Cell

In biology, the structural and functional unit of all living organisms, which exists as an independent unit of life in bacteria and protozoans, and first described by Robert Hooke (1635-1703) in 1665 with the aid of a light microscope.  In other living organisms, they form colonies or tissues.  Each cell contains protoplasm differentiated into cytoplasm …

Causality (in philosophy)

Covers three distinct meanings.  To begin with, there is causation (the causal relationship between two things when the first is a necessary and/or sufficient condition the occurrence of the second), the causality principle (a statement of the law of causation in the form ‘The same cause always or invariably produces the same effect’), and causal …

Causal pathway

The sequence of causes leading to the outcome of interest.  In epidemiology and the design of clinical trials, the identification of causal pathways leading to pathology is a major objective.  In studying development, normal or pathological, causal pathways can be more readily identified from retrospective studies than from longitudinal data gathered prospectively.  Structural equation modelling …

Causality (as a psychological phenomenon)

Perception of cause-effect relationships among objects.  The roots of this interpretation of causality lie with David Hume (1711-1776) who argued that causality is not a logical relationship waiting to be discovered, but rather is based on inferences derived from experiencing a succession of events.  With this contention, he shifted the study of causality from logic …

Causal determinism (or causalism)

The doctrinal assertion of the causality principle.  In general terms, it advocates the idea that every event is necessitated by antecedent events and conditions, together with the laws of nature.  Pursued thoroughly enough, it has been held, then it will explain all phenomena and thus give rise to a Theory of Everything. See Cause (or …

Caudal

From the Latin word for a ‘tail’, it means at the back or end of the longitudinal axis of the body or organ, and in the brain toward the brain stem.  Used as a directional term in anatomy and physiology. See Dorsal, Neurulation, Rostral, Ventral

Catecholamines

A group of hormones that act as neurotransmitters, which are mainly manufactured by the chromatin cells (the secretory organelles) of the medulla of the adrenal glands and from the postganglionic fibbers of the sympathetic nervous system.  The most abundant catecholamines are three closely related chemical messengers:epinephrine (adrenaline), norepinephrine (noradrenaline) and dopamine, all of which are …

Categorical perception

A perceptual phenomenon by whichvarious instances of stimuli equally distant from each other in their physicalproperties are mapped to different perceptual categories (i.e., /b/ and /p/).  Thus, it means that a change insome variable along a continuum not perceived as gradual but as an instance of a discrete categorie.  Some stimuli are perceived as belonging to …