Introduction to Cardiovascular System Flashcards
Cardiovascular system
1st major organ system to function in embryo
All blood vessels begin as what?
Condensations of mesodermal mesenchyme (blood islands) during week 3
Blood islands will rise to what?
Blood cells
Vessels
Heart
Blood islands that would become the heart form where?
In splanchnic mesoderm around future head and neck of embryonic disc (cariogenic region)
When embryonic heart reaches the thorax, it is what?
A pair of endothelial tubes in the body’s midline that fuse into a single tube on Day 20
On what day does the heart start pumping?
Day 22
Are the earliest heart chambers paired or unpaired?
Unpaired
What are the chambers from tail to head?
sinus venosus, atrium, ventricle, and bulbs cordis
Sinus Venous– will become…
- Smooth-walled part of R atrium, coronary sinus, and SA node
- Also contributes to posterior wall of L atrium
Atrium gives rise to?
Ridged parts (pectinate muscles of R and L atria
Ventricle
Strongest pumping chamber
- gives rise to L ventricle
Bulbus cordis
The truncus arteriosus (4a), gives rise to R ventricle, pulmonary trunk, and 1st part of aorta
What shape does the heart take on when the 4 chambers appear?
S- shape
- ventricle moves caudally and atrium cranially. Bending occurs due to rapid growth of ventricle and bulbus cordis
What happens as a result of cardiac looping during week 4?
The heart folds on itself and assumes its normal position in left part of the Thorax with atria posterior and ventricles located in a more anterior direction
What happens by month 2?
The heart is divided into the 4 definitive chambers by formation of midline atrial and ventricular septa and valves
- Develop from regional thickenings of endocardium: endocardial cushions