Function of the Placenta

Question 1

What is the function of placental villi?

Answer 1

Maternal and foetal exchange of substances, maternal blood perfuses intervillous space

Question 2

What happens to placental blood flow during pregnancy?

Answer 2

Increases - larger foetus, more structures need supplied

Question 3

What is the function of the umbilical vein?

Answer 3

Carry oxygenated nutrient rich blood from the placenta to the foetus

Question 4

What is the function of the umbilical arteries?

Answer 4

Carry deoxygenated blood, that is nutrient depleted from the foetus to the placenta.

Question 5

What are the different functions of the placenta?

Answer 5

SERPENT
S - storage
E - endocrine
R - respiration
P - protection
E - excretion
N - nutrition
T - transfer

Question 6

What does this placenta do in its role in storage?

Answer 6

Metabolises glucose, stores as glycogen until it is required.
Synthesises and stores cholesterol
Iron and fat solubel vitamins

Question 7

What is the endocrine function of the placenta?

Answer 7

Creates an endocrine environment - maintain pregnancy and prenatal development
Will secrete
Human chorionic gonodotrophin
Human chorionic somatomommotropin
Progesterone
Oestrogen

Question 8

What is the role of human chorionic gonadotropin in pregnancy?

Answer 8

Stimulates the corpus luteum to produce progesterone to maintain the pregnancy.
Highest at the end of the first trimester (10 weeks) then decline.
Thicknes uterine lining and stops menstuation

Question 9

What is the function of human chorionic somatomammotropin hormone during pregnancy?

Answer 9

Stimulates milk glands in the breast for breast feeding.
Creates a mild insulin resistance in the mother, increases glucose supply to the foetus

Question 10

What is the function of progesterone during pregnancy?

Answer 10

Prevents contraction - stops miscarriage in early pregnancy
Aids the growth of the uterus wall including glands and blood vessels.
Encourages placenta growth.

Question 11

What is the function of oestrogen during pregnancy?

Answer 11

Promotes the growth of maternal breast tissue and prepares for lactation
Stimules the growth and correct function of the placenta
Regulates other hormone levels
Aids the development of organs such as lungs, liver and kidney

Question 12

What is the function of the placenta in respiration?

Answer 12

Transfer of gaseous oxygen and carbon dioxide, alongside nutrients and waste bilaterally between the foetus and mother.
Assisted by high fetal haemoglobin levels, bohr effect, haldane effect and increased maternal respiratory rate and slight alkalosis

Question 13

What is the role of the placenta in protection?

Answer 13

Filters substances of high molecular weight by acting as a semi permeable membrane
This has an immunological function, provides passive immmunity is later pregnancy
Helps prevent infection
Prevents antigen reactions as different blood circuits

Question 14

What substances can cross the placenta barrier that are potentially harmful to the foetus?

Answer 14

Many viruses, parasitic and protozoal diseases such as HIV and rubella
Medicines and drugs (some may be helpful)
Poisons and carbon monoxide

Question 15

What is the role of the placenta in excretion?

Answer 15

Diffusion of mainly carbon dioxide from the foetus into mothers blood
Small amounth of urea and uric acid excreted
Bilirubin

Question 16

What role does the placenta have in nutrition?

Answer 16

Provides foetus with nutrients from mothers diet:
amino acids and glucose - growth and energy
Caclium and phosphorus - for bones and teeth
Iron and minerals - formation of blood.
Amino acids require active transport into the foetus
In later preganancy fats and fat soluble vitamines cross the placenta.

Question 17

What is meant by the parasitic relationship between the foetus and mother?

Answer 17

THe foetus depletes the mother of nutrients and oxygen
Has adpated to take this from the mother even if her own supply is low

Question 18

How are substances transferred between the foetus and the placenta.

Answer 18

Facilliated by uteroplacental circulation (mom) and fetoplacental circulation (baby).
By diffusion of water soluble
Endocytosis of macromolecules
Active transport mechanisms e.g calcium