CV Embryology Kahn Flashcards
(57 cards)
1
Q
Where is the first evidence of heart formation?
A
Splanchnic layer of lateral plate mesoderm (just said splanchnic later in class)
2
Q
What type of cells are within the splanchnic mesoderm?
A
Cardiac Myoblasts
3
Q
- What are these cells derived from?
A
- Cardiac Progenitor cells induced by underlying pharyngeal endoderm
4
Q
- What do blood islands in the same region form?
A
- Endothelial lined tubes and transitory blood vessels, definitive blood cells come from mesoderm around aorta later from liver even later from bone marrow
5
Q
- Where does the future heart begin?
A
- Cranial part of embryo, Buccopharyngeal membrane is landmark for this, it its just cranial to the buccopharyngeal membrane
6
Q
- What is the cardiogenic field?
A
- Endothelial lined tubes and myoblasts formed by the previous blood islands, just cranial to the buccopharyngeal membrane
7
Q
- What is above the cardiogenic field?
A
- Pericardial cavity which is derived from the embryonic cavity
8
Q
- What brings the heart into its natural anatomical position?
A
- Cranial and caudal folding of the embryo brings the heart into the thoracic region
9
Q
- What forms the two endothelial lined tubes on both sides of the heart?
A
- Blood islands produce angiogenic cells that dissolve into these endothelial lined tubes, they eventually become endocardial regions of the heart
10
Q
- What happens to these tubes?
A
- Fold into the midline and fuse to form a single endocardial tube
11
Q
- What surrounds tube (cell type)?
A
- Myoblasts that will become the myocardium of the heart
12
Q
- What surrounds the tube and eventually disappears, & serves no function?
A
- Cardiac Jelly
13
Q
- List the invaginations of the endocardial tube.
A
- Truncus arteriosus, bulbus cordis, primordial ventricles, primordial atria, sinus venosus
14
Q
- What will each of these invaginations ultimately form?
A
- Truncus arteriosus → aorta and pulmonary trunk, Bulbus cordis →inf. Part of aorta and pulmonary trunk & adjacent parts of two ventricles, Primordial ventricles → ventricles, primordial atria → atria, sinus venosus→ Right horn becomes right atrium, left becomes coronary sinus
15
Q
- How does blood enter the primitive heart? (Before Atria/Ventricle portioning)
A
- Sinus venosus
16
Q
- How are the atria and ventricles partitioned?
A
- Endocardial cushions grow towards each other, partitions atria from vessels and ventricles (produces a pattern with two holes penetrating septum that divides atria from ventricles)
17
Q
- Describe the formation of the AV valves
A
- Dense mesenchyme and myoblasts present, cavitation occurs and cells die, some are replaced by connective tissue which becomes chordate tendinae
18
Q
- What direction is blood originally shunted in atria?
A
- From right to left (mix of oxygenated and deoxygenated blood)
19
Q
- What is the crescent shape fold that grows down from the roof of the atria initially in atrial Septation.
A
- Septum primum
20
Q
- What does this form at the bottom of the atria?
A
- Osteum primum
21
Q
- What happens after this is formed at the top of the crescent shape fold?
A
- Osteum secundum (maintains shunting after closure of osteum primum)
22
Q
- What is the second structure that grows downward from the roof of the atria?
A
- Septum secundum
23
Q
- What develops in this structure?
A
- Foramen ovale
24
Q
- What now causes blood to be shunted from RA to LA?
A
- Pressure in RA is higher than left, pushes blood through foramen ovale into LA
25
25. What happens after birth in the case of question #24?
25. Pressure changes , LA is higher and maintains valve closure if it already has not fused
26
26. What is the function of the ductus arteriosus?
26. Short circuits lungs, sends oxygengated blood from RA directly into the aorta
27
27. What is the muscular part of the two ventricles derived from?
27. Develops from a ridge between the two ventricles
28
28. What forms the membranous part of the two ventricles?
28. Cotruncal (spiral ) septum descending to meet the endocardial cushion in the muscular ridge
29
29. What is probe patency of foramen ovale?
29. Foramen ovale did not fuse, no effect because it is a one way valve, present in 25% of pop.
30
30. Describe the condition of excessive resorption of septum primum.
30. Causes L to R shunt
31
31. Describe the condition of absence of septum secundum.
31. Again, L to R shunt
32
32. What is a common atrium?
32. No attempt at partitioning of atria at all, causes L to R severe shunting
33
33. Describe defects in ventricular septum.
33. Occur in membranous part of septum, systemic blood goes back into pulmonary circuit, too much blood pushing through pulmonary trunk → increased resistance → hypertrophy of RV → shunts blood from R to L → cyanosis called Eisenmenger complex
34
34. Defects in Septation of truncus arteriosus , describe Tetralogy of Fallot.
34. Aortic arch and pulmonary trunk are shifted to the R, pulmonary trunk is smaller than usual and aorta is a lot larger. Causes eisenmenger complex and cyanosis
35
35. Describe persistent truncus arteriosus
35. No Septation of aorta and pulmonary trunk, only one vessel leaving heart, causes cyanosis always accompanied by membranous ventricular defect.
36
36. Describe transposition of the great vessels.
36. Open into wrong chambers, causes R to L shunt and cyanosis occurs when AP septum fails to spiral
37
37. Describe patent ductus arteriosus.
37. Blood goes into pulmonary trunk and gets into aorta from ductus arteriosus, can lead to eisenmenger syndrome leads to cyanosis more quickly than atrial defects
38
38. Before birth the ductus arteriosus provides communication between what two structures?
38. Pulmonary Trunk and Aorta
39
39. The initial two endothelial tubes that fuse to form the heart develop in what layer?
39. Splanchnic mesoderm
40
40. Before birth, what structure overlaps the ostium secundum and appears to close it?
40. Septum secundum
41
41. What causes tetralogy of fallot?
41. A misaligned AP septum
42
42. Which of the aortic arches gives rise to the pulmonary arteries?
42. 6th aortic arch
43
43. Just before birth, all blood from the placenta goes through the liver. Describe its course through this organ.
43. Passes directly through via the ductus venosus
44
44. How many aorta’s does a developing embryo have?
44. Two pairs of dorsal aorta’s
45
45. How does blood exit the heart?
45. Through an aortic sac ( has l and r divisions, forms 6 arches)
46
46. Describe the aortic arches
46. Anteriorly they communicate with a horn like structure and loop out from dorsal aorta to this structure
47
47. What does arch 1-6 give rise to?
47. 1,2 disappear, 3 → common carotid and internal carotid a. , 4→ R. subclavian, and arch of aorta from l. common carotid to l. subclavian, 6→ L and R pulmonary arteries and ductus arteriosus
48
48. Why is the r. recurrent laryngeal n superior to the left?
A portion of aortic arch 6 disappears on the R side, on the L side the ductus arteriosus remains
49
49. What is preductal coartication of aorta?
49. Narrowing of aorta prior to the ductus arteriosus, => ductus arteriosus remains patent, if post ductal ductus arteriosus atrophies
50
50. What forms the common cardinal vein?
50. Anterior and post. Cardinal veins, the common cardinal vein also receives umbilical veinand two vitelline veins, sinus venosus receives common cardinal v.
51
51. What do the vitelline veins form?
51. Hepatic sinusoids, hepatic portal v. , hepatic veins, hepatic IVC
52
52. What happens to the R. umbilical vein?
52. Atrophies
53
53. What does the L. umbilical vein extend through the liver as?
53. Ductus venosus
54
54. What does the sinus venosus become?
54. Hepatic portion of IVC (later he says that the vitelline veins actually forms this, somewhat misleading from his lecture)
55
55. What does the superior and inf. Parts of the vitelline veins become?
55. Hepatic and renal veins, respectively
56
56. Describe pre-natal circulation.
56. Path 1: Umbilical v→ ductus venosus → IVC → foramen ovale → LA,LV → aorta → systemic → umbilical a.
Path 2: SVC → RA→ RV → Aorta (mixes oxygenated from path 1 with deoxygenated ) → systemic → umbilical a.
57
57. What does the umbilical arteries and veins atrophy to?
57. Umbilical v. → ligamentum teres hepatis
| a. Umblicial artery → medial umbilical ligaments
