Unit 2.L3-Development of Heart & Cardiovascular System Flashcards
(135 cards)
1
Q
Formation of the Earliest Cardiac field
By Day 15, what mesoderm splits and what is formed and how?
A
- Day 15: Caudally, Lateral plate mesoderm splits to forms the pericardial coelom cranially.
- How??: Cardiogenic cells in the Splanchnic lateral plate mesoderm move cranio-medially while the mesoderm is splitting.
2
Q
Formation of the Earliest Cardiac field
Blood islands develop by Day 18, what is formed and how?
A
Day 18: Blood islands develop & merge at the cranial end to form a horseshoe-shaped endothelial cell “Cardiac Tube”
3
Q
What forms the Cardic Tube (horseshoe-shaped endothelial cell)?
Day 18
A
Blood islands that develop and merge at the cranial end
4
Q
By Day 15, cardiac specification between what occurs? And which cells move?
A
- Cardiac specification between → endoderm/neural folds or epidermis, when mesodermal cells move to cranial ends
5
Q
What does the Primative Streak Mesoderm cells invaginate between? What direction does it go? And what does it form?
Day 15
A
The Primitive Streak Mesoderm cells invaginate between neural fold & endoderm and go latero-cranially to form cardiogenic sub-fields
1. Atria (outer)
2. LV, RV (Ventricles)
3. C/T (Conotruncus or Outflow tract) (inner)
6
Q
What is found in the Cardiogenic sub-fields?
A
- Atria (outer)
- LV, RV (Ventricles)
- Conotruncus; CT (Outflow tract;OFT) (inner)
7
Q
By day 18, what does the cardiogenic sub-fields become?
3 Somite Stage
A
Two cardiac crescents that form the Primary & Secondary Heart Fields
8
Q
What can be used to identify each type of cell in the primary and secondary heart field?
A
Lineage tracing identifies each type of cell using tissue-specific gene-promoters or specific RNA/protein markers (MLC; myosin light chain, C)
8
Q
What is the position of the Primary Heart Field and what is present there?
A
Primary Heart Field (Cranially):
Atria & Ventricle progenitor cells
8
Q
What is the position of the Secondary Heart Field and what is present there?
A
Secondary Heart Field (Caudally):
Outflow tract + Great Vessels
9
Q
At Day 18, what does the endothelial cell tube forms? And how does it move? And what occurs to the embryo?
A
The endothelial cell tube→“Angioblastic” cord→moves rostrally as the embryo head folds
10
Q
By Day 20, lateral folding forms what two structures that eventually move closer and fuse into what?
A
[2-pericardial coeloms + 2-heart tubes] come nearer & fuse → [2- heart-tube + 1-pericardial cavity]
10
Q
Where does the septum transversum develop?
A
The septum transversum develops most cranially
11
Q
How is the Dorsal Aorta formed?
A
Dorsal Aortae are formed bilaterally, independent of the heart
12
Q
What is the origin of the Primary/first heart field (FHF) and what does it form?
A
- Origin: Primitive streak
- Forms: Left & Right Atria & Left Ventricle: (LA + RA + LV)
13
Q
What is the origin of the Secondary heart field (SHF) and what does it form?
A
- Medial origin: Splanchnic Pharyngeal Mesoderm
- Forms: Right ventricle (RV), Outflow tract (CT or OFT)
14
Q
What does lateral folding cause?
A
MIdline fusion of 2 heart tubes
15
Q
When do we have a single heart tube?
A
Day 20
16
Q
By Day 20, lateral folding merges two heart fields. What else is merged and formed? (2)
A
- Merging/fusing endocardial (endothelial) cell lining) & formation of [2-heart tubes + 2-Aortae]
- Formation of the Cardiac Jelly (extracellular matrix/ECM/connective tissue) & Myocardium
17
Q
What suspends the tubular heart by day 22?
A
Dorsal mesocardium “suspends” the tubular heart
18
Q
By Day 22:
1. What starts to fuses into a single heart tube?
2. What differentiates and what does it form?
3. What type of -cardium forms?
A
- 2-heart tubes start to fuse into Single heart tube
- Cardiomyocyte differentiate→Muscular heart walls
- Epicardium (visceral pericardium) forms
19
Q
What is the origin of the Epicardium (visceral pericardium) formed by Day 22?
A
Origin: Mesothelial cells of the developing Sinus Venosus (PEO or Pre-Epicardial Organ)
20
Q
How is the heart tube and central tendon of the diaphragm formed? (What folds and what moves ventral to the foregut? What structures position switch? Where does the septum transversum lies and what does it form?)
A
- The head folds & the tubular heart/pericardial cavity move ventral to the foregut
- Positions of the pericardial cavity and septum transversum reverses
- Septum transversum lies posterior to the pericardial cavity & forms the “Central tendon of the diaphragm”
21
Q
What forms the central tendon of the diaphragm?
A
The Septum transversum that lies posterior to the pericardial cavity
22
What does the secondary heart field divide into?
1. Anterior heart field (AHF; at outflow-OFT)
2. Posterior heart field(PHF;at inflow-IFT)
23
What is the PEO? How does it develop? What does it give rise to?
* Pre-Epicardial Organ: Cauliflower-like protrusion of the **sinus venosus**
* Develops as a part of the **posterior heart field**, thus is **intracardiac**
* Giving rise to **epicardium**
24
What are the neural crest cells role in heart development?
**True extracardiac** contributors to heart development as they migrate from the neural crest
25
What is right looping of the cardiac tube?
26
What is the role of the Sinus venosus (SV)?
This is the **collecting compartment** of the heart. **Oxygenated blood** from the **placenta** and **deoxygenated blood** from **embryonic tissue** are **mixed in the sinus**
27
What is the Primative atrium (PA)?
This is the compartment destined for further partition to the **definitive atria**
28
What is the Primitive ventricle (PV)?
This is the compartment destined for further partition to the **definitive ventricles**
29
What is the role of the Bulbus cordis (BC)?
This will contribute to the **pulmonary trunk** and **aorta** along with the **truncus arteriosus**
30
What is the role of the Truncus arteriosus (TA)?
This will contribute to the **aortic arches**
31
What is the Fibrous skeleton (FS)?
This is the area of connective tissue proliferation, site of **future valves**
32
How is the heart loop primed to folding into the D-loop?
**Apoptosis** in the **dorsal mesocardium** will allow movement of the early heart tube within the pericardial cavity to **rotate & bend**
| Still attached to myocardial wall
33
By Day 22-28:
1. What happens to the dorsal mesocardium?
2. What sinus is formed?
3. What starts to fuse?
1. The **central part** of the **dorsal mesocardium degenerates**
2. Transverse **pericardial sinus is formed**
3. **Dorsal Aortae** starts to **fuse**
34
By the end of week 3 (D22) what happens to the heart tube?
* Heart tube starts **“beating"**
* **First: Spontaneous,asynchronous**
* **Later**, cells build a **directional rhythm without any electrical circuitry** or stimulation.
35
What happens to the heart at the end of Week 4?
Blood begins to flow (3D / 4D Doppler detects it)
36
When do we see all three layers of the heart?
end of week 4
37
What are the three distinct cell populations/layers that the cardiogenic mesoderm differentiates into?
1. Endocardium (inside)
2. Myocardium (muscle wall)
3. Epicardium (outer wall)
38
What is present in the Endocardium layer? (4)
Endocardium (inside):
* Endothelial lining
* Endothelial tube
* Valves
* Cardiac Connective tissue (fibrous scaffold)
39
What is present in the Myocardium layer? (3)
Myocardium (muscle wall):
* Myocytes/Myocardium
* Conduction system (Purkinje fibers)
* Myoendocrine cells (ANP-Atrial Natriuretic Factor)
40
What cells are present in the Epicardium layer? What do they form?
Epicardium (outer wall): **Mesothelial cells** of **Sinus Venosus** (from viseral) spread over the myocardium, forming **outer layer of the heart**(epicardium).
41
Epicardium gives rise to what? (2)
* coronary vessels
* Visceral pericardial lining
42
The fibrous pericardium is from where? What is a characteristic about it?
* From the body wall
* Muscular
43
Rapid growth elongates the heart tube, thus what happens?
**Rapid growth** elongates the tube, thus **bend/kinks** with **dilations & constrictions**
44
Heart detaches from what and is attached to what? This allows what?
Heart **detaches** from the **dorsal mesocardium** but is attached to **pericardial wall on either side**; thus, **freely ROTATE on its AXIS**
45
By Day 23-28, what occurs with heart looping?
Day23-28: **Dextral looping** (occurs on the right hand side)→U-shaped **D-loop (ventral, rightward looping)**→**Bulboventricular loop**
| S-shaped heart
46
D-looping forms S-Shaped heart with Bulbus Cordis & Primitive Chambers, what other structures are formed? (7)
* **Bulbus cordis, Conus cordis, Conus arteriosus & Truncus arteriosus**
* **Primordial ventricles: (PRV & PLV)**
* **Primordial atrium (PA)**
* **Sinus Venosus**
47
Anything coming through the heart, is coming through what? What about out of the heart?
* In: Sinus Venosus
* Out: Truncus arteriosus
48
* Where does the folding or D- looping take place?
* Where do structures move?
* What gives rise to the formation of the RV?
* At primordial ventricles
* Bulbus cordis and truncus arteriosus moves to the right then the primordial ventricles and atrium move to the left
* Bulbus cordis
49
What does right-sided/ventral looping cause (D-looping)?
causes common atrium to lift up dorsally
50
What dictates blood flow? (4)
* Cardiac cushions
* Atrioventricular (AV) Canal
* AV Valve
* Septa formation
51
By Day 35, AV endocardial cushions form on what? from where?
**AV endocardial cushions** form on the **dorsal & ventral walls of the AV canals** from **Cardiac Jelly (ECM) + Neural crest cells (NCCs)**
52
The AV endocardial cushions partially close what? Thus splitting into what? And functions as?
| Day 35
The cushions **partially close the AV canal** at the midline (Dorso-Ventrally), thus splitting it into **right & left AV canals** & functions as **primitive valves: the “AV valves”**
53
What are the AV cushions (inner and outer) made up of?
* **Inner: endocardial cells**
* **Outer: myocardial cells**
54
Heart Valves & Septal Membranes are sculpted via what?
**Endothelial–Mesenchymal Transformation (EMT)** (give rise to meschymal cells)
55
What does the primitive heart valves undergo?
**Extensive remodeling** to form **thin, delicate heart valve leaflets** in the **adult** heart
56
Myocardial Cells induce what? What does this result in?
**Myocardial Cells** induce **EMT in Endocardial Cells (ECs)**, resulting in **migratory mesenchymal cells** that **invade the extracellular matrix** (of cushions) forming **valves & membranous septa** of the heart.
57
What happens to the atrium by Day 27-28? And where does the septum premium grow towards?
Day 27-28: **Division of Atrium** →**LA+RA** occurs as the **Septum primum** grows towards **AV-endocardial cushion**
58
What forms the foramen primum?
| Day 27-28
Gap between **Septum primum & AV-endocardial cushion** forms **Foramen Primum** (hole in the atrial septum)
59
* Holes in the atrial septum allow what?
* How is blood shunted? what does this allow?
* **Holes** in the *atrial septum* allow **blood oxygenated by the mother**, coming from the **Vena Cavas (SVC/IVC)**, to **circumvent the pulmonary circulation** (lungs not formed).
* Thus, **Blood is shunted between RA→ LA→TA→body**
* This allows **ventricular walls to mature & thicken**
## Footnote
TA: Truncus arteriosus
60
what does the primordial inter-ventricular septum divide?
LV + RV
61
What eventually happens to the septum primum and foramen primum?
* **Septum primum grows**
* **Foramen primum almost disappears** as it **fuses with AV endocardial cushions**, **forming primordial AV septum**
* But before it closes new holes form!! Blood Shunting continues!
62
How is the primordial AV septum formed?
Septum primum grows & Foramen primum almost disappears as it fuses with AV endocardial cushions
63
Septum primum have perforations via what?
They fuse to form what?
Septum primum have perforations via **apoptosis**, which fuse to form **Foramen Secundum**
64
What does the Foramen Secundum ensure?
Ensures **continued shunting** of blood from right to left atrium, **bypassing the primitive lungs**
65
At week 5&6, what overlaps the Foramen Secundum and where does it grow from?
A **thick crescentic muscular fold, “Septum Secundum”** (very muscular) grows from the **ventrocranial wall of Right Atrium** & overlaps the Foramen Secundum
66
Flutter Valve of Foramen Ovale controls what?
Controls unidirectional blood-flow
67
How is the Flutter Valve of Foramen Ovale formed?
* **Muscular Septum Secundum** forms an incomplete partition, leaving a **hole** between the atria→**foramen ovale**
* Before birth, the **foramen ovale** allows oxygenated blood entering the right atrium to pass into the left atrium as the **septum premium is weak/pliable**
* **Septum Secundum** is **muscular & rigid**; **does not allow opposite flow!**
68
What happens in week 6-7 to myocytes from LV and RV?
Week 6-7: **Myocytes from LV + RV**→**median ridge at the Ventricular apex**, where **muscular interventricular septum** grows **upwards** towards the endocardial cushions.
69
What does not touch the endocardial cushions? What does this form?
| Wk 6-7
**Interventricular septum** does not touch the cushions, forming a **intraventricular foramen** to **shunt blood**
70
What happens to the Ventricles at Week 6-7?
Ventricles **rapidly expand and thicken**
71
How does the interventricular formen close?
Interventricular foramen closes: **Two bulbar ridge fuse** with **endocardial cushion** forming a **membrane** that **touches** the lower muscular septum.
72
Ventricular cavities form what?
Ventricular Cavities→ Spongy muscular bundles→**trabeculae carneae formed**
73
Spony muscular Bundles form?
Bundles→ **Papillary muscles & tendinous cords (chordae tendineae)**
74
Tendinous cords run from the papillary muscles to what? What does this help form?
Tendinous cords run from the papillary muscles to the **AV valves** helps form the **cusps of the AV valves** and **“sculpts” them as mature valves**
75
What sculpts the Aortic and pulmonary "trunk valves"? And controls apoptosis to thin and form Vale Cusps?
**Swellings of the Subendocardial tissue** and **Migration of Cardiac Precursor Neural Crest Cells**
76
When does the conduction system of the heart occur?
Week 7-20
77
Where is the origin of the Sinoatrial Node (SAN)
**Natural Pacemaker**:
* SAN Origin→**right wall** of the **Sinus Venosus (SV)** or **IFT** & **fuses with right atrium**
* Mature SAN→high in the right atrium, at the SV opening.
78
What does the AV (Atrioventricular) Node (AVN) & Bundle of His do?
It conducts electrical impulse from **Atria**→ **Ventricles** via the **“Bundle of His”**, which has **right bundle branch & left bundle branch**
79
What is the origin of the AV Node?
AVN origin→**lower inter-atrial septum, superior to the endocardial cushions** near the **Coronary Sinus (CS) opening**
80
Where does electrical impulses from atria to venticles end up?
“Bundle of His”, which has right bundle branch & left bundle branch
81
What makes up the outflow tract?
Bulbus Cordis + Truncus Arteriosus
82
The outflow tract divides into what?
Two great vessels:
1. **Ascending Aorta (Systemic circulation)**
2. **Pulmonary Trunk (to Lungs)**
83
What is the mechanism of Outflow division?
**Truncal Ridges (TR)+ Bulbar ridges (BR)** expand and form **septa & divides OFT (OT)**
84
What divides Outflow Tract (OFT) into Aorta & Pulmonary Trunk (PT)?
Spiral Septa
85
Truncal (TR) + bulbar ridges (BR) partitions the Outflow Tract (OFT) by a spiral septa such that what forms (2)? And what do they supply?
**Aorta forms** & supplies:
* **Oxygenated Blood Outflow of Left Ventricle (LV) to the Systemic Circulation**
**Pulmonary Trunk (PT) forms** & supplies:
* **Deoxygenated Blood-flow of Right Ventricle (RV) to the Pulmonary Artery (PA)**
86
What happens during the closing of the interventricular foramen?
Incorporation of the **inferior edges of Left & Right Bulbus cordis ridges** into the l**eft & right edges of the Intraventricular septum** during the **closing of the interventricular foramen** begins the partitioning of the OFT
87
Partition of the OFT: Forms what?
Forms the **Aorta (connecting Left Ventricle)** and **Pulmonary Trunk (connecting Right ventricle)**
88
Teratogens (rubella virus) & multifactorial inheritance that cause congenital heart defects are how common?
8:1000 live births
89
What are the two types of dextrocardia? How common?
1. **Dextrocardia** w/ **Situs Inversus** (transposition of the abdominal viscera)
* Normal Heart function; no heart defects (all organs reversed)
2. **Isolated Dextrocardia**: The abnormal position of the heart & no displacement of viscera
* Severe cardiac defects (D-loop becomes L-loop)
* 1:10,000 live births
90
Atrial septal defects:
* More seen in who?
* 20% in ?
* 25% in?
* More seen in females
* 20% Down Syndrome
* 25% Patent Foramen Ovale (PFO)→ Incomplete adhesion of (Septum Primum + Septum Secundum)
91
# Clinical Significance of the other heart defects:
1. Ostium Secundum defects:
2. Endocardial cushion defect:
3. Sinus Venosus defect:
4. Common Atrium: Abnormal
5. Ventricular Septal defect:
1. **Ostium Secundum defects**: Endovascular catheter-based closures repairs it. **> females →3:1 ratio**
2. **Endocardial cushion defect**: **Cleft** in the anterior cusp of the **mitral valve**
3. **Sinus Venosus defect**: Abnormal absorption of the Sinus Venosus into the right atrium
4. **Common Atrium: Abnormal** [Ostium secundum + Ostium primum + sinus venosus]
5. **Ventricular Septal defect**: Direct mixing of LV + RV blood
92
Ventricular septal defects (VSDs):
* Percentage of all CHDs?
* More common in?
* What clinical manifestations are common?
* What happens to the VSDs?
* **Most common CHDs**: 25% of all heart defects
* More common in **males** (opposite of ASD)
* **Membranous VSDs are common; Incomplete closure of interventricular foramen**
* About **50% of VSDs close by end of 1st year**, and babies are fine.
93
What is the mechanism of ventricular septal defects?
**Right side** of the **endocardial cushion does not fuse** with the **aorticopulmonary septum** and the **muscular part of the interventricular septum**→**A persistent TA is seen!**
## Footnote
Persistent TA: mixing of blood d/t hole in the ventricle
94
Large Ventricular Septal defects (VSDs) have excessive what?
**Pulmonary blood flow** and **pulmonary hypertension, dyspnea and cardiac failure early** in infancy
95
By day 26, The heart tube joins with blood vessels in the embryo, connecting what? to form what?
The heart tube joins with **blood vessels** in the **embryo, connecting the stalk, chorion, and umbilical vesicle** to form a **functional cardiovascular** system having 3 branches by day 26
96
What are the three branches that are formed by day 26? And what are their functions?
1. **The Arterial System (Dorsal Aorta)** sends impure blood back into the Umbilical Artery (bilaterally)
2. **The Umbilical Veins**: Supply Nutrients & O2
3. **Vascular plexus of Vitelline veins** in the umbilical vesicle & **Cardinal Veins** connect to the heart tube
97
Early Embryonic Venous System to ________ venous return
Right-sided
98
The three paired veins drains what type of blood from what part of the body into the primordial heart (Atrium)?
* **2-Vitelline veins** drain **deoxygenated blood** from the **umbilical vesicle** into the Atrium.
* **2-Umbilical veins** drain **oxygenated blood** from the **chorion** into the Atrium.
* **2-Common cardinal veins** drain **deoxygenated blood** from the **body** to the Atrium.
99
Initial Bilateral Venous Return System becomes what? And blood comes into the what?
* Initial Bilateral Venous Return System becomes a **Right-sided venous return**
* Blood comes into the **Right Sinus Venosus & Right Atrium**
100
For right-sided venous return (Right Atrium), remodeling of the Bilateral System forms what?
For right-sided venous return (Right Atrium), remodeling of the Bilateral System forms **“Right sided blood shunt”**
101
What forms the left brachiocephalic vein?
**Anastomosis** of the **Anterior Left & Right Cardinal Vein** forms Left Brachiocephalic Vein
102
What occurs to the rest of the left Cardinal vein?
Rest of the left Cardinal vein is **Lost**→**END of left side blood flow**
103
What are the Three Drainages to the Heart (RA)?
**SVC + CS + IVC**
## Footnote
* SVC: Superior Vena Cava
* CS: Coronary Sinus
* IVC: Inferior Vena Cava
104
Superior Vena Cava (SVC) forms from?
Right Anterior Cardinal Vein + Right Common Cardinal Vein
105
Posterior Cardinal Veins drains into?
Mesonephroi & degenerates with it
106
Coronary Sinus transports blood from where?
Blood from heart muscles into RA.
107
Inferior vena Cava is the fusion of what?
Fusion of the 2 Vitelline Veins
108
What is the roof of azygos vein?
Blood (thorax + Abdomen)→SVC
109
During Venous System development what do the structures below become:
* Cardinal Vein Anastomosis→
* Umbilical Vein Anastomosis→
* Fusion to the “Right Vitelline Vein”→
* Cardinal Vein Anastomosis→**Superior Vena Cava (SVC)**
* Umbilical Vein Anastomosis→**"Ductus Venosus”** Bypass (Left-UV) (liver bypass)
* Fusion to the “Right Vitelline Vein”→**Portal Vein (Inferior Vena Cava) (IVC)**
## Footnote
Result: End of the Left Blood Return
110
What is the fetal circulatory system?
Blood supply to and from the placenta and 3 Shunts
111
Fetal circulatory system has 3 shunts to do what?
What are the 3 shunts?
Fetal circulatory system has 3 shunts to **divert blood from undeveloped organs** (lung & liver)
* 3 Shunts are:
1. **Ductus arteriosus** (do not want pressure from pul trunk to lung, connects aorta to pulmonary artery)
2.**Foramen Ovale** (limits the pressure on pul circulation, allows blood in the RA to reach LA)
3. **Ductus Venosus** (protects the liver by bypassing it)
112
Initially, three systems of veins are present for the IVC (Day 26). What are they?
1. **Umbilical veins** from the chorion
2. **Vitelline veins** from the umbilical vesicle
3. **Cardinal veins** from the embryo→**Subcardinal veins →Supracardinal veins→ Subsupracardinal veins**
113
How do we get the final form of the Inferior Vena Cava?
* The venous System in the Caudal portion of the Embryo **passes through various stages** of development.
* Several veins **form and degenerate**, giving rise to newer sets of venous system.
* However, **some remnants of each of these system** contributes to the **final form of the Inferior Vena Cava,** collecting deoxygenated blood rom the caudal-half of the body.
114
What is the Superior Vena Cava?
A valve-less system collects blood from the neck, head, upper extremities, and chest
115
Two dorsal aortae develop early and connect to what? via what?
Two dorsal aortae develop early and connect to the **heart tube** via **first aortic arch arteries**
| Formation of dorsal aorta and aortic arches
116
By day 26 the Truncus arteriosus is present which froms what?
Day 26: Truncus arteriosus→ **Aortic Sac**
* **3 Pharyngeal arch arteries→2 Dorsal aortae**
* **Vitelline & Umbilical arteries**
| Formation of dorsal aorta and aortic arches
117
What happens to the aortic arch arteries on 35 day (which arch arteries degenerate? What structure is formed)? later on? (what aortic arch degenerates, which on remains)
* 35 days: **1st & 2nd arch arteries mostly degenerate & a single dorsal aorta forms**
* Later: **5th aortic arch degenerates; III, IV & VI remain**
| Aortic arch arteris in the head, neck and thorax
118
Where is the location of:
* Aortic Arch I
* Aortic Arch II
* Aortic Arch III
* Aortic Arch IV
* Aortic Arch VI
Aortic Arch I: Maxillary Artery
* Aortic Arch II: Stapedial artery (rare)
* Aortic Arch III: Common cartoid artery and internal cartoid artery (external carotid artery us a angiogenic branch of AA III)
* Aortic Arch IV: Right side-right subclavian artery (proximal portion); Left side-aortic arch (portion btw the left common carotid and subclavian arteries)
* Aortic Arch VI: Right side-pulmonary artery; Left side-left pulmonary artery and ductus arterious
119
How is the ductus arteriosus formed? What does this allow?
* Left **Aortic arch VI** links **truncus arteriosus to the Left dorsal aorta**, forming **ductus arteriosus (DA)**, allowing blood to **bypass the lungs**
* This happens by connecting **pulmonary trunk to left aorta**
120
* Fetal pulmonary vascular resistance is what?
* 90% of the blood is shunted through what?
* What does the shunt allow?
* Fetal pulmonary vascular resistance is **high**
* **90% of blood shunted through the ductus arteriosus→aorta**
* **Shunt** also allows the wall of the **left ventricle to thicken**
121
Failure of the Ductus Arteriosus to close after birth is called what? And causes and leads to what?
* **Patent Ductus Arteriosus (PDA)** and the generation of a **left-to-right shunting**
* Leads to **pulmonary hypertension, heart failure & cardiac arrhythmias**
122
By Day 21 the Cardiovascular system begins to develop; _________ and ____________
By Day 21 the Cardiovascular system begins to develop; the **2-heart tubes** and **2 dorsal aortae**
123
__________ develops from blood islands at the _______most end of the U-shaped ___________. Heart tubes fuse and begin to beat by _______.
**Two primordial heart tubes** develops from blood islands at the **cranial** most end of the U-shaped **perocardio-peritoneal canal.** Heart tubes fuse and begin to beat by **week 4.**
124
___________ surrounding the heart tube forms the ____________
**Splanchnic mesoderm** surrounding the heart tube forms the **primordial myocardium.**
125
The heart primordium has 4 __________: the ________,__________,_______ and ________
The heart primordium has **4 chambers: the Bulbus cordis, Ventricle, Atrium**, and **Sinus Venosus**
126
The _____________ (primordium of the ascending aorta and pulmonary trunk) is continuous caudally with the ___________, which becomes part of the ventricles.
The **truncus arteriosus** (primordium of the ascending aorta and pulmonary trunk) is continuous caudally with the **bulbus cordis**, which becomes part of the ventricles.
127
As the heart grows, __________ gives the tube an S-shape, juxtaposing inflow (________) and outflow tract (____________) cranially.
As the heart grows, **D-looping** gives the tube an S-shape, juxtaposing inflow (**Sinus Venosus**) and outflow tract (**Truncus arteriosus**) cranially.
128
The heart becomes partitioned into ______ between the _____________.
The heart becomes partitioned into **four chambers** between the **fourth and seventh weeks**
129
Three systems of paired veins drain into the primordial heart: the ___________, the ___________ & _________
Three systems of paired veins drain into the primordial heart: the **vitelline system (portal system)**; the **cardinal veins** & **the umbilical veins**
130
The pharyngeal arches receive blood from ________ that arise from the _____________.
The pharyngeal arches receive blood from **pharyngeal arteries** that arise from the **aortic sac**
131
By 6-8 week, most of ______,_____, & __________ are lost. Rest form adult arterial arrangement of the _______________, __________ and __________ arteries.
By 6-8 week, most of **1st, 2nd & 5th arch arteries** are lost. Rest form adult arterial arrangement of the **carotid, subclavian**, and **pulmonary** arteries.
132
__________originates from the pulmonary trunk and connects to the __________suppling deoxygenated blood.
**Ductus arteriosus** originates from the pulmonary trunk and connects to the **L. dorsal aorta** suppling deoxygenated blood.
