Development Flashcards
Where are endocardia heart tubes derived from?
Splanchnic mesoderm
At what week and day does the two heart tubes fuse and laterally fold?
3rd week, day 16
During what weeks is the embryo most vulnerable? Why?
- week 3-8wks
- when most things are still developing. It’s growth from there on
At what embryologic phase does laterality happen? What is laterality of the heart?
- gastrulation- week 3
- left and right sides of heart form
At what week and day does the fetalheart begin to beat?
- week 4
- day 19-20
From top to bottom, name the 5 parts of the heart tube. Which is the outflow tract? Which is the inflow tract?
-Truncus arteriosus (outflow), bulbus cordis, ventricle, atrium, sinus venosus (inflow)
What does the Truncus arteriosus develop into?
- Ascending aorta and pulmonary trunk
- smooth part of left atrium that has pulmonary veins
What does the Bulbus Cordis develop into?
- smooth part of right ventricle (conus arteriosus)
- smooth part of left ventricle (aortic vestibule)
What does the ventricle and atrium of the heart tube develop into?
- ventricle: trabeculated portion of left and right ventricle
- atrium: trabeculated portion of left and right atrium (pectinate muscles)
What does the sinus venosus of the heart tube develop into?
- left horn: coronary sinus
- right horn: smooth part of right atrium (sinus venarum)
What direction does the arterial and venous end of the heart tube go when looping? When does cardiac looping end?
- arterial end loops downwards
- venous end loops upwards
- at day 28
If cardiac looping fails to happen properly, what can happen? What two other disorders is this usually associated with?
- dextrocardia: heart lies of RIGHT side instead of left, problem might start in gastrulation
- associated with situs inversus and Kartagener syndrome
What artery supplies the posterior one third of the interventricular septum?
Posterior interventricular branch of the right coronary artery
What artery supplies the anterior two third of the interventricular septum?
LAD
Down’s syndrome is usually associated with what type of cardiac anomaly?
Atrioventricular septal defect
What day does atrial septal development happen?
Day 30
The interatrial septum develops from what two things?
Septum primum and septum secondum
Endocardial cushions develop from what?
Neural crest cells
What septal opening shunts blood from the right to left atrium? How long does this remain?
- foramen ovale
- remains until after birth
What causes the two septa to press into each other? What structure does it close?
- when pressure of the left atrium increases
- closes the foramen ovale
Where do neural crest cells come from?
Neuroectoderm
What 3 things develop from Endocardial Cushions?
- aorticopulmonary septum
- valves: bicuspid, tricuspid, aortic, pulmonic
- interatrial septum and interventricular septum (membranous part)
What does cyanotic mean? Why are Atrial Septal Defects non-cyanotic?
- bluish discoloration from lack of 02
- there’s still oxygenated blood circulating, but mixing with deoxygenated blood
What are two causes of an Osteum Secundum Defect?
- Excessive resorption of the septum primum
- failure of the development of the septum secundum
What causes an Osteum Primum Defect?
Incomplete fusion of the atrioventricular Endocardial cushions
What is a Cor Triloculare Biventriculare or Common Atrium?
-defect caused from COMPLETE failure of the septum primum and septum secundum to form
When should the oval foramen close? What happens if it closes too early?
- during prenatal life
- causes hypertrophy of right atrium and ventricle. Left side of heart will be underdeveloped. Die soon after birth
When does the interventricular septum start to develop? When does it end?
- 4th week
- end of 7th week
What are the two parts of the interventricular septum? What are they formed by?
- thick muscular part: formed by septum from base of ventricle
- membranous part: formed by right and left conus swelling and Endocardial cushions
What is Membranous Ventricular Septal Defect? If the neural crest cells fail to migrate, why can that cause Membranous VSD? Is there cyanosis? What’s a common complaint of patients with this?
- opening through the interventricular septum
- Endocardial cushion gives rise to the membranous part of the IV septum. And neural crest cells give rise to Endocardial cushions
- non cyanotic, cyanosis appear over time if untreated
- fatigue on exertion
What develops from the fibrous part of the AV Endocardial cushions? They form from how many Endocardial cushions?
- Tricuspid and bicuspid valves
- 4
What are the semilunar valves? How many swellings of subendocardial cushions does it develop from?
- name for the aortic and pulmonic valves
- 3 swellings
What causes valvular stenosis? What’s the difference between pulmonary valvular atresia and aortic valvular stenosis?
- happens when semilunar valves are fused for a variable distance
- pulmonic: aortic root is normal, but pulmonic valve may be completely undeveloped. If there’s a PDA, there’s a change of blood to circulate
- aortic: super narrow opening through valve, your opening will be “pinhole” size
What is Ectopic Cordis? What causes it?
- heart outside body
- caused by failure of ventral body wall to close during lateral folding (review gastrochisis)
Pair of conotruncal swellings grow and twist around each other to form what?
Spiral aorticopulmonary septum (AP) (conotruncal septum)
What are three types of Truncus Arteriosis defects? Are they cyanotic?
- Tetrology of Fallot, Transposition of Great Vessels, Persistent Truncus Arteriosus
- yes, cyanotic
Between left-to-right and right-to-left shunt, which one causes cyanosis and which one doesn’t?
- left to right: no cyanosis
- right to left: cyanosis
What causes Tetrology of Fallot? What 4 defects are present?
- unequal division of the conus, causing anterior displacement of the aorticopulmonary septum
- VSD, overriding aorta, right ventricular hypertrophy, pulmonary stenosis
The upper end of the interventricular septum is what part? Where is it derived from?
- membranous part
- endocardial cushions
What disorder is associated with the teratogen Lithium? What causes this disorder?
- atrialization of the right ventricle
- Ebstein anomaly
What is Eisenmenger syndrome?
-tricuspid isnt formed properly so blood backflows
What drug caused hypoplastic of absent limbs in newborns?
Thalidomide
Neural tube defect are associated with what drugs?
Valproic acid, phenytoin, carbamazepine
The right vagus passes posterior to what structure? The left vagus nerve crosses anteriolaterally to what structure?
- Root of the lung
- arch of aorta
Both vagus nerves descend into what mediastinum?
Posterior
Failure to form the aorticopulmonary septum is caused by what?
Failure of neural crest cells to migrate
