Medical dictionary

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Packed cell volume: measurement of the proportion of the blood occupied by the red blood cells. Normal values are 40-54% in males, 35-47% in females.
Pacemaker: the group of cells in the heart (or an electrical device) that starts off the electrical wave that causes a heartbeat.
Paget's disease: affects bone growth; the abnormality occurs in the bone cells. The regular ordered process of bone loss and formation does not take place properly; bone cells increase in number, become larger and also more active. The most common symptom is pain.
Palindromic rheumatism: intermittent episodes of arthritis.
Palliative: offering relief of symptoms or comfort without ameliorating the underlying disease process.
Palliative care: treatment aimed at relieving symptoms and pain rather than effecting a cure.
Pallor: the absence of normal skin color.
Palpable: something that can be felt.
Palpation: feeling with the hands.
Palsy: paralysis, or problems in the control of voluntary movement.
Panchakarma: a branch of ayurvedic medicine that deals specifically with detoxification.
Pancreas: a large gland behind the liver that gives off digestive juices and insulin.
Pancreatic enzymes: proteins made by the pancreas that aid in digestion.
Pancreatitis: inflammation of the pancreas.
Pancytopaenia: condition in which there are reduced numbers of all types of blood cells.
Panic attack: an episode of anxiety where you feel unwell and scared. It comes on suddenly and you will usually be worried that you have something seriously wrong with you.
Panniculitis: inflammation of fat under the skin.
Papillitis: optical disk inflammation.
Papilloedema: swollen optical disk.
Papillomavirus: the large group of papova viruses that includes the cause of genital warts or condylomata.
Papule: a small elevation or bump on the skin.
Paraesthesia: abnormal sensations such as burning, tingling or pins and needles.
Paralysis: a complete or partial loss of muscle function and/or loss of sensation.
Paranoia: a form of psychosis characterized by mood changes and emotional instability.
Paraplegia: paralysis of the legs.
Paraprotein (malignant): malignant paraprotein is a form of antibody characteristic of, and produced by, malignant cells of the mature b-cell type, for example in multiple myeloma. Its presence in the blood acts as an important marker of disease.
Parasite: an organism living in or on another organism.
Parasympathetic system: deals mainly with the digestion, fights off infection, controls the immune response and tries to conserve energy in order to ensure survival.
Parenchyma: functional tissue of an organ.
Parenteral: outside the digestive tract. This term refers to intravenous, subcutaneous and other non-oral modes of administering medications and therapies.
Paresis: weakness or paralysis. In cerebral palsy, these terms are typically combined with another phrase that describes the distribution of paralysis and weakness, e.g. paraparesis.
Parkinson's disease: a chronic degenerative disease of the brain.
Paronychia: inflammation of the nail skin.
Parotitis: swollen glands.
Paroxysmal: in sudden attacks.
Paroxysmal nocturnal haemoglobinuria (PNH): a rare disorder characterised by an increased rate of break- down of red blood cells and decreased production of white blood cells and platelets. This leads to excretion of the red blood pigment, haemoglobin, in the urine, particularly at night.
Parturition: giving birth.
Patellofemoral syndrome: normally, as the knee bends, the patella slides smoothly along a groove in the thigh bone. However, under certain conditions the patella may experience forces which push it against the sides of the groove, causing pain. Additionally, inflammation and roughening of the smooth underside of the patella may occur.
Pathogen: disease-producing organism.
Pathogenesis: the manner in which a particular infectious microbe causes disease.
Pathological: related to the study of disease.
Pathologist: a doctor who specialises in the cause and diagnosis of disease and how disease affects the organs of a body.
Pediculosis: lice.
Pelvic Inflammatory Disease (PID): a gynaecological condition caused by an infection (usually sexually transmitted) that spreads from the vagina to the upper parts of a woman's reproductive tract in the pelvic cavity.
Penicillinase: penicillin-destroying enzyme.
Pepsin: an enzyme produced in the stomach that aids digestion.
Peptic: digestion-related.
Peptic ulcer: an ulcer of the alimentary mucosa, usually in the stomach or duodenum, exposed to acid secretion.
Peptide: a short sequence of amino acids.
Percutaneous: through the skin.
Perennial: persistent.
Perforation: a break through the wall of the gut.
Perfusion: through passage of fluid.
Perianal: back passage-related.
Periarthritis: joint inflammation.
Pericarditis: inflammation of the lining of the heart.
Peridural: outside the brain/spinal cord.
Peri-menopause: the time around the menopause, usually beginning 3 to 5 years before the final period.
Peri-natal: around the time of birth -- shortly before to shortly afterward.
Perineal: pelvis-related.
Perineum: the area of the body between the anus and the genitals. In men, it is between the testicles and the anus; in women, it is between the vagina and the anus.
Peri-operative: immediate pre and post-operative.
Peri-oral: mouth-related.
Peri-orbital: eye socket-related.
Peripheral blood stem cell: there are small numbers of stem cells in the circulation. These are known as peripheral blood stem cells (PBSC).
Peripheral neuropathy: nerve damage characterized by sensory loss, pain, muscle weakness and wasting of muscle in the hands or legs and feet. It may start with burning or tingling sensations or numbness in the toes and fingers.
Peristalsis: pushing of food though the gut.
Peritoneum: the lining of the abdominal cavity.
Peritonitis: infection of the peritoneum.
Perthes' disease: a form of avascular necrosis of the hip occuring in children or adolescents. It causes a limp with hip or knee pain between the ages of 5 and 11 with boys normally more affected than girls.
Pertussis: whooping cough.
Petechiae: small red or purple pin-head spots on the skin. They are small haemorrhages and usually the result of a shortage of platelets.
Phagocytosis: the process by which white blood cells such as macrophages engulf and destroy foreign material, dead tissues and cells.
Pharmacodynamics: study of biochemical and physiological effects of drugs.
Pharmacokinetics: the study of the action of a drug in the body over a period of time, including the processes of: absorption, metabolism and excretion.
Pharmacological: drug science-related.
Pharyngitis: sore throat.
Pharynx: the space behind the mouth.
Phenotype: the characteristic appearance and function of a cell or tissue.
Phenylketonuria (PKU): a congenital inability to break down the amino acid phenylalanine to tyrosine.
Philadelphia chromosome: an abnormalchromosome associated with chronic myeloid leukaemia and some cases of acute lymphoblastic leukaemia. The philadelphia chromosome is formed when part of chromosome 9 attaches to chromosome 22.
Phlebitis: vein inflammation.
Phlebography: vein X-ray.
Phlegm: sputum, thick, sticky, stringy mucus produced by the respiratory tract, usually as the result of irritation, inflammation, or infection of the airways.
Phobia: an unusually high level of worry about a certain situation. This may be about an animal - such as rats, spiders and snakes - or having to do something - like flying, speaking in public or going to the dentist. Just thinking about the cause of your worry can bring on the symptoms of anxiety.
Photophobia: abnormal sensitivity to light.
Photosensitivity: over-sensitivity to light.
Photosensitization: development of over-sensitivity to sunlight.
Physiotherapy: conventional techniques used to treat muscle and joint ailments.
Pigmentation: skin colouring.
Piloerection: hair standing on end.
Pineal gland: a gland within the brain, whose function is to secrete the hormone melatonin.
Pituitary gland: a tiny structure, located behind the hypothalamus, which secretes many important hormones.
Pityriasis: scaling of the skin.
Placebo: a comparison substance against which experimental drugs are sometimes compared. A placebo traditionally is an inactive substance resembling the experimental treatment.
Placenta: a temporary organ in the womb that allows a fetus to receive nutrients, oxygen and other substances (such as medications) from the mother and to eliminate carbon dioxide and other wastes.
Plantar fasciitis: a frequent cause of pain over the sole of the foot and centre of the heel, more often in men than women.
Plaque: a deposit of fatty substances such as cholesterol, hardened with fibrous matter and calcium in an artery affected with atherosclerosis.
Plasma: the watery, yellowish fluid that carries white and red blood cells and platelets through the circulatory system.
Plasma cells: large cells derived from the lymphocytes that form antibodies. Not normally found in circulating blood but restricted to bone marrow and lymph nodes.
Plasma cell leukaemia: the end stage of myeloma when immature plasma cells are found circulating in the blood.
Plasmacytoma: a localised area of myeloma-like disease, either in a bone or in the other tissues of the body. If there is only one such area it is called solitary plasmacytoma.
Platelets: tiny cell-like bodies derived from megakaryocytes in the bone marrow. Circulate in the blood and play an important role part in the prevention and control of bleeding.
Plegia: see paresis.
Pleura: the serous membrane lining the chest cavity and covering the lungs.
Pleurisy: inflammation of the pleura.
Pneumonia: infection of the lungs.
Pneumonitis: inflammation of the lungs.
Pneumothorax: a collapsed lung.
Polarity therapy: a holistic energy medicine that uses a combination of bodywork, stretching exercises, cleaning diet and health awareness to assist the body's own healing process.
Polyarteritis nodosa (PAN): a rare form of vasculitis of unknown aetiology involving the inflammation of predominantly medium and small arteries and impaired circulation in the tissues that the arteries supply.
Polyarthralgia: pain in many joint.
Polyarthritis: from the Greek language, poly=many; thus polyarthritis is inflammation in many joints. There are many different types of polyarthritis, one of the commonest beingrheumatoid arthritis.
Polycystic ovary syndrome: a condition in which the ovaries become bigger and covered in small cysts.
Polycythaemia rubra vera (PRV): a condition characterised by the over-production of red blood cells by the bone marrow. Diagnosis is based on an increased number and volume of red cells. The total number of white blood cells and platelets may also be increased.
Polydipsia: chronic thirst.
Polymorphic: in a variety of shapes.
Polymyalgia rheumatica (PMR): a rheumatic condition which implies painful involvement of the muscles (myalgia) although the muscles themselves are not actually inflamed. PMR is characterised by severe, painful morning stiffness, especially in the shoulders and thighs. There may additionally be inflammation of the blood vessels (arteries) of the skull which is called temporal arteritis.
Polymyositis: an autoimmune disease causing inflammation of the muscles, usually affecting shoulders, hips, thigh areas and (less commonly) neck muscles. When the skin is also affected, the condition is called dermatomyositis.
Polyneuritis: inlammation of the nerves.
Polyneuropathy: a disease process involving a number of peripheral nerves.
Polyp: tissue bulging from the surface of an organ.
Polypeptide: a chain of amino acids connected end-to-end.
Polytherapy: treatment using several drugs.
Polyunsaturated fatty acids: fatty acids in which more than one area of the molecule is not saturated with hydrogen.
Polyuria: urinating often.
Polyvalent: with more than one valence.
Porphyria: a group of rare, inherited blood disorders.
Port: the name of the tube or channel through which the endoscope and surgical instruments are passed in keyhole surgery.
Portacath: a form of central venous line in which the whole of the line is surgically implanted within the body, unlike a hickman line. A membrane just below the skin gives access by a simple skin puncture to a line running straight into one of the main blood vessels.
Portal Vein: the large vein that carries blood from the gut to the liver.
Port-wine stain: a red or purple birthmark. Port-wine stains are present at birth and grow with the child. They do not improve with time. They can occur on any part of the skin surface but cause most concern when they affect the face. They are also called naevus flammeus.
Posterior: referring to the back part of a structure.
Posthypnotic suggestion: makes use of the 'time sense' in which the suggestion given to the subject is instructed to commence after the hypnotic session has terminated.
Postnasal drip: a discharge from the back of the nose into the back of the throat.
Postpartum: after childbirth.
Postprandial: after a meal.
Potentiation: joint action of two drugs.
Prader-Willi Syndrome: a syndrome that affects both boys and girls equally from birth.
Preclinical: before the disease becomes recognisable.
Precordial: heart and chest-related.
Precordium: the part of the chest wall covering the front of the heart.
Predisposition: tendency.
Pre-eclampsia: complication of late pregnancy.
Preleukaemia: a general term referring to some non-cancerous blood disorders, such as myelodysplasia which carry an increased risk of the patient developing acute leukaemia. The expression is misleading because only a minority of patients with these conditions developleukaemia.
Preoperative: before an operation.
Prepartum: before childbirth, during pregnancy.
Prepuce: foreskin.
Presynaptic: before a nerve/organ joint.
Prevalence: the total number of people in a specific population who are living with a particular condition or disease at a given time.
Priapism: continuous erection.
Primary: first.
Proctitis: inflammation of the rectum.

Proctoscope: a short, rigid metal tube used to look into the rectum and anus.
Proctoscopy: examination of the rectum and anus with a proctoscope.
Progenitor cell or precursor cell: immature cell in the bone marrow which is responsible for producing mature blood cells.
Progesterone: one of the female sex hormones produced by the ovaries.
Progestogen: the synthetic form of progesterone.
Prognosis: an assessment of the likely benefits of treatment for a patient, particularly concerning the: chances of cure and complete recovery.
Prokinetic: drugs that stimulate muscles in the gut to move food.
Prolapse: the downward displacement of an organ from its normal position.
Prolymphocyte: an early lymphocyte precursor. Not commonly seen in the blood but in prolymphocytic leukaemia they may be present in large numbers.
Prolymphocytic leukaemia: a variant of chronic lymphocytic leukaemia in which the malignant cells have a more immature appearance.
Pronation: turning the forearm down, so that the palm faces downward.
Prophylaxis: any means taken to prevent disease, eg. immunisation.
Proptosis: protruding eyes.
Prosthesis: replacement of an absent body part.
Prostate: a gland found at the base of the bladder in men that produces semen.
Prostatitis: prostate inflammation.
Prosthesis: artificial limb.
Protease: any enzyme that catalyzes the breakdown of peptide bonds in a polypeptide or protein.
Protein: large molecules made up of long sequences of amino acids.
Proteinuria: too much protein in the urine.
Prothrombin: blood factor II.
Protocol: a plan that describes the details of a clinical trial, its rationale, goal, the drugs involved, their dosage levels, treatment duration and who and how many may participate.
Protozoon: single-cell creature.
Proximal: nearest.
Pruritic: itchy.
Pruritis: itching, sometimes severe.
Pruritus ani: itching around the anus.
Pseudogout: a painful, sudden attack of a hot very swollen, red joint, caused by calcium crystals in the joint (mainly the knee). Also known as pyrophosphate arthropathy / pyrophosphate deposition disease.
Psoriasis: a common skin condition in which scaly pink patches form on the arms, knees, back and scalp.
Psoriatic arthritis: a special type of arthritis that sometimes (less than 10% of cases) affects patients with psoriasis. Often affecting small joints it can be painful.
Psychogenic: caused by mental factors.
Psycholeptic: hopelessness and inertia-related.
Psychomotor: involving motor effects of mental activity.
Psychosis: a severe mental illness.
Psychotherapy: usually refers to psychoanalytic or psychodynamic therapists but can also refer to other pyschological treatments that have not been endorsed by professional associations.
Psychotropic: mood-altering.
Ptosis: droopy upper eyelid.
Puberty: the period when secondary sex characteristics develop.
Puerperium: a period of six weeks after childbirth.
Pulse: the rhythmic pulsation of an artery as blood is pumped through it.
Pulmonary embolism: embolism of pulmonary arteries, most frequently by detached fragments of thrombus from leg or pelvic vein.
Puerperium: time as vagina and uterus return to normal after birth.
Pulmonary: lung-related.
Purgative: strong laxative.
Purine: nitrogen containing compound which can be broken down to uric acid.
Purpura: a condition characterised by the occurrence of purple spots on the skin, often accompanied by bleeding from the gums.
Purulent: pusy.
Pus: a thick liquid, made up of white blood cells, lymph, and the remains of dead bacteria, that collects at the site of infection.
Pustular: boil-like.
Pustule: a small circumscribed elevation of the skin, containing purulent material.
Pyelitis: inflammation of kidney pelvis.
Pyelonephritis: inflammation of the kidney and its pelvis.
Pyloric sphincter: the muscle between the stomach and the small intestine.
Pyloric stenosis: a narrowing of the opening between the stomach and the small intestine.
Pyloroplasty: an operation to widen the opening between the stomach and the small intestine.
Pylorus: narrow outlet of stomach.
Pyogenic: pusy.
Pyrexia: fever.
Pyrogenic: fever-causing.

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