L4 Physiology Flashcards by Linz Betts

What are the main characteristics that are shared with non-mammals

Endothermy /Homeothermy
Sub-cutaneous fat
Circulation and respiration

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Endothermy/homeothermy characteristics

Maintain relatively
constant body
temperature (Tb)
• Energy sources within
body

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What is homeothermy

Different between endothermy because homeothermy doesnt require you to make your own internal body heat-(For example, poikilotherms and ectotherms could also be homeotherms) it is just simply the ability to maintain a consitant and stable body temperature.

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What are the purposes of subcataneous fat

Insulation and energy storage

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What is endothermy?

Ability to generate heat internally and maintain a stable body temperature

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What is ectothermy?

Body temperature as a result from outside sources; such as basking. (Relying on external sources for heat supply)

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What is a poikilotherm?

Where the internal temperature changes with the environment - very variable and opposite of homeothermy.

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What is diurnal?

operating through the day - opposite to nocturnal

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What are the pro’s of homeothermy?

Homeostasis
• Independence from
thermal regimes
– Diurnal
– Seasonal
– Geographical
• Continuous activity
– Physical
– Nutritional, Feeding
– Biochemical activity
• Enzymes
• O2
– CNS function-nervous system and information processing

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Cons of homeothermy

Hyperthermia
• Physiological damage
• Water loss
• Circulatory efficiency
• Structural damage
• Proteins, lipid membranes
Hypothermia
• Enzyme function
• Lipid membrane
• Cell damage (Freezing

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Whats the difference between hypothermia and hyperthermia?

Hyper-thermia - excessive heat

Hypothermia - too much heat loss

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About how much (%) of energy is spent on heat regulation?

80-90%

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VO2= C(Tb – Ta) -Explain

VO2 = Volume of oxygen used or metabolic cost
C= Conductance (How insulated you are/how you keep in heat - prevent the loss of heat)
Tb = Body temperature
Ta = Ambiet (outside) temperature

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What is the thermal neutral zone

An endotherms tolerable temperature range 36-38 degrees in eutherians (lower critical temperature and higher critical temperature)

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What does TNZ stand for

Thermal neutral zone

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Why are thermal neutral zones variable in mammals?

Difference in mass - larger animals require less energy to maintain heat. Smalller animals require more energy to maintain heat.

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What is basal metabolic rate?

BMR - state of homeostatis in regards to energy - minium required to exist. There is also a relationship between BMR and body mass.

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What is inertia

This tendency to resist changes in their state of motion

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Metatherian BMR tend to be what compared to eutheria?

Lower.

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What types of ‘vores are there?

Carnivore, Herbivore, omnivore, insectivore and foliovore

What is a foliovore?

Those which eat specifically leaves - sloth and koala

Which types usually have low metabolic rates?

Foliovores
– Soil/Litter omnivores
– Ant/termite specialists

Which types usually have high metabolic rates?

Small carnivores
– Shrews
– Aquatic carnivores (stoats/weasel etc)

What is Bergmanns Rule?

Theory that body size increases with latitude/temperature –> Surface area to volume ratio (larger animal tends to have a lower surface area to volume ratio which means conducatnace rate is lower (the rate at which heat is lost to the environment)).

Why is Bergmanns rule questioned?

Challenged as a rule – Reproductive rates – Rate of change insufficient

How would you go about conserving enegry by using the equation?

Minimise Tb – Ta | • Minimise C (Conductance) - be heterothermic --> regional or temporal

What is regional and temporal heterothermy

Regional --> different temperatures within the body. Temporal --> different temperatures at different times

usually, which parts of the body are can be regional heterothemic?>

Limbs/Tail/Nose/Ears – Vasoconstriction--> Beaver tail or dolphin fins with countercurrent heat exchange (there is still circulation but at a lower temperature)

What is vasoconstriction

the constriction of blood vessels, which increases blood pressure.

What animals use temporal heterothemy?

bats, dormice

What are the three types of variation in temporal heterothermy?

Daily torpor – Seasonal torpor – Profound hibernation

Torpor can occur daily and seasonal, t/f?

true

General characteristics of hibernation (NOT torpor) - such as dormice and marmot

``` Profound hibernation • Major drop in Tb • To ~1oC from Ta • Reduced oxygenation • Suspended respiration (apnoea) • Reduced heart rate • Arousal if Ta drops endogenous heat generation -adipose tissue/fat ```

What are the ways to generate heat?

``` Rapid arousal • Shivering • Non-shivering thermogenesis (NST) • Brown Adipose Tissue • Fat metabolism – 10x muscular heat product • High density mitochondria • Highly vascularised • Cold > Cell proliferation ```

Why do edible dormice and bears hibernate in caves?

stable temperature (thermal inertia)

What is hibernacula?

Where animals go/seek refuge ready for hibernation

in order to keep in heat, animals need to minimise the difference between what? (The equation)

Body temperature and ambient temperature (and vary conductance- on another slide)

what is piloerection?

Goosebumps- involuntary erection of hair follicles in response to cold triggers

how do animals keep insulated

piloerection, increase of thickness of hair through winter pelage hair, construction of hair effects insulation aswell (pronghorn) - hollow fibres with alot of air, fat layers (particulary in marine mammals).

The surface area : Volume ratio is bigger or smaller in smaller mammals than biggers mammals?

Bigger. larger animals have smaller surface area:volume ratio.

What is Allens rule?

Animals living in more extreme environments have smaller extremeties than animals living in stable environments (reducing heat loss)

What are the methods of evaporative cooling?

Sweating, spreading of saliva (fruit bats), urination, panting

what is a Xeric environment?

Dry environment

How do mammals source water in arid envrionments?

drinking and metabolic water(from digestion of food)

How do mammals conserve water?

``` Kidney function – Resorption, concentration • Gut function – Resorption from faeces • Lactation – Milk concentration-less water to young – Consumption of waste • Diet (higher water content) • Behaviour(exposure to heat) • Respiration – Water exchange ```

Metabolic water is a result of what?

aerobic metabolism

Which desert mammal relies entirely on metabolic water?

Kangaroo rat

How do camels tolerate heat?

``` Circadian variation • Thermal inertia – Late day ~ 40oC – Adaptive hyperthermia – Avoids evaporative cooling • Night=Rapid heat loss • Tolerate dehydration – Minimal blood volume loss – Interstitial, intracellular fluid • Reduce water loss – Nasal countercurrent – Urine concentration – Faecal dehydration ```