Topic 5 & 6 Cardiac Part 2 Flashcards by Rachel ramella

Heart Tube day 23
Newly formed heart tube starts to bend
Cephalic part bends ?

ventrally, caudally, and to the right.

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Heart Tube day 23
Newly formed heart tube starts to bend
Caudal part bends ?

dorsocranially, and to the left.

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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

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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

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Regions: Dorsal Aorta and Aortic Sac become?

Becomes the common outflow tract

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Bulbus Cordis become?

Primitive RV

KNOW

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Primitive Ventricle become?

Primitive LV

KNOW

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Atrioventricular Sulcus become?

Divides atria from ventricles

KNOW

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Paired Primitive Atria become?

Will form common atria

KNOW

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Sinus Venosus become?

Eventually forms the coronary sinus and oblique vein of the LA

KNOW

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Day 23-28

Heart undergoes a series of folding that leads to the formation of what?

the bulboventricular loop

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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)

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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

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Because the two ends are fixed, heart tube is forced to bend in order to adapt itself to ?

the pericardial space

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Atria initially paired–forms ?

common atrium

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Atrioventricular unction remains narrow

Forms ?

AV Canal–connects common atrium and ventricle

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Bulbus Cordis is narrow, except what ? which forms what?

proximal 1/3

Will form trabeculated part of RV

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Junction between the ventricle and the bulbus cordis externally is the

bulboventricular sulcus
Remains narrow
Called the primary interventricular foramen

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When the heart is folding the primary interventricular foramen is what?

bulboventricular sulcus (Junction between the ventricle and the bulbus cordis externally)
Remains narrow

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Atrial portions of the Heart Tube dilate Form?

[Heart folding Atrium]

Common Atrium

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Atrium “climbs up” the dorsal pericardial wall
Takes what with it?

[Heart folding Atrium]

Atrioventricular junction with it

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Atrioventricular junction remains narrow
Now called? does what?
[Heart folding Atrium]

AV Canal

Forms the communication between the atrium and the primitive ventricle.

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During Heart folding – Ventricle also dilates

Acquires a ?

larger lumen

Junction of the ventricle and the bulbus cordis remains narrow

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During Heart folding – Ventricle

Junction of the ventricle and the bulbus cordis remains narrow, Junction is now called?

intraventricular foramen

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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?

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