Online Medical Dictionary

Letter S

SAD: Acronym for Seasonal Affective Disorder.
Sarcoma: A malignancy developing from the transformation of cells of the connective tissues, such as that which composes bone, fat tissues and cartilage.
SARS: Acronym for Severe Acute Respiratory Syndrome.
Scabies: A skin infection induced by the parasite Sarcoptes scabiei, a contagious mite which burrows under the skin causing an allergic reaction. Symptoms include redness, ratch and intense itching.
Scapula: The shoulder blade.
Scheuermann's Disease: Juvenile osteochondrosis of the spine, wherein the vertebrae develop unevenly resulting in kyphosis, hunchback or curvature of the spine. Physical therapy and bracing are common treatments for Schuermann's disease, with some cases necessitating surgery involving spinal fusion.
Sciatic Nerve: The longest and widest nerve of the body, running from the lower back down to the leg.
Sclera: The protective, fibrous, opaque outer coat of the eye. Also called the whites of the eye.
Scleritis: Inflammation of the sclera, the outer layer of the eye, usually occurring in conjunction with another disease, such as rheumatoid arthritis or a connective tissue disorder. Treatment can range from a course of anti-inflammatory drugs to surgical operation in severe cases when corneal tissue has been damaged.
Sclerosis: Usually referring to the stiffening or hardening of tissue, due to the development of connective tissue in place of the bodily region-specific tissue.
Scoliosis: An abnormal, side-to-side curvature of the spine, often resembling an S in shape. Scoliosis may be congenital (condition present at birth), idiopathic (no known cause), or a neuromuscular condition that occurred in association with another medical condition such as cerebral palsy, spina bifida, or physical injury.
Seasonal Affective Disorder (SAD): A mood disorder characterized by periods of depression during the winter or autumnal months, experienced in greater intensity than the individual experiences normally. Depressive symptoms include oversleeping, overeating, nausea and social withdrawal. Light therapy and meditation are common treatments sought to relieve the symptoms of SAD.
Sepsis: Often referred to as blood poisoning (septicemia), sepsis involves a systematic inflammation response of the whole body due to the presence of an infectious agent in the bloodstream, lungs, skin or other body tissue. Sepsis usually necessitates immediate intensive care. If left untreated, sepsis may result in multiple organ failure.
Septum: An anatomical wall, usually dividing a bodily cavity into two or more pathways, such as in the nasal septum, which provides a wall of cartilage between the nostrils of the nose.
Severe Acute Respiratory Syndrome (SARS): A disease of the respiratory system caused by SARS coronavirus, posing a fatality rate of up to 50 per cent in contractors over the age of 65, known to cause outbreaks if not contained.
Sex Chromosomes: The chromosomes which determine the sexual characteristics of an organism. In humans and most mammals, a pair of XX chromosomes determine a female while an XY set determines a male.
Shingles: A viral disease caused by the same varicella zoster virus that causes chickenpox. Long after a case of chickenpox has cleared, the dormant virus may induce infection causing the painful, blistering rash symptomatic of shingles. Treatment aims to reduce the pain and discomfort caused by the infection, which may include topical analgesics and/or antiviral medications. Also termed herpes zoster.
Shunt: A biological (naturally formed) or mechanical (implemented) passage or hole which allows for the movement of fluid.
Sickle Cell Disease: Also called sickle-cell anemia, sickle-cell disease is a genetic blood disease caused by a mutation in a hemoglobin gene, which impedes the flexibility of red blood cells and induces them to take on a rigid, abnormal shape. Sickle-cell anemia usually takes onset in childhood, and can lead to a variety of complications including stroke, harmful infection, spontaneous abortion, chronic renal failure and chronic pain. The majority of sickle-cell disease occurs in Africa. Disease management includes consistent observation and daily penicillin and folic acid supplement.
SIDS: Acronym for Sudden Infant Death Syndrome.
Skin Graft: The replacement of lost or damaged skin, due to disease, burn or other condition, with skin, most commonly and effectively, from another area of the same individual's body.
Sleep Apnea: A sleep disorder involving shortness of breath, or abnormal pauses in regular breathing patterns, amid sleep. Sleep apnea may be diagnosed in a polysomnogram, a sleep study testing method. Sleep apnea may be unrecognizable to the individual, but for inducing daytime fatigue due to disturbed sleeping cycles. Treatment varies on the severity of the condition, from changing sleeping position to wearing a mouthpiece that shifts the jaw to keep airways open, with the most severe cases necessitating surgery to correct for airway obstruction.
Slipped Disc: See Spinal Disc Herniation.
Small Cell Lung Cancer: Also called small cell carcinoma or oat cell carcinoma due to the shape of the cancerous cells; a highly malignant, metastatic cancer of the lung, or in some cases other cancers such as prostate or cervical. Small cell lung cancer is highly associated with smoking. Treatment includes a combination approach of chemotherapy and radiotherapy.
Smallpox: A highly contagious viral disease caused by the variants Variola major and Variola minor, characterized by a bumpy skin rash, fluid-filled blisters and fever. Hemorrhagic smallpox induced bleeding in the skin and gastrointestinal tract and poses a virtually 100 per cent fatality rate. Smallpox vaccination within days of contracting the disease can mediate the symptoms and effects of the ordinary-type smallpox.
Somatic: Regarding the body cells or the body cavity. Somatic mutations are the cause of many types of cancer developments.
Somnoplasty: A medical procedure conducted to treat chronic snoring, nasal obstruction, and/or obstructive sleep apnea by delivering radio frequency energy to an area of tissue determined to be causing obstruction, thereby shrinking the obstructive tissue.
Spastic Colitis: See Irritable Bowel Syndrome (IBS).
Spastic Colon: See Irritable Bowel Syndrome (IBS).
Speculum: An instrument used to examine an anatomical cavity or passageway through a natural opening, such as the mouth to view the throat, or the ears to view the eardrum.
Spina Bifida: A congenital malformation caused by the failure of the embryonic neural tube to close completely amid embryonic development. Spina bifida results in the incomplete development of vertebrae overlying the spine. If this gap is wide enough, the spine may protrude. Though surgery can correct the physical appearance of this protrusion, it cannot completely restore the normal function of the spine to the area affected, though fetal surgeries to correct the malformation are still in clinical trial. Spina bifida severity ranges from the relatively mild occulta, or hidden form, to the more severe myelomeningocele form, wherein the protuding spine may cause areas of the back, muscles in the legs, the hips or knees to be affected by paralysis, numbness of feeling, or pain.
Spinal Disc Herniation: A tear induced, often by simple everyday occupational tasks, such as long seated periods or heavy lifting, causing the central soft portion of the intervertebral disc to bulge out from the torn outer, fibrous ring of the disc. Spinal disc herniation may result in inflammation, pain and/or root compression. Surgery is not usually required to treat spinal disc herniation, and is normally viewed as a final resort. Symptoms can usually be mediated through a course of anti-inflammatory medication, pain killers and physical therapy.
Spinal Stenosis: A condition, usually debilitating, resulting in the narrowing of the spaces between the spine (the spinal canal), resulting in compression of the nerve roots and spinal cord. Spinal stenosis may be the result of age-related spinal degeneration, osteoporosis, tumour, or spinal disc herniation. Depending on the area of the spine affected, spinal stenosis may induce pain in the abdomen, lumbar, legs, buttocks or feet, or cause incontinence. Surgical procedures to treat spinal stenosis appear to vary in effectiveness.
Spinal Tap: Lumbar puncture; a procedure conducted to obtain a sample of cerebrospinal fluid for diagnostic testing and analysis or, on rare occasion, to relieve intracranial pressure.
Spleen: An organ located in the upper left abdominal quadrant, near to the stomach, functioning to synthesize antibodies, remove aged red blood cells and serve as a blood reservoir in the instance that hemorrhagic shock should occur. Removal of the spleen has been found to increase the risk of contracting some diseases or conditions.
Spontaneous Abortion: A miscarriage; the inability of an embryo or fetus to survive the pregnancy.
Sputum: Matter brought up from the respiratory tract that may be coughed up and spat out, such as mucus and/or phlegm.
Squamous Cell Carcinoma: A cancer of the squamous epithelium, a scaly appearing tumour, that may develop wherever these cells are found, such as in the skin, lungs, bladder, mouth, cervix, vagina and esophagus. Dependent on locale and manifestation, squamous cell cancers range in treatment method and prognosis. The human papilloma virus is believed to be associated with some forms of squamous cell carcinomas.
SSRI: Abbreviation for selective serotonin reuptake inhibitors, commonly used as a mood stabilizer or treatment for of depression.
Stapes: The tiny, stirrup-shaped bone of the middle ear.
Staph Infection: An infection caused by the Staphylococcus bacteria, a common inducer of a variety of human infections and disease, including food poisoning and many hospital-acquired infections. Staph infection of the skin results in abscess and boil. When staph infection enters the bloodstream, fever and low blood pressure may ensue. Staph is also present in toxic shock syndrome. Treatment and prognosis depends on the type of infection or disease induced by the Staphylococcus bacteria.
Stasis: The cessation of regular bodily fluid flow, such as blood flow through a blood vessel (hemostasis).
Stem Cell Transplantation: The use of stem cells in the treatment of disease. Stem cells are commonly attained from bone marrow, placenta or umbilical chord blood and transplanted in individuals with certain cancers or disease usually affecting the blood, bone marrow or immune system. It is now being posed that stem cell transplantation could have positive effect on the treatment of HIV.
Stenosis: An abnormal narrowing of a tubular bodily structure, such as a blood vessel (vascular stenoses), which may be induced by a variety of conditions including diabetes, infection, smoking and inflammation.
Sternum: The breast bone.
STI>/dt>: Abbreviation for sexually transmitted infection.
Stomach Cancer: Also known as gastric cancer, cancer of the stomach may develop in any part of the organ and metastasize, particularly to surrounding organs such as the esophagus, liver, lungs and lymph nodes. The majority of stomach cancer is believed to be induced by infection of the bacterium Helicobacter pylori, with genetic factors and gastritis increasing the risk for cancerous development. Surgery to remove cancerous tissues is the most common treatment, followed by chemotherapy; however treatment is dependent upon the individual case. Stomach cancer is one of the most prevalent forms of cancer faced globally.
Strep Throat: A contagious pharyngitis induced by infection of the group A Streptococcus bacteria. Also termed streptococcal tonsillitis. Sore throat, fever and swollen lymph nodes are symptomatic of strep throat. Strep throat may clear naturally or be treated by an antibiotic and/or analgesic course of medications.
Stroke: A disturbance or impediment in blood flow to the brain, caused by occlusion or hemorrhage, disabling the area of brain affected from functioning. Manifestations of this disturbance may be an inability to move an area of one side of the body, impeded speech capabilities or loss of a field of vision on one side. Stroke is one of the leading causes of death and disability in adults in globally. Age, diabetes, high blood pressure, high cholesterol and smoking are all added risk factors for the chance of stroke occurring. Stroke may be treated in-hospital, followed by a regimen of speech or physical therapy, dependent on case.
Synovial Fluid: The fluid that fills joints and lubricates cartilage; a target of rheumatoid arthritis.
Syphilis: A sexually transmitted infection (STI) caused by the spiral-shaped bacteria Treponema pallidum. Treatment includes a course of penicillin. If left untreated, syphilis can become fatal and may increase the risk of HIV transmission.
Systemic: Affecting the whole body, or multiple tissues and organs.
Systole: The stage in the cardiac cycle at which point the heart muscle (myocardium) is contracting.