Gas Exchange Terms: FISH 4500

Aerobic Metabolism (Respiration)

The dominant form of respiration in all organisms when oxygen is available

Anaerobic Metabolism (Respiration)

A less efficient form respiration used when an organism doesn’t have access to enough oxygen for aerobic respiration

Oxygen Consumption Rate

Amount of oxygen required by a fish over a given length of time.  Influenced by life stage, body weight, activity level, critical oxygen threshold, and feeding

Gill Arch

Bone or cartilage supporting gill rakers and gill filaments

Gill Filaments

Paired filaments extending off the back of the gill arch.  Support lamellae and help form gill sieve.

Septum

Tissue between the gill filaments that separates them.

Gill Sieve

Formed by gill filaments, ensures that water flow through the gills is laminar

Laminar

smooth, linear, non-turbulent

Lamellae

flattened, plate-like structures extending from the upper and lower surfaces of the gill filaments.  Location of gas exchange between fish and water.

Epithelia

Outer layer

Partial Pressure

The pressure a gas would exert if it occupied the container by itself.  Gasses flow from high to low partial pressure.  Somewhat similar to concentration.  Annotated as P_O2, P_CO2, etc.

Counter-current Exchange

System in which blood and water flow past each other in opposite directions; maximizes gas exchange

Hemoglobin (Hb)

The protein in red blood cells that binds to O2

Heme

the oxygen binding iron (Fe) in hemoglobin

Tetrameric

a molecule with four parts

Monomeric

a molecule with one part

Cooperative Binding

binding of one molecule facilitates the binding of other molecules

Half-saturation Value (P50)

The PO2 in blood at which hemoglobin is 50% saturated

Bohr Effect

decreasing pH causing hemoglobin to have lowered oxygen affinity

Root Effect

High levels of CO2 cause hemoglobin to have redduced capacity of O2, even at high PO2

Carbonic Anhyrase

An enzyme that assists rapid inter-conversion of carbon dioxide and water into carbonic acid, protons and bicarbonate ions

Ram venitilation

Fish swims constantly to force water across gills

Spiracle

An opening behind the eye that channels water into the buccal cavity and over thee gills.

Buccal-Opercular Pump

A system in which, by opening and closing the mouth and operculum, and moving  the lower jaw, a fish can pump water across its gills.

Accessory Breathing Organ

Any of a number of non-gill organs that fish use for gas exchange. These can include the skin, swim bladders, true lungs, etc.