Or eat? From mom, of course. Shown is a detailed representation of the placenta. And this is where all these interactions occur. The fetus could not grow and develop without oxygen and nutrients from the mother. Wastes from the fetus
must also be removed in order for it to survive. The exchange of these substances between the mother and fetus occurs through the placenta.How does a
developing baby breathe?
Placenta and Related Structures
Placenta
The placenta is a temporary organ that begins to form from the trophoblast layer of cells shortly after implantation. The placenta continues to develop and grow to meet the needs of the growing fetus. A fully developed placenta is made up of a large mass of blood vessels from both the mother and fetus. The maternal and fetal vessels are close together but separated by tiny spaces. This allows the mother’s and fetus’s blood to exchange substances across their capillary walls without the blood actually mixing.
The fetus is connected to the placenta through the umbilical cord, a tube that contains two arteries and a vein. Blood from the fetus enters the placenta through the umbilical arteries, exchanges gases and other substances with the mother’s blood, and travels back to the fetus through the umbilical vein.
The fetus and the placenta. Notice the fetus is attached to the placenta by the umbilical cord, made of two arteries and one vein.
Amniotic Sac and Fluid
Attached to the placenta is the amniotic sac, an enclosed membrane that surrounds and protects the fetus. It contains amniotic fluid, which consists of water and dissolved substances. The fluid allows the fetus to move freely until it grows to fill most of the available space. The fluid also cushions the fetus and helps protect it from injury.
Summary
- The placenta allows nutrients and wastes to be exchanged between the mother and fetus.
- The fetus is connected to the placenta through the umbilical cord.
Review
- What makes up a placenta?
- Describe the role of the placenta in fetal development.
- What is the umbilical cord? What occurs in the umbilical cord?
fertilization | union of a male sperm cell and a female egg cell |
implantation | the attachment of the zygote to the uterine wall |
embryo | the developing child from the time of implantation until about the eighth week of development |
fetus | developing embryo in the uterus |
amniotic sac | a thin, fluid-filled membrane that surrounds and protects the developing embryo |
umbilical cord | a ropelike structure that connects the embryo and the mother's placenta |
placenta | a thick, blood-rich tissue that lines the walls of the uterus during pregnancy and nourishes the embryo |
labor | the final stage of pregnancy in which the uterus contracts and pushes the baby out of the mother's body |
prenatal care | steps that a pregnant female can take to provide for her own health and for the health of her baby |
birthing center | a facility in which females with low-risk pregnancies can deliver their babies in a homelike setting |
fetal alcohol syndrome [FAS] | a group of alcohol-related birth defects that includes both physical and mental problems |
miscarriage | the spontaneous expulsion of a fetus that occurs before the twentieth week of a pregnancy |
stillbirth | a dead fetus expelled from the body after the twentieth week of pregnancy |
heredity | all the traits that are biologically passed from parents to their children |
chromosomes | threadlike structures found within the nucleus of a cell that carry the codes for inherited traits |
genes | the basic units of heredity |
DNA | the chemical unit that makes up chromosomes |
genetic disorder | a disorder caused partly or completely by a defect in genes |
amniocentesis | a procedure in which a syringe is inserted through a pregnant female's abdominal wall into the amniotic fluid surrounding the developing fetus |
Chorionic villi sampling | a procedure in which a small piece of membrane is removed from the chorion, a layer of tissue that develops into the placenta |
gene therapy | the process of inserting normal genes into human cells to correct genetic disorders |
developmental tasks | an event that needs to happen in order for a person to continue growing toward becoming a healthy, mature adult |
autonomy | the confidence that a person can control his or her own body, impulses, and environment |
scoliosis | a lateral, or side-to-side, curvature of the spine |