Topic 5 & 6 Cardiac Part 2 Flashcards
Heart Tube day 23
Newly formed heart tube starts to bend
Cephalic part bends ?
ventrally, caudally, and to the right.
Heart Tube day 23
Newly formed heart tube starts to bend
Caudal part bends ?
dorsocranially, and to the left.
Newly formed Heart Tube day 23 does 3 things ?
- -Newly formed heart tube starts to bend
- -Bulges into the pericardial cavity
- -Attached to dorsal wall by mesoderm
Newly formed heart tube (day 23ish)– when attached to dorsal wall by mesoderm what eventually happens?
Mesoderm eventually ruptures
Leaves heart tube suspended in pericardial cavity
Regions: Dorsal Aorta and Aortic Sac become?
Becomes the common outflow tract
Bulbus Cordis become?
Primitive RV
KNOW
Primitive Ventricle become?
Primitive LV
KNOW
Atrioventricular Sulcus become?
Divides atria from ventricles
KNOW
Paired Primitive Atria become?
Will form common atria
KNOW
Sinus Venosus become?
Eventually forms the coronary sinus and oblique vein of the LA
KNOW
Day 23-28
Heart undergoes a series of folding that leads to the formation of what?
the bulboventricular loop
Day 23-28
Heart undergoes a series of folding creating the bulboventricular loop. The Heart tube also grows rapidly where? forming what?
Heart Tube grows rapidly in length, especially the midsection (Bulbus Cordis and Ventricle)
Because the two ends are fixed, heart tube is forced to bend in order to adapt itself to the pericardial space.
Forms what shapes? what order are the components in?
a U-Shape
Then Forms an S-Shape
Oriented so that the atrium and sinus venosus lie superior to the bulbus cordis, ventricle and dorsal aorta/aortic sac
Because the two ends are fixed, heart tube is forced to bend in order to adapt itself to ?
the pericardial space
Atria initially paired–forms ?
common atrium
Atrioventricular unction remains narrow
Forms ?
AV Canal–connects common atrium and ventricle
Bulbus Cordis is narrow, except what ? which forms what?
proximal 1/3
Will form trabeculated part of RV
Junction between the ventricle and the bulbus cordis externally is the
bulboventricular sulcus
Remains narrow
Called the primary interventricular foramen
When the heart is folding the primary interventricular foramen is what?
bulboventricular sulcus (Junction between the ventricle and the bulbus cordis externally) Remains narrow
Atrial portions of the Heart Tube dilate Form?
[Heart folding Atrium]
Common Atrium
Atrium “climbs up” the dorsal pericardial wall
Takes what with it?
[Heart folding Atrium]
Atrioventricular junction with it
Atrioventricular junction remains narrow
Now called? does what?
[Heart folding Atrium]
AV Canal
Forms the communication between the atrium and the primitive ventricle.
During Heart folding – Ventricle also dilates
Acquires a ?
larger lumen
Junction of the ventricle and the bulbus cordis remains narrow
During Heart folding – Ventricle
Junction of the ventricle and the bulbus cordis remains narrow, Junction is now called?
intraventricular foramen
Heart Folding –Bulbous Cordis
At the venous pole, growth proceeds to a point where the expanding common atrium has drawn the originally paired sinus venosus together until it consists of _____?
a midportion and right and left horns
Heart Folding –Bulbous Cordis
At the venous pole, growth proceeds to a point where the ______ has drawn the originally paired _____ together until it consists of a midportion and right and left horns?
expanding common atrium
sinus venosus
Heart Folding Day 24
Diverticula appear in two sharply defined areas
-Along front of endocardial tube
-Just proximally and distal to the primary
interventricular foramen
Heart Folding Day 24
Diverticula appear – Just proximally and distal to the primary interventricular foramen.
–Early embryonic Ventricle is the?
Primitive LV
Heart Folding Day 24
Diverticula appear – Just proximally and distal to the primary interventricular foramen.
–Proximal 1/3 of bulbus cordis is the??
Primitive RV
Heart Folding Day 24
Diverticula appear – Just proximally and distal to the primary interventricular foramen.
–Primitive LV is the?
Early embryonic Ventricle
Heart Folding Day 24
Diverticula appear – Just proximally and distal to the primary interventricular foramen.
–Primitive RV is the?
Proximal 1/3 of bulbus cordis
Diverticula on the Folding Heart do what?
expand the capacity of the heart
Give them the densely trabeculated appearance
The trabeculae inside the heart leads to? (4)
valves, chordeae tendinae, papillary muscles, and atrioventricular valves
During heart folding the heart is still a single tube, Externally, it’s appearance is suggestive of a 4-chambered organ.
Abnormalities in Cardiac looping, is responsible for what cardiac defects? (3)
Ventricular inversion (corrected transposition), juxtaposition of the atrial appendages, and Double outlet right ventricle
-Aortic arches–the order of BC, CC, TA during heart folding
truncus arteriosus–conus cordis –bulbus cordis
Mid 4th week the sinus venosus receives blood from the right and left what?
right and left sinus horns
Sinus Venosus-
Each horn receives blood from 3 veins
Vitelline vein
Umbilical vein
Common Cardinal vein
Sinus Venosus – Communication between sinus and atrium will eventually shift to the right caused by what?
Caused by shift in blood in venous system
Occurs at about 4-5 weeks.
Sinus Venosus communication between sinus and atrium is ?
wide open
Obliteration of the right umbilical vein and left
vitelline vein, Occurs what week?
5th week
Left sinus horn loses importance
the left common cardinal vein become
obliterated at what week?
All that remains?
At week 10
All that remains of the left sinus horn is the oblique vein of the left atrium and the coronary sinus.
Right Sinus horn is a what?
Shunt of blood left to right enlarges right sinus horn
Right horn and vein are the only communication between the original sinus
venosus and the atrium
Right Sinus horn forms what?
Forms the smooth walled part of the right atrium.
Right horn and vein are the only communication between what?
the original sinus venosus and the atrium
Sinuatrial orifice is what?
entrance to the common atrium
Sinuatrial orifice is flanked on each side by?
valvular folds
Right and left venous valves
Sinuatrial orifice – Left venous valve fuses with?
fuses with the atrial septum
Sinuatrial orifice – Superior part of the right venous valve does what?
disappears
Sinuatrial orifice – Inferior part of the right venous valve becomes the
becomes the valve of the IVC and the valve of the coronary sinus
During atrial septation, the left atrium begins to form ?
sprouts of the pulmonary veins that grow towards the lungs
Cardiac Septation – Facts
Starts? lasts?
Starts at Day 27
Lasts 10 days (Day 27-37)
During which the embryo grows from 5mm to 16-17mm
The formation of the cardiac septa occur
simultaneously
During this time, no major changes in external appearance
Cardiac Septation, at day 27, primitive right and left ventricles are local widenings of the original heart tube
Connected to each other via ?
narrow channel - Interventricular Foramen
Cardiac Septation, at day 27, Blood reaches primitive LV via small opening from the primitive atria – which is the?
AV Canal
Cardiac Septation, at day 27, During ventricular development, 2 important processes occur simultaneously, that result in the “chamberization” of the ventricles - what are they?
–Division of the AV Canal into a Right and Left –AV orifice via the endocardial cushions
Ventricular Septation
Endocardial Cushions develop where?
Develop in the Atrioventricular and Conotruncal regions
Endocardial Cushions assist in the formation of what?
Assist in the formation of the atrial and ventricular (membranous) septa, AV Canals, Valves, Aortic and Pulmonary Channels
At the end of week 4, Atrioventricular
endocardial cushions appear at the AV Canal – how many?
- 2 lateral AV cushions appear on the right and left side of the canal
- Anterior and posterior cushions push into the lumen and fuse
Anterior and posterior cushions push into the lumen and fuse, and results in ?
the complete division of the canal into right and left AV orifices.
Final and the end of week 5.
The role of the endocardial cushions is to ?
Form a barrier between the atria and ventricles
Right–left division of the canal
– The resulting canals are eventually occupied by the mitral and tricuspid valves.
The ventricular septum is formed by what?
the outgrowth of the muscular ridge at the interventricular foramen.
The ventricular septum grows upward from what part of the heart where?
apex of the heart to the base of the heart.
The ventricular septum is formed by the outgrowth of the muscular ridge at the interventricular foramen.
—2 primative ventricles do what??
expand
Medial walls become apposed and merge
Interventricular foramen is the space above what?
-membranous septum
Shrinks when the conus septum is complete
(ventricular septation) Outgrowth of tissue from the endocardial cushion along the top of the muscular interventricular septum closes what?
the foramen
Fuses with the abutting part of the conus septum
At day 27-28, the paired atria fuse together for form a common atrium.
Atrial septation occurs simultaneously and in cooperation with what?? and lasts how long?
ventricular septation
Atrial septation also lasts approximately 10 days
Sickle-shaped crest grows from the roof of the ?
common atrium
Sickle-shaped crest grows from the roof of the common atrium
it is the first portion of the ? and extends towards what?
Septum Primum
Extends toward the endocardial cushions in the AV Canal.
Sickle-shaped crest grows from the roof of the common atrium does not connect to what? and leaves a space called what?
Does not connect to endocardial cushions. Leaves a space called the Ostium Primum
How is the Ostium Primum formed?
Formed by the opening between the lower rim of the septum primum and the endocaridal cushions
(Sickle-shaped crest grows from the roof of the common atrium does not connect to endocardial cushions)
How does the Ostium Primum close?
Extensions of the endocardial cushions grow along the edge of the septum primum, closing the Ostium Primum
Before closing the Ostium Primum what occurs and forms?
Before closure, Apoptosis (cell death) makes perforations in the upper part of the septum primum
Forms the Ostium Secundum
Allows for blood flow to shunt from the right to the left
Lumen of the Right Atrium expands (result of
incorporation of the sinus horns)
New crest-shaped fold appears called?
Septum Secundum
Septum Secundum Extends where?
downward to the septum in the AV canal
Overlaps with the Ostium Secundum
-Remaining hole is called the Foramen Ovale
Septum Secundum overlapping with the Ostium Secundum and the remaining hole is called ?
the Foramen Ovale
ATRIAL SEPTATION
•The septum secundum then grows downward, covering the _____
•The septum secundum then grows further downward and creates a ______
•The two septa together now act as a valve to allow blood to enter the left atrium via the foramen ovale, then the_____
- foramen secundum
- foramen ovale at the ECC.
- septum secundum
OUTFLOW TRACT SEPTATION
By the 5th week opposing ridges appear in the truncus, these cushions lie what two locations? and where will they grow?
These cushions lie on the right superior wall
—Will grow distally and to the left.
And on the left inferior wall
—Will grow distally and to the right
Both cushions grow toward the aortic sac, Twist around each other and eventually fuse
OUTFLOW TRACT SEPTATION
cushions grow toward the aortic sac, twist around each other and eventually fuse to form what?
Form the aorticopulmonary septum
Divides the truncus into aortic and pulmonary channels.
OUTFLOW TRACT SEPTATION
the aorticopulmonary septum divides into what?
Divides the truncus into aortic and pulmonary channels.
OUTFLOW TRACT SEPTATION
Cushions appear along the right dorsal and left ventral walls of the conus cordis
Grow toward each other and distally
unite with? divide what?
Unite with the truncus septum
Divides the conus into anterolateral portion (RV outflow) and posteromedial portion (LV outflow)
OUTFLOW TRACT SEPTATION
Partitioning of the outflow tract
Truncus Arteriosus becomes?
–Aorta
OUTFLOW TRACT SEPTATION
Partitioning of the outflow tract
Conus Cordis becomes?
–Pulmonary Artery
Created by a septum that forms in the outflow tract from these swellings
AV Valves:
Each AV orifice is surrounded by ?
local proliferations of mesenchymal tissue
AV Valves:
Each AV orifice is surrounded by local proliferations of mesenchymal tissue.
Blood hollows out and thins the tissue on the ventricular surface than what happens??
Valves form
- Remain attached to ventricular wall by muscular cords
- Muscular tissue degenerates and is replaced by connective tissue over time
AV Valves:
When the valves for they remain attached to ventricular walls by muscular cords and are replaced by what over time?
Muscular tissue degenerates and is replaced by connective tissue over time
Semilunar Valves: are what/ found where?
Small tubercles found on main truncus
swellings
Tubercles hollow out on the upper surface
Valves are fully developed by what day?
55
Day 1-2: Fertilization
Day 6-7: ____________
Day 16-20: Appearance of Celom and Blood Islands
Day 20: Endocardial tubes are present and begin fusing
Day 22: Main heart tube begins to beat
Day 23-28: Heart Folding
Day 27-37: Atrial and Ventricular septation and development
Day 29: Outflow tract septation
Day 55: Complete
Implantation of blastocyst into uterine wall
Day 1-2: Fertilization
Day 6-7: Implantation of blastocyst into uterine wall
Day 16-20: Appearance of Celom and Blood Islands
Day 20:___________
Day 22: Main heart tube begins to beat
Day 23-28: Heart Folding
Day 27-37: Atrial and Ventricular septation and development
Day 29: Outflow tract septation
Day 55: Complete
Endocardial tubes are present and begin fusing
Day 1-2: Fertilization
Day 6-7: Implantation of blastocyst into uterine wall
Day 16-20: Appearance of Celom and Blood Islands
Day 20: Endocardial tubes are present and begin fusing
Day 22: Main heart tube begins to beat
Day 23-28: Heart Folding
Day 27-37: Atrial and Ventricular septation and development
Day 29: __________
Day 55: Complete
Outflow tract septation
Day 1-2: Fertilization
Day 6-7: Implantation of blastocyst into uterine wall
Day 16-20: Appearance of Celom and Blood Islands
Day 20: Endocardial tubes are present and begin fusing
Day 22: ________________
Day 23-28: Heart Folding
Day 27-37: Atrial and Ventricular septation and development
Day 29: Outflow tract septation
Day 55: Complete
Main heart tube begins to beat
Day 1-2: Fertilization
Day 6-7: Implantation of blastocyst into uterine wall
Day 16-20: Appearance of Celom and Blood Islands
Day 20: Endocardial tubes are present and begin fusing
Day 22: Main heart tube begins to beat
Day 23-28: Heart Folding
Day 27-37: _________________
Day 29: Outflow tract septation
Day 55: Complete
Atrial and Ventricular septation and development
Day 1-2: Fertilization
Day 6-7: Implantation of blastocyst into uterine wall
Day 16-20: Appearance of Celom and Blood Islands
Day 20: Endocardial tubes are present and begin fusing
Day 22: Main heart tube begins to beat
Day 23-28: _________
Day 27-37: Atrial and Ventricular septation and development
Day 29: Outflow tract septation
Day 55: Complete
Heart Folding