Embryology (2) Flashcards
Cardiovascular and Respiratory Systems
From what germ layer does the cardiovascular system arise?
The mesoderm
Which organ system is the first to function in a foetus?
The cardiovascular system
When will the foetal heart first cause circulation?
3 weeks
What is the cardiogenic area?
The cardiogenic area is where the heart first begins to develop. It is derived from splanchnic mesoderm cells. Elongated cardiogenic cords form here.
State the progression of mesenchyme in the heart.
Mesenchyme thickens to form the myoepicardial mantle. Which then becomes the epicardium and myocardium.
What is the heart tube made of?
Myoepicardial layer, cardiac jelly (secreted by myoblasts, is connective tissue), endocardium
State the 5 primitive heart regions.
Truncus arteriosus, bulbus cordis, primitive ventricle, primitive atrium, and the sinus venosus
Which cardiac structure receives the umbilical vein, the vitelline vein and the common cardinal veins?
The sinus venosus
What does the truncus arteriosus mature into?
Ascending aorta and pulmonary trunk
What does the bulbus cordis mature into?
Right ventricle
What does the primitive ventricle mature into?
Left ventricle
What does the primitive atrium mature into?
The anterior atria and the auricles
What does the sinus venosus mature into?
Posterior right atrium, SA node and coronary sinus
What is the precursor structure to the AV septum?
Endocardial cushions
Name the septa of the immature IA septum.
Septum primum and septum secondum
What causes the formation of the foramen secondum?
Apoptosis of the septum primum upon minimising the foramen (ovale) primum
State the time period in which the IV septum develops.
Between the 4th and 7th week
State the development of the heart in days.
18: heart appears from cardiogenic area
20: cardiogenic cords-endocardial tubes-heart tube
21: pumping blood
22: heart tube develops into 5 primitive structures
22-28: heart is in an S-shape
28: septa form
W5-8: AV valves form
W5-9: semilunar valves form
What organ is formed during gastrulation?
The gut
When does upper respiratory tract formation begin?
Weeks 3-4
Describe upper respiratory tract formation.
The olfactory placode is a thickened region of the ectoderm and it develops in the anteroinferior part of the head. Placode invaginates posteriorly to connect with the foregut. Foregut develops from endoderm and becomes pharynx. A thin oronasal membrane separates the 2 cavities. The primary palate forms at 5 weeks from 2 medial swellings of the maxillary processes that merge to form the palate. At 7 weeks the oronasal membrane ruptures and forms the oronasal cavity.
Fill out a table discussing the products of the gut tube, from the foregut, midgut and hind gut as well as its derivatives.
