Cardiovascular Embryology Flashcards
the heart and blood vessels are derived from
- mesoderm
heart forms and begins beating in which week of development?
- week 4
longitudinal folding does what?
- moves the heart into the newly formed thorax
transverse folding does what?
- creates 3D trunk
- brings right and left sides together in ventral midline
development of all blood-carrying vessels
- mitosis of angioblasts to form clusters
- lumens develop
- vessel walls create blood cells
- fusion of neighbor vessels to form network of interconnected vessels.
development of blood-carrying vessels occurs during which week?
- week 3
early circulation
- embryo already large enough to need heart and vessels to carry blood everywhere
where does the heart pump blood in week 4?
- body
- placenta
what do arteries and veins supply in week 4?
- body
- placenta
how long does it take for the heart to develop?
- 5.5 weeks
hearts starts out as
- right and left blood vessel (angioblastic cords)
transverse folding heart development
- brings 2 cords together in anterior midline
- fuse and creates one heart tube
- develops all 3 layers
the heart tube begins to beat on which day?
- Day 22-23
composition of heart tube
- single, straight tube
- subdivided into regions
blood flow through tube
- sinus venosus
- atrium
- ventricle
- bulbus cordis
- truncus arteriosus
sinus venosus becomes part of
- right and left atria
bulbous corgis becomes part of
- right and left ventricles
truncus arteriosus becomes part of
- aorta
- pulmonary trunk
heart tube folding
- atrium and ventricle change their locations and acquire their permanent positions
final positions after heart tube folding
- ventricles located anteriorly
- atria located posteriorly
important central structure in subdivision of atrium and ventricles
- endocardial cushion
what is one thing you always need to subdivide the atrium
- always need a hole in the wall between the atria
atrial subdivision step 1
- septum primum grows from roof to endocardial cushion
atrial subdivision step 2
- first hole is foramen primum that forms
- later disappears
atrial subdivision step 3
- holes form in septum
atrial subdivision step 4
- coalesce to form foramen secundum
atrial subdivision step 5
- septum secundum grows to right side of septum primum, from roof to endocardial cushion
atrial subdivision step 6
- foramen ovale is the hole in the septum secundum
septum secundum covers the
- foramen secundum
the openings in atrial subdivision
- foramen ovale
- foramen secundum
blood flow in fetal heart
- right atrium
- foramen ovale
- foramen secundum
- left atrium
why is pressure different in fetal heart
- due to pressure differences in atria
- prenatal shunt
septum primum in early fetal heart
- pushed to left and acts as an open valve of foramen ovale
subdivision of ventricle requires
- no hole is required in the septum
subdivision of the ventricle process
- interventricular septum grows from floor to endocardial cushion
- closes interventricular foramen
development of the atrioventricular valves
- arise from the endocardial cushion
role of truncus arteriosus
- subdivides into aorta and pulmonary trunk/artery
development of truncus arteriosus
- forming longitudinal aorticopulmonary septum
- PLUS twisting to achieve final positions
what does the fetus use for breathing
- not its lungs. uses amniotic sac
- so they don’t need much blood to the lungs
2 arteries in prenatal circulation
purpose
- umbilical arteries
- blood from iliac artery to placenta
vein in prenatal circulation
purpose
- umbilical vein
- placenta -> inferior vena cava
3 shunts in prenatal circulation
- ductus venosus
- oval foramen
- ductus arteriosus
purpose of ductus venosus
- help umbilical vein bypass liver
location of oval foramen
- between heart atria
purpose of oval foramen
- bypass pulmonary circulation
blood flow with oval foramen
- blood flows right atrium -> left atrium
location of ductus arteriosus
- between pulmonary artery and aorta
purpose of ductus arteriosus
- bypass pulmonary circulation
blood flow with ductus arteriosus
- pulmonary artery -> aorta
PO2 of umbilical vein
- 30 mmHg
O2 sat of umbilical vein
- 80% O2 sat
most inferior vena cava blood through oval foramen
- oval foramen -> LA -> LV -> aorta -> upper body
most superior vena cava blood through oval foramen
- RA -> RV -> pulmonary artery
most pulmonary artery blood through ductus arteriosus
- goes to the lower body
remnant name of umbilical vein
- ligamentum teres
remnant name of umbilical arteries
- medial umbilical ligaments
remnant name of ductus venosus
- ligamentum venosum
when does the ductus venous close
- closes at birth
- permanent by 1 week
remnant name of oval foramen
- oval fossa
when does the oval foramen close
- closes at birth by septum primum valve
- permanent by 5 years
remnant name of ductus arteriosus
- ligamentum arteriosum
when does the ductus arteriosus close
- constricts by 10 hours
- closes by 24 hours
- permanent by 1-2 months
what drug closes a ductus
- indomethacin
how do you keep a ductus open?
- prostaglandins E1 and E2
transition from prenatal to postnatal life
- baby takes a breath
- pulmonary artery resistance decreases
- blood flows into lungs through pulmonary artery
- pulmonary venous blood flows into left atrium
- left atrial pressure becomes greater than right atrial pressure
what happens when left atrial pressure becomes greater than right atrial pressure
- septum primum valve pushed against septum secundum valve and covers oval foramen