In the uterus, the pig fetus receives oxygen through a unique structure called the umbilical cord. This cord connects the fetus to the placenta, a specialized organ that develops in the mother's uterus during pregnancy. The placenta contains numerous blood vessels from both the mother and the fetus, allowing for the exchange of gases and nutrients.
1. Maternal Blood: Oxygenated maternal blood, carrying oxygen and nutrients, enters the placenta through the mother's uterine arteries.
2. Placental Exchange: Inside the placenta, the maternal blood vessels are located close to the fetal blood vessels, but they do not directly mix. Oxygen and carbon dioxide diffuse across the thin walls of the blood vessels, allowing for the exchange of gases.
3. Fetal Blood: The oxygenated fetal blood absorbs oxygen from the maternal blood, while the carbon dioxide from the fetus diffuses into the maternal bloodstream. The deoxygenated maternal blood then returns to the mother's circulation through the uterine veins.
4. Fetal Circulation: The oxygenated fetal blood, carrying the absorbed oxygen, is transported back to the fetus through the umbilical cord's umbilical vein. It enters the fetus's body and circulates throughout its organs and tissues, delivering the vital oxygen needed for growth and development.
Elimination of Waste:
Similar to obtaining oxygen, the fetus rids itself of waste products, primarily carbon dioxide, through the placenta and umbilical cord:
1. Fetal Circulation: Deoxygenated fetal blood, carrying carbon dioxide and other waste products, travels through the umbilical cord's umbilical arteries.
2. Placental Exchange: As the deoxygenated fetal blood reaches the placenta, carbon dioxide diffuses out of the fetal blood vessels and into the maternal bloodstream. Oxygen simultaneously moves in the opposite direction.
3. Maternal Circulation: The maternal blood carries the waste products, including carbon dioxide, back to the mother's lungs through the uterine veins. In the lungs, the carbon dioxide is released during exhalation.
This remarkable exchange of gases and nutrients, facilitated by the placenta and umbilical cord, sustains the developing pig fetus until birth. After birth, the piglet will be able to breathe on its own and obtain oxygen directly from the air.