3.1 Flashcards
(10 cards)
- What are the main structural features of the adult heart?
The adult heart is a four‐chambered muscular pump divided into right and left sides. It has two atria and two ventricles, four valves (two atrioventricular valves and two semilunar valves) that regulate unidirectional blood flow, and two outflow tracts that lead to the pulmonary and systemic circulations.
- What is the primary function of the adult heart?
The heart functions as the body’s workhorse, pumping deoxygenated blood from the right side to the lungs for oxygenation, and then circulating oxygenated blood from the left side to the rest of the body.
- What is the primitive heart tube, and when does it form?
The primitive heart tube is formed by the fusion of the bilateral endocardial heart tubes around 20–22 days of gestation. It represents the initial, simple tubular structure from which the complex, multi‐chambered adult heart develops.
- What are the main regions of the primitive heart tube and what adult structures do they form?
The primitive heart tube is subdivided into: the truncus arteriosus (which gives rise to the aorta and pulmonary trunk), the bulbus cordis (contributing to the right ventricle), the primitive ventricle (forming the left ventricle), the primitive atrium (developing into the right and left atria), and the sinus venosus (which is incorporated into the right atrium and atrioventricular region).
- What is heart tube looping and why is it important?
Heart tube looping is the early bending and twisting of the primitive heart tube that establishes the spatial orientation and alignment of the future chambers. This process is essential for subsequent septation and correct positioning of the outflow tracts relative to the atria and ventricles.
- How do endocardial cushions contribute to cardiac development?
Endocardial cushions are localized thickenings within the heart tube that develop in the region of the atrioventricular canal and outflow tract. They give rise to the atrioventricular septum and are foundational for forming the AV valves, directing proper separation between atria and ventricles.
- What is the foramen ovale and what role does it play in fetal circulation?
The foramen ovale is an opening in the septum between the right and left atria of the fetal heart that allows blood to bypass the non-functioning fetal lungs, directing it from the right atrium to the left atrium. After birth, with the initiation of lung breathing, it normally closes to ensure separate pulmonary and systemic circulations.
- How does outflow tract septation occur during heart development?
Outflow tract septation involves the formation of the aorticopulmonary septum through spiral (conotruncal) septation of the truncus arteriosus, which divides it into the aorta and pulmonary trunk, thereby establishing separate routes for systemic and pulmonary blood flow.
- How are the fetal heart regions related to adult heart structures?
The fetal heart regions have direct adult counterparts: the truncus arteriosus becomes the aorta and pulmonary artery; the bulbus cordis contributes mainly to the right ventricle; the primitive ventricle forms the left ventricle; the primitive atrium develops into both atria; and the sinus venosus is incorporated into the right atrium and parts of the AV canal.
- Why is proper embryological development of the heart crucial for its function?
Correct embryological development of the heart—including proper heart tube formation, looping, septation, and valve creation—is essential to ensure the efficient separation and circulation of oxygenated and deoxygenated blood. Disruptions in these processes can lead to congenital heart defects that compromise cardiovascular function.
