Topic 7 - Key Terms

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autonomic nervous system - That part of the nervous system that controls ‘involuntary’ actions of many systems including the gut and much of the cardiovascular and respiratory systems. Comprises the sympathetic and parasympathetic systems. (T7)

countercurrent heat exchange - A countercurrent exchanger consists of a pair of channels lying in close proximity that contain fluids (or gases) flowing in opposite directions, e.g. where heat loss from the body core to the extremities is minimised by heat transfer between adjacent blood vessels before reaching the outer body surfaces. (T7)

Heterothermy - The regulation of body temperature within a limited range (but not as narrow a range as in homeothermy), independently of ambient temperature by switching between strategies and utilising torpor. (T7)

Lipolysis - The splitting of triacylglycerols into free fatty acids and glycerol by the action of a lipase enzyme (e.g. hormone-sensitive lipase HSL, lipoprotein lipase). (T7)

metabolic rate - The amount of energy used by an organism in unit time. (T2)

An organism’s energy utilisation per unit time, including overall biochemical activity of the tissues, thermogenesis, movement, digestion, growth, etc. There are many ways of measuring metabolic rate, and hence many different units used to express it, of which the most basic is watts (W). (T7)

non-shivering thermogenesis - Often used synonymously with thermogenesis (generation of heat) in brown adipose tissue. Strictly, NST includes all metabolic thermogenesis except that produced by shivering. (T7)

Osmolarity - Measure of the solute concentration of a solution. (T7)

Phenology - Describes the study of periodic events relating to either the timing of the first occurrence of seasonal biological phenomena (e.g. leaf growth, first migratory sighting) or more often, the timeframe in which they occur. (T7)

Riparian - Environment that forms interface between land and water adjacent to rivers and streams. (T7)

standard metabolic rate - Environmental temperature changes affect body temperature and the metabolic rate of an ectotherm, so the minimum metabolic rate will be different at various temperatures and is called its standard metabolic rate (at a specified temperature). (T7)

substrate cycle - Takes place when two metabolic pathways run in opposite directions simultaneously, catalysed by different enzymes, dissipating energy in the form of heat. (T7)

sympathetic nervous system - Part of the autonomic system which controls many involuntary processes (e.g. the gut and the cardiovascular and respiratory systems). Nerves carry signals from the sympathetic system using neurotransmitters such as noradrenalin. (T7)

Thermogenesis - The process of producing heat in human or animal body tissues, although thermogenesis also takes place in some plants. (T7)

Tolerance - The capacity to endure changing environmental conditions without adverse reaction. (T7)

Torpor - State of controlled lowered body temperature and metabolic rate. (T7)

trophic match–mismatch hypothesis - Suggests that the reproduction of predators is more successful at times when this is matched with peak prey availability. It attempts to explain variation within a predator population by relating its phenology to prey species at the next trophic lower level. Thus it is a measure of reproductive success due to how well the phenology of the prey is matched by and able to meet the requirements of its predator. (T7)

UCP1 - The protein in the inner mitochondrial membrane of brown adipocytes that defines this type of cell. It provides a route for protons to move down their concentration gradient from the outside to the inside of the inner mitochondrial membrane without ATP being synthesised. (T7)

Zooplanktivorous - Organisms that consume zooplankton (heterotrophic, generally small organisms living and drifting both horizontally and vertically in bodies of water). (T7)