Development of the Cardiovascular System Flashcards
*CVS consists of the ____ function early when simple diffusion of nutrients can no longer supply the metabolic needs of the developing embryo
heart, blood vessels and blood cells
*Heart begins to beat on the ____ of incubation in chicken and on the ____ of gestation in man
2nd day
23rd day
*the mechanism involves the ____ and a later ____ which both mean the process of ____
early vasculogenesis
angiogenesis
blood vessel formation
The blood islands in the yolk sac consist of two types of primordial cells: ____ are hematopoietic that gives rise to blood cell lines & ____ (the angioblasts; angeion=vessel) give rise to the endothelial cells of the blood vessels
inner most cells
Outer cells
*Heart tube
At about 3rd week of gestation ____ from the ____ appear to form plexus of vessels lying deep to the horse-shaped prospective ____
angioblastic blood islands
splanchnic mesoderm
pericardial cavity
*Heart tube
These small vessels develop into paired ____
endocardial heart tubes
*Heart tube
Splanchnic mesoderm proliferates and develops into ____ which give rise to the
myocardium and the epicardium
epimyocardial mantle
*Heart tube
Bilateral endocardial heart tubes continue to develop and connect with a pair of vessels, the ____, located on either side of the midline
dorsal aortae
*Heart wall
____ and ____ growth of the embryo shift the endocardial tube medially, ventrally, caudally and fuse in the midline as single endocardial tube beneath the ____
Lateral and cephalic
foregut
*Heart wall
Endocardial tube is surrounded by ____
rich in hyaluronic acid that facilitates cell
movement on the subsequent remodeling of the endocardium
cardiac jelly
*Heart wall
The resulting heart tube is suspended in the pericardial cavity by ____ dorsally and _____ ventrally
dorsal mesocardium
ventral mesocardium
When the heart tube is formed, the embryo is in the ____; about 3mm in length; has 4-12 somites and neural tube is also forming, the heart begins to beat
4th week of gestation
*Subdivisions of the Embryonic Tube
As the heart tube fuses, several ____
appear. From the cephalic to posterior end, the bulges are: truncus arteriosus, conus arteriosus (bulbus cordis), primitive ventricle, atrium and sinus venosus
bulges and sulci
*Subdivisions of the Embryonic Tube
The veins connect to the heart tube via the ____ while the paired dorsal aortae arise
from the aortic arch which in turn arise from the aortic sac=the most cephalic end of the bulbus cordis
sinus venosus
*Subdivisions of the Embryonic Tube
The sulci present are the _____ between
the bulbo cordis and the ventricle, atrioventricular sulcus between the atrium and the ventricle
bulboventricular sulcus
*Subdivisions of the Embryonic Tube
With the convolution the _____ degenerates
dorsal mesocardium
*Subdivisions of the Embryonic Tube
With the process of convolution, the ____ flexure seen is between the bulbos cordis and ventricle
first
*Subdivisions of the Embryonic Tube
- The ____ that is formed shifts this region of the heart to the right and ventrally
- The 2nd flexure = ____ is between the atrium and the ventricle and this region of the heart is shifted to the left and dorsally
- As growth progresses, the atria shift cephalically
bulbo ventricular loop
antrioventricular loop
*Subdivisions of the Embryonic Tube
Sinus venosus gradually shifts right to empty into the _____
right atrium
*Subdivisions of the Embryonic Tube
- ____ is represented inside the heart as
the bulboventricular flange - The bulboventricular flange and the muscular interventricular septum begin to separate the ____ (becomes the left ventricle) from the ____ (becomes the right ventricle)
Bulboventricular sulcus
primitive ventricle
proximal bulbos cordis
*Subdivisions of the Embryonic Tube
- Atria continue to grow and bulge forward on the either side of the bulbus cordis, and shifts bulbus medially
- With increased blood flow, the ____ regresses
- Thus, primitive 4 chambered heart is formed and blood flows from the veins to sinus venosus, to atria, to ventricles, to conus, to truncus, to aortic sac, to dorsal aorta.
bulboventricular flange
*Atrial septation
_____ develop in the dorsal (inferior) and
ventral (superior) walls of the heart which grow toward each other as cardiac jelly proliferates deep to the endocardium
Endocardial cushion
*Atrial septation
At the same time there is a developing septum from the ____ that grows toward the cushion
dorsocranial atrial wall
*Atrial septation
The septum primum, and the intervening space is called _____
foramen (ostium) primum
*Septation of the Heart
At about ____, the heart begins to septate into 2 atria, 2 ventricles, the ascending aorta and the pulmonary trunk
2nd month
*Atrial septation
As the septum reaches the endocardial cushions closing the foramen primum, a 2nd opening = ____ appears in the septum primum
foramen secundum
*Atrial septation
S2 (septum secundum) forms an incomplete partition (at right of foramen secundum) and leaves and opening called the ____
foramen ovale
*Ventricular Septation
____ (IV) grows as a ridge of tissue from the caudal heart wall toward the fused endocardial cushions
Muscular interventricular septum
*Ventricular Septation
There remains an opening called ____ which closes by a ____, outgrowth of the inferior endocardial cushion and connective tissue from the muscular IV septum= memb IV septum
interventricular foramen
conal ridge
*Septation of the Bulbus cordis
____ appear 1st as bulges in the truncus on the right superior and left inferior walls
Truncal swelling (ridges)
*Septation of the Bulbus cordis
They enlarge and fuse in the midline to form the ____ which spirals as it develop
distally separating the distal pulmonary artery from the aorta
truncal (aorticopulmonary) septum
*Septation of the Bulbus cordis
- Same time the right dorsal and left ventral conal ridges form and fuse in the midline
- ____ helps divide the proximal aorta from the pulmonary artery and contributes to the memb. IV septum
Conal septum
*Septation of the Bulbus cordis
- Truncal and conal septa fuse to form a ___ degree spiral and form the aorta
- Neural crest cells which migrate in that part contribute to _____
180
conal and truncal septa
*Cardiac Valve Formation
____ develop in the aorta and pulmonary
artery as localized swellings of the endocardial tissue
Semilunar valves
*Cardiac Valve Formation
- ____ develop as subendocardial and endocardial tissues projecting in the AV canal
- These swellings are excavated from the ventricular side and invaded by muscle
AV valves
there is communication between the right and left atria which causes a left to right
shunting of blood due to lower pressure in the pulmonary circulatory system
* Consequently, there is a mixing of oxygenated (systemic) and deoxygenated (pulmonary) blood
* Two types: primum type involves endocardial cushions and secundum type involving S1 or S2
Atrial septal defect (ASD)
the most common of all congenital heart defects
* There is a massive left to right shunting of blood and pulmonary hypertension; absence of IV septum results in a common ventricle
Ventricular septal defect (VSD)
condition wherein the aorta arises from the right ventricle and pulmonary trunk from
the left
* Anomaly is due to the failure of the trunco-conal swellings to grow in the normal spinal direction
* There is also VSD and persistent ductus arteriosus, however, they make life possible as they provide a way for oxygenated blood to reach the entire body
Transposition of great vessels-
when trunco-conal swellings fail to grow
* Single artery= the truncus arteriosus arise from both ventricles above the ventricular septal defect, allowing pulmonary and systemic blood to mix
* Distally, the single artery divides into aorta and pulmonary trunk by an incomplete septum
Persistent Truncus Arteriosus-
results from a single error: the conus septum develops too far anteriorly giving rise to two unequally proportioned vessels= a large aorta and a smaller stenotic pulmonary trunk
Tetralogy of Fallot-
4 main characteristics of tetralogy of fallot:
- Pulmonary stenosis
- VSD of the membranous portion
- Overriding aorta
- RV hypertrophy due to shunting of blood from L to R
the primitive heart tube folds to the left in a
mirror of a normal bulboventricular loop
* This usually occurs when all organ systems are reversed, a condition called situs inversus
Dextroaorta-
