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Home >>Zoology Dictionary >> Respiratory Movement - Ruminant
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Respiratory Movement - The movements of part or parts of the body that ensures a fresh supply of air or water for the respiratory organs. Many insect bodies, especially of the larger species, pulsate at intervals forcing stale air out of the tracheae and drawing in a fresh supply. Lobsters and many other aquatic arthropods wave certain appendages about and create a current of water over the gills. Fishes take water in through their mouths and the muscles of the pharynx pump it out over the gills. Tetrapods expand their chests to draw air into the lungs. The movement of the diaphragm in mammals aids respiration by altering the size of the thoracic cavity containing the lungs.
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Respiratory Pigments - Substances which occur in blood and increase its oxygen carrying capacity. The bestknown and the most efficient is haemoglobin the reddish purple pigment of vertebrate such as earthworms. This is a complex iron containing compound which occurs in the corpuscles of vertebrate blood or in the plasma in other animals. At high oxygen concentrations (e.g. at. the respiratory surface) the pigment combines with oxygen and forms oxyhaemoglobin which is bright red. In the body tissues the oxygen concentration is low.
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The oxyhaemoglobin in the blood breaks down and releases oxygen which passes to the tissues. If the haemoglobin content is reduced. oxygen shortage will occur. For example, carbon monoxide forms a stable compound carboxyhaemoglobin-with the pigment which cannot then carry oxygen. Haemocyanin, in which the metallic element is copper, is found in many crustaceans and in molluscs such as octopuses and squids.
It turns blue when oxygenated. All respiratory pigments have in common the fact that they form unstable compounds with oxygen which break down at the low oxygen which break down at the low oxygen concentration found in the tissues. Insects, in which the. tracheae carry oxygen straight to the tissues, have no , respiratory pigments.
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Respiratory Quotient (R.Q.) -The ratio of carbon dioxide produced to the volume of oxygen consumed during the same period. The value differs according to the type of food material being oxidised.
Rhizopoda - (See Sarcodina).
Rod - Light sensitive cell of retina. Not sensitives to colour.
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Resting Cell - A term used to describe a cell not at the time undergoing division, although it may he very active in other ways.
Retina - The light sensitive layer of the eve.
Roundworms - (See Nematoda).
Rumen - (See Ruminant).
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Rhesus (Rh) Factor - A subsatnce (antigen) that is found in the blood of a fairly constant proportion of the human population of an area about 83% of the British population. Its Occurrence is controlled by a set of linked genes. People with the factor are known as Rh positive blood, antibodies may be formed and they may attack a further transfusion of Rh positive blood. It is. thus ,essential that Rh negative people receive only Rh negative blood in transfusions. During pregnancy an Rh negative mother may receive the rhesus antigen from an Rh positive embryo. The mother will develop antibodies which can remain in her blood and may damage a further Rh positive baby.
This is why it is necessary for expectant mothers to have blood tests. If it is known in advance that there is a likelihood of the baby's blood being damaged, transfusion apparatus can be made ready and the baby can be saved.
Rodentia - Order of mammals including rats, mice, squirrels, beavers, etc.-the gnawing mammals. In terms of species and numbers, it is the largest mammalian order. Members are characterised by the possession of a pair of continuously growing incisor teeth in each jaw. Rodents are never very large the capybara is the largest at the size of a small pig. Their rapid breeding rate has probably contributed to their success as also has their ability to colonise a wide variety of habitats, The incisor teeth have enamel only on the front surface so that they have sharp cutting edges. There are no canines and only a few cheek teeth.
Rotifera - Phylum of minute acoelomate animals occurring in vast numbers in fresh water and often mistaken for protozoans, although they are definitely many-celled. Rotifers are characterised by a crown of cilia which act as locomotory organs and also collect food, Although they are so tiny, rotifers have a complete food canal together with excretory and nervous systems. There is no blood system, however. The sexes are normally separate but in many species the male is extremely rare and the females reproduce by parthenogensis.
Ruminant - Cud-chewing animal-deer, antelopes, sheep, cattle, and giraffes. All belong to the order Artiodactyla and are herbivorous. Food is swallowed without chewing. and is passed into the rumen-the first chamber of a complicated stomach. From there it is later regurgitated into the mouth for chewing-chewing the cud. A certain amount of bacterial breakdown of cellulose takes place in the rumen.
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