Voluntary generation of skeletal muscle tension without muscle shortening or any changes in joint angle. This type of contraction occurs when carrying an object in front of the body with its weight pulling the arms downwards. Gripping a tennis racket is another example. The length of the muscle at the point of contraction determines the …
Category Archives: Uncategorized
Isomorphism
In mathematics, a one-to-one correspondence between the elements of two or more sets or classes that preserves the structural properties of the domain (e.g., the Arabic numerals 1, 2, 3 and the Roman numerals I, II, III). In biology, it refers to similarity in form or structure between two or more substances or entities. Three …
Isocortex
Same as cerebral cortex, but the preferred technical term; ‘iso’ refers to the similar six-layered structure the cortex has throughout its extent. See Cell migration, Cerebral cortex (or pallium), Neocortex
Irreversible thermodynamics
An extension of classical thermodynamics to non-linear systems and far-from-equilibrium situations in which self-organization may occur. It shows how new forms of order may emerge via state transitions when energy flows exceed the dissipating capacity of an existing structure. The process by which this is achieved is irreversible (i.e., once a new structure emerges, the …
Ischemia
Local anemia due to mechanical obstruction (mainly arterial narrowing or disruption) of the blood supply. See Anoxia, Brain damage studies, Hypoxia, Hypoxic-ischemic encephalopathy, Periventricular hemorrhagic infarction (PHI), Periventricular leucomalacia (PVL)
Iodine deficiency
An insufficient quantity of iodine and essential constituents of thyroxine (T4) and triiodothyronine (T3), which are necessary for normal growth and development. The sensitivity of different organs to iodine deficiency varies, with the brain being particularly susceptible during the fetal and early postnatal period, and if severe enough, leading to endemic cretinism (if diagnosed in …
Irregular words
Words that contain inconsistent grapheme-to-phoneme correspondences (e.g., break). See Exception words, Grapheme, Grapheme-phoneme correspondences, Phoneme, Regular words
Iodine:
Discovered by Bernard Courtois (1777-1838) in 1811, iodine is a trace element, essential to (human) life, found in rocks, seawater and some types of soil. Sea fish and shell fish are also good sources of iodine, and it can be found in milk in the UK. It has an important biological function in that it …
Intuitive theory of something
A child’s set of ideas on a domain. Intuitive physics may include the notion that one moving object has just one speed, a notion that applies well to the front mudguard of a bicycle, but not to the front wheel whose spin is very rapid at the tire surface and much slower next to the …
Invagination
A morphogenetic process involving the inward folding of an unbroken layer of cells into the central cavity of the blastula during the initial stage of gastrulation. It results in a considerable re-organization of the embryo from a spherical balls (i.e., blastula) into a multilayered organism, with differentiated germ layers (viz: entoderm. mesoderm, ectoderm) See Bastula, …