EMBRYOLOGY

Question 1

How does the fetus compensate for a lack of Amniotic fluid volume.

Answer 1

By reducing its movements and saving energy

Question 2

How does oligohydraminos cause fetal hypoxia

Answer 2

By causing compression of the lungs which hinders their development

Question 3

metabolic state the fetus shifts to in order to conserve metabolic energy

Answer 3

nREM

Question 4

How does p50 increase and what effect does it have on the punching pressure of O2

Answer 4

Increase in Temperature, PC02, 2.3-DPG and increased H+ concentrations, increase affinity of O2 towards haemoglobin and thus, increase punching pressure by increasing p50

Question 5

Why does fetal haemoglobin have a higher affinity then adult haemoglobin?

Answer 5

HF consists of two beta and two gamma chains

Question 6

Steps in which compensated respiratory alkalosis takes place to transport CO2 to maternal lungs

Answer 6

Double Bohr and Haldane effects
 CO2 is transported to the placenta
 Diffuses across villi into the intervillous space
 CO2 acidifies the maternal blood in the intervillous
space
 Acidification encourages release of maternal O2
which diffuses across the villi to be taken up by fetal
Hb
 Empty maternal Hb takes up fetal CO2 and
transports back to maternal lungs.

Question 7

A.How does 50% of Oxygenated blood get transported to the liver and why?

B.How and where does the other 50% of blood get transported

c.Compare relative pressures of blood in the Liver and the other location where it is transported

Answer 7

A-Shunted via the ductus venosus
B-Transported to the inferior vena cava
c-As arteries are narrow, gets transported at a higher pressure towards the inferior vena cava

Question 8

How does mixing of Deoxygenated and Oxygenated blood get prevented

Answer 8

Due to the oxygenated blood travelling faster then the deoxygenated blood

Question 9

How does mixing of Deoxygenated and Oxygenated blood get prevented

Answer 9

Due to the oxygenated blood travelling faster then the deoxygenated blood

Question 10

Function of a patent foramen ovale

Answer 10

Allows oxygenated blood to shunt from the right atrium to the left atrium

Question 11

How does the O2 content of the blood in the Right Ventricle increase

Answer 11

Oxygenated blood mixes with the venous blood, entering the Right Atrium and the majority of it is transported into the descending aorta

Question 12

What can cause extra O2 to be “spilled” into the blood moving down the descending aorta

Answer 12

Aortic ithsmus

Question 13

Oxygenated blood transport steps

Answer 13

1.Placenta to liver
2.Liver to IVC via ductus venosus – no mixing
3.IVC to right atrium (RA)
4.Through the foramen ovale to left atrium (LA)
5.LA to left ventricle (LV) – gains some
deoxygenated blood from lungs, slightly drops
oxygenation
6.LV to ascending aorta
7.Feeds heart, upper body, brain (PaO2/SaO2 higher
than stream two)

Question 14

Deoxygenated blood transport steps

Answer 14

1.Blood returns to heart via IVC – no mixing
2.IVC to RA – picks up more O2 from oxygenated
stream
3.RA to PA to lungs – only 8%, rest is shunted
through ductus arteriosus
4.Ductus arteriosus to ascending aorta
5.Picks up some more O2 from ascending aorta spill
over via the aorta segment called the aortic
isthmus
6.Feeds lower body (PaO2/SaO2 lower than stream
one)

Question 15

Which chemoreceptors detect hypoxia in the peripheral arterioles

Answer 15

Aortic and Carotid Body

Question 16

Effects of vasoconstriction and bradycardia on blood flow

Answer 16

Causes a constant supply of oxygenated blood to be supplied to the brain and heart

Question 17

Effects of blood flow on liver

Answer 17

Foramen ovale, causes more blood to shunt to the left ventricle and thus, be pumped to tissues and organs with a higher metabolic requirement then the liver

Question 18

Experiment of ANS parasympathetic response towards bradycardia

Answer 18

Cut Vagus Nerve
Use muscuranic parasympathetic receptor blocker such as atropine

Question 19

Chemoreflex control experiment method

Answer 19

Cutting carotid sinus nerve

Question 20

FHR fall purpose

Answer 20

Reduced cardiac work, which protects the heart from injury during hypoxic periods

Question 21

Experiment of ANS sympathetic response towards bradycardia

Answer 21

Using an alpha-1 adrenergenic antagonist

Question 22

Endothelial activity mechanisms

Answer 22

Controlled via vasodilation caused by nitric oxide endothelial vasodilators.

Question 23

How energy is conserved and also, how is the metabolic demand of organs, in low O2 supply met.

Determine one disadvantage of energy conservation by the fetus

Answer 23

Ductus venosus, reduces blood flow to the liver, reduces mixing in RA as the speed of Oxygenated blood exceeds venous blood, and also, the majority of the blood which crosses the Foramen Ovale to move from the Right Atrium to the Left atrium is oxygenated.

Energy is conserved as fetus enters an NREM state and also, initiates apnea, by stimulating the respiratory centres of the medulla.
Also, decrease in body movements, conserves energy at the expense of delayed development.

Question 24

WHAT ARE THE THREE MAIN REGIONS OF THE PLACENTA

Answer 24

Decidua Basalis
Chorionic Vili
Amniotic sac