.10a)
- Discuss lactic acid levels in the blood and muscles during the course of a deep dive (Fig. 25.10b)
- Discuss what is happening to lactic acid levels in the blood following a deep dive (Fig. 25.11
- Based on the study of O2 needs and stores, the aerobic dive limit of young Weddell seals weighing 140 kg is calculated to be 10 minutes,
whereas that for a fully grown 400-kg Weddell seal is calculated to be about 20 minutes. Why might small individuals in general be expected to have shorter
aerobic dive limits than large individuals?
- What is decompression sickness (the "bends" ?)
- Why is only nitrogen and not carbon dioxide or oxygen that divers have to worry about when breathing compressed air?
- Why do humans get the bends and how does the Weddell Seal avoid the problem?
- Why aren't deep diving marine mammals affected by nitrogen narcosis?
Define, explain the importance to the physiology of diving mammals, and give an example of the following
- Carrying capacity
- Total blood stores of oxygen
- Diving response
- Peripheral vasoconstriction
- Oxygen debt
- Aerobic dive limit
- Decompression sickness or the �bends�
- Nitrogen narcosis
- Oxygen toxicity
CHAPTER 26: OSMOREGULATION and EXCRETION
- What is the difference between interstitial and intracellular fluid? Why are they usually different?
- How are ionoregulation and osmoregulation similar?
- What is the difference between ionoregulation and osmoregulation?
- What are the benefits of ionoregulation and osmoregulation?
- What are the costs of ionoregulation and osmoregulation?
- Discuss what is being shown in Figs 26.3a and 26.3b in regard to osmoregulation and osmoconformity.
- In figure 26.3c, how are the green crab, mussel, and shrimp responding to changes in salinity.
- Why are there no freshwater osmoconformers?
- Compare and contrast the advantages and disadvantages of being an osmoconformer versus an osmoregulator.
- What are the three sources of water for animals?
- What is the disadvantage of drinking salty water?
- How do kangaroo rats survive without having to drink water?
Define, explain the importance to animal physiology, and give an example of the following
- Isosmotic animal
- Hyperosmotic animal
- Drinking water
- Dietary water
- Metabolic water
Chapter 27 Water and Salt Physiology
- Fig 27.1 shows water-salt relations in a freshwater animal. Be able to label and discuss the major
sources of movement of salts and water in and out of the organism and the mechanisms (diffusion, etc.) responsible.
- Fig 27.7a shows water-salt relations in a freshwater bony fish. Be able to label and discuss
the major sources of movement of salts and water in and out of the organism and the mechanisms (diffusion, etc.) responsible.
- Fig 27.7b shows water-salt relations in a marine bony fish. Be able to label and discuss the
major sources of movement of salts and water in and out of the organism and the mechanisms (diffusion, etc.) responsible. .
- Fig 27.9 shows wate-salt relations in a marine shark. Be able to label and discuss the major sources
of movement of salts and water in and out of the organism and the mechanisms (diffusion, etc.) responsible.
- What are the main osmotic and ionic challenges of freshwater teleosts (advanced bony fish) and how are
these challenges met?
- What is the role of the integument in osmoregulation?
- What osmoregulatory problems do most marine vertebrates face?
- What are the main osmotic and ionic challenges of marine teleosts and how are these challenges met?
- How do hagfish osmoregulate?
- Discuss osmoregulation in the life cycle of sea lampreys.
- How do sharks (elasmobranchs) avoid water loss in salt water?
- How do marine sharks (elasmobranchs) regulate water and salt?
- Explain how Latimeria (the coelacanth) and marine elasmobranchs solve the osmotic problem of a
vertebrate in sea water and why their bodies are slightly hyperosmotic
- Describe osmoregulation in marine elasmobranchs. How are urea and TMAO important to this process?
- Review the strategies for salt and water balance in aquatic animals that live in-between fresh water and
the marine environment. What is a hyper-isosmotic regulator; a hyper-hyposmotic regulator?
- Why is a teleost fish in the ocean like a desert animal?
- Explain osmotic and ion (salt) regulation in marine and fresh water teleosts.
- Explain how the salmon is able to osmotically move between fresh water and sea water.
- Explain osmotic and ion (salt) regulation in fresh-water amphibians.
- Compare and contrast the osmoregulatory strategies used by, marine invertebrates, marine teleosts and
freshwater teleosts. For each you must mention the relative osmolarity of their body fluids to that of the environment in which they live.
- Cite the greatest advantage and disadvantage of terrestrial life.
- Why do amphibians face greater osmotic regulation problems than other terrestrial vertebrates? How
do some frogs and toads minimize this problem?
- List the various ways by which water is gained or lost in terrestrial animals.
- How do kangaroo rats maintain water balance? How are they able to survive in hot dry deserts?
- Identify how marine reptiles and birds regulate their salt balance.
Define, explain the importance to animal physiology, and give an example of the following
- hyperosmotic regulator
- hyposmotic regulator
- Chloride cells
- Salt glands
- Rectal gland
Chapter 28 Excretion
- What are the six main functions of the kidney in maintaining homeostasis?
- Draw and label a mammalian nephron. For each division you label, indicate what goes on there in the formation of urine.
- Describe the function of Bowman's capsule, proximal convoluted tubule, distal convoluted tubule, loop
of Henle, and the collecting duct of a nephron.
- What is the advantage of ultrafiltration? How does it work?
- What is 'primary urine', and how does it differ from urine that is eliminated from the body.
- How is the pH of the blood regulated by nephrons?
- The two main mechanisms in urine formation are ultrafiltration and active pumping. Describe what is
meant by each term, and how each contributes to urine formation. What are the main factors that influence the functioning of each mechanism?
- How is the osmotic gradient in the kidney produced?
- How is the osmotic gradient of the kidney used to produce hyperosmotic urine.
- Explain how the different properties of the ascending and descending Loop of Henle are important for urine formation.
- How does the structure of the kidney and its nephrons differ in mammals that live in aquatic, mesic, and arid habitats?
- What is the vasa recta? What is its role in urine formation?
- Why is inulin used to measure the glomerular filtration rate. Give an example of how it works.
- What is the glomerular filtration rate when urine production is 0.5 l/hr and the inulin concentration
in the urine is 25 times that of the blood?
- What is renal clearance? What are the expected values for substances that are filtered only? Filtered
and resorbed? Filtered and secreted?
- What is the tubular resorption maximum? What happens when it is exceded?
- The normal GFR is 125 ml/min and the normal concentration of blood glucose is 1 mg/ml.
- How many mg/min of glucose are reabsorbed by the kidneys by a person with these values, if there is no glucose in the urine?
- The kidney can reabsorb a maximum of 375 mg/ml of glucose. What would the blood glucose level (in
mg/ml) have to exceed before glucose is excreted in the urine?
- Why wouldn't a normal person be expected to excrete glucose, even after eating a sugar-rich meal?
- Renal Function
- Calculate the GFR in L/hr from the following values
- [Inulin] in urine: 2.0 mg/L
- [Inulin] in Plasma: 0.02 mg/L
- Urine Output: 50 ml/hr
- For the same individual, calculate the apparent GFR based on urea
- [urea] in urine: 55.0 mg/L
- [urea] in Plasma: 0.5 mg/L
- Urine Output: 50 ml/hr
- Is there a net secretion or reabsorption of Urea in the renal tubules? What is the amount in mg/L?
- Describe how ADH can regulate water retention/loss.
- How does ADH (antidiuretic hormone) regulate urine osmolarity and volume?
- What is the role of ADH (AntiDiuretic Hormone) in regulating urine volume and osmolarity in the mammalian kidney?
- How do alcohol and caffeine affect urine production?
- What are the three most common nitrogenous end products found in animals? What are their advantages
and the disadvantages with the major three? Discuss waste of organic carbon, energy loss, water loss, toxicity and water solubility.
- Compare and contrast the three main methods of excreting nitrogenous wastes in animals in terms of water conservation.
- Why do aquatic organisms that are capable of at least a transient terrestrial existence accumulate
urea, instead of ammonia, when on land? What is the advantage of switching between ammonia and urea excretion?
- Which major groups of animals excrete uric acid? What are the two major evolutionary advantages for
them in excreting uric acid?
- Aquatic birds such as ducks excrete uric acid even though they almost always are near a source of drinking water. Why?
- Discuss the processes and locations involved in water and salt regulation in insects.
- If insect Malpighian tubules do not use ultrafiltration, how then do they produce excreta?
- Insects excrete nitrogenous wastes from protein metabolism primarily as solid uric acid. How do they produce this solid?
Define, explain the importance to excretion, and give an example (where appropriate) of the following
- Uric acid
- Renal cortex
- Renal medulla
- Bowman�s capsule
- Proximal convoluted tubule
- Loop of Henle
- Distal convoluted tubule
- Collecting duct
- Hydrostatic pressure
- Primary urine
- Osmotic pressure
- Vasa recta
- active secretion
- active reabsorption
- Glomerular Filtration Rate.
- Renal clearance
- Tubular maximum
- Antidiuretic hormone
- Malpighian tubule
Chapter 29 Desert Mammals
- Why is it more difficult for small animals to remain cool under hot desert conditions?
- Explain what is illustrated in HWA Fig. 29.1 regarding body mass and evaporation for the upper line (walking animals).
- Explain the advantage of being large in a hot environment. I.e., explain the
importance of large body size large in a hot environment.
- Compare water gains and losses in a water-dependent versus a water-independent large desert mammal (Fig. 29.6).
- Why do many large desert herbivores do most of their feeding around dawn rather than other times of the day?
- What are the main advantages of the high amplitude cycles of body temperatures in oryxes during the summer (Figure 29.11a)?
- Why do camels have higher amplitude daily body temperature cycles when water is not available?
- Why do camels have lower amplitude daily body temperature cycles when water is available?
- What is the most important reason that camels can lose more body water than humans?
- Compare and contrast adaptations for surviving in hot dry climates in small desert mammals such as kangaroo rats and large water independent desert
mammals such as Oryx.