medical vocabulary

Glossary
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ART

Assisted reproductive technology

Active transport

Movement of substances across a semipermeable membrane from areas of low concentration to high concentration requiring the input of energy

Adenosine triphosphate

Also known as ATP; high energy-carrying molecule found in cells

Afferent division

The system of nerve tissue that brings impulses towards the CNS

Allele

An alternative form of a gene

Amino acids

The individual units or building blocks of a protein

Antigen

Any substance that can trigger an immune response

Artefact

Any object made by humans, eg tools or weapons

Autoimmune condition

A condition that involves the body's immune system attacking the body's cells or tissues, eg diabetes mellitus type 1, rheumatoid arthritis and gout

Autonomic nervous system

Also known as ANS; the division of the nervous system responsible for the control of involuntary muscles and glands

Axon

A thin extension of neuron that carries impulses away from the cell body

Axon terminals

Small knob-like structures found at the end of an axon that store and release neurotransmitter substances

Blastocyst

A hollow ball of cells formed during early embryonic development

Cell body

Contains the nucleus and organelles of a neuron to control and maintain normal functioning

Central nervous system

Also known as CNS; the division of the nervous system consisting of the brain and spinal cord

Cerebral cortex

Specialised area of the cerebrum in humans that coordinates emotions, higher order thinking and problem solving, perception of senses and control of voluntary muscle movements

Chemoreceptors

Receptor cells that detect changes in chemical concentrations, ie oxygen, carbon dioxide and hydrogen ion concentrations

Chronic

A disease that persists over a long period of time; it may be progressive, result in complete or partial disability or even lead to death

Cleavage

The splitting of a fertilised egg into a number of cells

Compatability

The ability to combine different blood types without the body launching an immune response against the foreign blood

Contagious

Type of disease transmissible by direct or indirect contact

Denature

To cause a protein (eg enzyme) to lose some of its original properties; often this occurs due to temperature or pH changes

Dendrites

Thin extensions of a neuron that conduct impulses towards its cell body

Dendron

A single dendrite found on a sensory neuron

Diabetes insipidus

A condition caused by low secretion of antidiuretic hormone that results in extreme thirst and frequent urination; this is not to be confused with diabetes mellitus, which is related to lack of insulin secretion

Diabetes mellitus type 1

Also known as 'juvenile onset' diabetes; an autoimmune condition that results in the destruction of insulin-producing beta cells; treatment involves insulin replacement via injection or pump

Diabetes mellitus type 2

Also known as 'mature onset' diabetes; a condition linked to insufficient levels of insulin or cells becoming insensitive to insulin that prevents glucose from being taken up; can be managed with healthy diet/lifestyle

Donor

A person who gives tissue (blood) or organs

Dorsal root of spinal cord

A division of a spinal nerve attached to the posterior (back) of the spinal cord

Efferent division

The system of nerve tissue that takes impulses away from the CNS

Embryology

The study of the development of an embryo

Endocrine glands

A type of gland that secretes substances directly into the bloodstream

Endocrine system

System of ductless glands responsible for the production and secretion of hormones as chemical messengers in the body

Epigenetics

The study of changes in phenotype or gene expression caused by mechanisms other than the DNA sequence, eg the environment

Epigenome

An extra genome that switches genes 'on' or 'off'

Evolution

The continuing process of change

Exocrine glands

Ducted glands that secrete substances through tiny tubes called ducts to their target cells or organs, eg lacrimal, pancreas and sweat

Facilitated diffusion

Diffusion of substances across a semipermeable membrane with the assistance of carrier proteins

Fatty acids

The building blocks or basic units of lipids

Feedback

Information received about an event-mechanism in the body

Feedback loop diagram

A diagram used to show a response to a stimulus; usually involves the components of stimulus, receptor, modulator, effector, response and information about the type of feedback

Founder effect

When a small group forms a new colony, isolated from the main population, without the full representation of gene variation

Ganglion

A group or cluster of neuron cell bodies within a section of a nerve

Gene flow

The movement of genes between populations by interbreeding or migration

Gene frequency

Also known as gene allele frequency; gene frequency is the number of times that a gene occurs in a population

Gene pool

The sum total of all the genes possessed by the individuals in a population

Gestational diabetes

A condition in which women without previously diagnosed diabetes exhibit high blood glucose levels during pregnancy; the condition rarely continues after the birth of the child

Gland

A structure or organ that secretes a substance

Gluconeogenesis

The process of manufacturing new glucose molecules from molecules other than carbohydrates, ie fats and amino acids

Glycogenesis

The process of converting glucose to glycogen in the liver and muscles

Glycogenolysis

The process of breaking down glycogen into glucose

Half-life

The time required for a given amount of a radioisotope to decrease by half its value due to radioactive decay

Heart palpitations

An awareness of the heart beating in an abnormal pattern - either too fast, too slow or irregularly

Heterozygous

Possessing different alleles for a given characteristic

Homeostasis

The maintenance of a steady state within the internal environment

Homozygous

Possessing identical alleles for a given characteristic

Hormones

Chemical messenger molecules secreted from endocrine glands that produce responses in their target cells or organs when present, eg thyroxine, prolactin and insulin

Hot flushes

A sensation of heat or 'flushing' that occurs suddenly; a symptom associated with the onset of menopause

Hydrophilic

Molecules that are soluble in water or can interact with water

Hydrophobic

Molecules that are insoluble in water or are water repelling

Hypothalamus

Region within the brain responsible for the regulation of many homeostatic mechanisms and endocrine activity

Immune response

A response triggered by a foreign substance or microbe entering the body

Incontinence

Involuntary urination or defaecation; this is a condition usually experienced by older men and women

Index fossil

Can be the remains of an organism that was known to live only during a limited time period in the past

Infundibulum

Stalk of tissue connecting the pituitary gland to the hypothalamus

Insomnia

An inability to sleep

Interneuron

Type of neuron found within the CNS that links sensory and motor neurons; also referred to as a relay, association or connector neuron

Libido

Sexual urge or desire

Lifestyle related

A term to describe conditions that have been contributed to by one or several factors related to a person's lifestyle, for example overeating, smoking or too little exercise

Lipogenesis

The process of storing glucose as fat in the tissues

Lipolysis

The process of breaking down fats to glucose

Locus

The position of a gene on a chromosome

Medulla oblongata

Structure located at the top of the spinal cord responsible for regulation of many homeostatic mechanisms including heart rate and breath rate

Melanoma

A malignant form of skin cancer that forms in melanocytes (pigment producing cells)

Messenger RNA

Also known as mRNA; the template molecule made from DNA that travels out of the nucleus to the ribosomes (the site of protein synthesis in the cell)

Metamorphisis

A change in an organism's physical structure that occurs during its development

Migration

The movement of individuals or populations into or out of a geographic location

Mobilisation

To activate or release into a system

Monogenic inheritance

Characteristics or traits determined by a single pair of genes

Motor end plate

The axon terminal that connects to muscle tissue

Motor neurons

Neurons that carry impulses away from the CNS

Multiallelic inheritance

Characteristics or traits that are governed by a gene that can have more than one alternative form

Multifactorial inheritance

Conditions and diseases that are influenced by more than one pair of genes and by environmental factors

Mutation

A sudden and permanent change in the structure of a gene or chromosome

Myelin sheath

Fatty, insulative layer formed by Schwann cells that can surround some dendrites, axons and functions to increase the speed of a nerve impulse

Myelinated

A neuron with a myelin layer

Natural selection

Theory proposed by Charles Darwin that states: individuals best adapted to their environment are most likely to compete successfully and survive to reproduce, passing on their favourable characteristics to their offspring and over many generations increasing these characteristics in the population

Negative feedback

A series of events where a response removes or reverses an initial stimulus or change; abbreviated to (-ve) feedback

Nerve

A bundle of nerve fibres held together by connective tissue

Nerve impulse

An electrical signal passed through a neuron or nerve

Nervous system

System of specialised nervous tissue that receives, processes and transmits information from the internal and external environments

Neurilemma

Protective membrane that covers the myelin surrounding some axons/dendrites; assists in the repair of axons and dendrites

Neuron

A single nerve cell

Neurotransmitter

Chemical produced from an axon terminal that assists in passing an impulse from one neuron to another

Night sweats

When hot flushes occur at night, the result is often profuse sweating

Nodes of Ranvier

Gaps along the myelin sheath of axons and dendrites; these gaps increase the speed of a nerve impulse

Noradrenaline

Chemical hormone released from the adrenal medulla that also acts as a neurotransmitter

Osmosis

The diffusion of water through a semipermeable membrane from an area of high water concentration to an area of low water concentration

Parasympathetic nervous system

Division of the ANS that is stimulated to return internal body functions to normal (after periods of stress or activity)

Pathogen

Any disease-causing organism, eg bacteria, virus, fungi and parasites

Peripheral nervous system

Also known as PNS; comprises all the nerve tissue that lies outside the CNS

Phenotype

The expression of a gene; the physical appearance of an organism in respect to a particular characteristic

Phospholipid

A double-layered arrangement of phosphate and lipid molecules that form cell membranes; the hydrophobic lipid ends face inwards and the hydrophilic phosphate ends face outwards. Sometimes known as a lipid bilayer

Pigmentation

Colour of skin is due to the deposition of melanin which is a colouring matter; melanin is produced by specialised cells called melanocytes

Pituitary gland

Endocrine gland known as the 'master gland' located in the brain which produces, stores and secretes hormones

Polygenic inheritance

Characteristics or traits determined by more than one pair of genes acting together

Polypeptide chains

Chains of amino acids that when linked together form new protein molecules

Population

A group of organisms of the same species living together at a particular place and time

Positive feedback

A series of events where a response increases or supports an initial stimulus or change; abbreviated to (+ve) feedback

Protein synthesis

The process of building new proteins from long chains of amino acids; the cell's DNA is responsible for controlling this process

Protein-based hormone

Type of hormone which is water soluble and secreted from the pituitary, pancreas and adrenal medulla

pH

The scale used to measure the acidity or alkalinity of a substance; the scale is numbered 1-14 with 1 being highly acidic and 14 highly alkaline

Radioactive isotope

An element with an unstable nucleus that emits radiation

Random genetic drift

A change in the allele frequency due to chance not natural selection in small populations

Receptor

Specialised cells that receive stimuli from the environment

Reflex

An involuntary response to a stimulus, eg blinking or swallowing

Reflex arc

The path taken by a nerve impulse during a spinal reflex

Retina

Innermost layer of the eye; it lines the rear portion of the inside of the eye where light rays focus; houses photoreceptors (light receptors)

Schwann cells

Specialised cells that produce myelin in neurons

Selection pressure

Factors that can reduce reproductive success in a population

Self-antigen

Any large molecule produced in a person's body that does not cause an immune response in that person

Sensory neurons

Neurons that bring impulses from receptors towards the CNS

Signal molecules

Neurotransmitters or hormones that either pass through or attach to receptors on the cell membrane to cause a response

Signal receptors

Sites located on the cell membrane that link with signal molecules in order to transport them to the interior of the cell

Simple diffusion

The movement of substances from areas of high concentration to low concentration (no energy required)

Somatic division

The division of the PNS that carries impulses to voluntary muscles

Species

A group of similar organisms that are capable of interbreeding and producing fertile offspring under natural conditions

Steroid hormone

Type of hormone which is fat soluble and produced from the gonads and adrenal cortex

Stimuli

Internal or external changes that initiate a response

Stimulus-response feedback model

A diagram used to explain how the changes to the body are responded to so as to maintain homeostasis

Strata

Layers of sedimentary rock

Subspecies

A subdivision of a species consisting of an isolated population of interbreeding organisms

Sympathetic nervous system

Also known as fight or flight; division of the ANS that stimulates internal body functions in times of stress or activity

Synapse

The gap between two neurons that allows for the transmission of a nerve impulse

Tay-Sachs disease

A genetic disorder caused by a missing enzyme that results in the build up of a fatty substance in the nervous system - results in disability and death

Thermoreceptors

Receptor cells that detect changes in blood temperature and temperature of the external environment

Ventral root of spinal cord

A division of a spinal nerve attached to the anterior (front) of the spinal cord

Vertebrates

A subphylum within the phylum Chordata; animals with backbones

Vesicles

Small sacs that store neurotransmitters in the axon terminal

Vestigial

Relating to a body part that has become small and lost its use because of evolutionary change



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