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A biochemical cascade, also known as a signaling cascade or signaling pathway, is a series of chemical reactions that occur within a biological cell when initiated by a stimulus.
A fanning honeybee exposes Nasonov's gland (white – at tip of abdomen) releasing pheromone to entice swarm into an empty hive. A pheromone (from Ancient Greek φέρω (phérō) 'to bear' and hormone) is a secreted or excreted chemical factor that triggers a social response in members of the same species.
In physiology, a stimulus [1] is a change in a living thing's internal or external environment.This change can be detected by an organism or organ using sensitivity, and leads to a physiological reaction. [2]
The Trigger Effect is a 1996 American thriller film written and directed by David Koepp and starring Kyle MacLachlan, Elisabeth Shue and Dermot Mulroney. The film follows the downward spiral of society during a widespread and lengthy power outage in Southern California .
There are three basic types of secondary messenger molecules: Hydrophobic molecules: water-insoluble molecules such as diacylglycerol, and phosphatidylinositols, which are membrane-associated and diffuse from the plasma membrane into the intermembrane space where they can reach and regulate membrane-associated effector proteins.
For many years, it was believed that the axon hillock was the usual site of initiation of action potentials—the trigger zone. It is now thought that the earliest site of action potential initiation is at the axonal initial segment: just between the peak of the axon hillock and the initial (unmyelinated) segment of the axon. [3]
Early forms of the receptor theory of pharmacology stated that a drug's effect is directly proportional to the number of receptors that are occupied. [14] Furthermore, a drug effect ceases as a drug-receptor complex dissociates. Ariëns & Stephenson introduced the terms "affinity" & "efficacy" to describe the action of ligands bound to receptors.
An immune response is a physiological reaction which occurs within an organism in the context of inflammation for the purpose of defending against exogenous factors. These include a wide variety of different toxins, viruses, intra- and extracellular bacteria, protozoa, helminths, and fungi which could cause serious problems to the health of the host organism if not cleared from the body.