Chapter 10 - Temperature Adaption and Regulation
Terms in this set (161)
Describe Warm-blooded Vs. Cold blooded.
-Birds and mammals typically maintain their body temperature above that of the environment, and have been called warm blooded (Tb>Ta)
Why are "Cold-Blooded" and "Warm-Blooded" terms incorrect?
-Cold blooded animals can have a higher Tb than a mammal
-Some mammals and birds allow Tb to decline to near freezing (i.e. hibernation)
-Greek for changeable or variable
-Assumed to be cold-blooded; body temperature fluctuates with surroundings (variable Tb)
-Most become more and more inactive as temperature drops
-amphibians, reptiles, fish
-Greek for different
-Refers to animals that at times have high and regulated body temperature, but are like cold-blooded animals at other times (e.g. hibernators; Tb can decline)
-Greek for like or similar
-Usually maintain a high body temperature and remain active in low and high Ta
-Maintain body temperature PHYSIOLOGICALLY, not just by behavior
-E.g. birds and mammals
What are the terms endothermy and ectothermy used for?
-Used to distinguish between birds and mammals that maintain their body temperature by metabolic heat production and animals such as lizards that can maintain high body temperatures just by basking in the sun
maintain high body temperature by internal heat production
-Depend on external heat source for heat production (primarily solar radiation)
-thermal conditions outside the body determine the Tb (metabolic heat production insignificant)
What would call an organism that produces its own heat and has a constant body temperature via physiological process?
What would call an organism that does not produce its own heat and has a constant body temperature via physiological process?
What would call an organism that does not produce its own heat and does not have a constant body temperature via physiological process?
What would call an organism that produces its own heat and does not have constant body temperature via physiological process?
What are the mechanisms for heat exchange?
Direct transfer of heat between two solid material in physical contact
-heat flows from regions of high to low temperatures
What is the equation for heat production?
Q = kA (delta T/L)
Q=rate of heat exhcange
A=Area in contact for conduction (SA)
T=difference in temperatures
L=distance between two temperatures
When does rate of heat exchange via conduction increase or decrease?
-Increases with increasing thermoconductivity and surface area and differences in temperature
-Decreases with increase distance of two temperatures
Relate Ficks law and physiological process of diffusion to rate of heat exchange and physiological processes for conduction.
What is thermal conductivity?
-Expression for how easily heat flows in a material
-Most animal thermal conductivity values are similar to air (low conductivity due to still air trapped in insulating materials)
-prevents excessive heat loss due to low conductivity of air
What is insulation?
The recipricol of thermal conductivity
-resistance to heat flow
What effects insulation?
1) Pelage or plumage thickness
2) Body size
3) Immersion in water
How does pelage or plumage effect insulation?
e.g. insulating values of fur or feather increases with thickness of material
-Increases the L value (distance of body surface and environment) kind of like in ficks law with increase in distance for diffusion
How does body size effect insulation?
-Larger animal tend to have higher insulation value partially because they are able to produce more hair and still remain mobile
-also related to lower surface area to volume ratio
do smaller animals ALWAYS have lower insulation values?
No, small mammals have fur with higher insulation value per unit mass than larger mammals
How does immersion in water effect insulation? what are the 3 reasons it has this effect?
-Lowers insulating value in water
1) Water has thigher thermoconductivity than air
2) Fur compressed to lower thickness values
3) Fur cannot be pilorected (held upright) to maintain insulating air space
What is convection?
-Transfer of heat by movement of a fluid (air, water)
What is the equation of convection?
Q = Hc(Ts-Ta)
where Hc=convection coeffcient, which depends on wind speed, shapes of body part and orientation in the wind
T=difference between surface and ambient temperature
What is the convection coefficient proportional to?
Is proportional to (srtV)(sqrtD)
where V=wind speed and D= diameter of cylindrical body part (legs, torso)
What are the 2 types of convection?
-caused by temperature differences (heat waves)
-Caused by external forces such as wind currents (flowing over surface)
What is radiation?
All physical objects emit electromagnetic radiation
What is the stefan-boltzman equation?
-Intensity of radiation
Hr = T^4
What does intensity of radiation emitted by an object dependent on?
-Intensity of radiation emitted by an object (across all wavelengths) depends on the surface temperature, proportional to the fourth power of absolute temperature
-much more radiation is emitted from a body if surface temp is very high
What is net radiative heat exchange?
-Animals not only emit, but they also adsorb thermal radiation from their environment
-if Ta>Ts radiation may be from the environment to the organism
-Usually tends to be opposite we actually have a lower ambient temperature
How can cold stress be avoided?
Cold stress can be avoided by burrowing into snow: snow is a barrier to radiant heat exchange because a lot of air space in the snow (doesn't transmit very well)
Describe how a bird loses net radiative heat.
- A bird (15 degrees) loses heat in NET fashion to tree trunks (-10 degrees) by
thermal radiation as it flies past them on a cold winter night
-The bird also loses heat in net fashion to the night sky (-40 degrees). More than half
of a bird's total heat loss may be by thermal-radiation heat transfer
Evaporation of water dissipates considerable heat
-To transfer 1hg of water wapor at room temp requires 584
-can be a very good cooling mechanisms
Describe how evaporation can be used for cooling (2)?
-even if an animal is not heat stressed, there is considerable evaporation of water from the respiratory tract, and also passive diffusion of water vapour from the skin
Aquative vs. terrestrial thermoregulation?
differnt energy balance (no evaporation or radiation in aquatic limited to increasing temperature of minimizing conductive heat loss)
compare aaqutic poikilotherm to terrestrial poikilotherm.
1) Aquatic poikiliotherm generally has Tb = Ta
2) In contrast terrestrial poikilotherms can use therm radiation heat transfer or evaporation to change Tb relative Ta
What are the types of temperature regulation in ectotherms?
1) Behavioural adaptions
2) Use of conduction
3) Muscular heat production
4) Eccritic temperature
What are types of behavioural thermoregulation?
1) Use of solar radiation
Describe use of colour.
-A dark skin surface substantially increases amount of solar energy adsorbed (melanophores can contract or expands)
- Iridophores reflect radiation
-Melanophore stimulating hormone released (pituitary) in response to stress or thermorecpetors
Describe use of posture.
-Orienting the body at right angles to the sun's rays and flattening the body increase surface area also allows organisms to attain temperatures much higher than ambient
Describe behavioral thermoregulation in lizards. (comparison between lizard model temperatures and actual lizard temperatures)
The distribution of the body temperature of the real lizards is far less variable than the distribution of the temperatures of inanimate lizard model.
-Result of behavioral thermoregulation
-Ectotherms that adsorb heat by basking in sunlight
- Direct transfer of thermal energy from sunlight to the body
- Peruvian lizard living at high elevation and has low temp in the morning to the point that early on in the day to the point where their body temp is 3x the air temperature
Describe what uses conduction.
What are thigotherms?
-Ectotherms that adsorb heat from substrate (e.g. sun-heated rocks)
- Not directly adsorbing solar heat, get heat from a substrate
- Alligator lizards, skinks
Describe muscular heat production
-Random uncoordinated contractions of muscles to convert ATP-bond energy to heat (shivering thermogensis)
-Brooding pythons use this mechanism to brood their clutch of eggs
Describe Eccritic temperature.
-Preferred body temperature
-changes posture to maintain preferred Tb one reached (lizard)
-always a reason why eccritic temp is kept
How do organisms stay at eccritic temp?
adjusting rates of heating and cooling
Describe adjusting rates of heating and cooling.
-Rate of heating twice as fast as rate of cooling
-rates in water are higher than in air (higher conductance in water)
Describe marine iguana eccritic temp.
- Galapagos marine iguana: feeds in water 22-27 degrees (below eccritic temp)
- Basks on rocks to warm itself in sun
Heating rate 2x cooling
Rates in water > air
Maximize rate of heating and minimize rate of cooling through cardiac changes. Have a circulatory response by reducing heart rate during cooling period. Heating happens faster than cooling due to cardiac response
What are the two types of ectotherms?
BOTH: not metabolic energy expended
What are Eurytherms?
-Wide temperature; essentially do not thermoregulate
What are stenotherms?
Narrow temperature;regulate Tb within a narrow range using heliothermy or thigmothermy
What is the eurythermal advantage?
-Not metabolic energy or time expended on thermoregulation
BUT: enzyme function, digestion, growth, action potentials may be compromised
What is the stenothermal advantage?
-Relatively precise thermoregulation without metabolic costs
-metabolic rate 1/10 of endotherm
BUT: acitvity limited daily and seasonally
What are temperature limits to life in ectotherms?
-some organisms can operate within a wide range of temperatures others only in a very narrow range
-can change with time; depends on duration of exposure
-temperature of organisms in relation to Ta
What are the 2 temperature limits to life?
1) Tolerance to heat
2) Tolerance to cold
Describe tolerance to heat.
-No active vertebrates known to carry out life above 50 degrees
ice fish have a lower limit
-desert iguana almost 50
Describe the alpine Pika.
Pika live in alpine environments above the treelines, they have a limited ability to tolerate high temperatures. The problem is with climate change species ranges are moving up in elevation moving to accommodate changes in temperatures ~ exceeding thermal tolerance with nowhere to go so losing species. Disperse by getting down to lower valleys by going down into the valleys???? Maybe do it at night or cooler seasons?
What can happen if tolerance to heat is surpassed?
Heat damage and death
What are some of the things that cause heat damage and death (4)?
1) Denaturation of proteins
2) Thermal inactivation of enzymes
3) Inadequate oxygen supply
4) Temperature effects on membrane structure
Describe denaturation of proteins. what are mechanisms to prevent this?
-At high temperatures proteins can be denatures
- But heat shock proteins can help repair 3D structure ~ increase expression of stress proteins with increasing heat
Describe the thermal inactivation of enzymes.
-Effects substrate affinity
Describe inadequate oxygen supply.
-Especially in water breathers
-solubility of water decreases with increasing temperature
-Not just limited by these constraints (airated hot water fish will still. metabolic exhaustion?)
Describe temperature effects on membrane structure.
-Temperature affects interactions between phospholipids and functional proteins
Describe tolerance to cold.
-Species specific, toelrance varies
-e.g. tropical fish in aquaria die at 10 degrees
What are the types of cold tolerance.
1) Freeze tolerance
2) Freeze intolerance
Describe freeze tolerance.
-Animal can survive extensive freezing and ice formation in the body
-mostly freezing of the extracellular fluids (not within cells)
-Cell membranes can withstand puncture by ice crystals
-resistance to cellular desiccation
Describe the mechanisms organisms apply for freeze tolerance.
1) As ice forms outside of the cell, freezing of pure water results in osmosis from the cell to equilbriate the concentration of solutes between the inside and outside of the cell (causes the cell to shrink and desiccate)
2) Organic solutes (glucose, glycerol) enter intra and extracellular fluids to increase concentration of solute to equilibrate with solution w/o desiccation
3) Limits water loss from cells
4) Ice nucleating agents in extracellular fluid (proteins;lipoproteins) ~promoting ice formation outside the cell
What is freeze intolerance?
animal will die if there is any internal ice formation
What are the types of freeze tolerance (freeze susceptible)?
2) antifreeze compound
-A sample of pure water can be cooled far below 0 degrees without the formation of ice
-reptiles, amphibians, some benthic fish, arctic ground squirrels
What is supercooling not advantageous?
- Not an advantage if freezing actually occurs because don't have the ability to withstand any ice formation
What are antifreeze compounds?
solutes increase total solute concentration, low freezing point
How do organisms utilize antifreeze compounds?
- If ice occurs frequently in environment, can't rely on supercooling
- Increase solute concentration (glycoproteins; glycerol, NaCl, glucose)
- Lower freezing point
- Same idea as freeze tolerance, just don't promote ice formation
What are some examples of organisms using antifreeze compounds?
- Marine teleost at sea ice produce long chain glycoproteins in their liver; interferes with H bond formation
○ Tree frogs: body fluids contain 3% glycerol
What are the physiolocal responses of poikilotherms to their environments?
1) Q10 effect
2) thermal acclimation/acclimatization
3) Seasonal varation in temperature tolerance
4) Geographic temperature variation in temperature tolerance
describe the general idea of physiogical responses of poikilotherm to their environment.
-Increasing Tb accelerates most processes
-Hence metabolic rate increases with Ta and Tb
What is the Q10 effect?
-Temperature coeffcient; the increase in metabolic rate cause by a 10 degree increase in temperature
(if rate doubel, Q10=2)
What is the Q10 value for most pokilotherms? can their value increase indefinitely?
-Cannot increase indefinitely-will eventually level off
-Have a value between 2-3
What is acclimatization?
Compensation for temperature in the natural environment (e.g. temperature tolerance with climatic changes)
What is acclimation?
Temperature compensation under experimental conditions
What is compensation through accliamtion?
-Tendancy of metabolic rate to return to its orginal level following a change in Ta
Compare lizards that are acclimated at different temperatures.
Lizards acclimated to the cooler ambient temperature have a higher average metabolic rate at any given temperature than those acclimated to warmer ambient temperature
Describe compensation response during acclimation and response with sudden temperature change.
-In partial compensation, after a sudden drop in body temperature, the metabolic rate rises during acclimation but does not return to its original level
Describe a chronic response to temperature change in lizards.
-Because of accliamtion, the chronic metabolism-temperatur curve is relatively flat compared with acute metabolism-temperature curves.
Why does acclimation with a chronic response have a flat slope?
- Amounts of rate-limiting enzymes in electron transport, or numbers of mitochondria, are increased at lower temps. Because these response take time the initial response to follow the steeper line, then they follow the line of the chronic slope
What is seasonal variation in temperature tolerance?
- Often the range of thermal tolerance differences between summer and winter in the same species
- In the summer they have a higher high temp tolerance (higher lethal temperature)
- In the winter lower lethal temperatures
- Can affect geographic distributions of species
Describe geographic variation in temperature tolerance.
- Influences geographical distribution of related species
Describe temperature tolerance curves in ectotherms.
-Describe maximum range
- Since limits of temp tolerance modified by previous thermal history, how far can limit be pushed?
thermal history, how far can limit be pushed?
Total area within each section means a wider lethal temperature range across all acclimation temperatures
Describe rate of acclimation.
Compensation is due to thing like physiological/aerobic responses are what are driving these processes
-If you remove things like oxygen this will affect the rate of accliamtion for a period of time
Describe temperature regulation in endotherms.
-Endotherms attemps to regulate body temperature, typically within a narrow range, even though they exist from the arctic/antarctic to deserts
Describe body temperature in endotherms.
Generally fluctuates within 1-2degrees throughout the day
Describe interspecific variation in core temperatures.
considerable varaition between types of vertebrates, which is related to metabolic rate
Describe temperature distribution in the body's effects of body temperature.
-Also related to energy metabolism
-Also related to energy metabolism
-Heart, leung, kidneys and brain = 72% of heat production
the rest is in the skin and msucles
What is the thermoneutral zone?
-Metabolic rate remains constant through a range of temperatures for endotherms
- Range of temps over which metabolic rate remains maintains constant
- Metabolic heat must be lost at the same rate as it is produced
Describe the width and range of the TMZ. how are larger and smaller animals impacted?
Width and temperature range in TNZ vary across species.
Body SIZE: Larger animals have wider TNZ range
Arctic adapted vs tropical: tropical species have narrow TNZ
What is the lower critical zone?
-Metabolism increases below this temp to regulate Tb
What is the upper critical temperature?
-Metabolism increases above this temp to regulate Tb
What is metabolic conductance?
-Refers to the total heat flow from the organisms to the surroundings
Body core -> skin -> fur -> air
What is the equation for metabolic conductance?
M = C (Tb-Ta)
k= conductivity coeffcient
A= surface area
What types of adjustments can organisms make to effect metabolic conductance?
K=Alter blood flow through skin, change conductivity of fur
SA=Change by behavioural means
l=Change depth of fur by pilorection;increased thickness in winter
What is the slope of conductance?
-At temperatures below LCT, how much an animal must increase metabolism depends on conductance
What do different slopes mean?
Low slope means animal has high insulation and a low C
-Steep slope means animals have low insulation and high C
Compare the insulation of tropical vs. arctic species.
Tropical: high conductance and LCT 20-30 degrees
- must increase metabolism drastically for even small temperature drop
Arctic: Low conductance (high insulation) and much lower LCT. Rate of change/slope is much slower when you go below LCT compared to tropical
What are the 3 possible adaptions for surviving cold?
1) Decrease rate of heat loss
2) Increase rate of heat production
3) Abandon thermoregulation and allow body temperature to decline
What are the mechanisms to minimize thermal ocnductance/minimize heat loss(7)?
1) Body size
2) Postural adjustments
4)Use of external insulation
5) Insulation of fur/please/plumage
6) Peripheral or regional heterothermy
7) aquatic adaptions
What is the importance of body size?
-Larger animals have a lower mass specific thermal conductance (lower surface area to volume ratio)
-Larger animals have a lower LCT
-Bergmann's rule (Average body size tend to increase as you increase latitude)
Describe postural adjustments.
A sphere has a minimum surface area to volume ration
-mos energetically favorable shape
- When 2 bodies have same temp, no heat flow between them
- Also decreases exposed surface area
- e.g. bank boles at 4 degrees can reduce costs from 3.5 to 3.0kJ/g/d by huddling
Describe use of external insulation.
- e.g. nesting material
- Flying squirrels add lichens to nest
- Marten use coarse woody debris
Describe insulation of fur/pleage/plumage.
- After insulation to reduce conductance in winter
- e.g. bears in summer lose 52% of insulation value of winter fur
- Skin surface temp stays close to core temp
- **insulation on the outside of skin surface
Describe peripheral/regional heterothermy.
-High metabolic cost at low Ta
-Some endotherms allow temp of peripheral tissue to decline (e.g. skin and appendages)
-Heat low from appendages: High SA:V and poor isulation
What type of heat exchange is used with regional heterothermy?
Countercurrent heat exchange
Describe countercurrent heat exchange.
-Allows heat exchange between warm arterial blood and cold venous blood returning from extremities
When the arteries and veins are close together, allowing countercurrent heat exchange to occur,
some of the heat lost from the arterial blood enters the venous blood. The temperature of the venous blood thus rises as the blood travels toward the body
What is rete?
Countercurrent arrangement of arterial and venous capillaries
What about animals with countercurrent heat exchange (large animals) that live in low latituttidues?
- Are they going to overheat cause of inherited mechanisms (coutner-current hear exchange)
- Select lower temperature areas in the mountain (cooler temperature ranges higher in the mountain)
- Arterial vessels dilate and constrict surroundings veins
- Returning venous blood diverted through veins closer to skin
What are aquatic adaptions to cold stress? Low Tb? Increase metabolic rate? increase body insulation?
-Many seals and whales live in near-freezing waters near arctic and antarctic; they are much more numerous in cold waters than the tropics
-the temperatures are low and water has a high therm conductance
- Lower Tb? NOPE (Tb similar to other mammals)
- Increase metabolic rate? NOPE. Doesn't change
-Increase body insulation to reduce heat loss? YES. Blubber
-Thick enough that skin temperature is almost equal to water temperature
-Almost no heat lost to water from body core
What happens to an aquatic organisms with blubber when metabolic activity of water temperature increases?
- Can allow blood to flow through the blubber to external surface
- Bypass insulating layer (other mammals cannot do this)
- If water is warm or metabolic rate increases during fat swimming, seals and whales can bypass insulator and send blood to surface
What about appendages in aquatic endotherms that aren't insulated?
-Flippers and tail flukes lack blubber and are poorly insulated
-central arteries are surrounded by many veins (heat transferred from arteries to veins)
What are mechanisms for heat production in endotherms (2)?
2) Non-shivering thermogenesis
-Contraction of skeletal muscle to increase heat production
-uncoordinated and random muscle contractions
What are two types of NST?
1) Brown adipose tissue (BAT)
2) Specific dynamic effect
Describe brown fat.
-Specialized for metabolic heat production along neck and between shoulders in mammals
- Highly vascularized (using a lot of oxygen) and rich in mitochondria in neonates and hibernators. Hibernators increase and decrease brown fat amounts depending on season
-Heat released from mitochondrial electron-transport cycle that produces heat without ATP synthesis and breakdown
Describe specific dynamic effect.
-Important energetic way to produce heat without using expensive mechnisms like thermogenesis
-heat produced following ingestion of a meal
-Can reduce required shivering and NST
What is natural hypothermia?
-Some mammals and birds allow the core Tb to decline
-Animal is able to spontaneously arouse (rewarm) to its normal Tb using endogenous heat production (shivering or NST)
-While temperature is declining metabolic cost is declining
What are the types of natural hypothermia?
-Temperol heterothermy (short duration/part of the day)
-Pronounced natural hypothermia accompanied by decrease metabolism, respiratory rate, heart rate, and lack of motor coordination, with no response to external stimulation
- For arousal Brown fat as well as shivering is important
- Entry very rapid but rate determined by thermal conductance of animal
-Smaller animals enter torpor faster/arousal is faster as wel;
Why use torpor? what are the 3 stages of torpor?
-Use torpor because of energy saving and some water savings (animals in hot climates)
2) Period of torpor
What is critical body temperature?
-Affects ability to arouse from torpor
-Minimum critical Tb that will maintain, even if Ta drops below it
-Endogenous heat production increases to maintain Tb
-Not freezing point of tissues; reflects difficulty of arousing from torpor
-Minimum Tb below which arousal is not possible
-Long-term torpor, usually in response to winter cold and food deprivation
-Substantial drop in Tb
-Most hibernators are small with high metabolic rate that requires high food intakes BUT not all small animals are hibernaotrs
How are bear special hibernators?
-Moderate decrease in Tb -> arouse more readily because of this moderate decrease
-5-10 degree decline in temperature
-Heart rate drops to 8BPM
VO2 declines to 25% - weight specific metabolic rate is similar to other hibernators
What are arousal rhythms?
Body temperature fluctuates up and down; terminal arousal is the last of the season
-fluccuates between hibernation and arousal
Why is their arousal through hibernation(5)?
1) Energetic costs
2) Blood cleansing
3) Sleep patterns
4) Brain dendrites and synapses
5) Immune function
Describe energetic costs
- 80% of all energy used is for arousal
- Heat produced in brown fat
- Also major cost of torpor
Describe blood cleansing.
Describe sleep patterns.
- The animals don't go through REM sleep (deep sleep) they're going through low wave sleep which allows for decline in Tb
- Builds up sleep debt so they have to wake up to sleep
Describe brain dendrites and synapses.
- Lost during hypothermia
- Repite arousal would allow them to restore those connections and synapses in the brain
Describe Immune function.
- Restored during arousal
- Normal immune response is downregulated during hibernation. Arousal to restore immune function repeatedly during that process to clear out any pathogens
Spontaneous vs facultative hibernator?
1) Response to phtoperiod (day length)
2) Only when deprived of food and water
How is temperature regulated by endotherms in the heat (4)?
1) Dissipating extra heat
2) Body size importance
3) Brain temperature regulation
Describe temperature regulation in the heat for endotherms.
-At high temperatures, evaporation is the key item in heat balance
-evaporative heat loss increasses exopenetially with Ta
- If Ta = Tb there is no heat loss by conduction
- Solar radiation cannot be changed
Evaporation is the key variable
What are the means of dissipating excess heat (3)?
1) Cutaneous water loss
2) Respiratory water loss
3) Saliation, licking, urinating
Describe cutaneous water loss.
Mammals: sweating (humans, cattle, deer, camels; not all mammals have functional sweat glands)
Increasing evaporative heal loss
Describe respiratory water loss.
Mammals pant, birds use gular fluttering (rapidly flapping membrane in upper throat)
Relying of respiratory water loss (liquid water to water vapour through the respiratory tract)
Describe salivation, licking, urinating.
Spread saliva on fur or skin; lick limbs to cool by evaporation from surface; some birds urinate on legs (urohydrosis); seals urinate on hind flippers.
What are the advantages and disadvantages?
panting: provides own air flow over moist surface, so facilitates evaporation
○ Does not deplete electrolytes as sweating does
○ BUT: can alter pH of blood
Describe the importance of body size.
-Smaller animals have relatively larger surface area:volume ratios, so are more affected by heat gain
-Smaller animals must evaporate a proportionally larger amount of water to maintain constant body temperature
Describe brain temperature regulation?
-Hyperthermia may be an effective strategy for tolerating Ta and minimizing evaporative heat loss, but high Tb (>42 degrees) can comprimise brain function
-Brain temp usually regulated 2-3 degrees lower than Tb
What are the ways of brains temperature regulation?
1) Countercurrent heat exchange
3) Facial cooling
Describe countercurrent heat exhcnage.
- Carotid artery flows past sinus of venous blood from nasal passages
- Evaporative cooling in the nasal region (air coming in through nasal region is cooler) and arterial blood very warm
- Heat from arterial blood is dissipated into nasal mucousa before it goes to the brain
Describe the advantages of panting.
Cooling nasal blood even further
What is facial cooling?
- Cavernous sinus. Carotid artery wraps around the sinus and dissipates to the cavernous sinus before it heads to the brain
What is estivation?
-Torpid state induced by lack of food and/or water during high environmental tempratures
- Physiologically indistinguishable from torpor, except for higher Tb response
-Good for osmoregulation
What are the advantages of a relatively constant body temperature?
1) Increased rate of enzyme activity
2) increased force and velocity of muscle contraction
3) Optimal temperature for enzyme catalysis if body temperature is constant
4) Activity level independent of ambient temperature
What is the disadvantage to constant body temperature?
-High energy expenditure for thermoregulation during inactivity and at low air temperature
-greater fraction of energy spent on maintenance
Describe warm-blooded fish.
-Large streamline, fast-swimming preadtors (tunas, sharks)
-Temperatures in CERTAIN body regions exceed water temperature
-Want to increase temperature around swimmin axil muscles
Since fish lose heat quite readily in the gills how do they prevent this?
-Countercurrent heat exchange
-Rete mirabile (wonderful net)
-As venous blood flows outward, it loses heat to the closely positioned arterial blood, which carries heat inward again
What is a warm-blooded fish?
YOU MIGHT ALSO LIKE...
ASCP MLT/MLS Certification Exam (BOC) Preparation
Chapter 9 Animal Physiology
Animal Physiology Exam #2 Ch 10
OTHER SETS BY THIS CREATOR
Evolution and Life, Continental drift/plate tectonics
General Science Review - Basics of Matter, Chemistry
General Science Review - History/Methods, The Cosmos
Chemistry - Organic Compounds
THIS SET IS OFTEN IN FOLDERS WITH...
Chapter 22/23: Gas Exchange and Respiratory System
Chapter 24/25: Blood
Nutrition, Feeding and Digestion - Chapter 6