Cardiovascular System Flashcards
Early Phases of the Embryo
Diffusion from fluid secreted by uterine gland
When Embryo increases in size and complexity
diffusion system of nutrition is insufficient. There is an urgent need for a circulatory system that can carry nutrients and oxygen to the tissues and remove carbon dioxide and other waste products of normal metabolism
Angiogenesis
Process of blood vessel development
Mesoderm –>
mesenchyme (pluripotent cells) -> angioblastic tissue (hemangioblasts)-> cardiovascular system
Cardiogenic Field
Horseshoe-shaped structure. Blood forming cavities in the visceral mesoderm -> coaslesce and form the primitive heart, blood vessels, and blood cells.
Cardiogenic Field –>
Endocardial tubes —> cardiac tube
Endocardial tubes
tubes first composed of only endothelial cells, make contact caudally with the developing venous system.
Cardiac Tube
caudal portion fuses and becomes surrounded by myoblasts to form the myocardium. Composed of bulbus cordis, ventricle and atrium
Loop Formation
In conjuction with a relatively complex division of the cardiac tube into four chambers, will result in the formation of the blood pumping organ necessary for the survival.
Aortic Arches
Series of 6 paired embryological vascular structures that give rise to the great arteries of neck and head. Defects in aortic arches = defects of the great arteries of the body
Primitive atrium divided into
left and right atria
Primitive ventricle divided into
left and right ventricles
Truncus arteriosus divided into
outflow tracts of aorta and pulmonary trunk
Heart Development step 1
the primary atrial septum formed and development of the interventricular septum begun
Heart Development step 2
Primary atrial septum has fused with the endocardial cushions, and a secondary foramen has been formed
Heart Development step 3
The secondary atrial septum formed and a passage (foramen ovale) between primary and secondary septa connects the right and left atria. Interventricular septum fused with endocardial cushions
Atrial Partitioning (1)
Ostium primum allows the initial passage of blood from the right to the left atrium as the primary atrial septum grows.
Atrial Partitioning (2)
When ostium primum closes, it is replaced by the ostium secundum. Blood is still able to pass from the RA to the LA
Atrial partitioning (3)
The secondary septum grows to the right of the primary septum and the primary septum serves as the valve for the foramen ovale in the secondary septum, preventing return of blood into the right atrium
Atrial Partitioning After Birth
Lungs will expand with first breaths which creates a sudden blood pressure drop in pulmonary circulation. This pushed the primary septum against the secondary one (physiological closure), These fuse and the foramen ovale becomes the fossa ovalis (anatomical closure)
Truncus arteriosus
gets divided into ascending aorta and pulmonary trunk by a sprial aortico-pulmonary septum. The spiral formation of the septum ensures that blood form the right ventricle flows into the pulmonary trunk and that the blood from the left ventricle flows into the ascending aorta.
Transposition of the great vessels
When the septum is straight, causes this transposition. Deoxygenated blood from the right ventricle flows into the ascending aorta and the highly oxygenated blood from the left ventricle flows into the pulmonary trunk. Incompatible with life
Fetal blood circulation
Designed for in utero aqueous environment so lungs get little blood. 3 shuts: Ductus venosus, Foramen ovale, and Ductus arteriosus (->ligamentum arteriosum). All must close soon after birth.
Placenta to umbilical vein to ductus venosus in liver to heart and foramen ovale to arch of aorta and ductus arteriosus to descending aorta to umbilical arteries.
Cardiovascular System functions
Maintenance of adequate blood flow (cardiac output)
Delivery of oxygen, nutrients, hormones, electrolytes, and water to peripheral tissues
Removal of carbon dioxide and other metabolic waste products
Maintenance of normal thermoregulation
Maintenance of normal glomerular filtration rate (GFR) and urine output