development of the cardiovascular system 1 Flashcards
what are the 4 main stages of the development of the heart?
- development if the primordial heart tube
- looping of the heart tube
- atrial and ventricular septation
- development of the outflow tract
what which part of the developing embryo form the circulatory sysytem?
the lateral plate splanchnic mesoderm
what happens in week 3 during the development of the circulatory system?
Angiogenic cell islands collect in
the lateral plate splanchnic mesoderm, move towards the midline and coalesce to form the two primitive heart tubes
what is the first system to form in the developing embryo?
the cardiovascular system, so nutrient and waste can be delivered and removed from the rapidly growing number of cells
when does the primordial heart start to function?
at week 4
describe the creation of the primitive heart?
- paired endothelial strand (angiogenic cords) appear in the cardiogenic mesoderm
- these cords canalize to form heart tubes
what forms the blood vessels around the body and where are they found in the embryo at week 3?
angiogenic cell clusters. they are found in the walls of the yolk sac, allantois, connecting stalk and chorion
describe how the heart tube and pericardium are reorientated so the heart tube is dorsal to the pericardial cavity
the pericardial cavity begins dorsal and the heart tube ventral. but when the cranial end of the embryo folds on itself the heart tube becomes dorsal and the pericardial cavity becomes ventral
what form the fibrous pericardium and the parietal layer of the serous pericardium?
the somatic lateral plate mesoderm
what forms the visceral layer of the serous pericardium?
the splanchnic mesoderm
name the 5 sections of the fused primitive heart tube from top to bottom?
- truncus arteriosus
- bulubus cordis
- ventricle
- atrium
- sinus venosis
what does the truncus arteriosis form?
the aorta and pulmonary arteries
what does the bulbus cordis form?
right ventricle and parts of the outflow tract
how many aortic arches are there?
6
over which three days of development does the primitive heart tube fold?
day 22-24
what causes the primitive heart tube to fold and form the bulboventicular loop?
the bulbus cordis and ventricle grow faster than the other regions
what happens if the primitive heart tube loops to the left instead of the right?
you get dextrocardia
when does partitioning of the heart occur?
around day 27-37
what separates the right atroventricular opening from the left atrioventricular opening forming left and right atrioventricular canals?
the endocardial cushion
describe he partitioning of the primordial atrium?
- septum primum extends down from the top of the primordial atrium
- below septum primum is the foramen primum
- as septum primum reaches the endocardial cushion and foramen primum gets smaller, a second foramen opens in septum primum, above foramen primum, this is called foramen secundum.
- septum secundum now begins to extend down from the top of the atrium and extends down to the endocardial cushion.
- as it does this a foramen forms in it just below foramen secundum, this is foramen ovalis.
- the top part of septum primum, above foramen sucundum degenerates
what is the function of foramen ovale?
allows bood to pass from the right atrium to the laft as the lungs are not functional
what happens to foramen ovale after birth?
- the pressure in the left atrium is greater than that in the right so it keep the foramen closed
- septum primum fuses with septum secundum
- this form fossa ovalis
what are the 4 clinically significant types of atrial septal defect?
- foramen sucunum defect
- endocardial cushion defect with foramen primum defect
- sinus venosus defect
- common atrium
1 and 2 are most common
how are the right and left ventricles partitioned off?
the muscular portion of the interventricular septum extends up form the base on the ventricle. The aorticopulmonary septum then extends down and fuses with the muscular part, forming the membranous part of the septum.
what is the foramen called between the ventricles before the membranous part of the septum forms?
the interventricular foramen
what is the septum called that divides the truncus arteriosus in to the aorta and the pulmonary artery?
the aorticopulmonary septum
what shape is the aorticopulmonary septum?
spiral, round 180 degrees
what are the early pacemakers of the heart?
primordial atrium and then sinus venosus
what is though to causes cot death (sudden infant death syndrome)?
abnormalities of conducting tissue
what does the primitive ventricle of the heart tube form?
the left ventricle
what does the primitive atrium of the heart tube form?
parts of right and left atria
what does the sinus venosus form?
superior vena cava and right atrium
what are some causes of congenital heart diseases?
rubella infection in pregnancy
maternal alcohol abuse
maternal drug treatment and radiation
genetic
what causes transposition of the great vessels?
- failure of the aorticopulmonary septum to spiral
2. defective migration of neural crest cells
what is tetralogy of fallot?
- Pulmonary stenosis (obstruction of right ventricular outflow)
- Ventricular septal defect (VSD)
- Dextroposition of aorta (“overriding” aorta)
- Right ventricular hypertrophy
what causes tetralogy of fallot?
unequal division of the conus anterior displacement of aorticopulmonary septum
