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Primary metabolism in a plant comprises all metabolic pathways that are essential to the plant's survival. Primary metabolites are compounds that are directly involved in the growth and development of a plant whereas secondary metabolites are compounds produced in other metabolic pathways that, although important, are not essential to the functioning of the plant.
In response to dental caries, there may be production of more dentin toward the direction of the pulp. This new dentin is referred to as tertiary dentin. [82] Tertiary dentin is produced to protect the pulp for as long as possible from the advancing bacteria. As more tertiary dentin is produced, the size of the pulp decreases.
Tertiary dentin on the surface of a gorilla tooth. The darker area indicated by the white arrow is tertiary dentin and has formed as a response to tooth wear. Wear on the surface of a tooth can lead to the exposure of the underlying dentin. When wear is severe tertiary dentin may form to help protect the pulp chamber. [4]
Tertiary dentin is deposited at specific sites in response to injury by odontoblasts or replacement odontoblasts from the pulp depending on the severity of the injury. Tertiary dentin can be divided into reactionary or reparative dentin. Reactionary dentin is formed by odontoblasts when the injury does not damage the odontoblast layer.
Odontoblasts also secrete tertiary dentin when irritated. Tertiary dentin secreted by odontoblasts is often due to chemical attack, either by chemicals diffusing through the dentin and insulting the odontoblasts, or by diffusion of toxic bacterial metabolites down the dentinal tubules in the instance of a carious attack with dental decay. This ...
Parenchyma is a versatile ground tissue that generally constitutes the "filler" tissue in soft parts of plants. It forms, among other things, the cortex (outer region) and pith (central region) of stems, the cortex of roots, the mesophyll of leaves, the pulp of fruits, and the endosperm of seeds.
Dentin is classified into three types: primary, secondary, and tertiary. [ 24 ] [ 25 ] Secondary dentin is a layer of dentin formed after the tooth's root has fully formed. Tertiary dentin develops as a result of a stimulus, such as a carious attack or wear.
Plant nutrition is a difficult subject to understand completely, partially because of the variation between different plants and even between different species or individuals of a given clone. Elements present at low levels may cause deficiency symptoms, and toxicity is possible at levels that are too high.