Addiction and neural ageing
Addiction and neural ageing

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Glossary for SD805_2
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absorptive state

Period after a meal during which glucose is entering the bloodstream after its absorption from the gut.


A neurotransmitter. (Adj. cholinergic.)

action potential

A pulse of electricity that is generated in neurons and travels their length. The means of communication within neurons. Action potentials are ‘all-or-none’, meaning that they either occur in full or not at all.

active site

The region of an enzyme molecule where the substrate binds and catalysis occurs.

active transport

Transport processes across membranes that require the expenditure of energy and use specialised transport molecules.

adaptive characteristics

Variations in body structure, or function, or behaviour, which give some members of a species a survival advantage and hence increase their chances of leaving more surviving offspring than other members of the same species.

adenosine triphosphate



adipose tissue

Tissue composed of fat cells (adipocytes). The site of storage of fats (triacylglycerols).


Term used in psychology and psychiatry as a way of describing a person’s responses of emotion and attention to events in the world around them.


A process to do with sensations of pleasure and displeasure.

afferent neuron

A neuron that conveys information to a structure. Often used to mean neurons that convey information to the central nervous system, i.e. sensory neurons.


A substance that mimics the natural effect of a neurotransmitter by occupying receptor sites for the natural substance.


One of several alternative forms of a gene occupying a given locus on a chromosome.


Focused on an object in its own right, rather than in relation to oneself.

allosteric site

Region of an enzyme molecule where the regulatory molecule (often the end-product of a metabolic pathway) can reversibly bind. This results in a change in shape of the active site and so modifies substrate binding and enzyme catalysis.

amino acid

Building block of polypeptides and proteins, so named because of the presence of the amino, –NH2, and carboxylic acid, –COOH, groups of atoms in their structure. There are 20 common naturally occurring amino acids.


Brain structure with a primary role in motivation and emotion.

amyloid precursor protein (APP)

A large transmembrane glycoprotein, which has been shown to play a major role in the pathogenesis of Alzheimer’s disease, as well as other related cerebral amyloid diseases. APP is made of 695 amino acids (APP-695). In 1988, three research groups simultaneously reported the isolation of cDNA clones that were shown to contain one or two additional domains compared with original APP-695. One of them showed extensive similarity to the Kunitz family of serine protease inhibitors (KPI) and resulted in a 56 amino acid insertion within the extracellular domain of the precursor protein. Therefore, the APP gene transcript and the corresponding APP protein that contain the nucleotide sequence or amino acid sequence, respectively, encoding this insert are denoted as KPI-APP or APP-751. APP-695 is predominantly expressed in the brain during development. The level of KPI-APP or APP-751 increased during ageing.


Term describing metabolic reactions that result in the synthesis of materials and in which energy is consumed.


Reduction in the intensity of pain.


A means of specifically relieving pain, e.g. injection of morphine, as distinct from an anaesthetic, which reduces all sensations.

animal model

The study of a particular non-human animal in such a way as to reveal general properties, e.g. about how a human might function.

anorexia nervosa

The relentless pursuit of thinness through self-starvation, even as far as death.


A substance that occupies the nerve synapse receptor sites and blocks the natural transmitter’s receptor occupation and so inhibits its action.

anterograde amnesia

An inability to remember new information for any length of time.


The three-base sequence in a tRNA molecule that is complementary to a particular threebase sequence (the codon) in an mRNA molecule.


A molecule that opposes oxidation reactions brought about by free radicals, hence the name antioxidant. The term is often applied to substances that can trap free radicals; for example, vitamin E is an antioxidant.


That which produces, or increases, anxiety.


Tending to reduce anxiety.


American Psychological Association.


General medical term used to describe a disturbance of speech caused by damage to the brain; strictly, an absence of speech.

apolipoprotein E (ApoE)

The purified protein component of a lipoprotein particle. In mammals, a group of eight apolipoproteins will most often be present in a set ratio. This complex molecule serves a wide variety of functions in the blood, including transport of fat from tissue to tissue.


Amyloid precursor protein.


Something unnatural that arises as a result of an experimental intervention. For example, a structure that is seen when a cell preparation is examined under the microscope may appear to be a natural cell component, but may actually be the result of an alteration in the cell’s structure caused by the procedures used to prepare the specimen for microscopy.


Derived from a history of associations, as in Pavlovian conditioning.

associative conditioning

The process by which an organism forms an association between two events. The term covers both classical and instrumental conditioning. In either case, one event owes its strength to its pairing with some other event.

associative learning

Learning by experience to associate two events that have been paired (e.g. the sight of a needle with the effect of heroin).


The smallest particle of an element, consisting of a core of protons and neutrons (the nucleus) surrounded by electrons.


Adenosine triphosphate. Each molecule of ATP is made up of a nucleotide base, a sugar unit and a chain of three phosphate groups.  ATP is the energy currency of the cell.  Energy is stored as ATP in the reaction between ADP (adenosine diphosphate) and Pi (inorganic phosphate):

ADP + PiArrow ATP

and is made available as required via the breakdown of ATP to ADP and Pi.

autoimmune disease

Type of disease in which the immune system of an organism attacks the normal healthy body of the same organism. Autoimmunity or immunological reactions caused by antibodies or T lymphocytes can produce severe inflammation or be innocuous, as when directed to intracellular autoantigens. Autoimmunity can develop spontaneously or be induced experimentally by immunisation with autoantigens or with antigens that are cross-reactive with them.

autonomic ganglion

A collection of cell bodies of neurons within the autonomic nervous system.

autonomic nervous system (ANS)

That branch of the nervous system that is responsible for controlling the activity of smooth muscle, cardiac muscle and glands of the body.


Concerned with the theory of value.

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