Placenta

Question 1

What are the parts of the placenta?

Answer 1

Question 2

What are the properties of the placenta?

Answer 2

• Discoidal
• Maternal aspect is divided into 15-20 cotyledons

Question 3

What are the properties of placental blood?

Answer 3

• Enters cotyledons via 80-10p spiral aa and leaves via uterine vv tributaries
• Maternal blood space surrounds villus trees and holds 150ml blood
• Foetal blood is separated from maternal blood

Question 4

What is placental abruption?

Answer 4

• Placenta peels away from uterine wall before delivery
• Can cause poor foetal growth as deprived of oxygen and nutrients
• Can cause maternal bleeding
• Can cause premature and stillbirth
• Occurs in 1/100 pregnancies

Question 5

What is placenta previa?

Answer 5

• Low-lying placenta which covers most or all of cervix opening
• Block babies exit from uterus
• Potential tearing of blood vessels connecting to placenta, causing bleeding during labour
• Can cause premature birth
• Occurs in 1/200 pregnancies

Question 6

What is placenta accreta?

Answer 6

• Placenta implants too deeply and firmly to uterine wall
• May cause excessive bleeding during delivery
• Occurs in 1/2500 births

Question 7

What are some placenta-mediated conditions?

Answer 7

• IUGR
• Pre-eclampsia
• Diabetic pregnancy (cause malformation)
• Smokers pregnancy (cause small size)
• Pregnancy at altitude

Question 8

What does the intraembryonic coelom form?

Answer 8

Pericardial cavity

Pleural cavity

Peritoneal cavity

Question 9

What are the 3 longitudinal columns formed by the intraembryonic mesoderm?

Answer 9

Paraxial

Intermediate

Lateral plate

Question 10

What does the prochordal plate form?

What does the neural tube form?

What does the cloacal plate form?

Answer 10

Mouth

Brain and spinal cord

Anus

Question 11

What does the medial, intermediate and lateral somites form?

Answer 11

Skeleton

Muscle

Skin

Question 12

What does the somatopleuric mesoderma and sphlanchopleuric mesoderm form?

Answer 12

Striated muscle

Gut smooth muscle

Question 13

What is the chorion composed of?

Answer 13

Trophoblast and extraembryonic mesoderm