Medical Glossary: R

Radiation Therapy

Method of treatment for cancer using x-rays or gamma rays, usually from a cobalt source to deter the proliferation of malignant cells by decreasing the rate of mitosis of impairing DNA synthesis.

Radioactive Scan

A test in which liquid radioactive material is injected into the body and scanned to find a problem within part of the body.

Rectus Muscle

Muscles of the body that have a relatively straight form. Rectus muscles include the rectus abdominis and the rectus femoris.

Red Blood Cells

A concave disk containing hemoglobin surrounded by a lipoid membrane. It is the major cellular element of the circulating blood and it serves primarily to transport oxygen. The number of red blood cells is about 4 and 4.5 million per cubic millimeter in women (4.5 and 5 million per cubic millimeter in men).

The average lifespan of a red blood cell is between 110 and 115 days after which it is removed from the bloodstream. New red blood cells are produced at about the rate of 1% daily to keep levels constant. Red blood cells originate in the marrow of long bones. Also called erythrocytes.

REM

Abbreviation of rapid eye movement; a type of sleep pattern. REM sleep periods alternate with the nonrapid eye movement sleep periods and last from a few minutes up to half and hour.

REM sleep is when all dreaming occurs. Infants usually begin their sleep period with REM sleep whereas in adults REM sleep usually follows the four stages of nonrapid eye movement sleep.

Respiratory Depression

A term used to describe breathing difficulties found in a newborn baby.

Retina

A membrane of the eye consisting of nervous tissue and comprising ten layers. It is contiguous with the optic nerve sending visual impulses to the brain.

The retina is soft and contains rhodopsin which gives it its purple tint. If exposed to direct sunlight it will become clouded.

Rh Negative

A blood group coding to note that the patient lacks the rhesus antibody in their blood.

Rho(D) Immune globulin

A passive immunizing agent which is administered to Rh-negative mothers after abortion, miscarriage, ectopic pregnancy or regular delivery of the baby. Adverse reactions include anaphylaxis.

Rh Sensitivity

Phrasing used in hematology (the study of blood) to note incompatibility of two blood groups; one containing the Rh factor and its absense in the other.

Rhesus Factor

An antibody agent that is present in the red blood cells of about 85% of the population. Those with the agent are Rh+ (Rh Positive), those without it are Rh- (Rh Negative). Blood typing is ordered by ABO classification and Rh+/-.

Should a person who is Rh- receive Rh+ blood they may develop hemolysis and anemia.

Rh+ infants developing in the uterus of an Rh- mother may be exposed to and react to the antibodies present in her blood destroying the fetal red blood cells leading to erythroblasstosis fetalis.

In some cases a person who has the Du variant of the Rh Factor is considered an Rh+ donor but and Rh- recipient in order to avoid hemolytic reactions. Its name derives from the fact that it was first discovered and isolated in the blood of Rhesus monkeys.

RhoGAM

Medication given to prevent isoimmunization, given during pregnancy if an Rh- mother is carrying an Rh+ baby. See also Rhesus Factor.

Rooting Reflex

A normal feeding reflex present in newborns until about 3 - 4 months of age (although it may persist until 12 months).

The reflex is apparent when the baby's cheek is stroked or touched along the side of the mouth. The baby will turn its head toward the side that is stimulated and begin to suck.

Round Ligament Pain

Pain during pregnancy that results from the stretching of ligaments bordering each side of the uterus.

Rubella

A contagious virus lasting approximately 2 or 3 days that is characterized by fever, a mild upper respiratory infection, lymph node enlargement and a fine red rash. Incubation time is about 12 to 23 days.

During pregnancy fetal anomalies such as heart defects, cataracts, deafness and mental retardation may result if the mother contracts the disease during the first trimester.

A fetus that has been exposed to the virus in utero is immune for up to 30 months after birth. Vaccination is recommended for all children to minimize the chances of an epidemic and thus protect pregnant women.

Vaccination is not provided for mothers who are already pregnant, and pregnancy is to be avoided for three months after receiving the vaccine. Also called German Measles.

Rupture of the Membranes

Rupturing of the amniotic sac releasing the amniotic fluid. It is usually one of the first signs of the onset of labor. Also called the Breaking of the waters.

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