The Placenta

• Allows female mammals to carry the Allows female mammals to carry the young inside their bodies during early young inside their bodies during early development.development.• During pregnancy, the developing During pregnancy, the developing foetus receives all its nutrients via the foetus receives all its nutrients via the placenta.placenta.• All the waste products in the foetus’s All the waste products in the foetus’s blood are removed via the placenta.blood are removed via the placenta.• The placenta also produces hormones.The placenta also produces hormones.

The Placenta

The Placenta

The Placenta

The placenta consists of thousands The placenta consists of thousands of tiny branched fingers of tissue of tiny branched fingers of tissue called CHORIONIC VILLI these called CHORIONIC VILLI these project into the endometrium. The project into the endometrium. The maternal blood vessels maternal blood vessels surrounding the chorionic villi surrounding the chorionic villi break down forming maternal break down forming maternal blood sinusesblood sinuses

The Placenta

The PlacentaDiagram showing chorionic villiDiagram showing chorionic villi

The PlacentaTable showing exchange of materials across the

placenta

Mother to Foetus Foetus to Mother

•Oxygen •Glucose •Amino acids •Lipids, fatty acids & glycerol •Vitamins •Ions; Na, Cl, Ca, Fe •Alcohol, nicotine + other drugs •Viruses •Antibodies

•Carbon dioxide •Urea •Other waste products

The Placenta

short diffusion distances;breakdown of membranes;placenta has a large S/A:Vol;because of chorionic villi and lacunae;slow movement of blood at exchange surfaces;transport proteins present for facilitated diffusion of glucose;transport proteins present for active transport of ions and a.a’s;