Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «S»:
Siamese twin: Identical (monozygotic) twins that did not separate fully from one another but are still partially united. Due to the incomplete division of one fertilized ovum. Such twins are known medically as conjoined twins.
Conjoined twins are popularly known as Siamese twins after Chang and Eng...
Sibling: A brother or sister....
Sibship: The total number of children born to a set of
parents. Siblings belong to a sibship....
Sicca syndrome: An autoimmune disease, also known as Sjogren syndrome, that classically combines dry eyes, dry mouth, and another disease of connective tissue such as rheumatoid arthritis (most common), lupus, scleroderma or polymyositis.
There is a great preponderance of females. About 90% of Sjog...
Sick building syndrome
Sick building syndrome: A condition caused by exposure to various noxious agents that affect persons employed in a "sick building," usually an office or other building that houses many people working in close proximity to one another.
Sick building syndrome characteristically occurs in tight buil...
Sick sinus syndrome
Sick sinus syndrome: Symptoms of dizziness, confusion,
fainting, and heart failure due to a problem with the sinus node of
the heart, which acts as the body's natural pacemaker. If the sinus
node is not functioning normally, it is reflected in an abnormally
slow heart rate (bradycardia). This c...
Sickle cell anemia
Sickle cell anemia: A genetic blood disease due to the presence of an abnormal form of hemoglobin, namely hemoglobin S. Hemoglobin is the molecule in red blood cells that transports oxygen from the lungs to the farthest areas of the body.
Sickle cell anemia affects millions of people throughout the ...
Sickle cell disease
Sickle cell disease: A genetic blood disorder caused by the presence
of an abnormal form of hemoglobin. These hemoglobin molecules tend to aggregate
after unloading oxygen forming long, rod-like strictures that force the red
cells to assume a sickle shape. Unlike normal red cells, which are usual...
Sickle cell trait
Sickle cell trait: The condition in which a person has one
copy of the gene for sickle cell (and is called a sickle
heterozygote) but does not have sickle cell disease (which requires
two copies of the sickle cell gene). If two people with sickle cell
trait mate and have children together, each ...
Sickle hemoglobin: Hemoglobin S, the most common type of abnormal hemoglobin and the basis of both sickle
cell trait and sickle cell anemia.
Hemoglobin S differs from normal adult hemoglobin (hemoglobin A) only by a single amino acid substitution (There is the substitution of the amino acid valine...
Sickness, acute mountain (AMS)
Sickness, acute mountain (AMS): Acute mountain sickness
(AMS) is the illness that results from being at high altitude. AMS
is common at very high altitudes, that is above 8,000 feet (2,440
meters). Three-quarters of people have mild symptoms of AMS over
10,000 feet (3,048 meters). The occurren...
Sickness, altitude: Altitude sickness (or altitude illness) is a disorder caused by being at high altitude. It more commonly occurs above 8,000 feet (2,440 meters).
The cause of altitude illness is a matter of oxygen physiology. At sea level the concentration of oxygen is about 21% and the baromet...
Sickness, morning: Nausea and vomiting of pregnancy.
Morning sickness is a misnomer, because it can occur at
any time of the day (though not at night during sleep) and it is not a sickness. It is a normal characteristic of early pregnancy.
Morning sickness is now believed to be a good thing since ...
Sickness, motion: Motion sickness is a very common disturbance of the inner ear that is caused by repeated motion such as from the swell of the sea, the
movement of a car, the motion of a plane in turbulent air, etc. In the inner ear (which is also called the labyrinth), motion sickness affects th...