Fetal Blood Circulation

During fetal development, the placenta functions as the ________ and _____ for the fetus.

Lungs; Liver

The placenta supplies the fetus with _____ and _______ and eliminates fetal waste products.

Oxygen; nutrients

The fetal _____ and _____ need only enough ______ to nourish their growing tissue as they are "nonfunctional"

lung; liver; blood

What is this highlighted vein? What is its function?

Umbilical vein; Brings oxygen and nutrient rich blood from the placenta into the fetus

What is the highlighted structure? What is its function?

Ductus venosus; connects umbilical vein and caudal vena cava, bypassing liver sinusoids

What is the highlighted structure? What is its function?

Foramen ovale- opening in the intraatrial septum; shunts 60% of oxygen-rich blood from RA to LA

What do the ductus venosus and foramen ovale ensure?

Together they ensure that O2 rich blood reaches the developing heart and brain

What is the highlighted structure? What is its function?

Ductus arteriosus; shunts blood from the pulmonary trunk to the aorta, bypassing lungs- enter the aorta distal to the brachiocephalic trunk thereby ensuring no dilution of the O2 rich blood headed for the head

What is the highlighted structure? What is its function?

Umbilical artery; large branches of the terminal aorta, return blood to the placenta for oxygen replenishment and waste elimination

What happens to the umbilicus once the animal is born?

It is bitten or broken, and the first breath is taken

What happens once the umbilicus is disconnected after birth?

This expands the lungs and relieves pressure on the vessels and capillaries of the lung, allowing them to expand. As the vessels open, resistance to blood flow drops, allowing more blood through the pulmonary arteries to reach the lungs.

What happens to the ductus arteriosus after birth?

It is closed soon after birth due to the increased O2 content of the blood flowing through it.

What is the ductus arteriosus called after it closes?

Ligament arteriosum; allows even more blood to reach lungs

What is Patent ductus arteriosus?

Failure of the ductus arteriosus to close following birth

On inspiration, the thorax ____ in two directions.

expands

On inspiration, the thorax expands laterally due to what?

Contraction of the intercostal muscles

On inspiration, the thorax expands caudally due to what?

Contraction of the diaphragm, which flattens

On inspiration, ribs move _______.

cranially