chapter 29.3 and 32 thermoregulation

Why is countercurrent flow more efficient than concurrent flow or parallel flow at exchanging heat (or other materials?) Explain some different ways that countercurrent heat exchange is used by animals in thermal regulation.

Concurrent exchange has high initial heat transfer but quickly reaches equilibrium. Separate flows may allow heat to escape. e.g. large extremities in desert animals Countercurrent exchange allows for maximum transfer of heat (or other materials). Since the flows are continuously intertwined they reach maximum heat. Really good for cold pawed animals. Like Wolves, can keep the paws cold but maximize the internal temperature.

What are endotherms vs. ectotherms? How do they relate to the terms in the previous question?

Endotherms gain most of their heat through their own metabolism. Ectotherms gain most of their heat from external sources. They tell us where the heat or non heat comes from for the homeotherms and pokiliotherms.

Be able to use Fourier's law to explain how thermoregulatory adaptations miminize (or maximize) heat transfer between an animal and its environment.

Fourier's Law for heat transfer via conduction: Q = k A ∆T / d where: Q = amount of heat transferred A = heat transfer area k = thermal conductivity of the material ∆T = temperature difference between the two sides of the transfer d = material thickness (m, ft, etc.) The main factor in this is the delta T. Which can show the differential between the tempatures of the objects. if it is very high this can create a high heat exchange, but if this is very small it can be a minimal difference. Conduction is an easy one to see, and convection is when the wind blows by the wind picks up heat from you and you lose heat. radiation is at rest and we are naturally giving off heat to the enviorment.

What is the TNZ, and which type of animal does it apply to?

Homeotherm metabolic rate is lowest in the thermoneutral zone (TNZ). A thermal neutral zone (TNZ) is essentially an endotherm's temperature tolerance range. Within the TNZ the basal rate of heat production is in equilibrium with the rate of heat loss to the external environment. The endotherm does not have to use large amounts of energy to control its temperature within the thermal neutral zone, the organism adjusts to the temperatures within the zone through different responses requiring little energy.

Graph metabolic rate vs. environmental temperature for homeotherms and poikilotherms. Be able to explain why the curves look the way they do. Why do homeotherms generally have much higher metabolic costs relative to poikilotherms?

Homeotherms have to use more enegry to keep the internal environment constant, unlike the poi ones they can adapt and not have to expand energy because they are adaptable.

]What are the 4 mechanisms of heat transfer? Give some examples of thermoregulatory adaptations or behaviors that utilize each.

Mechanisms of environmental heat transfer • Radiation • Convection • Conduction • Evaporation . Evaporation is sweat and cools the body. RADIATION The heat generated from within the body is given-off to the surrounding atmosphere. Heat from the sun CONVECTION Convection is the process of air or water flowing by the skin and carrying away body heat. It's convective heat loss that you try to prevent by staying as still as possible in the water. Staying still, the boundary layer of water next to the skin is heated by the body and remains undisturbed. If you move around in the water, you disrupt that boundary layer of warmer water, and that increases heat loss. CONDUCTION The body conducts heat to whatever the skin is in direct contact with. Conductive heat loss occurs when the skin is subjected to either cold air or water, but it is especially critical in water, as your body loses heat about 25 times faster in water than in air of the same temperature.

What are poikilotherms vs. homeotherms? (what type of animal is which) How do these terms relate to regulators vs. conformers? Be able to graph body temperature vs. external temperature for each of the two.

Poikilotherms basically keep their internal temperature adaptable to the outside environment, they're conformers. Homeotherms regulate their internal environment and keep it constant. Homeotherms keep their temperature constant and the pokilotherms have a positive slope with tempature. homeotherms (mammals and birds) (Poikilothermic animals include types of vertebrate animals, specifically fish, amphibians, and reptiles, as well as a large number of invertebrate animals. The naked mole-rat is the only mammal that is currently thought to be poikilothermic.)

Be able to list/describe/recognize different methods of thermoregulation and thermogenesis. Are any used primarily (or exclusively) by endotherms vs. ectotherms?

Thermoregulation, Shivering endothermic; increases metabolic heat production. Sweating, endothermic, increases metaboilc production and causes evaporation to cool down. non-shivering thermogenesis (brown fat) This process takes place in a specialized type of fatty tissue called brown adipose tissue (BAT) (FIGURE 29.10). The mechanism used by BAT to make heat is uncoupling of oxidative phosphorylation. In this process, no ATP is made. Instead, heat is made directly in the mitochondria because the proton gradient in the mitochondria is short-circuited. Behavioral regulation is used by both but it is also exclusively used by ecotherms to adjust their body temperature.