Circulatory Sytem Development II Flashcards
Interventricular septum development
. Muscular ridge that develops on floor btw primitive ventricles near apex of heart
. Grows sup. Toward atrioventricular endocardial cushions
. Muscular portion partitions off primitive ventricles except for small area in region close to atrioventricular valves
Conus cordis during ventricular development
. Overrides outflow of both primitive ventricles
. TA immediately cranial to this
Aorticopulmonary (spiral, truncoconal, conotruncal) septum
. Decides TA and conus cordis
. Spirals as it courses down though TA and conus cordis
Truncus ateriosus (TA) divided into____
Ascending aorta and pulmonary a.
What forms sup. Part of definitive left ventricle and blood flow?
. Left part of conus
. Sends blood into ascending aorta
Superior part of definitive rightventrile formation and blood flow
. Right part of conus
. Sends blood to pulmonary a.
Aorticopulmonary septum
. Completes sup. Portion of interventricular septum that’s membranous section
. Bisects 4-cusp valve present in TA dividing it into 3-cusp pulmonic and aortic valves
Ventricular septal defect
. Caused by defect in interventricular septum in its sup. Aspect where it is formed by aorticopulmonary septum
. Causes blood to be shunted from L to R side of the heart causing pulmonary hypertension
. Less common defect present in thicker muscular portion of septum
Result of persistent TA
. Failure of aorticopulmonary septum to develop
. TA and conus cordus not divided into aorta and pulmonary trunk
. Assoc. w/ ventricular septal defect
. Undivided conus overrides both ventricles and receives blood from both sides
. Infants die w/in first 2 years if untreated
Transposition of great arteries
. Aorticopulmonary septum descends straight down instead of spiraling
. Aorta arises from the right ventricle and pulmonary trunk from left ventricle
. Must be accompanying septal defect or patent ductus arteriosus for survival so there can be mixing of oxygenated and deoxygenated blood
. Leading cause of death in infants under 1 year old w/ cyanotic heart disease
Tatralogy of Fallot
. Combo of 4 cardiac defects
. Caused by unequal division of conus cordis and TA by aorticopulmonary septum
. Aorta abnormally large and pulmonary trunk is abnormally small
. Causes cyanosis of lips and fingernails
. Treated surgically in 1st year of life
4 defects in tetralogy of fallot
. Pulmonary trunk stenosis
. Ventricular septal defect
. Overriding aorta (over outflow of both ventricles)
. R ventricular hypertrophy from inc. pressure from pulmonary stenosis
Vitelline aa. Evolve into unpaired gut vessels called
. Celiac a.
. Sup and inf. Mesenteric aa.
Aortae supply ____ to placenta
Paired umbilical aa.
Aortic arches in great vessel development
. Paired aa. That arise from TA and supply each branchial arch
. Terminates in dorsal aorta on the same side
Number of aortic arch pairs and qualities
6 pairs
. Develop sequentially cranial to caudal
. Many arches disappear (1st disappeared by the time the 6th forms)
. Many larger aa. Supplying head, neck and upper extremity derive from aortic arches
Coarctation of the aorta
. Abnormal narrowing of aorta in area of ductus arteriosus
. Preductal or postductal
. Embryological basis
Preductal form of coarctation
. More serious
. Lumen of ductus arteriosus constricts at birth
. Lower half of body receives little/no circulation damaging organs
Postductal form of coarctation
. More common, less serious
. Has collateral circulation in place at birth that allows the blood to bypass blockage and provide adequate circulation to lower half of body
Double aortic arch (aortic ring)
. Distal portion of right dorsal aorta fails to degenerate
. Causes double arch that encircles esophagus and trachea
. Causes problems w/ breathing or swallowing
Retroesophageal right subclavian a.
. Due to persistence of distal portion of right dorsal aorta
. Causes R. Subclavian a. To arise from aortic arch and crosses post. To esophagus causing difficulty swallowing
Prenatal circulation flow
. Blood leaves fetus via umbilical aa. Depleted of O2 and nutrients w/ waster products
. Placenta removes waste and replenishes nutrients via diffusion
. Blood returning to fetus in single umbilical v. Rich in nutrients and O2
. Greater part of blood goes to cranial Half via shunts
. Umbilical v. Goes through liver and to heart
. Highly oxygenated blood in IVC enters RA and mixes w/ deoxygenated blood from SVC
. Blood passes through interatrial septum into LA then enters LV
. Pumped into ascending aorta
Ductus venosus
. Shunt that allows bulk of blood to bypass liver and flow directly to IVC
Small amount of blood from developing RA goes into ____
Right ventricle through tricuspid valve
. Distributed by RV and pulmonary a. To developing lungs
Blood in developing pulmonary a. Moves into ____
. Arch of aorta via ductus arteriosus
Where does fetal blood flow go after moving to ascending aorta
. Most distributed to cranial half of embryo via carotid and subclavian aa.
. Blood remaining goes to caudal half of fetus
What occurs to ductus arteriosus postnatally
. Contracts from inc. O2 content of blood
. Closes off opening btw arch of aorta and left pulmonary a.
. Lumen replaced by fibrous CT forming ligamentum arteriosum
What occurs to ductus venosus
. Collapses and becomes ligamentum venosum
What occurs to umbilical aa. Postnatally?
. Contract in response to blood-borne O2 level
. Lumens filled w/ fibrous CT creating obliterated umbilical aa. That lie in ant. Abdominal wall (medial umbilical ligaments)
. Proximal umbilical aa. Remains patent giving off branches that supply urinary bladder (sup. Vesicular aa.)
What occurs to umbilical vv. Postnatally?
. Collapses bc no blood is returning form baby to placenta
. Intra-abdominal portion fills w/ fibrous CT and become round ligament of the liver (ligamentum teres hepatitis) that lies w/in falciform ligament
Patent ductus arteriosus
. Ductus arteriosus fails to close
. Doesn’t form ligamentum arteriosusm
. 2-3x times more common in females
. Most common malformation following maternal rubella infection
. Indomethacin administered to cause closure before resorting to surgery
Heart rotation during development
. Slight rotation to left along its longitudinal axis
Dextrocardia
. Reversal of heart’s normal position
Situs inversus
. Reverses normal symmetry of body
. Complete: all organs reversed
. Partial: reversal of 1+ organs but not everything, more likely manifest w/ difficulties
