Medical terms - Letter S (page 11) | MedicalVocabulary.org

Sign, Babinski

A neurologic reflex that constitutes an important medical examination based upon what the big toe does when the sole of the foot is stroked. If the big toe goes up, that may well mean trouble. The Babinski sign is…
Sign, Gottron

A scaly, patchy redness over the knuckles seen in patients with dermatomyositis, an inflammatory muscle disorder. (See polymyositis).
Sign, Kernig

A clinical hallmark of meningitis, inflammation of the meninges, the membranes covering the brain and spinal cord. The test for Kernig sign is done by having the person lie supine (flat on the back), flex the thigh so…
Sign, Lhermitte

Sudden transient electric-like shocks extending down the spine triggered by flexing the head forward. Due to a disorder such as compression of the cervical spine (the portion of the spinal cord within the neck). One…
Sign, Macewen

A sign to detect hydrocephalus and brain abscess. Percussion (tapping) on the skull at a particular spot (near the junction of the frontal, temporal and parietal bones) yields an unusually resonant sound in the presence…
Sign, Tinel's

An examination test that is used by doctors to detect an irritated nerve. Tinel's sign is performed by lightly banging (percussing) over the nerve to elicit a sensation of tingling or 'pins and needles' in the…
Sign, toe

An important neurologic test based upon what the toes do when the sole of the foot is stimulated. If the big toe goes up, that may mean trouble. The toe sign, also called the Babinski reflex, is obtained by stimulating…
Signal transduction

A basic process in molecular cell biology involving the conversion of a signal from outside the cell to a functional change within the cell. A signal (such as a hormone or neurotransmitter) interacts with a receptor on…
Signal transduction pathway

The course by which a signal from outside a cell is converted to a functional change within the cell
Signature

1) That part of the prescription that contains the doctor's directions to the patient. For example, the signature might say 'take twice daily with food'. Also known as the sig.. 2) The outward appearance of a natural…
Sikimitoxin

Poisonous substance found in the Japanese star anise, which is also called sikimi
Silencing, gene

A mechanism by which cells shut down large sections of chromosomal DNA. Gene silencing is done by incorporating the DNA to be silenced into a form of DNA called heterochromatin that is already silent. The process of…
Silent stroke

Stroke: Small strokes that do not cause any symptoms. Silent strokes still damage brain tissue. The most common symptom of a stroke is weakness or paralysis on one side of the body or the other. There may be a partial…
Silica

The chief component of sand and a substance responsible for lung disease and cancer. Crystalline silica of respirable size is primarily quartz dust occurring in industrial and occupational settings in the form of fine…
Silicatosis

See: Silicosis
Silicosis

A form of lung disease resulting from occupational exposure to silica dust over a period of years. Silicosis causes slowly progressive fibrosis of the lungs, impairment of lung function and a tendency to tuberculosis of…
Silk Road disease

Behcet's disease. Called Silk Road disease because it is most common and more severe in people originating from countries along the Silk Road, the vast network of ancient trade routes connecting China with the…
Silver

A metal used in some medications and in many 'natural' remedies, as well as in silver amalgam for filling cavities in teeth. Silver has antibiotic properties. However, overuse of silver, or use of products containing…
Silver bullet

Or magic bullet. 1. The perfect drug to cure a disease with no danger of side effects. The term magic bullet was first used in this sense by the German scientist Paul Ehrlich to describe antibody and, later, the drug…
Silver poisoning

Silver poisoning, medically termed argyria, causes ashen gray discoloration of the skin (and other tissues of the body). Due to chronic use of silver salts. For example, a medical report related the case of a woman, now…
Simian crease

A single transverse palmar crease, a minor variation associated with Down syndrome (trisomy 21). Also called a four-finger crease, single palmar flexion crease, single upper palm crease, or line. There are most often…
Simian virus 40

See: SV40
Single base change

A change in which a single base in the DNA differs from the usual base at that position. These single base changes are also called SNPs or 'snips.' Millions of SNP's have been cataloged in the human genome. Some SNPs…
Single gene disease

Any genetic disorder caused by a change affecting only one gene. There are thousands of single-gene diseases including achondroplasia, cystic fibrosis, hemophilia, Huntington disease, muscular dystrophy, and sickle cell…
Single nucleotide polymorphism

A change in which a single base in the DNA differs from the usual base at that position. Abbreviated SNP and pronounced snip. Millions of SNP's have been cataloged in the human genome. Some SNPs are responsible for…
Single palmar flexion crease

See: Simian crease
Single palmar flexion line

Simian crease
Single transverse palmar crease

Preferable term for what historically was called a simian crease. See: Simian crease
Single transverse palmar line

Simian crease
Single upper palm crease

See: Simian crease
Single upper palm line

See: Simian crease
Single-blind

Term used to described a study in which either the investigator or the participant, but not both of them, is unaware of the nature of the treatment the participant is receiving. Also called single-masked
Single-masked

See: Single-blind
Single-payer health care

A system of health care characterized by universal and comprehensive coverage. Single-payer health care is similar to the health services provided by Medicare in the US. The government pays for care that is delivered in…
Singultus

A rarely used medical word for an ordinary hiccup. A hiccough is an extraordinary type of breathing movement involving a sudden intake of air (inspiration) due to an involuntary contraction of the diaphragm accompanied…
Sinoatrial node

The sinoatrial node (the SA node) is one of the major elements in the cardiac conduction system, the system that controls the heart rate. This stunningly designed system generates electrical impulses and conducts them…
Sinuous

Curving in and out; in a serpentine, wavy form; winding. From the Latin noun 'sinus,' which means 'curve, fold, or hollow' and also was borrowed directly to designate the 'and out; in a serpentine, wavy form; winding…
Sinus

1. An air-filled cavity in a dense portion of a skull bone. The sinuses decrease the weight of the skull. The sinuses are formed in four right-left pairs. The frontal sinuses are positioned behind the forehead, while…
Sinus arrhythmia

The normal increase in heart rate that occurs during inspiration (when you breathe in). This is a natural response and is more accentuated in children than adults. The 'sinus' refers to the natural pacemaker of the…
Sinus barotrauma

Sinus troubles, particularly with pain and a feeling of pressure, due to changing atmospheric pressures, as when going up or down in a plane. Also called aerosinusitis or barosinusitis.
Sinus bradycardia

A regular but unusually slow heart beat (60 beats/minute or less at rest). Sinus bradycardia can be the result of many things including good physical fitness, medications, and some forms of heart block. 'Sinus' refers…
Sinus headache

A headache caused by pressure within the sinus cavities of the head, usually in connection with infection of the sinuses. Signs and symptoms of sinus headache include pain and tenderness in the sinus area, discharge…
Sinus node

The sinus node is one of the major elements in the cardiac conduction system, the system that controls the heart rate. This stunningly designed system generates electrical impulses and conducts them throughout the…
Sinus rhythm

The normal regular rhythm of the heart set by the natural pacemaker of the heart called the sinoatrial (or sinus) node. It is located in the wall of the right atrium (the right upper chamber of the heart). Normal…
Sinus tachycardia

A fast heartbeat (tachycardia) because of rapid firing of the sinoatrial (sinus) node. The sinoatrial (or sinus) node is the natural pacemaker of the heart. It is located in the wall of the right atrium (the right upper…
Sinus, cavernous

A large channel of venous blood creating a 'sinus' cavity bordered by the sphenoid bone and the temporal bone of the skull. The cavernous sinus is an important structure because of its location and its contents which…
Sinus, ethmoid

See: Ethmoid sinus
Sinusitis

Sinusitis: Sinusitis is inflammation of the lining membrane of any of the hollow areas (sinuses) of the bone of the skull around the nose. The sinuses are directly connected to the nasal cavities. Picture of the anatomy…
Sir Charles Bell

See: Bell, Charles
SiRNA

Abbreviation for small inhibitory RNA, a short sequence of RNA which can be used to silence gene expression