Heart Flashcards
what is skeletal muscle formed from
periaxial mesoderm
what is cardio and smooth muscle formed from
visceral lateral plate mesoderm
When does the cardiovascular system form?
mid 3rd week
What does CPC stand for?
cardiac progenitor cells
Why does the cardiovascular system form in the third week?
the trophoblast cannot satisfy the blastocyst’s nutritional rqeuirements by diffusion only
What layer are CPC cells located?
epliblast
What does the intraembryonic cavity (ceoleum) do?
separates the visceral and parietal lateral plate mesoderm
what forms within the visceral lateral plate mesoderm?
blood islands
What are the two heart fields?
primary and secondary heart fields
What are the only structure of head and neck that migrate down?
neural crest cells
CPC are induced by ____ to form ____ and _____
endoderm
myoblasts, hemangioblasts
What form the blood islands?
Hemangioblasts
Where are blood islands formed?
primary and secondary heart fields
what do blood islands form? (two things)
numerous primitive blood vessels (endothelial lined tubes) & blood stem cells
What do the numerous endothelial lined tubes unite and form?
right & left larger endothelial-lined tubes
Myoblasts from VLPM attach to what tubes?
endothelial lined tubes
ASD appears in what location of atrial septum?*
center of atrial septum
the primary and secondary cardiac field fuse together and form what?
a single aorta & 1 pericardial cavity
What does cardiac jelly form?
cardiac mesenchyme
What does cardiac mesenchyme form?
atrial and ventricular septation
What moves the primitive heart from dorsal to ventral position?
head fold
The head fold pushes the primitive heart in what direction
from dorsal to ventral
The truncus arteriosus will eventually become what?
aorta & pulmonary trunk
The sinus venousus will eventually become what?
atria
Lateral folding fuses what 2 things together?
2 large endoethelial lined heart tubes
2 dorsal aorta
The endothelial lined heart tubes are fused everywhere except:
truncus arteriosus
Initially the heart is connected dorsally to the pericardial cavity by what?
dorsal mesocardium
What happens as the heart bulges into the pericardial cavity?
the attachment to the dorsal mesocardium rips away
when the heart rips away from dorsal mesocardium what does it form?
transverse pericardial sinus
After the transverse pericardial sinus is formed, what end is heart tube suspended from?
rostral end
what is the rostral end of the heart called (in the beginning, right after transverse pericardial sinus is formed)?
truncus arteriosus (atrial end)
What is the caudal end of the heart called (in the beginning, right after transverse pericardial sinus is formed)?
sinus venosus (venous end)
How is the heart suspended at the caudal end (as the heart is elongating into the pericardial cavity)?
by septum transversum - the venous end goes into it
What is the cardiac jelly involved in forming?
heart septas/walls and connective tissue skeleton of heart
What is located b/w the inner endothelial tube & outer myocardium?
cardiac jelly
What two things does epicardium form?
most of visceral pericardium & coronary arteries
What makes up the myoepicardial mantle?
epicardium and the myocardium
What does endocardium form?
endothelial heart tube (progenitor heart cells)
What does myocardium form?
progenitor heart cells + surrounding visceral lateral plate mesoderm
what does epicardium form?
visceral pericardium
coronary arteries - endothelium & smooth muscles
what does cardiac jelly form?
cardiac mesenchyme
CT skeleton of heart
What forms the primitive right ventricle?
bulbus cordis
What forms the mid part of bulbus cordis & outflow tracks of both ventricles?
conus cordis
What forms the distal part of bulbus corids & proximal aorta & pulmonary trunk?
truncus arteriosus
What forms b/w the conus cordis & tuncus arteriosus to separate them into aorta & pulmonary trunk?
endocardial cushions form conotruncal/bulbar ridge with conotruncal septum (neural crest) (pg 10)
What will the aortic sac form?
distal aorta
The growth of bulbus cordis is controlled by what?
neural crest cells
What day does the heart tube begin to bend? (and week)
day 23 ,week 4
What direction does the heart tube fold?
counter clockwise
What causes the heart to fold counterclockwise?
the bulbus cordis and primitive left ventricle grow faster than other parts of tube
What is the name of the congenital defect where heart apex is located on right side of body due to improper rotation (clockwise) of the heart tube?
Dextrocardia
Describe Dextrocardia
Rotates CW instead of CCW
congenital defect where heart apex is located on right side of body due to improper rotation (clockwise) of the heart tube
What is Dextrocardia of embryonic arrest?
heart is shifted slightly more to right than normal
What is Dextrocardia situs invertus?
heart is a mirror image of normal heart but on right side
What is dextrocardia situs invertus totalis?
the viscera is reversed, but is it rarely perfectly reversed so usually associated with congenital heart defects
What forces the atria superiorly?
cardiac looping
the atrioventricular canal allows blood to flow from where to where?
sinus venousus to truncus arteriosus
What causes partitioning of the AV canal?
cardiac jelly
What week does the AV canal get partitioned, forming primtiive atrium and ventricle?
mid4th to end of 5th
by the end of the 4th week, what form the endothelial cells of heart that are transformed into mesenchymal cells?
dorsal & ventral endocardial cushions
What do the dorsal and ventral endocardial cushions do as they grow?
they merge together
what forms when the endocardial cushions merge together as they grow?
form septum intermedium w/ right & left atrioventricular canals
As the heart grows and there is more cardiac looping, describe the affect on the AV canal
heart wall size is increased, septum intermedium & AV canals shift left
If the septum intermedium doesn’t form, what happens?
the heart won’t form
What is septum intermedium made of?
VLPM
What forms the AV valves?
dense mesenchyme which comes from cardiac jelly
What happens to common atria at end of 4th week?
it divides into 2
What divides the atrium into 2 but leaves an opening?
septum primum
What is the opening that is left by the septum primum when it makes atrium called?
foramen primum
what is the foramen primum?
a shunt to bipass lungs, allows blood to go b/w left and right atria
what will happen to upper part of septum primum?
it will disappear
what is the name of the second membrane that grows down to the right of septum primum?
septum secundum
what will septum primum eventually fuse with and form?
fuses with endocardial cushions and form septum intermedium
as the septum primum fuses with endocardial cushions, what else happens that allow continuous flow of oxygenated blood to left and right atrium?
openings develop in central part of septum primium - they are called foramen secundum
What is the name of the second muscular membrane to the right of the septum primum?
septum secondum
pressure after birth causes fusion of what with what?
septum primum with septum secundum
the septum secundum creates what fossa and how?
fossa ovale - creates it when the lower segment of secundum receeds
The “upper limb” and “lower limb” are part of what?
septum secundum
How does septum secundum form?
grows down from septum premum and up from septum intermedium
How does lower limb form? (heart)
incorporation of sinus horns into right atrium
When openings develop in the central part of septum primium it allows what?
continuous flow of oxygenated blood to left atrium
where does blood flow in right left shunt?
from right atrium to left atrium
what must always be preserved until the atrial wall is fully formed?
right-left shunt
What does ASD stand for?
atrial septal defect
What is the most common type of ASD?
Ostium secundum atrial septal defect
What causes Ostium secundum atrial septal defect?
Excessive reabsorption of septum primum
or
incomplete development of septum secundum
What is the result of Ostium secundum ASD?
left to right shunt mixing of oxygenated & deoxygenated blood in center of atrial septum
What causes Ostium primum ASD?
Non-fusion of septum primum with septum intermedium
What is the result of ostium primum ASD?
lower portion of atrial septum: left to right shunt mixing of oxygenated & deoxygenated blood
tricuspid valve cleft
what is a tricuspid valve cleft
elongated hole in anterior leaflet
What causes patent foramen ovale (PFO)?
Smaller than Ostium secundum ASD
-Foramen ovale doesn’t seal at limbus
What is the result of PFO?
Left → Right shunt mixing of oxygenated and deoxygenated blood
Can PFO fix itself?
if it is small it may fix itself, if it larger might need surgery
What causes hypoplastic left heart syndrome?
-Premature closure of foramen ovale
What is the result of hypoplastic left heart syndrome?
Prevents blood from reaching left heart so its underdeveloped and right heart is enlarged
Incompatible with post natal life
During the process to have atrial openings, what happens on the venous ends initially?
sinus venosus open into middle of primitive right atria
right and left horn of equal size
What 3 veins go off of the equally sized right and left horn off of the sinus venosus?
umbilical vein
vitelline vein
common cardinal vein (and anterior and posterior)
What does the umbilical vein do when it comes off of the left and right sinus venous horn?
carries oxygenated blood from palcenta
What does the vitelline vein do when it comes off the left and right sinus venous horn?
drains yolk sac
What does the common cardinal vein do when it comes off of the left and right sinus venous horn?
anterior cardinal vein drains head and neck
posterior cardinal vein drains trunk
As time passes what happens to the two horns (that come off of sinus venous) regarding their size?
right horn increases in size
left horn decreases, parts of it will merge with right
The sinoatrial orifice moves and opens into what?
it opens into what will become the right atrium
What will the anterior cardinal vein become?
SVC
What will the posterior cardinal vein become?
IVC
What part of the heart gives rise to the anterior rough part?
right half → primitive atrium
the sinuatrial orifice from right horn opens into what?
right atrium
how is the sinus verarum formed?
right valve of right horn & septum intermedium smoothing over most of right atria
How is the right atria divided internally and externally?
crista terminalis internally
terminal sulcus externally
The rough part of atria is made of what?
pectinate muscles
Absorption of the right horn of the sinus venosus gives rise to what?
the posterior smooth part or sinus venarum part and right half of the Atrioventricular canal (A-V canal)
Besides absorption of the right horn of sinus venosus, what else gives rise to AV canal
endocardial cushions
Inferior part of the right sinuatrial valve forms what?
the valves of IVC and coronary sinus
What forms the rough part of left atria?
trabeculated auricle
Primordial pulmonary veins are an outgrowth of what?
dorsal left atrial wall (just left to septum primum)
primordial pulmonary veins will eventually develop a connection with what?
developing lung buds
As the left atrium grows what veins are incorporated into it?
pulmonary veins
Is most of the left atria smooth or rough and why?
smooth - incorporation of primordial pulmonary vein into enlarging left atrial wall
The left half of the AV canal is mainly from what?
endocardial cushions
What will form the adult muscular part of IV septum?
primordial interventricular septum
Initial growth of the primitive ventricle partition is due to what?
enlargement of the ventricular walls
further enlargement of the primitive ventricle partition is due to what?
myoblast activity in the septum
What is another name for ventricular septum?
Primitive ventricle partition
What are the two parts of the ventricular septal wall?
muscular & membranous part
When does the interventricular close by?
week 7
what closes the interventricular foramen at week 7?
membranous IV septum
portions of ventricular wall break up to make what 3 things
trabeculae carnea, papillary muscles and chordae tendinae
left umbilical vein forms what
round ligament of liver
what allows blood to bipass the liver
ductus venosus shunt
what does ductus venosus shunt carry
blood
right and left recurrent larngeal nerve come off of what two totally different areas
right: proximal part of sublavian artery
left:
what makes up majority of foramen ovale?
septum primium & septum segundum
Describe lymph in developing embryo
see pg 52-55 in cardiovascular power point
do supracardinal veins form the right sublavian artery?
no
what do supracardinal veins form?
azygous & hemiazygous
Does ligmentum arteriosum shunt blood?
no
after birth what happens to ductus arteriosum
becomes ligmentum arteriosum
what happens to the third and fourth arotic arch
they stick around
what happens to first and second and fifth aortic arch
they disappear
what forms descending aorta
dorsal aorta
The hepatic sinusoids that can be observed histologically in an adult liver are derived from which veins
vitelline veins
How soon should the ductus arteriosus close after birth?
1-2 hours
What is the coronary sinus derived from?
the sinus venosus.
What is the smooth part of the right ventricle called
conus arteriosus
What is the conus arteriosus (smooth part of right ventricle) derived from?
bulbus cordis
What is the proximal part of the aorta derived from
truncus arteriosus
What is the trabeculated part of the right ventricle
derived from?
primitive ventricle
Muscular VSD is caused by perforations in what septa
muscular interventricular septum.
What are the four things that characterize the tetraology of fallot?
- Pulmonary stenosis- narrow right ventricular region
- Interventricular septal defect
- Overriding of the Aorta
- Right ventricular hypertrophy
A partial development of the AP septum results in what?
Persistent truncus arteriosus
What clinical correlation is it if the conotruncal septum is missing?
persistent truncus arteriosus
misalignment of bulboconal and ventricular septa and underdeveloped endocardial cushions is what pathology?
membranous ventricular septal defect
The proximal part of the internal carotid artery is derived from which aortic arch?
3
The proximal part of the right subclavian artery is derived from what aortic arch?
4
portal vein is derived from what vein?
right vitelline vein
Superior mesenteric vein is derived from what?
vitelline veins
What are the renal veins derived from?
subcardinal veins
