Chemotaxis

Chemotaxis is the directed movement of cells along a chemical concentration gradient. Cells move toward attractants or away from repellents by sensing how chemical concentration changes across space or time.

Chemoreceptor: A receptor that detects chemical molecules and initiates a cellular response. Chemoreceptors detect attractants or repellents and begin the signaling that guides movement.
Chemical gradient: A spatial change in the concentration of a chemical substance. Chemotaxis depends on concentration differences that provide directional information.
Neutrophil: A short-lived white blood cell that engulfs microbes and is abundant at sites of acute inflammation. Neutrophils use chemotaxis to reach infected or damaged tissue.
Klinokinesis: A change in movement rate in response to stimulus intensity, without orienting toward its source. It changes how quickly an organism moves rather than steering it along a chemical gradient.
Bacterial chemotaxis: The system by which bacteria bias their swimming in response to chemical gradients. Its run-and-tumble strategy is a well-characterized example of gradient tracking.
Diffusion: The net movement of particles from regions of higher concentration to lower concentration. Diffusion often creates or disperses the gradients that cells follow.
Leukocyte extravasation: The passage of white blood cells from the bloodstream through vessel walls into tissue. Chemotactic signals help guide leukocytes after they leave the circulation.
Phototaxis: Directed movement toward or away from a light source. It uses light, rather than a chemical gradient, as the directional cue.
CheY: A bacterial response regulator whose phosphorylation changes the rotation of flagellar motors. CheY links receptor signals to changes in swimming direction.
Cell migration: The movement of cells from one location to another. Chemotaxis is a directional form of cell migration.

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