9.3 & 9.4: Thermoregulation & Water Balance

Thermoregulation

is the regulation of internal temperatures by negative feedback mechanisms

Where does thermoregulation occur?

At the surface

What would happen if an organism fails to thermoregulate?

It can succumb to he extreme temperatures that cause proteins to unfold and loose their function

Conduction

flow of thermal energy in direct contact

Convection

Transfer of thermal energy within a fluid

Radiation

transfer of thermal energy in the form of electromagnetic radiation

Evaporation

process by which liquid is transformed into a gas via a gain in thermal energy

Homeotherms

Maintain a stable body temp regardless of the temp of the external environment ex mammals, birds

Poikilotherms

Body temp varies with and often matches the temp of the external environment. Ex. fish, reptiles

Endotherms

Maintain body temp by internal mechanisms ex mammals

Ectotherms

Maintain body temp by absorbing thermal energy from environment. ex fish

Advantages & Disadvantages of Endothermy

Advantages:

• able to maintain stable body temp

• can remain fully active over a wider range of temps

Disadvantages:

• are relient of food tomaintain body temp (use metabolsim to cool/heat)

• have higher energy requirments

Advantages & Disadvantages of Ectothermy

Advantages:

• can obtain thermal energy from the environment (don’t use metabolism to heat/cool)

• have lower energy requirments

Disadvantages:

• not able to maintain a stable body temp

• activity is limited by environmental temps

Torpor

short term state of reduced metabolic rate and body temp that reduces demand for energy during night or day ex nocturnal animals

Hibernation

Extended torpor of small mammals during the winter, greatly reduce metabolic rate that enables animal to survive winter by reducing energy demand in deficit of food ex hedgehogs

Estivation

state of torpor that enables animal to survive in the summer by reducing demand for energy ex. ground squirrels

Other thermoregulatory structures & behaviours animals use

• insects can excersize to maintain a core body temp above environmental temp

• uneven dist of fur on dugs

• Birds fly on a hot day with their legs extended

• dogs and other animals pant to expel thermal energy from mouth

• elephants and animals with big ears release thermal energy through the large suraface area of their ears.

Why do humans and other terrestrial vertebrate require aqueous environment

must maintain constant volume, solute cond, and temp

Why do animals need to maintain a water balance?

water is not abundant on land, so mechanisms need to be in place to conserve water and maintain homeostasis

Why do animals needs an excretory system?

to expel wastes and manage water and solute levels in the body

Osmotic pressure

the pressure that resuts from a diff in solute conc between the 2 sides of a selectively permeable membrane

Hyperosmotic

higher conc of solute and low conc of wate

Hypoosmotic

lower solute conc and higher water conc

Isooosmotic

2 solutions that have equal solute (water conc)

Hydrostatic Pressure in Plants

water entering cells create turgor pressure that keeps plants rigid and supports stems and leaves

Osmoregulation

process of actively regulating the osmotic pressure of bodily fluids and cells

Excretion

the elimination of wate products from body

Why is excretion so closely ties with osmoregulation?

Because the aqueous environments act as a solvent for this waste, and elimating these wastes in the solvent helps maintain osmotic pressure and conc

Ammonia

in bony fish, amphibians etc. NH₃, Needs lots of water to eliminate

Urea

in mammals, sharks and aquatic reptiles, needs small amount of water to eliminate