Glossary
This is a list of some medical terms that you may come across on this site, in books or during discussions with healthcare professionals.
- A-delta fibres: Fast-acting nociceptive nerves that end near the skin surface. They transmit acute pain messages.
- Agonist: A molecule that activates a cell receptor.
- Analgesia: See Analgesic.
- Analgesic: Pain-relieving medication.
- Anterior: At the front.
- Barium enema: Procedure in which a liquid containing a substance called barium is put into the rectum and colon via the anus. Barium is a silver-white metallic compound that helps to show the image of the lower gastrointestinal tract on an X-ray.
- Bradykinin: A small protein that relaxes the smooth muscle in blood vessel walls and activates pain receptors.
- Brainstem: The portion of the brain that connects to the spinal cord, it consists of medulla oblongata, pons and midbrain.
- C-fibres: Slow-acting nociceptive nerves deeper in the body, which transmit chronic pain messages.
- Calcitonin gene-related peptide (CGRP): CGRP is a peptide found in nerve cells, which increases the activity of other nerve cells further up the pathway.
- Capillaries: Tiny blood vessels between arteries and veins that distribute oxygen-rich blood to the body.
- Catheter: Thin, flexible tube through which fluids enter or leave the body.
- Central nervous system (CNS): The brain and spinal cord.
- Cerebellum: The portion of the brain mainly responsible for balance and co-ordination.
- Cerebral hemispheres: The two halves of the cerebrum.
- Cerebrum: The largest portion of the brain, divided into two hemispheres that each contain four lobes. Its functions include speech, memory, vision, personality and muscle control in certain parts of the body.
- Cervical: When discussing the spinal column, this refers to the region of the neck.
- Compound analgesics: Combinations of a simple analgesic and another compound, usually codeine or caffeine.
- Contrast medium: A substance that blocks X-rays and shows up white on an X-ray film. It allows a radiologist to examine the organ or tissue it fills.
- Corpus callosum: A thick band of nerve fibres that connects the two cerebral hemispheres of the brain.
- Dermis: The second layer of the skin. Contains a support structure, blood vessels, nerves and hair follicles.
- Dorsal horn: Part of the spinal cord located towards the back of the body, which acts as a gate for pain messages.
- Enkephalins: Naturally occurring molecules in the brain. Enkephalins attach to special receptors in your brain and spinal cord to stop pain messages. These are the same receptors that respond to morphine and other opioid analgesics. Enkephalins also affect other functions within the brain and nervous system.
- Endorphins: Naturally occurring molecules made up of amino acids, the building blocks of proteins. Endorphins attach to special receptors in the brain and spinal cord to stop pain messages. These are the same receptors that respond to morphine and other opioid analgesics.
- Epidermis: The tough outer protective layer of the skin.
- Epidural: Epidural medications are medications injected into the space where spinal fluid circulates around the spinal cord. They can block pain or other sensations (nerve activity) to the lower half of the body without shutting off muscle activity.
- Foramina: Holes in the skull that the cranial nerves pass through.
- Frontal cortex: The portion of the brain involved with reasoning, planning, abstract thought and other complex thinking functions in addition to motor function.
- Histamine: A chemical made in the body that is involved in inflammation (swelling, heat, pain and redness associated with damage to the tissues of the body), particularly during allergic reactions. Histamine causes blood vessel walls to relax, which increases the blood supply to the damaged tissue (making it red) and allows more fluid to move from the bloodstream into the tissue (making it swell). Antihistamines, used to treat allergies, block the effects of histamine.
- Hives: A condition in which red, itchy, and swollen areas appear on the skin - usually as an allergic reaction from eating certain foods or taking certain medications.
- Hormones: Chemical substances which act as messengers in the body and have direct effects on body tissues.
- Hypothalamus: The part of the brain that controls body functions such as eating, sleeping and sexual behaviour. It maintains body temperature and chemical balance, and regulates many hormones.
- Intrathecal: Injection into the innermost membrane surrounding the central nervous system.
- Intravenous: Into a vein.
- Limbic system : The portion of the brain that produces emotions.
- Midbrain: Part of the brain stem from which the nerves controlling eye movement and eyelid opening arise.
- Motor neurone: A nerve cell that innervates muscle cells.
- Nerve: A bundle of neurones.
- Neurone: Nerve cell.
- Neurotransmitter: Chemical involved in transmitting nervous messages across the gap between neurones.
- Nociceptive neurone: Nerve cell associated with a nociceptor.
- Nociceptor: A structure that recognises signals from inside or outside the body, including temperature, pressure and chemicals. When activated, it sends signals to nerve cells, which carry the messages to the central nervous system (the spinal cord and brain).
- Pain ladder: The World Health Organization Pain Ladder uses a rational, stepwise approach to pain management, starting with the weakest medications first, and progressing up the ladder if the pain is not controlled. It also recommends taking painkillers by the clock (at regular times) and by mouth and also states that pain relief should be tailored to the individual.
- Partial agonist: Molecule that activates a cell receptor, but does not cause as much of a physiological change as does a full agonist.
- Peptide: Any compound consisting of two or more amino acids, the building blocks of proteins.
- Peripheral nerves: Nerves that run to and from the central nervous system (the brain and spinal cord) to and from all other areas of the body. The nerves carry sensory messages (such as touch and temperature) and motor messages, which make the tissues and organs of the body carry out their functions, e.g. muscles contract for movement.
- Posterior: At the back.
- Prostaglandins: A group of substances that have many effects in the body, including playing a role in inflammation (swelling, heat pain and redness associated with damage to the tissues of the body), contraction of smooth muscle (e.g. in blood vessel walls) and maintaining a constant body temperature.
- Sensory neurones: Nerve cells within the nervous system responsible for converting external stimuli from the organism's environment into internal electrical impulses.
- Sensory receptor: Structure that recognises a stimulus in the internal or external environment of an organism. In response to stimuli, it creates graded potentials or action potentials (a nerve signal) in the nerve cell to which it belongs, or in an adjacent one.
- Simple analgesics: Medications containing a single drug, that are used to treat pain – such as paracetamol, aspirin and non-steroidal anti-inflammatory drugs (NSAIDs).
- Somatosensory cortex: The part of the brain responsible for processing stimulation coming from the skin, muscles, bones, tendons and joints. It plays a part in determining pain intensity.
- Spinal column: The bones of the back. The spinal column protects the spinal cord and allows for movement of the body in various ranges of motion.
- Spinal cord: The bundle of nerves that extends from the base of the brain to the small of the back. It processes information and conducts impulses between the brain and the rest of the body.
- Stimulus: An internal or external event which generates nervous system activity or response.
- Substance P: A protein substance that stimulates nerve endings at an injury site and within the spinal cord, increasing pain messages.
- Thalamus: Part of the brain that serves as a relay station to and from the cerebral cortex. Amongst other messages, it relays pain signals.
