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depolarization

n. a reduction in the electric potential across the plasma membrane of a cell, especially a neuron, such that the inner surface of the membrane becomes less negative in relation to the outer surface. Depolarization occurs when the membrane is stimulated and sodium ions (Na+) flow into the cell. If the stimulus intensity exceeds the excitatory threshold of the neuron, an action potential is created and a nerve impulse propagated. Compare hyperpolarization.

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Psychology term of the day

December 22nd 2024

family

family

n.

1. a kinship unit consisting of a group of individuals united by blood or by marital, adoptive, or other intimate ties. Although the family is the fundamental social unit of most human societies, its form and structure vary widely. See biological family; extended family; nuclear family; permeable family; stepfamily.

2. in biological taxonomy, a main subdivision of an order, consisting of a group of similar, related genera (see genus).

3. a collection of mathematically or statistically related entities. For example, a set of statistical tests conducted when there are more than two groups for an independent variable within an analysis of variance constitutes a family of tests. See also family-wise alpha level; family-wise error rate. —familial adj.