Regulating the Internal
Environment
Homeostasis
Body Temperature
Water Balance
Metabolic Waste Disposal
Homeostasis Overview
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Regulators – internal change is moderated
in a changing environment e.g. birds
Conformers – allow internal change with
certain external changes
Budget = balance of loss and gain,
animals are open systems e.g. water
maintenance via intake overcomes losses
via breathing, sweating, urination, etc.
Q10 Effect
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The multiple by which a particular
enzymatic reaction or overall metabolic
process increases with a 10°C
temperature change in the body.
For example, if the hydrolysis of amylose
into maltose is 3.7 times greater at 25°C
than at 15°C in fire belly toads, the Q10 is
3.7 for that reaction.
Each animal has an optimal range of temp
If it’s
warmer, I
digest faster.
Heat Loss
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Conduction = direct transfer of heat from
cold water or hot rock
Convection = transfer of heat by
movement, wind
Radiation = emission of electromagnetic
waves by all objects greater than absolute
zero, sun
Evaporation = water needs a lot of energy
to evaporate, sweat, humidity
Ectotherms vs Endotherms
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Ectotherms have such low metabolic rates
that they rely mostly on the environment
to determine their body temp
Endotherms have such high metabolic
rates that body temp is higher than the
environment
Endotherms have an advantage, but it is
costly!
Thermoregulation
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Insulation – many organisms have fat as
an insulator.
Vasodilation vs vasoconstriction
Countercurrent heat exchange – minimize
heat loss in the extremities by allowing for
close proximity of arteries and veins –
venous blood is warmed by arterial blood
as it re-enters the body from the limbs.
Thermoregulation Cont.
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Evaporative heat loss cools terrestrial
animals.
Behavioral responses – basking in the sun,
warm rocks, find shade, enter cool water,
hibernation, migration
Change in metabolic rate - endotherms
Mammals and Birds
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Heat can be increased by movement of
muscles including shivering.
NST – nonshivering thermogenesis –
certain animals have mitochondria that
increase their metabolic activity to
produce heat instead of ATP
Insulation
Sweating, panting,
Amphibians and Reptiles
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Temperature controlled mostly by behavior
Some extras: bull frogs secrete mucous,
marine iguanas of the Galapagos –
vasoconstriction, female pythons “shiver”
to become endothermic when incubating
eggs
Dinosaurs?
Fish!
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Most are ectotherms
except for a few large
active fish such as the
great white shark,
swordfish and bluefin
tuna. They maintain a
countercurrent exchange
with large arteries full of
cold blood from the gills
entering tissues just
below the skin. Branches
deliver oxygenated blood
to deep muscles.
Invertebrates
Most are ectotherms
 Some flying insects are endotherms –
Hawk moth, bumblebees, honey bees –
they use flight muscles to generate heat
 Bumble bee queens can us countercurrent
exchange to allow heat to release
from the thorax and incubate eggs.
 Bumble bees also huddle
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Feedback Mechanisms
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Thermoregulation – see teachers flow
chart.
Acclimatization
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Endotherms - insulation layer
Ectotherms – metabolic processes –
enzymes may have different forms at
different times of the year = temperature,
cellular membranes may have a higher
concentration of unsaturated fats based
on temp
“antifreeze” - prevents ice crystalization in
fish, frogs, arthropods and their eggs
Heat shock Proteins
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Found mostly in tissue culture, they are
proteins that maintain the stability of
other proteins, keep them from denaturing
in either stress or heat. Found in yeast,
bacteria, plant cells and animal cells!
Torpor
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Physiological state of inactivity
Hibernation
Estivation
Osmoregulation
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Management of the body’s water content
and solute(salt) content.
Transport Epithelium
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Layer or layers of
specialized epithelial
cells that regulate
solute movement.
Prevalent in marine
birds and ocean fish.
Remove salt to
maintain water
balance.
Nitrogenous Wastes
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Ammonia – common in aquatic species,
lost from epithelial tissue of gills, kidneys
relatively inactive. In freshwater exchange
of Na+ into cells and NH4+ out.
Urea – produced by liver, less toxic than ,
water soluble NH4, organisms use energy
to make and lose water to remove it.
Amphibians probably switch.
N waste continued
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Uric acid – land snails, insects, birds and
many reptiles
Even less toxic than urea and can be
excreted with less water loss as a
semisolid paste.
Costs more energy than urea
Build up of urea in an egg may be toxic
Osmotic Balance
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Over time the uptake and removal of
water must balance in all animals.
Remember what happens to an animal cell
in salt water or distilled water?
Osmoregulator
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Animal that must continually adjust its
internal osmolarity because it is not the
same as its environment.
Osmoconformer
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Animal’s inner osmolaritly is equal to its
surroundings – isoosmotic
I’m the only
vertebrate that is an
osmoconformer!
You are one
ugly hag!
Fish have special problems
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Marine fish have the dilemma or too much
salt and possible water loss via direct
contact with water and gill epithelial cells.
They excrete excess salt via gills and scant
urine. Obtain water from gills and food.
Chondricthyes have a rectal gland that
removes salt – special organ
Freshwater fish excrete large amounts of
water through very dilute urine.
Anhydrobiosis
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Some arthropods and rotifers can survive
for many years in a dried out state
Excretory Systems
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Selective reabsorption – body accumulates
fluid, and maintains water balance
through reabsorption of some solutes and
secretion of others.
Fluid is accumulated by filtration – blood
pressure or hydrostatic pressure
accumulate the nitrogenous waste.
Protonephridia
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Network of dead-end tubules lacking
internal openings. They branch through
the body with the smallest ones capped by
a flame bulb.(Osmoregulation mostly)
It has a tuft of cilia that draws the water
out of the tubule to the outside.
Most of metabolic waste is removed via
diffusion.
Metanephridia
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Internal openings that collect body fluids
and remove it via cilia.
Found in most Annelids – earthworms
have two per segment.
Remove nitrogenous waste and
osmoregulate as well.
Malphigian tubules
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Insects and other terrestrial arthropods
Removes nitrogenous waste and maintains
water balance.
Collects and then leads to rectum. Most
of the water is reabsorbed into the
hemolymph and waste is secreted with
feces.
The Kidney!
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A = Blood, arteries
and veins
B = Renal Calyx
C = Ureter
D = Renal Medulla
E = Renal Cortex
Label animation for
nephron
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Step by step animation