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ANAT 400 - Embryology > Cardiovascular Development A > Flashcards

Cardiovascular Development A Flashcards

1
Q

Where does the cardiogenic crescent develop from and what does it become?

A

Lateral plate mesoderm forms on both sides of the embryonic disk and around the cranial end of the disc.

This discs fold ventrally and fuse at midline

In the cranial portion , a crescent of splanchnic mesoderm makes up the cardiogenic crescent that makes the heart

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2
Q

Lateral plate mesoderm folds ______ and joins at _______

______ enveloped inside (forms gut) with ______ around the gut (smooth muscle and connective tissue)

A

Lateral plate mesoderm folds ventrally and joins at midline

Endoderm enveloped inside (forms gut) with splanchnic mesoderm around the gut (smooth muscle and connective tissue)

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3
Q

All cavities form from the _________

A

Intraembryonic Coelom

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4
Q

What is the cardiac crescent?

A

Cardiac crescent/cardiogenic mesoderm

  • A crescent of splanchnic mesoderm around the cranial end of the embryo is specified to become heart tissue
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5
Q

How is the primitive heart tube formed?

(1)

A
  1. Differentiation within splanchnic mesoderm at cardiac crescent: some of the sp. meso undergoes MET → differentiates as endocardium and assembles into endocardial tubes; rest becomes myocardium
  2. Creates bulge off gut tube → endocardial tubes on each side fuse → Primitive heart tube \ dorsal aortae also fuse to form a single descending aorta

MET = mesenchymal to epithelial transition

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6
Q

How is primitive heart tube formed (2) - following MET in splanchnic mesoderm:

A
  1. Differentiation within splanchnic mesoderm at cardiac crescent: some of the sp. meso undergoes MET → differentiates as endocardium and assembles into endocardial tubes; rest becomes myocardium
  2. Creates bulge off gut tube → endocardial tubes on each side fuse → Primitive heart tube \ dorsal aortae also fuse to form a single descending aorta
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7
Q

What are the three layers of the primitive heart tube?

A
  • Endocardium - from MET of splanchnic mesoderm
  • Cardiac Jelly (extracellular matrix secreted by cardiomyocytes)
  • Myocardium (differentiating cardiomyocytes/sp meso)
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8
Q

After folding, there is a flap of splanchnic mesoderm (_________) anchoring the heart to the foregut

A

After folding, there is a flap of splanchnic mesoderm (Dorsal Mesocardium) anchoring the heart to the foregut

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9
Q

What happens to the dorsal mesocardium?

A

Dorsal Mesocardium = flap anchoring heart forming connection to gut

  • Eventually disintegrates so heart will be anchored ONLY by incoming and outgoing vessels
    • Loses connection between heart and gut
    • Allows heart activity
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10
Q

Fusing of the endocardial tubes could be described as ________

A

Fusing of the endocardial tubes could be described as two tubes joining in the middle with openings at the top and bottom for bloodflow

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11
Q

How does the heart reposition with body folding?

A

Heart is moved from cranial disc inferiorly into the thorax because brain overgrows everything

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12
Q

The first aortic arch connects to the _______

A

dorsal aortae

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13
Q

What is the process that changes the endocardial tube?

A

Looping process changes tube

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14
Q

Label the diagram

A

First aortic arches - connect to dorsal aortae

Aortic Sac - expanded base leading into arteries

Left horn of sinus venosus - receives venous input

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15
Q

Label the diagram

A

Outflow Tract

Primitive Ventricle

Primitive atrium

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16
Q

What is the first step to making a mature heart from the primitive heart tube?

A

Cardiac looping

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17
Q

Formation of the cardiac loop:

Primitive heart tube folds and loops to bring ___________

At the same time, a series of _____ and _____ divide primary heart tube

Heart tube forms on day ____ and starts to beat on day ____ blood circulation begins by day _____

A

Formation of the cardiac loop:

Primitive heart tube folds and loops to bring the four presumptive chambers of the heart into correct spatial relation to each other

At the same time, a series of constrictions and expansions divide primary heart tube = give dif parts their own identities

Heart tube forms on day 21 and starts to beat on day 22 blood circulation begins by day 24 (wall of yolk sac gives early blood)

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18
Q

As a result of cardiac looping, the ventral midline shifts_______

A

As a result of cardiac looping, the ventral midline shifts -bends and twists to the right

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19
Q

What is the 1st morphological L-R patterning of the heart?

A

The tube bending and twisting to the right - primitive ventricle bulging to the right

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20
Q

Growth of primitive heart tube:

Heart tube grows through ______, but also by ________ from ______

A

Growth of primitive heart tube:

Heart tube grows through proliferation, but also by addition of cells from migrating into the tube at the arterial and venous poles

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21
Q

With heart looping, the heart tube bends into a ____ shape

Primitive atrium moves _____ and _____ (behind/posterior to _______)

Right ventricle comes from ________

A

With heart looping, the heart tube bends into a U shape

Primitive atrium moves superiorly and posteriorly (behind/posterior to outflow tract)

Right ventricle comes from migrating cells

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22
Q

When cardiac looping is complete the outflow tract is between the ______ with the _______ partly surrounding the outflow tract

A

When cardiac looping is complete the outflow tract is between the atria with the atrial appendages (auricles) partly surrounding the outflow tract

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23
Q

Label the heart tube in its C-shape bend:

A
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24
Q

As the atria moves superiorly, what happens to the sinus venosus (connected to the atria)

A

When atria move superiorly, so does the sinus venosus

  • Sinus venosus leads into atria → pulled up and posterior
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25
Where is the outflow tract in relation to the atria after heart looping?
The atria are posterior to outflow tract (outflow tract anterior to atria)
26
How do we get from atria posterior to OT to atria hugging OT?
Atrial appendages grow out and “hug” outflow tract Lumen remodels and connection changes
27
What needs to be done after heart looping?
* Heart must be divided into chambers 1. separation of atria from ventricles 2. ventricular remodeling 3. septation of atria
28
SEPTATION OF HEART TUBE \_\_\_\_\_\_\_\_\_ grow outward from walls of heart tube and constrict lumen of the \_\_\_\_\_\_\_\_
SEPTATION OF HEART TUBE Endocardial cushions grow outward from walls of heart tube and constrict lumen of the atrioventricular canal
29
What are the endocardial cushions?
Cardiac jelly extracellular matrix (ECM) secreted by myocardium + cells derived from endocardium * Secondary step: some endocardial cells undergo EMT to populate cushions (cells and ECM)
30
How does division of atrioventricular canal occur?
* Four tissue cushions grow in endocardium around atrioventricular canal * Dorsal and ventral cushions fuse to form septum intermedium * All four cushions will contribute to *AV valves (tricuspid (Rt) and bicuspid (Lft))*
31
Initially, the AV canals connects the right and left atria with only the \_\_\_\_\_\_\_ The AV valves are made by \_\_\_\_\_\_\_\_\_\_\_
Initially, the AV canals connects the right and left atria with only the _Left ventricle (Primitive atrium with septum forming = 2 atria both connected to LV)_ The AV valves are made by _remodeling of endocardial cushions_ (Dorsal endocardial cushion in image sculpted into valves)
32
What ventricular remodeling is required?
We have rv and lv stacked. Need to be flipped so they're side by side = two circulations * Align everything properly to allow two separate circuits of blood
33
Remodeling of ventricles: * At the end of **cardiac loop formation**: * _______ connect both atria to left ventricle * Only ________ connects to outflow tract * After **remodeling**: * Right ventricle connects to _______ and \_\_\_\_\_\_\_ * Left ventricle connects to _____ and \_\_\_\_\_\_
Remodeling of ventricles: * At the end of **cardiac loop formation**: * _AV canals_ connect both atria to left ventricle * Only _Right ventricle_ connects to outflow tract * After **remodeling**: * Right ventricle connects to _right atrium and pulmonary trunk (pulmonary circulation)_ * Left ventricle connects to _left atrium and aorta (Systemic circulation)_
34
Septation of atria: * Adult interatrial septum formed by \_\_\_\_\_\_\_\_
Septation of atria: * Adult interatrial septum formed by _fusion of two embryonic partial septa_ * Septum primum - thin and delicate (flap) * Septum secundum - thick and muscular (wall) * Together form a one way flap valve * Both have large openings that allow blood to shunt from right to left atria
35
Septation of atria: What are the two embryonic partial septa that fuse to form the adult interatrial septum? What does this septum allow in terms of blood flow?
* Adult interatrial septum formed by _fusion of two embryonic partial septa_ * **Septum primum** - thin and delicate (flap) * S**eptum secundum** - thick and muscular (wall) * Together form a one way flap valve * Both have large openings that allow blood to shunt from right to left atria
36
Why must fetal blood be shunted from right atrium to left atrium?
* Lungs are inactive during fetal development * Oxygenated blood supplied by umbilical vein * Little blood can flow through collapsed lungs → blood shunted away from lungs * Pulmonary and systemic circulations do not become truly separate until birth
37
How does the atrial septum form?
First the thin, flexible **septum primum** grows down from posterior wall of primitive atria down towards septum intermedium - leaves a gap called the **ostium primum** Second the thick, muscular **septum secundum** grows (again from posterior wall of primitive atria down towards septum intermedium)
38
When septum primum grows, at first it doesnt fully extend to the septum intermedium, leaving a (temporary) gap called the \_\_\_\_\_\_\_ Subsequently, cells in the *superior portion* of the septum primum will undergo apoptosis and create a new hole, the \_\_\_\_\_\_\_\_.
When septum primum grows, at first it doesnt fully extend to the septum intermedium, leaving a (temporary) gap called the _Ostium primum_ Subsequently, cells in the *superior portion* of the septum primum will undergo apoptosis and create a new hole, the _Ostium Secundum_ - ostium primum will then close.
39
The septum secundum maintains an inferior hole, the \_\_\_\_\_\_\_
The septum secundum maintains an inferior hole, the _foramen ovale_ _These holes SHOULD NOT overlap_
40
The Atrial septum is made of ______ septa, each with a \_\_\_\_\_\_\_: _______ (top) and \_\_\_\_\_\_(bottom) = holes do not overlap (important for closing this shunt after birth)
The Atrial septum is made of _2_ septa (*Septum primum and septum secundum)*, each with a _hole_: _Osteum secundum_ (top - on septum primum) and _formamen ovale_ (bottom (Septum secundum)) = holes do not overlap (important for closing this shunt after birth)
41
What keeps the atrial septum open to allow blood to shunt from right atrium to left atrium?
* Higher pressure on right side of heart → septum primum can be pushed enough to let blood flow through the foramen * Because the holes don't overlap, when they are pushed together → forms complete wall → fuses overtime to form interatrial septum
42
Label the image
blue is aortic sac
43
How does the the atrial septum change after birth?
* Lungs inflate and blood flow from placenta is lost * pressure changes (PR \< PL) * Septum primum will be pushed against the septum secundum → closing the interatrial wall * Two will fuse to form the atrial septum (foramen ovale becomes fossa ovalis)
44
What are the two portions of the interventricular septum?
* Myocardium grows upward to form a partial separation * Superior *Membranous portion* → endocardial cushions contribute to this portion * Inferior *Muscular portion* → myocardium contributes to this portion
45
Why is there a delay in the interventricular septum formation?
Delay because don't want to close off Left Ventricle (there is no blood flowing into Left Ventricle from Pulmonary Circulation)
46
What separates the outflow tract into two?
Endocardial cushions → separate outflow tract into two and contribute to membranous portion of interventricular septum
47
What are the most common type of CHD (coronary heart disease)?
Ventricular septal defects (VSDs) - usually involve the membranous IV septum
48
How does the outflow tract change with fetal heart development?
* Outflow is initially through a common channel * Outflow becomes divided into two by a septum to form aorta and pulmonary trunk
49
What type(s) of cells populate the Endocardial cushion ECM?
Endocardial cells and neural crest cells
50
How does septation of the outflow tract occur?
* Fusion of the septum begins in the middle and proceeds superiorly and inferiorly * As the outflow tract is being divided it is also twisting
51
Label the image of the outflow tract
A. Trunococonal septae B. Right auricle C. Right ventricle D. Superior endocardial cushion E. Muscular ventricular septum F. Left Ventricle G. Right atrioventricular canal H. Left atrioventricular canal
52
The inferior edge of the outflow tract fuses with the \_\_\_\_\_\_\_, contributing to \_\_\_\_\_\_
The inferior edge of the outflow tract fuses with the _muscular ventricular septum_, contributing to _the membranous portion of the ventricular septum_
53
The image shows: * outflow tract stage? * Ventricular stage? * Connections?
* At this stage the outflow tract is divided and the ventricles are remodelled * Right ventricle connects to pulmonary trunk * Left ventricle to ascending aorta
54
\_\_\_\_\_\_\_\_ cells contribute to the outflow septum are are necessary for its proper formation
_Neural crest_ cells contribute to the outflow septum are are necessary for its proper formation
55
The cardiac neural crest arises from \_\_\_\_\_\_\_
The cardiac neural crest arises from _beside the hindbrain_
56
Label the image
57
How do the semilunar valves form?
two additional endocardial cushions form on opposite walls of the outflow tract (these are the *intercalated cushions*) Excavation of outflow tract cushions + intercalated cushions gives rise to semilunar valve leaflets
58
Label the image
Image shows semilunar valves after formation - formed by outflow tract cushions and intercalated cushions being excavated
59
Label the development of cardiac valves
60
The outer layer of the heart is an epithelium called the ________ (aka the \_\_\_\_\_\_\_\_)
The outer layer of the heart is an epithelium called the _epicardium_ (aka the _visceral pericardium_)
61
The epicardium is derived from:
Epicardium is derived from cells that originate in proepicardial organ and migrate over the surface of the heart
62
Epicardial cells migrate over the heart as an \_\_\_\_\_\_\_ Some ______ and invade the _____ to contribute to various structures
Epicardial cells migrate over the heart as an _epithelial sheet_ Some _delaminate_ and invade the _heart_ to contribute to various structures

ANAT 400 - Embryology (14 decks)

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