Lecture 9 Flashcards by Michaela Reyes

describe fetal respiratory? & circulatory conditions?

Lungs small and collapsed.
•Lungs filled with amniotic fluid.
•Lung volume too small to allow complete output of right
atrium through lung circuit.

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another way to say 
Lungs small and collapsed.
•Lungs filled with amniotic fluid.
•Lung volume too small to allow complete output of right
atrium through lung circuit.

Back-pressure of lungs too great

to allow much blood flow through lungs.

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There is enough blood flow to allow growth and

development, but not

gas transfer

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when do lungs not need to gas transfer?

in utero

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Before birth, it would be desirable for blood leaving the
right atrium to – for the most part – bypass the lung. There
are two ways: explain

1st: This is done via a structure called the DUCTUS
ARTERIOSUS. The DUCTUS ARTERIOSUS is a
connection between the sixth aortic arch (Pulmonary Arch)
on the LEFT side and the arch of the aorta (also on the left
side).
2nd: The FORAMEN OVALE is a hole between the right
and left atria, allowing blood to pass from the right side to
the left and not ever get pumped to the lungs.

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The DUCTUS ARTERIOSUS is a connection between

the sixth aortic arch (Pulmonary Arch) on the LEFT side and

the arch of the aorta (also on the left side).

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The DUCTUS ARTERIOSUS allows blood to

skip past the lungs and join up with the partially oxygenated blood that is being pumped out of the left ventricle.

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The FORAMEN OVALE is a hole between the

right and left atria, allowing blood to pass from the right side to the left and not ever get pumped to the lungs.

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So…

…where does spent blood from the fetus go? what artery?

Well, mom of course. It goes to the placenta that contacts

mom’s uterine wall via the UMBILICAL ARTERY.

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describe the umblical artery?

Remember that the distal end of the internal iliac artery is theold connection of the UMBILICAL ARTERY which goes
toward the placenta.

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what are the branches of the Internal Iliac Artery (In order)

Iliolumbar
Lateral sacral
Superior gluteal
Inferior gluteal
Internal pudendal
Obturator
Middle rectal
Inferior vesicle
Superior vesicle
The old umbilical
artery connects to
end of internal
iliac.

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The Umbilical Artery usually remains on_____

ONLY ONE SIDE, usually the left side.

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Oxygenated blood returning to the fetus returns via the

UMBILICAL VEIN of the fetus

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umbilical vein hooks up to

the fetus’ inferior vena cava

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explain arterial blood

Arterial blood from mother & placenta – laden with nutrients and
oxygen – come into contact of placenta of fetus via (now).

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Thus, the blood returning to the fetal heart is

this can cause what kind of problem?

HOWEVER

partially oxygen and nutrient rich.

This sets up the potential problem of it mixing in the right atrium with deoxygenated blood returning from the superior vena cava.

Due to the angle of entry of the blood from the inferior
vena cava and superior vena cava, their streams do not mix much.

MORE OXYGEN-RICH BLOOD FROM INFERIOR VENA CAVA PASS THROUGH FORAMEN OVALE OVER TO THE

left side

what is not going on during fetal respirtion?

what is the consequence of the volume

No venetalation going on yet
When you’re born spit that stuff out
Lungs provide resisatnace for flow- tough for blood to flow through it
*Consequence all of the volume that is full means that its hard for the blood to get through- called back pressure.
If there is back pressure- resistance to what structure next with that back strucuture be communicated-
This will affect the right atrium pushing backwards from the lungs

describe mixing of blood/

describe the blood in the ductus arteriousus

Highly oxy. Blood and low oxy blood mix dpwn in the other arch of the aorta

describe the formation of the formaen ovale

Flap of tissue is inside the left atrium
Understand prssure and how it moves
Gretater pressure on the right pushes flap so hole opens

moms uterus recieves blood from

internal illiac

describe the ductus venosus

don’t need to filter blood- mom does it
liver wants to take and store, you don’t need to store much
BIPASS both liver and IVC by ductus venosus DUMPS into right atrium

mixes deoxy-and oxy to the right atrium

after ductus venosus and your in the right atrium what are the two directions of blood flow

Forman ovale even before it has a chance skips over to left atrium
Way of bipassing the deoxygenated bllod of the IVC
Now ductus venosus articulates with foramen ovale so you can keep the blood separate

describe the next steps of blood flow after the two ways of blood flow post ductus venosus

From left atrium, moderately oxygen-rich blood passes to left ventricle and then out arch of aorta. Blood richest in oxygen & nutrients goes to heart wall, head (brain), neck, and arms. Somewhat more oxygen/nutrient depleted blood from superior vena cava – of course – enters right atrium, then right ventricle, then pulmonary artery. MOST of the right ventricular blood exits via the left pulmonary arterial branch – then to the DUCTUS ARTERIOSUS. This means that it eventually mixes with somewhat richer blood in the descending aorta, but ONLY AFTER the aorta has delivered blood to head, neck, and arms.

Remember, UMBILICAL VEINS enter the inferior vena cava. But

soon, they hook up with the hepatic portal system.

The right UMBILICAL VEIN eventually______, leaving only the

degenerates// left

It would not be desirable to mix oxygenated blood (from mom, umbilical vein) with deoxygenated in liver. So – a new pathway from the placenta to the upper region of the inferior vena cava bypasses the liver. It is called the - what does it do?

DUCTUS VENOSUS. It runs straight from the portal vein, bypassing the liver, to the inferior vena cava.

four things that need to be changed in the circulatory changed @ birth

1If fetal circulatory pattern were to persist after birth, right atrial blood would continuously spill to the left side via the foramen ovale. 2Blood of the pulmonary arch would miss the lung and go to the aorta, mixing there. 3This would result in hypoxia – lack of adequate oxygen in arterial blood. 4Lungs would be bypassed continuously, deteriorating quickly.

To prevent this, foramen ovale and ductus arteriosus MUST CLOSE AT why is this important

the moment of birth, Need to send blood to lungs Close at the same time so there’s no mixing

at the first breathe what happens to the ductus arteriosus

a powerful VASOCONSTRICTION closes the ductus arteriosus. (In a few days fibrous tissue begins to occlude it; in adult, it is left as a ligament, the LIGAMENTUM ARTERIOSUM.)

When blood stops flowing in from placenta via umbilical vein, what happens

ductus venosus closes off.

what is left of ductus venosus then what happens hint *postnatal portal vein*

In a few days fibrous tissue begins to occlude it; in adult, it is left as a ligament, the LIGAMENTUM VENOSUM. The umbilical vein become the ROUND LIGAMENT OF THE LIVER (also known as “ligamentum teres”). Together, ligamentum venosum and round ligament tie postnatal portal vein to navel ventrally and inferior vena cava dorsally.

describe the vagus nerve in terms of the ligamentum arteriosum

Note that this means the branch of the vagus nerve that hooked around it must STILL hook around it (LEFT RECURRENT BRANCH OF THE VAGUS NERVE), whereas the RIGHT RECURRENT BRANCH OF THE VAGUS NERVE hooks around the right sublcavian artery.

what is the remain of the foramen ovale

Eventually, the interatrial flap covering the FORAMEN OVALE fuse with the interatrial wall. The remaining area is the thinnest, smoothest part of the interatrial wall – the FOSSA OVALIS.

what is it called when the fossa ovalis has yet to form

(If foramen remains open, inappropriate blood mixing takes place – “Blue Baby”.)

whats special about fetal hemoglobin/ what can it combine with?

Due to fetal mixing of blood, FETAL HEMOGLOBIN is adapted specially. can combine with oxygen even more easily than ADULT HEMOGLOBIN – so it can pick oxygen OFF of the adult hemoglobin. This special property is lost within a few days after birth.

what are the changes of the liver during near birth what does this mean for the mother

At approximately week 27-30, enzyme function in the fetal liver changes to promote storage of GLYCOGEN(chain sugars). This stores up glycogen as a food source in case of temporary starvation between birth and mother’s first ability to produce milk for nursing.Mothers millk doesn’t come for like two days Liver stores food just incase mom is not ready to give baby milk