respiration
268
respiration (1) the oxidative degradation of nutrients (glucose, protein, fat)
through metabolic reactions within the cells, resulting in the production of
carbon dioxide, water and energy; (2) the exchange of gases between the
cells of an organism and the external environment, including external respiration, transport by the bloodstream and internal respiration. In small
aquatic animals oxygen may diffuse directly into the cells, while carbon
dioxide within the cells diffuses out; in larger animals special respiratory
systems have developed (gills in invertebrates and lower vertebrates, lungs
in higher terrestrial vertebrates).
respiratory quotient (RQ) the ratio of carbon dioxide emitted and the amount of
oxygen taken in. The respiratory quotient is a quantitative measure the type
of food being used by the body. From the respiratory quotient one can determine whether carbohydrates (RQ = 1), fats (RQ = 0.7) or proteins (RQ = 0.8)
are being used for respiratory needs. Usually the RQ value is around 0.85; at
starvation the value will drop to 0.7, as the body uses its fatty deposits. At
prolonged starvation the respiratory quotient may rise again, indicating the
utilization of proteins from muscle tissue (life-threatening process).
resting stages (resting cells, -spores, -eggs, cysts) are specialized eggs or cysts
(enclosing the entire organism) formed in a number of groups of small
organisms under unfavorable conditions (of light, temperature, ionic conditions, presence of poison, poor nutrient conditions, etc.). Resting stages are
resistant to such unfavorable conditions because of heavy cell walls, lowered
metabolic rate (dormancy), and reduced exchange with the surrounding
medium, and sink to the bottom to await more favorable circumstances.
Each of the algal classes typically represented in marine and freshwater
plankton (Bacillariophyta, Dinoflagellata, Euglenida, Cryptophyta, Cyanobacteria, Chlorophyta,
Prymnesiophyta) is characterized by one or several types of resting stages
known as akinetes, statospores, cysts, etc. Resting stages also occur in a
number of animal groups. They are best known in freshwater organisms
(where desiccation is a major problem): statoblasts in Bryozoa, gemmulae in
sponges, ephippian eggs in Cladocera, diapause eggs and cysts in copepods,
cysts in Nematoda, Rhizopoda, Tardigrada and Polychaeta. In the sea resting stages are
now known in Tintinnina, Copepoda (diapause eggs), Cladocera, Bacteria, and Fungi.
reticulum in protozoa, the pseudopodia (flowing extensions of the body used
for locomotion) can be interconnected, in which case they form a network
or "reticulum".
reversing thermometer mercury thermometer for measuring the temperature
under water. The principle is that the indication of the thermometer at a
given depth should be fixed, after which the thermometer is taken up again
without change through overlying water layers with different temperatures,
268
respiration (1) the oxidative degradation of nutrients (glucose, protein, fat)
through metabolic reactions within the cells, resulting in the production of
carbon dioxide, water and energy; (2) the exchange of gases between the
cells of an organism and the external environment, including external respiration, transport by the bloodstream and internal respiration. In small
aquatic animals oxygen may diffuse directly into the cells, while carbon
dioxide within the cells diffuses out; in larger animals special respiratory
systems have developed (gills in invertebrates and lower vertebrates, lungs
in higher terrestrial vertebrates).
respiratory quotient (RQ) the ratio of carbon dioxide emitted and the amount of
oxygen taken in. The respiratory quotient is a quantitative measure the type
of food being used by the body. From the respiratory quotient one can determine whether carbohydrates (RQ = 1), fats (RQ = 0.7) or proteins (RQ = 0.8)
are being used for respiratory needs. Usually the RQ value is around 0.85; at
starvation the value will drop to 0.7, as the body uses its fatty deposits. At
prolonged starvation the respiratory quotient may rise again, indicating the
utilization of proteins from muscle tissue (life-threatening process).
resting stages (resting cells, -spores, -eggs, cysts) are specialized eggs or cysts
(enclosing the entire organism) formed in a number of groups of small
organisms under unfavorable conditions (of light, temperature, ionic conditions, presence of poison, poor nutrient conditions, etc.). Resting stages are
resistant to such unfavorable conditions because of heavy cell walls, lowered
metabolic rate (dormancy), and reduced exchange with the surrounding
medium, and sink to the bottom to await more favorable circumstances.
Each of the algal classes typically represented in marine and freshwater
plankton (Bacillariophyta, Dinoflagellata, Euglenida, Cryptophyta, Cyanobacteria, Chlorophyta,
Prymnesiophyta) is characterized by one or several types of resting stages
known as akinetes, statospores, cysts, etc. Resting stages also occur in a
number of animal groups. They are best known in freshwater organisms
(where desiccation is a major problem): statoblasts in Bryozoa, gemmulae in
sponges, ephippian eggs in Cladocera, diapause eggs and cysts in copepods,
cysts in Nematoda, Rhizopoda, Tardigrada and Polychaeta. In the sea resting stages are
now known in Tintinnina, Copepoda (diapause eggs), Cladocera, Bacteria, and Fungi.
reticulum in protozoa, the pseudopodia (flowing extensions of the body used
for locomotion) can be interconnected, in which case they form a network
or "reticulum".
reversing thermometer mercury thermometer for measuring the temperature
under water. The principle is that the indication of the thermometer at a
given depth should be fixed, after which the thermometer is taken up again
without change through overlying water layers with different temperatures,