Bma Illustrated Medical Dictionary

photosensitivityAbnormal reaction to

sunlight. Photosensitivity usually causes

a rash on skin exposed to sunlight. This

often occurs because a photosensitizer

(such as some drugs, dyes, chemicals in

perfumes and soaps, and plants such as

mustard) has been ingested or applied

to the skin. Photosensitivity is also a fea-

ture of disorders such as systemic lupus

erythematosus. People who are suscepti-

ble to photosensitivity reactions should

avoid exposure to sunlight and photo-

sensitizers, and use sunscreens.

phototherapyTreatment with light, in-

cluding sunlight, ultraviolet light, blue

light, orlasers. Moderate exposure to

sunlight is the most basic form, and is

often helpful in treatingpsoriasis.

PUVAcombines the use of long-wave

ultraviolet light with a psoralen drug,

which sensitizes the skin to light. This is

used to treat psoriasis and other skin

diseases such as vitiligo. Psoriasis may

also be treated using short-wave ultravio-

let light, sometimes combined with the

application of coal tar.

Visible blue light is used to treat

neonatal jaundice (see jaundice, neona-

tal), which is due to high levels of the

pigment bilirubinin the blood. In pho-

totherapy, bilirubin is converted into a

harmless substance that can be excret-

ed. To maximize exposure, the baby is

undressed and placed under the lights

in an incubator to keep him warm.

phrenic nerveOne of the pair of main

nerves supplying the diaphragm. Each

phrenic nerve carries motor impulses to

the diaphragm, and plays a part in con-

trolling breathing. Injury to, or surgical

cutting of, 1 of the nerves results in para-

lysis of 1 half of the diaphragm.

physical examinationSee examina-

tion, physical.

physical medicine and rehabilitation

A branch of medicine concerned with

caring for patients who have become

disabled through injury or illness.

physiologyThe study of body func-

tions, including physical and chemical

processes of cells, tissues, organs, and

systems, and their various interactions.

physiotherapyTreatment with physi-

cal methods or agents. Physiotherapy is

used to prevent or reduce joint stiffness;

restore muscle strength; reduce pain;

inflammation, and muscle spasm; and

retrain joints and muscles after strokeor

nerve injury. Methods include heat

treatment,exercises, massage, ice-packs,

hydrotherapy, and TENS. Physiotherapy

is also used to maintain breathing in

people with impaired lung function,

and to prevent and treat pulmonary

complications after surgery. Techniques

include breathing exercises, postural

drainage, and administration of oxygen,

drugs, or moisture through a nebulizer.

physostigmineA drug used in the form

of eye-drops to treat glaucoma.

PHOTOSENSITIVITY PHYSOSTIGMINE

P

PHOTOTHERAPY

Newborn

baby

Incubator

Lamp gives

off blue

fluorescent

light

PHOTOTHERAPY FOR NEONATAL JAUNDICE

Eye

shield