Development of the Heart and Vascular System Flashcards
State the sources of mesenchyme of heart development.
Splanchnic mesoderm: heart muscle
Neural crest: connective tissue in the heart ie skeleton of the heart
Why is the cardiovascular system the first to fully function in an embryo?
This is to enable efficient delivery of various substances e.g. gases, nutrients, horomones and waste products within the rapidly growing embryo/foetus, which cannot rely on diffusion alone.
Outline the unique features of the foetal cardiovascular system.
Compared to the postnatal cardiovascular circulation:
(a) It lacks a functional pulmonary circulation.
(b) Has a placental circulation where gaseous exchange takes place.
(c) There is partial mixing of oxygenated and deoxygenated streams of blood.
The foetal cardiovascular system is designed to:
(a) Maintain blood flow to and from the placenta.
(b) Bypass/shunt the non-functional pulmonary circulation.
(c) Redirect relatively oxygenated stream of blood to the developing brain.
(d) Anticipate and handle radical circulatory changes at birth.
Briefly outline the process of angiogenesis.
Mesenchymal cells differenitate into angioblasts.
Angioblasts aggregate to form blood islands
Peripheral cells flatten to form the endothelial lining.
Briefly outline the process of hematogenesis.
Mesenchymal cells differenitate into angioblasts.
Angioblasts aggregate to form blood islands
Central cells of blood islands detach and differentiate into various blood cells.
Describe the formation of the primitive heart tube.
The cells in the periphery of the blood islands in the region of the future heart form the endocardial tubes.
These tubes are paired (hence there is a right and left tube).
The endocardial tubes fuse as the embryo folds, forming the primitive heart tube.
List the parts of the heart tube starting from the venous end.
(a) Sinus venosus
(b) Primitive atrium
(c) Primitive ventricle
(d) Bulbus cordis [has three parts: conus arteriosus, truncus arteriosus and a proximal segment]
State the derivatives of the sinus venosus.
It forms the smooth part of the right atrium called the sinus venarum.
It also forms the coronary sinus.
State the derivatives of the primitive atrium.
The primitive atrium undergoes interatrial septation.
It forms the rough part of the right atrium (musculi pectinati)/trabeculated part of the right atrium.
It also forms the left atrium.
State the derivatives of the primitive ventricle.
The primitive ventricle undergoes interventricular septation.
It forms the lower (trabeculated) parts of both right and left ventricles.
State the derivatives of the bulbus cordis.
It undergoes conotruncal septation.
The conus arteriosus gives rise to the upper (smooth) parts of the ventricles.
The truncus arteriosus gives rise to the roots of the major arteries (ascending aorta and the pulmonary trunk).
Name the four types of cardiac septation.
(a) Atrioventricular
(b) Interatrial
(c) Interventricular
(d) Conotruncal
Briefly discuss atrioventricular septation.
This refers to partial septation of the primitive atrium and the primitive ventricles.
It occurs by proliferation of the endocardial cushions, which grow towards each other.
Atrioventricular canals remain on either side of the fusion.
