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Home >>Biology Dictionary >> Cork Phellem - Corpus Luteum
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Conspecific. Member of the same species.
Constant length. If further contraction is prevented by putting weight of constant length of the muscle it is known as constant length.
Constant tension. In this type of muscle contraction the load remains constant throughout the period of shortening of muscle.
Constipation. It is a condition in which the faecal matter passes out of the body at prolonged intervals.
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Contact insecticides. These are the chemicals that kill insects if applied to their skin. Such chemicals can penetrate through the skin or they block the spirals.
Contorted. Overlapping and appearing to be twisted when in bud.
Copulation. It is a sexual act in which males transfer sperms into the body of females.
Coracoid.
It is one pair of cartilage bones that form the central side of pectoral girdle in bony fishes, reptiles and birds.
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Coral. Calcareous skeleton or fused skeletons of various coelenterates and Polyzoa or the skeleton together with the animals (polyps) which secrete it. The great bulk of most coral reefs is made by the madreporarians.
Cork (phellem). A protective waterproof plant tissue produced by the cork cambium. It develops in plants undergoing secondary growth and replaces the epidermis. Its cells, whose walls are impregnated with suberin, are arranged in radial rows and fir closely together except where the cork is interrupted by lenticels. Some cork cells become air-filled while others contain deposits of lignin, tannins, and fatty acids, which give the cork a particular colour. The cork oak (Quercus suber) produces cork that can be used commercially.
Corm.
It is an underground modified stem that grows vertically downwards. It is thich and fleshly e.g. colocais.
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Cormophytes. Plants possessing stem, leaf and root, i.e. ferns and related plants (pteridophyta) and seed plants (Spermatophyta).
Cornea. The transparent epitheliums and connective tissue at front surface of the eye of vertebrates, overlying iris and lens. Mainly responsible in land vertebrates for the refraction which results in focusing an image on retina.
Cornification. Conversion of cell material into keratin, e.g. in epidermis.
Constitutive Enzyme. Enzyme whose synthesis, unlike that of an adaptive enzyme (q.v) does not have to be induced by the presence of the substrate or similar substance.
Consumers.
Refers to those organisms which depend upon plants or animals for their food.
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Corolla. Usually conspicuous, often coloured part of a flower, within the calyx, consisting of a group of petals. See flower.
Coronary Vessels. Arteries and veins of vertebrates carrying blood supply of heart muscle.
Corpora allata. Small endocrine glands in the head of insects. Produce a juvenile hormone which ensures that the larva maintains larval characteristics after moulting rather than changing into an adult.
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Corpus Callosum. Broad tract of nerve fibres connecting the two cerebal hemisphere in mammals.
Corpus luteum. The yellowish body that forms in the cavity of a Graaffian follicle in the ovary of a mammal after the release of the egg cell. It secretes the hormone progesterone. Some species of sharks, reptiles, and birds have similar structure in their ovaries but the function of these is less well understood.
Cortex. An outer layer or ring.
Corticosteroid. (Corticoids). Various steroids produced in cortex of adrenal gland; some are hormones. The glucocorticoids, and synthetic analogues, are important drugs, especially for the suppression of inflammation.
Corticotropin. ACTH.
Corymb. Kind of inflorescence.
Cotyledon (seed leaf).
A part of the embryo in a seed plant. The number of cotyledons is an important feature in classifying plants. Among the flowering plants, the class monocotyldonae have a single cotyledoon and Dicotyledonae have two. Gymnosperms have either two cotyledons, as in Taxus (yews) and Cycas, or five to ten, as in Pinus (pines). In seeds without an endosperm, e.g. garden pea and braod bean, the seeds showing epigeal germination, e.g. runner bean, they emerge above the soil surface and become the first photosynthetic leaves.
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