The Placenta

Question 0

What invades the uterine wall?

Answer 0

Syncitiotrophoblast

Question 1

When does the blastocyst enter the uterine cavity?

Answer 1

Day 4/5

Question 2

When is the blastocyst fully embedded within the endometrium?

Answer 2

Day 10

Question 3

“Implantation is interstitial” explain this.

Answer 3

Uterine epithelium is breached and conceptus implants within stroma

Question 4

Why does placental membrane become progressively thinner?

Answer 4

Fetal needs have increased

Question 5

What happens to placental membrane as fetal needs increase?

Answer 5

Become progressively thinner

Question 6

Define haemomonochorial

Answer 6

One layer of trophoblast separates maternal blood from fetal capillary wall

Question 7

What are the two portions of the placenta?

Answer 7

• Fetal portion

- Maternal portion

Question 8

What is the fetal portion of the placenta made up of?

Answer 8

• Chorion frondsum

- Chorionic plate

Question 9

What is the maternal portion of the placenta made up of?

Answer 9

• Decidua basilis

- Decidual plate

Question 10

What is most intimately incorporated into the placenta?

Answer 10

Decidual plate

Question 11

What can be found between the chorionic and decidual plates?

Answer 11

Intervillus spaces

Question 12

What fills the intervillus spaces?

Answer 12

Maternal blood

Question 13

What projects into the intervillus spaces?

Answer 13

Decidual septae

Question 14

When are decidual septae formed?

Answer 14

During months 4/5

Question 15

What is the purpose of the decidual septae?

Answer 15

To divide the placenta into compartments called cotyledons

Question 16

What are three features of the first trimester placenta?

Answer 16

• The placenta is established
• Placental barrier to diffusion is relatively thick
• Complete cytotrophoblast layer between syncitiotrophoblast

Question 17

What are three features of the term placenta?

Answer 17

• Increased surface area for gas exchange
• Placental barrier to diffusion is now thin
• Cytotrophoblast layer is lost

Question 18

Which fetal blood vessels are present in the placenta?

Answer 18

• Two umbilical arteries

- One umbilical vein

Question 19

What is the function of the umbilical arteries?

Answer 19

Carries deoxygenated blood from fetus to placenta

Question 20

What is the function of the umbilical vein?

Answer 20

Carries oxygenated blood from placenta to fetus

Question 21

What is passive diffusion influenced by?

Answer 21

• Concentration gradient
• Barrier to diffusion
• Diffusion distance

Question 22

Which substances are actively transported?

Answer 22

• Amino acids
• Iron
• Vitamins

Question 23

Which substances move via facilitated diffusion?

Answer 23

Glucose

Question 24

Which substances move via simple diffusion?

Answer 24

- Water - Electrolytes - Gases - Urea - Urease

Question 25

List five teratogens that may cross the placenta.

Answer 25

- Thalidomide - Alcohol - Therapeutic drugs - Drugs of abuse - Maternal smoking

Question 26

List five pathogens that can cross the placenta,

Answer 26

- Varicella zoster (VZV) - Cytomegalovirus (CMV) - Treponema pallidum - Taxoplasma gondii - Rubella

Question 27

What four protein hormones are secreted by the placenta?

Answer 27

- Human chorionic gonadotropin (hCG) - Human placental lactogen - Human chorionic thyrotropin - Human chorionic corticotropin

Question 28

What two steroid hormones are secreted by the placenta?

Answer 28

- Progesterone | - Oestrogen

Question 29

Aside from hormones, what else does the placenta synthesise?

Answer 29

- Cholesterol - Fatty acids - Glycogen

Question 30

When does maternal IgG begin to be transported to fetus?

Answer 30

Week 14

Question 31

How is maternal IgG transported to the fetus?

Answer 31

Receptor mediated pinocytosis

Question 32

What divides intervillus space into cotyledons?

Answer 32

Decidual septae