fetal physiology

Question 1

The fetus receives O2 from the intervillous space through diffusion. How is this diffusion facilitated?

Answer 1

All of the available choices

b.
A thin membrane surrounding the villi

c.
The large surface area of the placental villi

d.
A high number of placental villi

oxygen diffusion to the fetus is facilitated by the high number and large surface area of the villi as well as the thin membrane separating the fetal and maternal circulations.

Question 2

How does maternal hypotension reduce fetal oxygenation?

Answer 2

By reducing oxygen availability in the intervillous space

fetal oxygenation is reduced as a direct result of reduced oxygen availability from the intervillous space from a reduced maternal cardiac output

Question 3

Through which mechanisms can a fetus compensate for acute hypoxia?

Answer 3

Increased cardiac output, reduced movements and a redistribution of blood flow

these are the primary mechanisms of compensation for acute fetal hypoxia

Question 4

In the CTG, how is normal baseline variability generated?

Answer 4

Balanced parasympathetic and sympathetic input

normal baseline variability is generated through balanced sympathetic and parasympathetic input to the sinoatrial node

Question 5

What typically happens to baseline variability as the baseline fetal heart rate rises?

Answer 5

It decreases

Correct, with increasing sympathetic innervation there is a rise in the baseline heart rate and a subsequent loss of sympathetic and parasympathetic balance, resulting in reducing baseline variability.

Question 6

In the fetus, where do catecholamines mainly come from?

Answer 6

The adrenal glands

while some catecholamines arise from the sympathetic nerve endings supplying the SA node, most come from the adrenal glands

Question 7

On average, in labour, how many seconds of uterine rest between contractions is required to maintain adequate oxygen levels within the intervillous space?

Answer 7

60-90 seconds

the average fetus requires approximately 60-90 seconds of complete uterine rest between contractions in order to maintain adequate oxygen levels within the intervillous space.

Question 8

What is the primary role of catecholamines?

Answer 8

To help the body meet physiological stress

the primary role of catecholamines is to help the body to meet physiological stress by increasing the heart rate and cardiac output (and oxygen pick up) and preferentially redirecting blood and oxygen to the vital organs.