Webster's New World Medical Dictionary

circulation, fetal
The blood circulation in the
fetus (an unborn baby). Before birth, blood from
the fetal heart that is destined for the lungs is
shunted away from the lungs through a short vessel
called the ductus arteriosus and returned to the
aorta. When this shunt is open, it is said to be a
patent ductus arteriosus (PDA). The PDA usually
closes at or shortly after birth, allowing blood to
course freely to the lungs.
circulatory
Having to do with circulation, the
movement of fluid in a regular or circuitous course.
circulatory system
The system that moves blood
through the body. The circulatory system is com-
posed of the heart, arteries, capillaries, and veins.
This remarkable system transports oxygenated
blood from the lungs to the heart and throughout
the body via the arteries. The blood goes from the
arteries to the veins by passing through the capillar-
ies. Then the blood that has been depleted of oxygen
by the body is returned to the lungs and heart via the
veins. See also 
artery; blood; heart; lung; respira-
tory system; vein.
circumcision, female
The excision (removal)
of part or all of the external female genitalia, includ-
ing the clitoris, and sometimes extending to the
labia. Female circumcision is practiced in some
parts of the Middle East and Africa, particularly
Sudan, and it is viewed with disfavor in other parts
of the world. Also known as female genital mutila-
tion. See also 
clitoridectomy.
circumcision, male
Surgery that removes the
protective ring of loose skin (foreskin) that normally
covers the glans of the penis. Circumcision dates
back to prehistoric times, and it may be performed
for religious or cultural reasons, or to promote
cleanliness. Newborn circumcision decreases the
risk of urinary tract infections and lowers the risk of
sexually transmitted diseases, including HIV. It also
diminishes the risk for cancer of the penis and
lessens the risk for cancer of the cervix in sexual