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Animal Physiology > Endothermy/ectothermy > Flashcards

Endothermy/ectothermy Flashcards

1
Q

Poikilothermy

A

Organisms that allow their internal temperature to fluctuate substantially

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2
Q

Homeothermy

A

Organisms that stay at the same temperature all the time

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3
Q

Most mammals can be considered to be ___________/____________

A

Endothermic homeotherms

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4
Q

Many marine and terrestrial invertebrates are ______/______

A

Ectothermic poikilotherns

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5
Q

What type of organisms are rare? Example?

A

Endothermic poikilotherms

Naked mole rats

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6
Q

Eurytherms

A

Can tolerate enormous range of temperatures, 20-30 degrees around normal

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7
Q

Stenotherms

A

Animals are intolerant of large temperature fluctuations

Eg Antarctic animals

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8
Q

Homeoviscous adaptation

A

Changing proportions of saturated/unsaturated fat composition of membranes in response to changes in temperature

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9
Q

Kleptothermy

A

Huddling to share heat

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10
Q

Mesothermy

A

An intermediate between ectothermy and endothermy

Currently thought to be used in dinosaurs which then led to endothermic birds

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11
Q

Uncoupling protein used in brown adipose tissue is?

A

Thermogenin

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12
Q

3 means by which heat is lost/gained

A

Conduction, convection, radiation (and evaporation)

Eg. Radiation from sun, conduction from heated rocks or volcanic vents

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13
Q

How does colour influence heat gain in pigeons?

A

Low wind speeds: black gain more than white

High: black tends to lose more heat

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14
Q

Thermal stability of water:

A

Aquatic organisms subject to colder, more stable temperatures

Size of marine environment buffers extreme heat increase and limited at lower end at water freezes (-1.8 for saltwater)

Greater range of temps in fresh water as tend to be shallower

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15
Q

Ectoderm cooling:

A

Tend to be passive and can be described by and exponential time constant

Hearing is usually slightly faster than this as there is an active component: pumping blood towards skin

Eg. Iguana basks in sun and pumps blood

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16
Q

Heat loss in water is due to:

In air due to:

A

Convection

Conduction

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17
Q

Relationship between heat loss and surface area in water:

Air:

A

Linear

Curved: smaller animals are more likely to lose heat through convection and larger through conduction

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18
Q

Draco and Anolis lizards

A

Draco and anolis (forest): thermoconformers

Anolis (sun) tend to have slightly higher than ambient body temperatures so must regulate temp in some way

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19
Q

The marine iguana is a:

A

Ectothermic homeotherm

Spend most of their time basking

Cool down when in water- limbs colder than body

Limits foraging time

Have to have small surface area to volume ratio so don’t cool down too quickly

20
Q

Many ectotherms undergo daily cycles

A

That roughly follow the cycles of ambient temperature

Eg. Monitor lizard: long periods of stable temperature, cools down at night but heat up towards morning. Fluctuation in ambient temperature which is lower than body temp means temp is regulated

21
Q

Ectotherms sometimes move positions to adjust temp to preferred level eg

A

Desert iguana in lab preferred temperature set up

22
Q

Behavioural fever

A

Deliberately move into hot temperatures to induce fever

23
Q

Monkey tree frog

A

Epidermal wax melts above 38 degrees so they can stabilise their temp using mucous glands

Wax prevents water loss but when it melts at high temp allow evaporative cooling

But lose lots of water and can’t always cool- often die in il nino

Wax distasteful to predators

24
Q

Zone of resistance

A

Area in which animal can survive very high temperatures for short periods of time

25
Q

Enzyme activity

A

Can be adapted to temp

Homologous proteins vary in enzymatic activity at diff temps but the same when in animals normal temperature

26
Q

Can express different _________ of enzymes eg _______________

On long timescales, may be expressed both temp isoforms at intermediate temp

A

Isoforms
Acetylcholinesterase

Don’t always express more active “winter” isoform due to symmorphosis, too much energy, waste products may be toxic

27
Q

Artic, sub arctic or northern temperate ____________(fish) use:

A 
Teleost
Glycoproteins or polypeptide antifreezes to suppress growth of crystals in tissues effective at low concentrations 
typically v potent 
Operate in small temp range 
Other fish supercool body fluids
28
Q

Brown adipose tissue contains

A

Many mitochondria for uncoupling to produce substantial heat increase

29
Q

Some animals keep their temperature _______ when ________ but let it _________ for the rest of the year. Some small __________ and ________ let their temperature __________ in the night but ________ in the day

A 
Constant
Mating
Fluctuate
Mammals
Birds 
Drop
Regulate
30
Q

How is endothermy characterised?

A

Temperature at which metabolic rate is stable and temperatures where it increases dramatically

31
Q

Describe the characteristic j-shaped curve of endothermy

A

Preferred temperature (thermoneutral zone): flat line as metabolic rate is stable

Above/below: metabolic rate increases to allow work to maintain temperature

Upper critical limit: above thermoneutral zone

Lower critical limit: below thermoneutal zone- slope of this is the animals conductance

Arctic species has large thermoneutral zones and shallow slopes as low conductance (due to fat/fur)

32
Q

Thermal adaptations

A 
Modify behaviour 
Vascoconstrict/dilate 
Shivering/non-shivering thermogenesis 
Swear
Uncoupling protein
33
Q

Insects

A

Can shiver by uncoupling flight muscles and wings

34
Q

Birds

A

Contract feathers to trap more air and reduce conductance

35
Q

Why do marine mammals invest more in blubber?

A

Fur would reduce hydrodynamic shape

36
Q

Evaporative cooling

A

Cost of substantial water loss when panting/sweating

37
Q

Gula flutter

A

Rapid movements of buccal area whilst increasing blood flow to improve evaporative cooling

Birds can also pant

38
Q

Dromedary

A

Dehydrated: stares a lot of ambient heat, loses more water through evaporation but not enough to combat extreme heat

Hydrated: huge amounts of evaporation offset heat gain from environment, body temp fluctuates less

39
Q

Kangaroo rat

A

Temporal countercurrent exchanger in nose

Reclaims water in exhaled air but cooling the air with fresh, inhaled air

Condenses on nasal wall

40
Q

Directing blood

A

Shunts and countercurrent exchange

Eg. Penguins have a counter current exchange system in which cold blood coming up from the feet is warmed by fresh blood moving into the feet. Stop heat loss from feet in contact with ice

Carotid rete in dogs: counter current exchange so hot blood doesn’t go into brain

41
Q

Diurnal cycles

A

Willow tit: turns off metabolic heat at night to save energy, rises in anticipation of morning

42
Q

Short term heat evasion:

A

Hiding (jerboa)
Wallowing (hippos)

Kleptothermy (mountain goats/sheep, penguins, bees)

43
Q

Opah

A

Moon/teleost fish

First truly endothermic fish (tuna can generate heat but only when contracting muscles)

Has large heart, large amount of muscle and blood through whole body- not expected for its cold environment

Heat from constant/quick flapping of pectoral fin

Elaborate insulated rete allows the blood to be warmed by flapping- blood leaving hills warmed, out is cooled

Full arch surrounded by white adipose tissue

Countercurrent

Don’t need to come to surface for warmth or to gulp (completely separate swim bladder)

Operates at deep, cold waters with high nutrient content

44
Q

Evolution

A

Thermogenesis may have evolved to maintain temp during incubation/development to maximise growth (not crocs- sex determination)

Ancestrally, all tetrapods ectothermic and birds and mammals evolved endothermy, lepidosaurs (reptiles that didn’t lead to birds) didn’t

Probs evolved to lower temp before increasing it

45
Q

Facultative endothermy

A

Indian pythons

Females wrap body around eggs when incubating and contract trunk muscles to shiver

Only when incubating

Not true endothermy

46
Q

Tegu lizards

A

Elevate body temp during reproductive season (October)

Still fluctuates with daily fluctuations and in temp of burrow but always slightly higher body temp

Thermogenesis correlates with heart rate suggested metabolic rate causes elevated body temp but also changes to conductance

Heterothermy, mesothermy and poikilothermy

47
Q

Californian ground squirrel

A

Pumps blood to tail to signal to rattlesnakes they have been seen

Animal Physiology (9 decks)

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