Encyclopedia

Attention

Attention is a cognitive process that allows to select some environmental stimuli, ignoring others. From an evolutionary point of view, it is an extremely useful mechanism for human survival because it allows us to organize the information coming from the external environment, which is constantly changing, and to regulate mental processes accordingly. Attention refers to …

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Carbon

Carbon [symbol C] (from Latin: carbo “coal”) is a nonmetallic and tetravalent (rarely bivalent) chemical element—making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Individual carbon atoms have an incomplete outermost electron shell. With an atomic number of 6 (six electrons and six protons), the first …

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Muscle tissue

Muscle tissue is excitable, responding to stimulation and contracting to provide movement, and occurs as three major types: skeletal (voluntary) muscle, smooth muscle, and cardiac muscle in the heart. Muscle tissue is composed of cells that have the special ability to shorten or contract in order to produce movement of the body parts. The tissue is …

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Biological tissue

A biological tissue is an ensemble of similar cells and their extracellular matrix, characterized by similar structure and functions. Tissues represent the next level of organization after cellular organization; in practice, they are formed by cells of the same type that associate together to perform a common function. Each tissue therefore possesses one or more …

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Nervous system

The nervous system is the major controlling, regulatory, and communicating system in the body. It is the center of all mental activity including thought, learning, and memory. Together with the endocrine system, the nervous system is responsible for regulating and maintaining homeostasis. Through its receptors, the nervous system keeps us in touch with our environment, …

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Muscular system

The muscular system is composed of specialized cells called muscle fibers. Their predominant function is contractibility. Muscles, attached to bones or internal organs and blood vessels, are responsible for movement. Nearly all movement in the body is the result of muscle contraction. Exceptions to this are the action of cilia, the flagellum on sperm cells, …

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Cytoplasm

The cytoplasm is the gel-like fluid inside the cell, which represents the portion (about half of the total volume of the cell) contained within the cell membrane present in both eukaryotic and prokaryotic cells. It consists of cellular organelles dispersed in a fluid matrix called the cytosol. It is the medium for chemical reaction. It …

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Glial cells [glia]

Glial cells (also called glia or neuroglia), are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses; supportive tissue of the brain, includes astrocytes, oligodendrocytes, ependymal cells and microglia. Unlike neurons, glial cells do not conduct electrical impulses; and they can reproduce. …

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Nervous tissue (neural tissue)

Nervous tissue allow the propagation of electrochemical signals in the form of nerve impulses that communicate between different regions of the body. Nervous tissue is formed by neurons (excitable cells) and non-excitable cells, which together constitute the neuroglia (see: glial cells) with functions of support, nutrition, facilitation in the conduction of the nerve impulse. Neurons are …

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Linear Variable Differential Transformer (LVDT)

A linear variable differential transformer (LVDT) is one of the most popular electromechanical devices used to convert small mechanical displacements (mechanical vibrations or mechanical motion of the order of a few millimeters or fractions of a millimeter) into amplified electrical signals (variable electrical current, voltage or electrical signals, and vice versa). LVDTs are linear position sensors. Drive …

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