Chapter 5: Temperature Relations Flashcards

A comprehensive vocabulary flashcard set based on lecture notes covering temperature relations, microclimates, energy allocation, heat balance factors, and thermal regulation strategies.

Microclimate

Small-scale climatic variation in factors such as temperature and precipitation, influenced by factors like altitude, aspect, vegetation, ground color, and burrows.

Aspect

The directional slope or slant of the ground, which affects exposure to sunlight and influences local microclimatic temperatures.

Principle of Allocation

An evolutionary principle stating that if an organism allocates energy to one physiological function (such as growth or reproduction), that energy is no longer available for other functions.

Acclimation

A physiological adjustment made by an individual organism in response to changes in temperature or other environmental conditions over time.

Metabolic Heat ($H_m$)

Energy generated internally by an organism through metabolic process, such as cellular respiration ($C_6H_{12}O_6 + O_2 \rightarrow H_2O + CO_2 + ATP$).

Conduction ($H_{cd}$)

The transfer of heat between two physical objects that are in direct contact with each other.

Convection ($H_{cv}$)

The transfer of heat between an organism and a surrounding fluid medium, such as moving air or water.

Radiation ($H_r$)

The transfer of heat through electromagnetic radiation, such as thermal radiation absorbed from sunlight or radiated into shade.

Evaporation ($H_e$)

Heat loss that occurs as liquid water transitions into gas, such as through sweating.

Poikilotherm

An organism whose body temperature fluctuates directly in response to variations in environmental temperature.

Homeotherm

An organism that maintains a constant body temperature despite fluctuations in external environmental temperatures.

Heterotherm

An organism that functions intermediate between a poikilotherm and a homeotherm, allowing its body temperature to vary temporarily.

Ectotherm

An organism that relies primarily on external environmental thermal sources to regulate its body temperature.

Endotherm

An organism that relies primarily on internally generated metabolic heat to regulate its body temperature.

Mesotherm

An organism intermediate between an ectotherm and an endotherm that utilizes internal heat generation with limited internal body temperature regulation (e.g., bumblebees, tuna).

Stilting

A thermoregulatory posture used by desert insects like tiger beetles, elevating the body on long legs to reduce conductive heat gain from the ground and increase convective heat loss.

Obelisking

A thermoregulatory posture in dragonflies where the abdomen is pointed directly upward toward the sun to minimize radiative heat gain ($H_r$).

Thermal Neutral Zone (TNZ)

The range of ambient temperatures over which an endothermic organism maintains a stable basal metabolic rate without spending extra energy for heat production or cooling.

Torpor

A state of lowered body temperature and decreased metabolic rate used by organisms to conserve energy during cold or harsh conditions.

Hibernation

A extended period of metabolic inactivity and dormancy during winter months.

Estivation

A period of metabolic dormancy and reduced activity occurring during summer months.

Cryoprotectant

A chemical substance produced in organisms (such as antifreeze proteins) that lowers the freezing point of body fluids to prevent damaging ice crystal formation.

Heat-Shock Proteins

Chaperone proteins that protect structural proteins from unfolding and denaturing under extreme thermal stress.

Skunk Cabbage Thermogenesis

A mechanism in skunk cabbage where starch is translocated from taproot to spadix, driving rapid cellular respiration to generate metabolic heat ($H_m$) capable of melting surrounding snow.