Flashcards in CVS S2 - The Heart as a Pump + Embryology S1 Deck (37)
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Name the compartments of the heart
Right atrium, left atrium, right ventricle, left ventricle
1
Where does each side of the heart pump blood to?
Left: systemic circulation
Right: pulmonary circulation
2
How long is the cardiac action potential?
~200-300ms
3
What controls contraction of the heart?
Pacemaker cells - normally the SAN (sino-atrial node) but if this isn't working then the AVN (atrio-ventricular node) can perform the same function
4
What is systole?
When the ventricles of the heart are contracting
5
What is diastole?
When the ventricles are not contracting
6
Describe atrial contraction
Not very forceful
Small volume of blood moved
Occurs just before ventricular systole
7
Describe the first heart sound
Caused by the closure of the A-V valves
"Lub" sound
Occurs in ventricular systole
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Describe the second heart sound
Caused by the closure of the semi lunar valves
"Dub" sound
Occurs in ventricular diastole
9
What do murmurs sound like and what causes them?
A "whooshing" noise
Caused by turbulent or disturbed flow eg through a narrowed valve
10
What is cardiac output?
Cardiac output = stroke volume x heart rate
This is the volume of blood pumped by the left ventricle per minute
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When is the cardiogenic field formed?
Gastrulation
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Where is the cardiogenic field just after formation and where and how does it move?
The cardiogenic field is initially at the cranial end of the embryo
Embryonic folding causes the field to move into the chest area
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What is the cardiogenic field?
Embryonic tissue from which the heart, blood vessels and blood develop
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When do the endocardial tubes form?
In the third week of development
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What happens after the formation of the endocardial tubes?
The endocardial tubes are brought together in embryonic folding and fuse at the mid line to create the primitive heart tube
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Describe the primitive heart tube
-Highly symmetrical
-Has four sections:
>Bulbus cordis
>Truncus arteriosus
>Primitive atrium
>Primitive ventricle
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How does the primitive heart tube sit in the pericardial cavity?
Suspended by a membrane which subsequently degenerates
18
What does looping achieve?
Places both the inflow and outflow cranially with the inflow dorsal (behind/posterior) to the outflow
Places primordium of right ventricle nearest to outflow tract
Places primordium of left ventricle nearest to inflow tract
Formation of the transverse pericardial sinus
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What will the primitive atrium become?
Contributes a SMALL component to the future atria
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What will the bulbis cordis become?
It will go on to form part of the right ventricle
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What will the primitive ventricle become?
The left ventricle
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What will the truncus arteriosus become?
It will give rise to the roots and proximal portions of the aorta and pulmonary trunk
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What does lateral/cephalocaudal folding achieve with respect to cardiac development?
Lateral folding causes formation of the primordial heart tube
Cephalocaudal folding brings the tube into the thoracic region
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Describe blood flow in the primitive heart tube
Linear at first
Caudal-end inflow from sinus venosus
Cranial-end outflow through aortic roots
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When does looping occur?
Between days ~23-28
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How does looping of the primitive heart tube proceed?
Continued elongation of the tube results in bending
The cephalic, cranial end bends ventrally, caudally and to the right
The caudal portion bends dorsally, cranially and to the left
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Describe communication between the atrium and ventricle after looping and what is the significance?
The communicate via the atrioventricular canal
This is the first division between the atrium and ventricle
28
What is the transverse pericardial sinus?
The space behind the cardiac outflow and in front of the inflow where a finger can be inserted
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