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51 Cards in this Set

  • Front
  • Back
Initial precursor cells of the CV system:
Precursor tissue of Angioblasts:
Extraembryonic Mesoderm
When do angioblasts first appear? Where?
Day 13 in the wall of the Yolk Sac
First thing that angioblasts do:
Aggregate into Blood Islands
Blood islands contain:
Precursors for Blood cells and Endothelial cells.
What do blood islands become?
Primitive blood vessels, with progenitor blood cells inside.
What do Angioblasts form other than Endothelial and Blood cells?
Intraembryonic blood vessels
What do intraembryonic blood vessels develop from?
Angioblasts in the intraembryonic mesoderm
Where does hematopoiesis occur
-At 1-2 months
-At 1.5-7 months
-At months 4-adult
1-2 months: Yolk sac
1.5-7 months: Spleen/Liver
4 mo->Adult: Bone marrow
What is the Heart derived from?
Splanchnic mesoderm
What is the u-shaped region of splanchnic mesoderm from which the heart develops called?
Cardiogenic plate
What is the Cardiogenic Plate located within?
Pericardial Coelom - an area ventral to the brain
What is the 1st thing that happens in cardiac development?
Splanchnic mesoderm from the cardiogenic plate migrates medially toward endoderm to form an ENDOTHELIAL PLEXUS.
What will the endothelial plexus form?
A layer of muscle that folds around a tube.
What is the tube that muscle folds around? What does it come from?
The Endocardium - comes from endothelial heart tube tissue.
What happens to the two sides of the U-shaped Pericardial Coelom?
They fuse together medially.
What causes the heart to be located ventrally?
Cranial-caudal folding of the embryo at weeks 3-4
A special region of mesoderm-derived mesenchyme accumulates adjacent to the Transverse portion of U-shaped intraembryonic coelom: what is it?
The septum transversum
What does the septum transversum become?
Diaphragm (part of it)
What unites the bilateral heart primordia in the midline?
Lateral folding of the embryo at weeks 3-4
How many segments does the inital Tubular heart have?
only 2
In what order do the initial segments of the Heart Tube form?
1-Primitive Right Ventricle and
Conus region (outflow)
2-Primitive Atrium
3-Truncus outflow region forms between Aortic Sac and Conus.
Important thing to remember re: the primitive tubular heart:
Its segments are NOT equivalent to the adult heart chambers (duh)
How are the 3 initial tissues of the heart arranged?
As a tube within a tube.
What is the outer tube?
What is the inner tube?
What is between the 2 tubes?
Outer = Myocardium
Inner = Endothelium
Between = Cardiac Jelly
What does the dorsal mesocardium lying above the developing heart tube become?
Epicardium - from the proepicardial organ
What is the Epicardium?
The visceral pericardium
What IMPORTANT structures does the Proepicardial organ contribute to?
Where does blood flow INTO the primitive tubular heart?
At the Sinus Venosus
What 3 vessels flow into the Sinus Venosus?
1. Umbilical veins
2. Vitelline veins
3. Common Cardinal veins
What blood is carried by umbilical veins?
Placental blood - oxygen rich
What blood is carried by Vitelline veins?
From the gut - oxygen poor
What blood is carried by Common Cardinal veins?
Blood from head/trunk - oxygen poor
Where does blood flow out of the primitive heart?
At the Bulbus Cordis (outflow) regionn
What specific outflow structure is at the top of the Bulbus cordis? What will it become?
Aortic sac - becomes Aortic arches.
What region of the developing embryo is supplied by the Aortic arches?
The pharyngeal arches
What important process begins right after the heart tube segments begin to form?
In what direction does looping almost always occur?
Where does the loop form?
Between Conus (PRV) and Ventricle (PLV) -> makes sense, because the apex forms between the R/L ventricles.
What is the hinge point formed by looping called?
Inner curvature
What occurs simultaneously with the right looping of the heart?
Right torsion of the heart
What does the cranial leg of the loop contain?
Bulbus (Primitive right ventricle)
What does the caudal leg of the loop contain?
Primitive left ventricle; later, AV canal, Atrium, and Sinus venosus.
What are 3 consequences of Cardiac Looping and Torsion in the EARLY PHASE?
1. Proper anatomic rltnships between heart segments establ.
2. Venous inflow & Arterial outflow regions come together
3. Outflow region elongates and subdivides.
What does the outflow region subdivide into during the early phase of looping?
-Conus cordis (proximal)
-Truncus arteriosus (distal)
What are the consequences of cardiac looping in late phase?
1. Both caudal/cranial legs contact at AV canal level
2. Inner curvature- contact pt
3. Conus outflow wedged into AV canal over both ventricles.
What changes in bloodflow are achieved during heart tube formation?
1. Flow goes from sloshing back and forth to unidirectional
2. 2 separate streams, one from ea ventricle; no phys. separtn.
What does the bloodflow from the left ventricle enter?
Left aortic arch #4 -> becomes the aorta.
What does the bloodflow from the right ventricle enter?
Left aortic arch #6 -> becomes Ductus arteriosus.
What is the ductus arteriosus?
A SHUNT that allows fetal circulation to bypass pulmonary circulation.
By what day does the heart begin to beat?