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ESA 2- Cardiovascular System > Development of the CVS > Flashcards

Flashcards in Development of the CVS Deck (140)
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91

What influences the course of the recurrent laryngeal nerves?

The caudal shift of the developing heart The expansion of the developing neck region The need for a foetal shunt between the pulmonary trunk and aorta

92

What links the primitive atrium and ventricle?

Atrioventricular canal

93

What is created to divide the two primitive atria?

An interatrial septum

94

What is created to divide the two primitive ventricles?

The interventricular septum

95

What is the result of the septation of the outflow tract?

Blood is diverted from two separate ventricles into separate circulations through the pulmonary trunk and the aorta

96

What does septation, and the creation of the interventricular and interatrial septums create?

4 chambers, and selective outflow

97

Where do the beginnings of septation occur?

The atrioventricular canal

98

What is the purpose of the atrioventricular canal?

After looping, the atrium communicates with the ventricle via this canal

99

What are endocardial cushions?

Tissue growing in the walls of endocardium

100

Where do endocardial cushions start developing?

In the atrioventricular region

101

What do the endocardial cushions do?

Protrude out into the canal, pushing into the initially patent channel. They grow towards each other and fuse in the muddle

102

What does the fusion of endocardial cushions create?

A platform dividing the developing heart into right and left channels, and so the beginning of a structure towards which walls can grow

103

Why is atrial septation complex?

Because need to separate and create two discreet atria, but also allow for a foetal shunt

104

What does division of the common atrium involve?

Formation of two septa, with three holes to allow the opportunity for blood to shunt in foetal life

105

What is the septum primum?

A wedge of tissue that grows down towards the fused endocardial cushions from the roof of the atrium

106

What is the ostium primum?

The hole present before the septum primum fuses with the endocardial cushions

107

What happens before the ostium primum closes?

A second hole, the ostium secondum, appears in the septum primum

108

What is the septum secundum?

A second, cresent shaped septum that grows

109

What is present in the septum secundum?

A small hole, the foramen ovale

110

What is true of the foramen ovale and ostium secundum?

They are staggered

111

Why are the foramen ovale and ostium secundum staggered?

So there is a right to left shunt, as the blood entering the right atrium via the vena cava causes a high pressure, pushing the septums apart so blood can flow

112

What do both the left and right atria have?

The auricles

113

What are the auricles?

Components derived from the primitive atrium

114

What does the right atrium absorb?

The sinus venosus

115

What does the left atrium absorb?

The pulmonary vein it sprouted, and its 4 branches

116

What is the fossa ovalis?

The adult remnant of the shunt used in utero to bypass the lungs

117

What are the components of the ventricular septum?

Muscular and membranous

118

What does the muscular portion of the ventricular septum form?

Most of the septum

119

How does the muscular portion of the ventricular septum grow?

Upwards towards the fused endocardial cushions

120

What does the growth of the muscular portion towards the endocardial cushions leave?

A small gap called the primary interventricular foramen