Mammals: Physiology, Homeostasis & Thermoregulation

A set of vocabulary flashcards covering the key concepts, mechanisms, and case study details of mammalian homeostasis and thermoregulation from Lesson 1.

Homeostasis

The regulation of an organism's internal conditions within ranges that support normal biological functioning, even when its internal or external environment changes.

Enzymes

Proteins that accelerate chemical reactions by lowering the activation energy required for those reactions to occur.

Thermoregulation

The regulation of body temperature through physiological, behavioral, and sometimes anatomical mechanisms.

Endothermic

Describing organisms in which metabolic processes provide much of the heat used to maintain their body temperatures.

Metabolism

The chemical reactions that sustain life, including those involved in cellular respiration, nutrient processing, and tissue maintenance.

Shivering

Rapid and involuntary skeletal muscle contractions that increase energy use and heat production without producing much useful external movement.

Non-shivering thermogenesis

A process that increases metabolic heat production without relying exclusively on muscle contractions, often utilizing specialized adipose tissue.

Brown adipose tissue

Specialized adipose tissue containing numerous mitochondria that is particularly important for non-shivering heat production in many small and newborn mammals.

Uncoupling protein 1

A mitochondrial protein in brown adipose tissue that allows energy from fuel oxidation to be released directly as heat rather than being captured entirely as ATP.

Fur insulation

An anatomical adaptation that traps a layer of relatively still air near the skin, acting as an insulating barrier that reduces heat transfer.

Peripheral vasoconstriction

The narrowing of blood vessels near the skin that reduces warm blood flow to the body surface, minimizing heat transfer to the environment.

Peripheral vasodilation

The widening of blood vessels near the skin that increases blood flow to the surface, facilitating greater heat exchange with the surroundings.

Radiation

The physical transfer of heat through electromagnetic waves.

Conduction

The physical transfer of heat through direct contact between materials.

Convection

The physical transfer of heat driven by the movement of air or water across a surface.

Evaporation

The loss of heat that occurs when liquid water changes into water vapor, utilized in cooling mechanisms such as sweating and panting.

Hypothalamus

A region of the brain containing temperature-sensitive neurons that integrates sensory information and coordinates physiological thermoregulatory responses.

Negative feedback

A homeostatic control mechanism where a change in a regulated variable triggers responses that oppose that change to keep it within suitable limits.

Scientific hypothesis

A testable explanation or relationship between variables that includes a proposed change, a predicted outcome, and a biological or physical explanation.

Independent variable

The specific factor that a researcher deliberately changes or manipulates during an experiment.

Dependent variable

The factor that a researcher measures in an experiment to observe the effect of the manipulated variable.

Controlled variables

Conditions and factors that remain constant throughout an experiment to prevent them from confounding the results.

Deer mouse ($20\,\text{g}$) response

A small mammal that frequently seeks sheltered spaces in cold environments to mitigate high rates of heat loss relative to its body mass.

Eastern gray squirrel ($500\,\text{g}$) response

A mammal observed curling up in cold weather to reduce its exposed surface area and conserve heat.

White-tailed deer ($70{,}000\,\text{g}$) response

A large mammal that conserves heat in cold conditions by changing its posture and seeking sheltered areas without exhibiting obvious shivering.