PEDS mod 1 Flashcards
The cardiovascular system is mostly derived from which germ layer?
Mesoderm
When does the CV system begin to function?
When does the blood start to circulate?
When does the heart start to beat/contract?
- Begins by the end of the third week (18-20 days)
- Blood is circulating in the third week.
- Heart starts to beat at the beginning of the 4th week (22 days)
When is the critical period of development for the CV system?
The critical period of development is from day 20 to 50 after fertilization.
Forms with clusters of angiogenic cells located in the cardiogenic plate.
Heart tube
The angiogenic cell clusters coalesce to form right and left what?
•The angiogenic cell clusters coalesce to form right and left endocardial tubes.
When are the endocardial tubes within the pericardial cavity fused?
•At approximately day 21 they are completely fused
Cardiac looping is normally to which side?
When is the cardiac loop complete?
Looping is to the right.
By day 28 the cardiac loop is complete.
- ___________ heart loops to the left instead of to the right.
- May coincide with situs inversus (all organs are reversed)
Dextrocardia
During which month does the heart begin to septate?
•During the second month, the heart begins to septate. (Divide into partitions)
What begins the separation of the heart into its chambers?
The endocardial cushions begin the separation of the heart into right and left, Upper and lower chambers.
The ______ _______ reduces the flow of blood from the right atrium to the left.
The septum primum reduces the flow of blood from the right atrium to the left.
The atrial septum continues to grow until the _______ _______ is nearly closed and the flow of blood almost ceases.
•It continues to grow until the foramen primum is nearly closed and the flow of blood almost ceases.
Apoptosis occurs in the _____ _______ causing an opening: the foramen secundum.
Apoptosis occurs in the septum primum causing an opening: the foramen secundum.
•The foramen secundum allows for continued delivery of oxygenated blood to the left atrium.
•Septum secundum nearly overlaps the foramen secundum creating the ______ ______.
Foramen ovale
•The foramen ovale establishes a one-way passage for blood from the right atrium to the left.
Ventricular septation starts when?
42 days
are formed from invagination & then dehiscence of myocardium to form valve & tensor apparatus.
True AV valves
valves are formed by ingrowth from the truncal wall.
The semilunar valves
What are the two biggest obstacles for the vascular system?
The need to bypass developing lungs.
Increased demand from proliferating tissues.
Oxygenated blood is supplied to the embryo via the?
umbilical veins
serves as the main collecting chamber for blood in the developing heart.
The sinus venosus
Blood pumped from the heart exits through the aortic arches before flowing through the paired
Dorsal aortae
Tissues are primarily supplied via efferent
Efferent segmental arteries
The dorsal aortae end in the umbilical arteries, which return mixed blood to the
Placenta for reoxygenation
The _____ veins (anterior, posterior and common) drain blood from developing tissues.
Cardinal veins
The deoxygenated blood is mixed in the _____ ______ and recirculated.
Mixed in the sinus venosus and recirculated.
Supply the yolk sac
Fuse and form the mesenteric arteries
- coeliac artery; supplies foregut derivatives
- superior mesenteric artery; supplies midgut derivatives
- inferior mesenteric artery; supplies hindgut derivatives
Vitelline arteries
Inferior vena cava
Superior mesenteric vein
Hepatic vein
Vitelline veins
•Cord is formed by the week
5
The umbilical cord normally contains
two umbilical arteries and one umbilical vein.
Umbilical arteries/veins are embedded within a loose, proteoglycan-rich matrix -
Wharton’s jelly
What are the three shunts in fetal circulation?
- Ductus arteriosus
- Foramen ovale
- Ductus venosus
Allows deoxygenated blood to flow from the pulmonary artery into the aorta and through it to the body.
Protects the lungs against circulatory overload.
Allows the right ventricle to strengthen.
Ductus arteriosus
The hole located in the septum between the atria. Allows highly oxygenated blood to shunt from the right atrium to the left atrium.
Foramen ovale
The foramen ovale and the ductus arteriosus are functional only…
The foramen ovale and the ductus arteriosus are functional only before birth. At or soon after birth, they normally close and become nonfunctional.
A fetal blood vessel– connects the umbilical vein to the inferior vena cava
Blood flow is regulated via sphincter
Carries mostly highly oxygenated blood
Ductus Venosus
Placental blood is ___% saturated w/ O2.
Returns to the fetus via …
The umbilical vein enters the body through the umbilical ring and travels along the anterior abdominal wall to the liver.
About 1/2 the blood it carries passes into …
The other 1/2 of the blood enters the …
Placental blood is 80% saturated w/ O2
Returns to the fetus via the single umbilical vein •The umbilical vein enters the body through the umbilical ring and travels along the anterior abdominal wall to the liver.
About 1/2 the blood it carries passes into the liver. •The other 1/2 of the blood enters the ductus venosus which bypasses the liver.
The ductus venosus joins the
Inferior vena cava
There, the oxygenated blood from the placenta is mixed with the deoxygenated blood from the lower parts of the body.
The initial inflation of the lungs causes important changes in the circulatory system:
Reduces the resistance to blood flow through the lungs
Results in increased blood flow from the pulmonary arteries
Consequently, an increased amount of blood flows from the right atrium to the right ventricle and into the pulmonary arteries
Less blood flows through the foramen ovale to the left atrium.
An increased volume of blood returns from the lungs through the pulmonary veins to the left atrium, which increases the pressure in the left atrium.
The increased left atrial pressure and decreased right atrial pressure (due to pulmonary resistance) forces blood against the septum primum.
Causing the foramen ovale to close.
Occlusion of the placental circulation causes
an immediate drop in blood pressure.
