Life, The Science Of Biology - Key Terms Chapter 40

Front 1

basal metabolic rate (BMR)

Back 1

The minimum rate of energy turnover in an awake (but resting) bird or mammal that is not expending energy for thermoregulation.

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brown fat

Back 2

In mammals, fat tissue that is specialized to produce heat. It has many mitochondria and capillaries, and a protein that uncouples oxidative phosphorylation.

Front 3

cardiac muscle

Back 3

A type of muscle tissue that makes up, and is responsible for the beating of, the heart. Characterized by branching cells with single nuclei and a striated (striped) appearance. (Contrast with smooth muscle, skeletal muscle.)

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conduction

Back 4

The transfer of heat from one object to another through direct contact.

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connective tissue

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A type of tissue that connects or surrounds other tissues; its cells are embedded in a collagen-containing matrix. One of the four major tissue types in multicellular animals.

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convection

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The transfer of heat to or from a surface via a moving stream of air or fluid.

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countercurrent flow

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An arrangement that promotes the maximum exchange of heat, or of a diffusible substance, between two fluids by having the fluids flow in opposite directions through parallel vessels close together.

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ectotherm

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[Gk. ektos: outside + thermos: heat] An animal that is dependent on external heat sources for regulating its body temperature (Contrast with endotherm.)

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effector

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Any organ, cell, or organelle that moves the organism through the environment or else alters the environment; for example, muscle, exocrine glands, chromatophores.

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endotherm

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[Gk. endo: within + thermos: heat] An animal that can control its body temperature by the expenditure of its own metabolic energy. (Contrast with ectotherm.)

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energy budget

Back 11

A quantitative description of all paths of energy exchange between an animal and its environment.

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epithelium

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A type of animal tissue made up of sheets of cells that lines or covers organs, makes up tubules, and covers the surface of the body; one of the four major tissue types in multicellular animals.

Front 13

error signal

Back 13

In regulatory systems, any difference between the set point of the system and its current condition.

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evaporation

Back 14

The transition of water from the liquid to the gaseous phase.

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feedback information

Back 15

In regulatory systems, information about the relationship between the set point of the system and its current state.

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feedforward information

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In regulatory systems, information that changes the set point of the system.

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heterotherm

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An animal that regulates its body temperature at a constant level at some times but not others, such as a hibernator.

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hibernation

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[L. hibernum: winter] The state of inactivity of some animals during winter; marked by a drop in body temperature and metabolic rate.

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homeostasis

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(home′ ee o sta′ sis) [Gk. homos: same + stasis: position] The maintenance of a steady state, such as a constant temperature or a stable social structure, by means of physiological or behavioral feedback responses.

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hypothalamus

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The part of the brain lying below the thalamus; it coordinates water balance, reproduction, temperature regulation, and metabolism.

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hypothermia

Back 21

Below-normal body temperature.

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internal environment

Back 22

In multicelluar organisms, the extracellular fluid surrounding the cells.

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interstitial fluid

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Extracellular fluid that is not contained in the vessels of a circulatory system.

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muscle

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Contractile tissue containing actin and myosin organized into polymeric chains called microfilaments. Muscle fiber A single muscle cell. In the case of striated muscle, a syncitial, multinucleate cell.

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negative feedback

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In regulatory systems, information that decreases a regulatory response, returning the system to the set point. (Contrast with positive feedback.)

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nervous tissue

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Tissue specialized for processing and communicating information; one of the four major tissue types in multicellular animals.

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organ system

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An interrelated and integrated group of tissues and organs that work together in a physiological function.

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organ

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[Gk. organon: tool] A body part, such as the heart, liver, brain, root, or leaf. Organs are composed of different tissues integrated to perform a distinct function. Organs, in turn, are integrated into organ systems.

Front 29

positive feedback

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In regulatory systems, information that amplifies a regulatory response, increasing the deviation of the system from the set point. (Contrast with negative feedback.)

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pyrogen

Back 30

Molecule that produces a rise in body temperature (fever); may be produced by an invading pathogen or by cells of the immune system in response to infection.

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Q10

Back 31

A value that compares the rate of a biochemical process or reaction over 10°C temperature ranges. A process that is not temperature-sensitive has a Q10 of 1; values of 2 or 3 mean the reaction speeds up as temperature increases.

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radiation

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The transfer of heat from warmer objects to cooler ones via the exchange of infrared radiation. See also electromagnetic radiation; evolutionary radiation.

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regulatory system

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A system that uses feedback information to maintain a physiological function or parameter at an optimal level.

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set point

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In a regulatory system, the threshold sensitivity to the feedback stimulus.

Front 35

skeletal muscle

Back 35

A type of muscle tissue characterized by multinucleated cells containing highly ordered arrangements of actin and myosin microfilaments. Also called striated muscle. (Contrast with cardiac muscle, smooth muscle.)

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smooth muscle

Back 36

Muscle tissue consisting of sheets of mononucleated cells innervated by the autonomic nervous system. (Contrast with cardiac muscle, skeletal muscle.)

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thermoneutral zone

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[Gk. thermos: temperature] The range of temperatures over which an endotherm does not have to expend extra energy to thermoregulate.

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tissue

Back 38

A group of similar cells organized into a functional unit; usually integrated with other tissues to form part of an organ.