Heart Development Flashcards by Sara Kayeum

In the adult heart, blood with low oxygen concentration enters the (left/right), while oxygenated blood enters the (left/right) side.

low oxygenated (venous blood) = right
oxygenated (arterial) = left

How well did you know this?

Not at all

Perfectly

Do lungs function during fetal life?

How well did you know this?

Not at all

Perfectly

In fetal life, oxygenated blood from _____ to _____

From placenta to RA

How well did you know this?

Not at all

Perfectly

In early embryo, what start to differentiate into endothelial cells? What do they form?

Mesenchymal cells – form primitive blood cells (will eventually anastomose to form vascular system)

How well did you know this?

Not at all

Perfectly

Where does the formation of primitive blood cells occur in early embryo?

At the wall of the yolk sac outside of the embryo proper

How well did you know this?

Not at all

Perfectly

How does heart primordium form?

Differentiation of endothelial tubes withs ome blood cells

How well did you know this?

Not at all

Perfectly

Where does heart primoridum originally form? What will occur due to location?

Originally placed above neural plate (above what will be brain). Requires tremendous movement and developmental rearrangement to relocate future heart

How well did you know this?

Not at all

Perfectly

Growth of what organ is tremendous at stage of relocating the future heart?

Brain

How well did you know this?

Not at all

Perfectly

During relocation of the future heart, what occurs so primitive heart changes position to what will become the definitive thorax?

Folding of the embryo

How well did you know this?

Not at all

Perfectly

The endocardial tube is surrounded by what layer?

Epimyocardium–where functioning heart cells will be. (heart surrounded by myocardium wall, then outside will have epimyocardium)

How well did you know this?

Not at all

Perfectly

The endocardial tube is initially connected to this structure, which will vanish

dorsal mesocardium

How well did you know this?

Not at all

Perfectly

During endocardial heart tube development, you get paired endocardial heart tubes which will eventually fuse to form a single heart tube. What did these initial two tubes start as?

Angiogenetic cell clusters

How well did you know this?

Not at all

Perfectly

What are the two ends of the heart tube?

Arterial and venous end

How well did you know this?

Not at all

Perfectly

In between the arterial and venous end, what does the heart tube have? What is weird about the structures?

Primitive ventricles and atrium except they are in the incorrect order! (Ventricle on top of atrium). Will need further rearrangement

How well did you know this?

Not at all

Perfectly

In the formation of the loop, what happens as result of bending the tube?

The atrium (bottom) will get pushed up and behind

How well did you know this?

Not at all

Perfectly

What is the symmetry like in the fetal heart? How is this different from the adult heart?

Everything is symmetrical in the arterial and venous sides, even when the loop is introduced. They are asymmetrical in the adult heart.

How well did you know this?

Not at all

Perfectly

After formation of the loop, what is formed?

Primitive canal (AV canal)

How well did you know this?

Not at all

Perfectly

What will grow out to divide the canal in half?

Endocardial cushions

How well did you know this?

Not at all

Perfectly

A primitive atrium and ventricle develop via the fusion of what?

Endocardial cushions –at this point, it resembles the adult heart more than ever before!

How well did you know this?

Not at all

Perfectly

What are the endocardial (AV) cushions, and where do they come from? Function?

Subset of cells in the primordial heart. Major role in proper heart septation

How well did you know this?

Not at all

Perfectly

The endocardial cushion gives rise to these two important structures of heart that are critical to proper formation of a 4-chambered heart

heart’s valves and septa

How well did you know this?

Not at all

Perfectly

The endocardial cushions consists of these two:

dorsal and ventral

How well did you know this?

Not at all

Perfectly

When do the endocardial cushions fuse into one?

Fusion occurred after atrium came up above ventricle during tube bending

Before birth, in which atrium is there higher pressure?

Higher pressure in Right atrium, lower in left.

How do you divide the atrium into two?

Via the septum primum and secundum

Describe action of septum primum. Why is there still no division?

Comes down from top, towards the fused endocardial cushion. Just as it's about to meet the endocardial cushion, the initial segment at top will degenerate, so there is still no division

What does the septum primum form due to its growing/degeneration of top? How does help in transition process of blood source?

A hole/valve develops from R to L top side of heart. If higher pressure in R atrium than left, you get blood flowing across. When L pressure is higher than R, it slams shuts like a trap door. Makes use of this when want to change source from umbilical vein to pulmonary vein

Describe action of septum secundum

Will grow down where septum primum failed to seal off the two atrium.

What does the septum secundum functionally form?

A one way valve -- if pressure is higher in RA, then blood will move from RA to LA by pushing the leaflet

What is on either side of the fused endocardial cushion?

A right and left atrioventricular canal

After the atrium is divided into two, is the atria and ventricle divided yet?

No, but there is a blueprint

What divides into the aorta and pulmonary trunk?

Truncus arterioris (just below the aortic arches on top)

What is one of the most common abnormalities?

Ventricular septum-divides the ventricles

What divide the tube intwo two compartments?

Ridges that grow outward, will come off different parts of the tube

How do ridges form the ventricular spetum

Ridges growing downward that divided the common trunk will come down to the fused endothelial cushion, leading to the muscular part of the intraventricular foramen

How does a ventricular septal defect occur?

Improper fusing of the bulbar ridges

How does division of the ventricles occur? (2 parts)

- muscular intraventricular septum will grow up to endocardial cushions, stops going all the way and leaves a hole - membranous portion is developed on top to finish off the divison

Different regions of the heart develop under control of different ____

transcription factors

Arterial end of the heart will have a series of aortic arches that develop symmetricaly/asymmetrically

symmetrically

There will be selective degeneration and differential elaboration of aortic arches that cause asymmetric differentiation. Important ones to know: - fourth arch = ? - sixth arch = ?

4th - aorta | 6th - pulmonary

Analagous to the aortic system, the venous system starts off symmetrical. But in adult, we know that all venous blood from SVC and IVC go to the RA> How does this occur? (4)

- Anastomoses will form between R and L side - shunt of venous system develops (poorly understood) - degeneration of selective structures - changes in liver

trace the circulation of oxygenated blood before birth: | from ___ --> ___ --> enters liver and ____, the latter which enables bypass of the liver to enter the ____ via ____

From placenta --> umbilical vein --> enters liver and DUCTUS VENOSUS --> inferior vena cava --> RA

How does level of oxygenated blood carried by IVC and SVC differ before birth?

IVC carries highly oxygenated while SVC carries low in oxygen (no source of O2 in superior)

Pulmonary vascular resistance before birth is (high/low)

High. Won't get blood flow from RA-->RV-->pulmonary trunk --> lungs

Ductus arteriosus is a shunt to bypass ___ to ____

pulmonary trunk to aorta (further relieves very high vascular resistance in pulmonary trunk

As states earlier, pressure is higher in RA than LA during fetal life. How does this effect blood flow?

Higher RA pressure will shunt blood to LA (via one way valve,) down to LV. The blood will then get pumped out to the aorta. This is good--oxygenated blood will get pumped out to rest of body -note that some will get into RV and get pumped out

Lungs require this for proper development

Surfactant. Lipid molecule that reduces surface tension of the lungs--so they can inflate

What happens to pulmonary vascular resistance after birth? Effect?

Dramatically decreases, so it's easier to get blood to and back from the lungs. Can now pump blood from right ventricle to lungs

How does the atria pressure dynamics change after birth? How does this effect the one way valve?

LA pressure will increase--will shut the one way valve

After birth, the following transformations occur in the three fetal shunts: umbilical vein --> ? ductus venosus --> ? ductus arteriosus --> ?

umbilical vein --> ligamentum teres ductus venosus --> ligamentum venosum ductus arteriosus --> ligamentum arteriosum

What happens to the foramen ovale?

Shuts to form a fossa--complete separation between the two atriums of the heart

Mixing of blood high in oxygen with blood low in oxygen within heart (Before/After) birth. Explain both scenarios

Before. Oxygenated blood carried by umbilical vein through ductus venosus to IVC to RA. Get deoxygenated from SVC After birth-oxygenated blood enters LA via pulmonary vein --no mixing of blood within heart

iCMs (induced cardiomyocytes) + | Importance in future approaches to adult heart disease?

resemble cardiomyocyte cells. Get reprogramed by TF's (Gata4, MEF2c, TBx) from fibroblasts. Have spontaneous contraction and action potentials] can't regenerate heart cells very well when lose them during heart attack, so can do transplantation in vivo.

What gives rise to the aortic arches?

Truncus arteriosus (common outflow channel for RV and LV)

blood from left ventricle enters aorta which passes to the right (in front of/behind) the pulmonary artery

behind

Blood from the RV enters the pulmonary artery which passes (in front of/behind) the aorta, turning (anteriorly/posteriorly) on the left side of mediastinum

in front of the aorta, passes posteriorly

3 fetal shunts and function:

1. foraman ovale: allows blood flow from RA to LA 2. ductus arteriosus: blood that got into RV to bypass pulmonary circulation 3. ductus venosus: blood from umbilical vein to IVC, bypassing liver