Verts 9.2 - Thermoregulation 2

insulation, conductance

Increased volume of ________ can prevent loss of heat through _________

- Fluffing/shedding of fur

- Increased blubber

Colder climates

In _______ ______ more insulation means less metabolic investment

Warmer climates

______ _______ insulation can negatively impact

- increase metabolic investment

Circulatory control of cutaneous heat exchange

-arteriovenous bypass capillary beds in skin

-when open, warmer blood is kept deeper (prevents heat loss)

- countercurrent exchange phenomena

Countercurrent heat exchangers

- very important in COLD environments

- manages heat loss at EXTREMITIES

- arteries surrounded by venous channels

- blood flows in opposite directions

cool, warm

In countercurrent heat exchangers ..

- Venous blood from extremities is very _______

- Arterial blood is very _____

heat

_____ from arteries is returned to veins in countercurrent exchangers

endpoints

Arteries are cooler when they get to _______ (Less body heat is lost to external environments)

Regional Heterothermy

- Allows for an endotherm to tolerate colder skin temperatures

- Conservation of core body temperatures (limits conduction of core body temp)

- (ex: feet of water birds dump heat / feet & nose are different than core temp)

Thermoregulation in fish

- Many fish are ECTOTHERMIC

- Lots of heat loss through gills

- Cool water and core blood are already in countercurrent mode (Gas/Heat exchange)

Heterothermic fish

- Some fish have higher metabolic rates

- VASCULAR RETIA in muscles

- Minimizes heat loss at the skin

Vascular retia

- vessels set up in counter current systems

- Warm blood from muscles used to keep core warm

Opah fish

- displayed whole body endothermy

- measured body temp over time & varied depths (stayed consistent)

Protective countercurrent exchangers

- Brain cooling in animals living in tropical locals

- Panting cools blood in PHARYNX (--> passes through heat exchanger to cool arterial blood)

- Before it goes to brain (MAINTAINS BRAIN TEMP)

Evaporative heat exchange

Blood flow rate and water loss rate in an exercising panting dog, also showing increments of rectal and brain temperature (Trectal and Tbrain ) but with Tbrain much lower due to the cooling effect of panting.

Gular Fluttering

- Some birds

- Flapping of gular skin, like a pant)

- To cool the blood by evaporation

- Protects the brain

Water retention

- Dromedary camels

- Water conservation helps maintain temp (lack of sweat/thick urine)

- Environmental dehydration causes increase in water retention

Physical

______ dehydration results in wide temp swings (dramatic spike/drop (ex: camels)

Huddling

- Emperor penguins (2500 in a group) use ______ to keep warm

- Social status determines rotation rates to inside of huddle

Futile metabolic cycles

Burn ATP in never ending cycles (just to make heat)

- portion of glycolysis

- Ion transportation and leakage

- Uncoupled fatty acid metabolism

Brown Adipose

- Coming out of torpor

- _______ has a lot of mitochondria

- Fat oxidation is UNCOUPLED from energy production

(- all energy is released as heat)

(- non-shivering thermogenesis)

Uncoupling proteins

- Fat is oxidized; Kreb's cycle runs; ETC runs

- Protons run through ______ _____ channels and NOT ATP synthase --> NO ENERGY MADE; ONLY HEAT RELEASED

smaller, larger

- Non shivering thermogenesis used by _____ animals (use a SIGNIFICANT amount of metabolism to maintain temp)

- _____ animals rely on insulation

Heater tissues in Fish

•Futile calcium pump loops

•Calcium channels in SR are kept open

•Ca-ATPase in SR membrane uses ATP to pump back in

•Heat generated

•Localized

endotherms

smaller body size = particularly an issue for _______ (smaller and smaller = dramatic increase in metabolic rate)

vs Lizards where it doesn't matter

Ectotherm Benefits

- Lower energy demands

- Low cost of energy conservation

- No cost to maintain constant body temp

- Smaller minimum body size

Endotherm Benefits

- Fewer latitudinal and altitudinal restrictions on distribution (better suited to predominantly cold climates)

- Fewer daily/seasonal restrictions on activity Higher Aerobic Capacity (lower cost of locomotion; fatigue less)

Ectotherm Disadvantages

- More latitudinal and altitudinal restrictions on distribution

- More daily/seasonal restrictions on activity

- Lower aerobic capacity

Endotherm disadvantages

- Higher energy demands

- High cost of energy conversion

- Over 90% of assimilated energy lost as heat

- Larger minimum body size

fluid compartments

Water is separated into ______ _____:

- Intracellular fluid

- Extracellular fluid

Intracellular fluid

- Water in cells

- Most of water

Extracellular fluids

- Plasma

- Lymph

- Interstitial fluids

- Transcellular fluids

Transcellular fluids

- Spinal fluid

- Joint fluid

- Serous fluids

Electrolyte

______ composition varies in Human body fluids (serum & interstitial vs Intracellular fluid)

Plasma, Interstitial, Intracellular

______ and ______ = contains more Cl- and Na+ ions

_______ = contains more Mg++ and K+ ions

ion, solute, osmotic pressures

Regulation

- Defined ____ and ______ concentrations in all fluid compartments

- Defines the _______ _______ in all compartments

Physiology

______ strives to maintain water and solute balance

- osmoregulation

- ionregulation

Vertebrate kidney

Roles of the _____ _____ :

1) Volume regulation

2) Solute concentration

3) Acid base balance

4) Water soluble waste

volume

The vertebrate kidney (Volume reg/solute conc) determines where _____ is distributed in plasma v. IF v. ICF

volume regulation

- Total volume fluid in body

- blood pressure

Solute concentration

- Salt ions

- Organic solutes

Acid base balance

excretion of acids (in kidneys)

Water soluble waste

- Nitrogen from catabolism of proteins and nucleic acids

Avoidance and tolerance

Environmental changes can affect osmoregulation... two regulation options for an organism:

Tolerance

conform & regulate

conform

change internal environment to match external

regulate

control internal so external changes are less important

Osmoregulatory strategies

osmoconformer = osmolarity of environment goes up --> body fluid osmo up

osmoregulator = less change in body fluid