Atlas de Anatomia do Corpo Humano - Central

The atlas of human body

Myelin Sheath
Myelin Sheath

The lipid-rich sheath surrounding AXONS in both the central and peripheral nervous systems. The myelin sheath is an electrical insulator and allows faster and more energetically efficient conduction of impulses. The sheath is formed by the cell membranes of glial cells (SCHWANN CELLS in the peripheral and OLIGODENDROGLIA in the central nervous system). Deterioration of the sheath in DEMYELINATING DISEASES is a serious clinical problem.

Ranvier's Nodes
Ranvier's Nodes

Regularly spaced gaps in the myelin sheaths of peripheral axons. Ranvier's nodes allow saltatory conduction, that is, jumping of impulses from node to node, which is faster and more energetically favorable than continuous conduction.

Neuroeffector Junction
Neuroeffector Junction

The synapse between a neuron (presynaptic) and an effector cell other than another neuron (postsynaptic). Neuroeffector junctions include synapses onto muscles and onto secretory cells.

Neuromuscular Junction
Neuromuscular Junction

The synapse between a neuron and a muscle.

Motor Endplate
Motor Endplate

The specialized postsynaptic region of a muscle cell. The motor endplate is immediately across the synaptic cleft from the presynaptic axon terminal. Among its anatomical specializations are junctional folds which harbor a high density of cholinergic receptors.

Synapses
Synapses

Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.

Synaptic Membranes
Synaptic Membranes

Cell membranes associated with synapses. Both presynaptic and postsynaptic membranes are included along with their integral or tightly associated specializations for the release or reception of transmitters.

Cell Membrane
Cell Membrane

The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.

Cell Membrane Structures
Cell Membrane Structures

Structures which are part of the CELL MEMBRANE or have cell membrane as a major part of their structure.

Tight Junctions
Tight Junctions

Cell-cell junctions that seal adjacent epithelial cells together, preventing the passage of most dissolved molecules from one side of the epithelial sheet to the other. (Alberts et al., Molecular Biology of the Cell, 2nd ed, p22)

Desmosomes
Desmosomes

A type of junction that attaches one cell to its neighbor. One of a number of differentiated regions which occur, for example, where the cytoplasmic membranes of adjacent epithelial cells are closely apposed. It consists of a circular region of each membrane together with associated intracellular microfilaments and an intercellular material which may include, for example, mucopolysaccharides. (From Glick, Glossary of Biochemistry and Molecular Biology, 1990; Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)

Coated Pits, Cell-Membrane
Coated Pits, Cell-Membrane

Specialized regions of the cell membrane composed of pits coated with a bristle covering made of the protein CLATHRIN. These pits are the entry route for macromolecules bound by cell surface receptors. The pits are then internalized into the cytoplasm to form the COATED VESICLES.

Caveolae
Caveolae

Endocytic/exocytic CELL MEMBRANE STRUCTURES rich in glycosphingolipids, cholesterol, and lipid-anchored membrane proteins that function in ENDOCYTOSIS (potocytosis), transcytosis, and SIGNAL TRANSDUCTION. Caveolae assume various shapes from open pits to closed vesicles. Caveolar coats are composed of CAVEOLINS. Caveolins;

Purple Membrane
Purple Membrane

Functionally and structurally differentiated, purple-pigmented regions of the cytoplasmic membrane of some strains of Halobacterium halobium. The membrane develops under anaerobic conditions and is made almost entirely of the purple pigment BACTERIORHODOPSINS. (From Singleton & Sainsbury Dictionary of Microbiology and Molecular Biology, 2d ed)

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