placenta
Meaning of placenta: The placenta forms in the uterus during pregnancy, exchanging oxygen, nutrients, and waste between a pregnant person and the developing fetus.
Definition of placenta
The placenta is a temporary organ that develops within the uterus during pregnancy, attaching to the uterine wall and connecting to the fetus through the umbilical cord. It allows oxygen, nutrients, and waste products to pass between the parent's bloodstream and the fetal bloodstream without the two blood supplies directly mixing under normal circumstances.
Beyond this exchange function, the placenta produces hormones that help maintain the pregnancy and prepare the body for childbirth and lactation, including hormones that support the uterine lining and regulate fetal growth. It also provides a partial barrier that limits, though does not eliminate, the passage of certain substances, including some infectious organisms and medications, from parent to fetus.
The placenta is expelled from the uterus after childbirth, in a stage sometimes called delivery of the afterbirth, and it is often examined afterward for size, structure, and any abnormalities, since placental problems can affect fetal growth and the course of pregnancy.
Used in a sentence
Ultrasound was used to evaluate the position of the placenta during the pregnancy.
Good to know
The placenta normally limits but does not completely block the passage of substances between parent and fetus, a partial barrier rather than an absolute one, which is why certain infections and medications can still affect fetal development.
Word origin
Where “placenta” comes from
Formed from Latin placenta, meaning a flat cake, a name reflecting the organ's flattened, disc like shape.