The Cardiovascular System Flashcards
What is the first functional organ system to be fully formed?
The circulatory system
What do the blood vessels and blood arise from?
visceral mesoderm of the yolk-sac wall, where hemangioblasts differentiate into:
- angioblasts ( endothelial precursor cells = EPCs)
- hematopoietic cells form blood cells)
Heart development begins at the ____ end of the _______, in an area called the _____ (in the visceral mesoderm of the yolk sac wall).
- anterior end
- embryonic disc
- cariogenic field
getting heart for baby, lots of ants at the front of cariogenic field
____________ coalesce (come together) to form a horseshoe-shaped primitive heart/ cardiac tube, as well as ________ on each side of the midline.
endothelial lined blood-forming cavities; paired dorsal aortae
The definitive cardiac tube forms when _________ surrounding the endocardial tube differentiates into _____ which forms the ____ and then a separate population of splanchnic mesoderm forms the ____.
splanchnic (visceral) mesoderm; myoblasts; myocardium; epicardium (visceral pericardium)
With antero-posterior folding of the embryo, the cardiac tube is brought to a _____ position with branches of the ventral and dorsal aortae extending cranially on each side of the midline
ventral
What are the 3 fetal structures involved in circulation?
Ductus arteriosus, Ductus venosus, Foramen ovale
How does blood flow into the pulmonary trunk during fetal circulation?
Blood can be shunted into the aorta through the Ductus arteriosus
What does the Ductus venosus do?
Carries highly oxygenated blood from the umbilical vein to the caudal vena cava
What happens to oxygenated blood returning to the heart in fetal circulation?
It enters the Right atrium and passes through the Foramen ovale to the Left atrium
What happens to the umbilical arteries and veins at birth?
They are obliterated
What happens to the Foramen ovale at birth?
It closes, forming a septum between the right and left atrium
What is the consequence of failure to close the Foramen ovale?
Atrial-septal defect (hole in heart)
What happens to the Ductus arteriosus at birth?
It is obliterated and retained as ligamentum arteriosum
What are the characteristics of arterioles?
Have 1-3 layers of smooth muscle
What are the characteristics of capillaries?
Have a single layer of endothelium and a basement membrane
What are the characteristics of venules?
Have a larger lumen and thin walls which drain capillaries
What are pericytes?
Facilitate blood flow and are involved in microvasculature repair and remodeling
Where are pericytes found?
Surrounding capillaries and postcapillary venules
What are two alternative microvasculature pathways?
Arteriovenous anastomoses (AV shunts)
Venous portal systems
What are the 3 layers (tunics) of arteries and veins from innermost to outermost?
Tunica intima
Tunica media
Tunica adventitia (externa)
What are the key differences between arteries and veins?
Arteries: thicker media, narrow lumen, no valves; Veins: larger lumen, thick adventitia, have valves
How many valves does the heart have?
4 valves
