Lecture 9 Flashcards
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.
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.
There is enough blood flow to allow growth and
development, but not
gas transfer
when do lungs not need to gas transfer?
in utero
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.
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).
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.
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.
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.
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.
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.
The Umbilical Artery usually remains on_____
ONLY ONE SIDE, usually the left side.
Oxygenated blood returning to the fetus returns via the
UMBILICAL VEIN of the fetus
umbilical vein hooks up to
the fetus’ inferior vena cava
explain arterial blood
Arterial blood from mother & placenta – laden with nutrients and
oxygen – come into contact of placenta of fetus via (now).
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/
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 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
