Flashcards in Resit Revision Deck (86)
Describe the pressure in utero, of the systemic and pulmonic pressure
Systemic - low
Pulmonic - high
Why is low systemic pressure and high pulmonic pressure beneficial in utero?
Allows maximum perfusion to other vital organs such as the brain, liver and tissues
How does oxygenated blood enter the fetal body from the umbilical vein?
From umbilical vein in to the hepatic portal vein where most of it flows through the ductus venosus in to the inferior vena cava. Only a small amount enters the liver.
Why is it beneficial for the right ventricle to pump blood into the ascending aorta?
The blood with the highest partial pressure of oxygen reaches the coronary arteries and brain via the ascending aorta.
Through which arteries does the fetal blood flow to enter the hypogastric arteries?
The internal iliac arteries
When do the hypogastric arteries become umbilical arteries?
Once they enter the umbilical cord
Where does the ductus venosus allow blood to flow from and to?
From the hepatic portal vein to the inferior vena cava
Where does the blood enter the fetal body from the umbilical vein?
Hepatic portal vein
What type of blood enters the right atrium and where from?
Oxygenated blood from the inferior vena cava and deoxygenated blood from the superior vena cava
What is the name of the valve between the right atrium and ventricle?
What happens to the blood in the right atrium?
Two thirds flows down to right ventricle through tricuspid valve
One third flows to left atrium through foramen ovale
What happens to the blood in the right ventricle?
Pumped in to the pulmonary arteries
What happens to the blood in the pulmonary arteries?
A small amount flows to the lungs to nourish lung tissue
The rest flows through the ductus arteriosus and in to the descending aorta
Where does the ductus arteriosus allow blood to flow from and to?
From pulmonary arteries to descending aorta
Where does the foramen ovale allow blood to flow from and to?
From right atrium to left atrium
What happens to the blood in the left atrium?
It is pumped through the biscuspid valve in to the left ventricle
What is the name of the valve between the left atrium and ventricle?
What happens to the blood in the left ventricle?
Flows in to ascending and descending aorta
Ascending leads to coronary arteries and brain
Descending to the lower body
How does deoxygenated blood leave the fetal body and enter the umbilical cord?
From the internal iliac arteries it flows in to the two hypogastric arteries, which become the umbilical arteries once they enter the umbilical vein
What happens to pulmonary vascular resistance when baby takes it's first breath?
Pulmonary resistance falls so pulmonary blood flow increases
What happens to the ductus venosus and systemic vascular resistance once the cord is clamped?
The ductus venosus begins to close and systemic vascular resistance rises
Approximately how many days does it take for the ductus venosus to completely close?
What causes the pressure to rise in the left atrium?
Increased pulmonary blood flow increases pulmonary venous return
What causes the foramen ovale to close?
The pressure in the left atrium becomes higher than the pressure in the right atrium which forces the valve to close
What maintains the ductus arteriosus?
What causes the ductus arteriosus to close?
A rise in partial oxygen pressure and a fall in prostaglandin levels
Approximately how many hours does it take for the ductus arteriosus to become functionally closed?
Following birth, what does the umbilical vein become?
The ligamentum teres which is found in the free border of the peritoneal ligament, the falciform ligament
Following birth, what does the ductus venosus become?
Degenerates to form the ligamentum venosum which lies in the fissure on the visceral surface of the liver