a group of carbohydrates, including sugars and starches

Sacroiliac joints

the pair of joints located in the pelvis between the sacrum and the hipbones


inflammation of the sacroiliac joints, which causes pain in the lower body


the triangular bone located at the bottom of the spine that is connected to the tailbone, the hipbones near the sacroilial joints, and the rest of the spine


see Seasonal affective disorder syndrome

Safe sex

measures taken to reduce the risk of acquiring a sexually transmitted disease, such as the use of a condom


a salt solution or any substance that contains salt

Salivary glands

a group of glands that secrete saliva into the mouth


a group of bacteria; includes a species that causes food poisoning and another responsible for typhoid fever


infection by salmonella bacteria


surgical removal of one or both fallopian tubes


inflammation of a fallopian tube


the surgical removal of one or both of the fallopian tubes and one or both of the ovaries


X-ray examination of the fallopian tubes


removal of abnormal scar tissue between a fallopian tube and nearby tissue


surgical opening of a fallopian tube for drainage or removal of an obstruction


a rare disease with no known cause that leads to inflammation in tissues throughout the body, including the lymph nodes, lungs, liver, skin, and eyes


a cancer in connective tissue, fibrous tissue, or blood vessels

Saturated fat

fats that contain the maximum amount of hydrogen possible, such as those found in meats and dairy products; can contribute to coronary heart disease and the development of some cancers

Saturday night palsy

temporary paralysis of the arm after extended pressure on a nerve in the armpit


a highly contagious skin disorder caused by a mite that burrows into the skin and produces an intense, itchy rash

Scarlet fever

an infectious childhood disease, caused by a streptococcus bacteria, that leads to a sore throat, fever, and rash


infestation by a parasitic blood worm that can damage the liver, bladder, and intestines


a group of mental disorders characterised by abnormal thoughts, moods, and actions; sufferers have a distorted sense of reality, and a split personality (thoughts do not logically fit together)

Schonlein-Henoch purpura

inflammation and leakage of blood vessels, causing a rash


pain along the sciatic nerve, which runs down the length of the leg to the foot; usually caused by pressure on the nerve due to disk prolapse or a tumour, abscess, or blood clot


the tough, white coating that covers and protects the inner structures of the eye


an immune system disorder of varying degree that can affect many areas of the body


treatment of varicose veins by injection of a solution that destroys them


a condition in which the spine curves to one side and usually curves toward the opposite side in another section to compensate, producing a characteristic S shape


the testing of an otherwise healthy person in order to diagnose disorders at an early stage


the sac containing the testicles


a disease caused by a lack of vitamin C, characterised by weakness, bleeding and pain in joints and muscles, bleeding gums, and abnormal bone and tooth growth

Seasonal affective disorder syndrome

a type of depression that seems to be linked to shorter periods of daylight during the fall and winter

Sebaceous cyst

a swelling that occurs under the skin, most commonly on the scalp, face, ears, and genitals; although usually harmless, can grow very large and become painful if infected


excessive oiliness of the face and scalp


the oily, lubricating substance that is secreted by glands in the skin


describes a disease or disorder that follows or is caused by another one


a group of drugs that have a calming effect; used to treat anxiety and pain, bring on sleep, and help relax a person before surgery


sudden uncontrolled waves of electrical activity in the brain, causing involuntary movement or loss of consciousness


an element needed by the body only in very small amounts that helps maintain tissue elasticity


fluid released during ejaculation that contains sperm along with fluids produced by the prostate gland and the seminal vesicles

Semen analysis

a procedure in which a semen sample is examined to determine the amount of sperm present, along with their shape and ability to move; commonly used in the treatment of male infertility

Seminal vesicles

two sac-like glands in men that produce part of the fluid in semen

Seminiferous tubules

coiled tubes inside of the testicle that are the site of sperm production


a type of testicular cancer that is made up of only a single type of cell

Senatorial node

the structure that regulates the heartbeat; a natural "pacemaker"

Senile plaques

abnormal deposits of a protein called amyloid in the brain; characteristic of Alzheimer disease

Sensorineural hearing loss

deafness caused by damage to the inner ear or the nerve that conducts signals from the ear to the brain

Sensory nerve

nerves that carry information about the body's senses toward the brain

Sensory organ

an organ that receives and relays information about the body's senses to the brain


the infection of a wound or tissue with bacteria, causing the spread of the bacteria into the bloodstream; now also known as systemic inflammatory response syndrome caused by a microbe

Septal defect

a birth defect in which a hole is present in the wall that separates the left and right sides of the heart

Septic arthritis

joint inflammation caused by a bacterial infection

Septic shock

a life-threatening condition in which tissues become damaged and blood pressure drops due to bacteria multiplying and producing poisons in the blood


a life-threatening condition in which bacteria multiply in the blood and produce toxic materials; commonly known as blood poisoning; now also known as systemic inflammatory response syndrome.


a chemical that transmits nerve impulses in the brain, causes blood vessels to constrict (narrow) at sites of bleeding, and stimulates smooth muscle movement in the intestines


the clear, watery fluid that separates from clotted blood

Sex chromosomes

the X and Y chromosomes that determine a person's gender; women normally have two X chromosomes and men normally have one X and one Y

Sex hormones

hormones responsible for producing sex characteristics and controlling sexual functions

Sex-linked disorder

a disorder that is caused by genes located on the sex chromosomes

Sexually transmitted disease

infections that are most commonly spread through sexual intercourse or genital contact


a bacterial infection of the intestines, causing abdominal pain and diarrhoea

Shin splints

pain and tenderness experienced in the lower leg as a result of damage or strain to leg muscles and tendons; usually caused by exercise


a nerve infection caused by the chickenpox virus, causing areas of painful rash covered with blisters


a reduced flow of blood throughout the body, usually caused by severe bleeding or a weak heart; without treatment, can lead to a collapse, coma, and death


an artificially constructed or an abnormal passage connecting two usually separate structures in the body

Sick euthyroid syndrome

Sick euthyroid syndrome (or euthyroid sick syndrome) is a condition where the measured levels of thyroid hormone (usually T3) are low, but without any accompanying symptoms of hypothyroidism. This usually occurs when the patient is very unwell for other reasons and is seen commonly in patients being treated in intensive care units with multiple medical problems.

Sick sinus syndrome

abnormal functioning of the structure that regulates the heartbeat, causing episodes of abnormal heart rhythm

Sickle cell anaemia

a genetic disorder in which the red blood cells are abnormal and deformed, causing anaemia (reduced ability to transport oxygen in the blood) and clogging of blood vessels; bouts of fever, headache, and weakness result

Sickle cell trait

a less serious form of sickle cell anaemia


see Sudden infant death syndrome


an examination of the rectum and the lowest part of the large intestine using a flexible viewing tube inserted through the anus


a group of compounds of silicon and oxygen; commonly used as implants in cosmetic surgery because they resist body fluids and are not rejected by the body


a respiratory disease caused by inhalation of dust containing the mineral silica

Single photon emission computed tomography

an imaging technique in which a radioactive substance is introduced into the body and the radiation emitted by the substance is detected by a camera and is transformed into cross-sectional images by a computer


a cavity within bone or a channel that contains blood; also refers to an abnormal tract in the body

Sinus Bradycardia

a regular heart rate of less than 60 beats per minute

Sinus rhythm

normal heart rhythm

Sinus tachycardia

a regular heart rate of over 100 beats per minute


inflammation of the lining of the cavities in the bone surrounding the nose (the sinuses), usually as a result of a bacterial infection spreading from the nose

Sjögren's syndrome

a condition characterised by dryness of the eyes, mouth, and vagina that tends to occur along with certain disorders of the immune system

Skin graft

a method of treating damaged or lost skin in which a piece of skin is taken from another area of the body and transplanted in a damaged or missing section

Skin patch

a sticky patch attached to the surface of the skin that releases drugs into the bloodstream

Skin patch test

a diagnostic test in which different allergens are taped to the skin to determine which causes an allergic reaction

Skin prick test

a test performed to determine a person's sensitivity to a certain allergen by applying it to a small needle and using that needle to pierce the skin


the bones that form the framework of the head and enclose and protect the brain and other sensory organs

Sleep apnoea

a condition in which breathing stops for very short periods of time during sleep

Sleeping sickness

an infectious disease in Africa spread by the bite of a tsetse fly that causes a fever and weakness

Slipped disk

the common term for disk prolapse

Small intestine

The small intestine is the start of the bowel and although narrower than the large bowel, is very much longer at around 7m. (The colon is around 1.5m). The small bowel is divided into different parts (from top to bottom) called the duodenum, the jejenum and the ileum. The small bowel is essential for the digestion and absorption of all the nutrients in our food.

Small-cell carcinoma

the most serious form of lung cancer


a highly contagious and often fatal viral infection that has been completely eradicated by immunisation


a sample of cells spread across a glass slide to be examined through a microscope


a mineral that plays a role in the body's water balance, heart rhythm, nerve impulses, and muscle contraction; present in table salt (sodium chloride)

Sodium bicarbonate

a substance used as an antacid

Solar plexus

the largest network of nerves in the body, located behind the stomach


pertaining to the body


an involuntary muscle contraction; can sometimes be powerful and painful

Spastic paralysis

spasticity involving partial paralysis


muscle stiffness caused by an increase in contractions of the muscle fibres


see Single photon emission computed tomography


an instrument that holds an opening of the body open so that an examination can be performed or a sample can be taken

Speech therapy

treatment to help someone overcome a problem communicating verbally


the male sex cell produced in the testicles

Sperm antibody

an antibody against sperm that can be produced by a woman's immune system

Sperm count

the amount of normally functioning sperm per some unit of semen; used to determine a man's fertility


a harmless cyst containing fluid and sperm that occurs in the tube through which sperm travel from the testicles


a contraceptive substance that kills sperm


a ring of muscle fibres located around a naturally occurring passage or opening in the body that opens and closes to regulate passage of substances


an instrument used to measure blood pressure

Spider nevus

a collection of dilated (widened) capillaries on the skin that creates a patch resembling a spider

Spina bifida

a birth defect in which a section of the baby's spine fails to develop completely, leaving the spinal cord exposed in that section

Spina bifida occulta

the least dangerous form of spina bifida, in which bones in the spine fail to close but there is no protrusion of the spinal cord or its fluid cushion out of the body

Spinal cord

a long tube of nerve tissue inside the spinal column, running from the brain down the length of the back inside of the spine

Spinal fusion

the surgical joining of two or more adjacent vertebrae using bone fragments; used to help severe back pain or prevent damage to the spinal cord

Spinal tap

another term for a lumbar puncture


the column of bones and cartilage running along the midline of the back that surrounds and protects the spinal cord and supports the head

Spiral fracture

a coiled break in a bone, resembling a corkscrew


a test of lung condition; a person breathes into a machine called a spirometer that measures the volume of air exhaled


an organ located in the upper left abdomen behind the ribs that removes and destroys old red blood cells and helps fight infection


surgical removal of the spleen


a device that is used to immobilise a part of the body

Splinter haemorrhage

a splinter-shaped area of bleeding under a fingernail or toenail


inflammation of the joints between the bones of the spine


the slipping of a vertebra in the spine over the one below it


a disorder in which the lower part of the spine is weakened by an abnormally soft vertebra


an infection with a fungus acquired through a skin wound; causes an ulcer at the site of infection and small, rounded masses of tissue near it


the tearing or stretching of the ligaments in a joint, characterised by pain, swelling, and an inability to move the joint


a digestive disorder in which nutrients cannot be properly absorbed from food, causing weakness and loss of weight


mucus and other material produced by the lining of the respiratory tract; also called phlegm

Squamous cell carcinoma

a type of skin cancer arising from flat cells of the epithelium; can also affect the lungs, cervix, and oesophagus


surgical removal of a stapes (a sound-conducting bone in the middle ear) that cannot move to transmit sound; performed to treat hearing loss caused by otosclerosis


common bacteria that cause skin infections and a number of other disorders

Status asthmaticus

a life-threatening asthma attack requiring immediate treatment

Status epilepticus

a life-threatening succession of epileptic seizures


see Sexually transmitted disease

Stein-Leventhal syndrome

see Polycystic ovary syndrome

Stem cells

cells that give rise to the different types of blood cells


narrowing of a body passageway


a device used to hold tissues in place, such as to support a skin graft

Stereotaxic surgery

brain surgery done through a small opening in the skull and guided by X-rays or computer-aided imaging techniques


a surgery performed to make a person incapable of reproducing; also refers to the process of killing micro-organisms on objects such as surgical instruments


the long, flat bone located at the centre of the chest


a group of drugs that includes corticosteroids, which resemble hormones produced by the adrenal glands, and anabolic steroids, which are similar to the hormones produced by the male sex organs


a baby that is born dead after the 28th week of pregnancy; also called late foetal death


a surgically formed opening on a body surface

Stomach bypass

a surgical procedure to treat an obstructed stomach or severe obesity in which the passage of food is diverted around the stomach and directly into the small intestine

Stomach stapling

a procedure in which the stomach is made smaller by partitioning it off using metal staples; used as an extreme treatment of severe obesity


another term for faeces


a condition in which the eyes are not aligned correctly, such as cross-eye (one eye points inward) and walleye (one eye points outward)

Straight-leg raising

a simple test performed in a doctor's office to check for disk prolapse


muscle damage resulting from excessive stretching or forceful contraction

Strangulated hernia

a hernia in which the protruding organ or tissue loses its blood supply, requiring emergency surgery

Strawberry nevus

a bright red, raised birthmark that usually disappears without treatment

Strep throat

a throat infection caused by streptococcus bacteria; characterised by a sore throat, fever, and enlarged lymph nodes in the neck


bacteria that cause a variety of diseases, including pneumonia and strep throat

Stress fracture

a bone break resulting from repeated pressure on the bone

Stretch marks

lines on the skin that occur when the inner skin layer is stretched thin and loses its elasticity


damage to part of the brain because of a lack of blood supply (due to a blockage in an artery) or the rupturing of a blood vessel; leads to complete or partial loss of function in the area of the body that is controlled by the damaged part of the brain


a pus-filled abscess in the follicle of an eyelash; caused by a bacterial infection


a medical term meaning "beneath the skin"


the layer of connective tissue under a mucous membrane

Suction lipectomy

see Liposuction

Sudden infant death syndrome

the unexpected, sudden death of an apparently healthy baby, the cause of which cannot be found; also called crib death


a solid cone or bullet-shaped object made up of a chemically inactive substance and a drug that is inserted into the rectum or vagina; used to administer a drug


the production of pus


a mixture of substances secreted by the air sacs of the lungs that prevents the air sacs from collapsing during exhalation


a woman who agrees to become pregnant and give her baby to someone else when the child is born


a surgical stitch that helps close an incision or wound so that it can heal properly

Sweat glands

tiny structures in the skin that secrete sweat

Sweat test

a measure of the saltiness of sweat to help diagnose cystic fibrosis

Swimmer's ear

see Otitis externa

Sycosis barbae

a bacterial infection of the hair follicles in the beard area

Sympathetic nervous system

the part of the autonomic nervous system that raises blood pressure and heart rate in response to stress


a condition in which fingers or toes are fused together


a group of symptoms that indicate a certain disorder when they occur together


surgical removal of the synovial membrane

Synovial fluid

a lubricating fluid secreted by the synovial membrane

Synovial membrane

the thin membrane that lines the inside of a joint capsule


inflammation of the membrane lining a joint capsule as a result of injury or infection or due to a chronic illness such as rheumatoid arthritis; characterised by redness, swelling, stiffness, and pain


a sexually transmitted disease; initially causes only painless sores on the genitals but can be life-threatening if untreated


affecting the whole body

Systemic inflammatory response syndrome

a condition characterised by having two of the following four clinical criteria: fever, rapid breathing, increased heart rate, and abnormal white blood cell count

Systemic lupus erythematosus

a disease of the immune system that causes inflammation of connective tissue in many areas of the body, including the skin, lungs, heart, joints, and kidneys

Systolic pressure

the blood pressure measured while the heart is contracting

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