Cardiac Dissection Flashcards
Explain the process whereby organs receive continuous, rather than pulsatile blood flow from the elastic arteries
elastic arteries have a large amount of elastic fibres/tissues
- these allow for the artery for expand/stretch as blood passes through and recoil after they have passed
= allows for a continuous pressure and blood flow to be maintained
What is the windkessel effect?
arterial elasticity gives rise to the Windkessel effect
- during systole, the elastic arteries act as a reservoir and store some of the ejected blood
- this distends/stretches the wall of the arteries
- during diastole, the remaining blood is forced out into the smaller arteries/capillaries and the arteries recoil
= this means the force generated by ventricular contraction travels along the aorta as a wave and there is continuous capillary flow throughout diastole
this helps to maintain a relatively constant pressure and reduces pulse pressure in the arteries despite the pulsating nature of blood flow.
Why is the atrial muscle much smaller than ventricular muscle?
ventricles have thicker muscular walls than atria because blood is pumped out at a much higher pressure
- have greater myocardium
What is the purpose of atrial contraction?
it is the last stage of ventricular diastole (ends diastole)
- occurs in order to fill the ventricles with the remaining blood
Where are the papillary muscles found?
are attached to the atrioventricular valves (mitral and tricuspid valves) via the chordae tendineae
- chordae tendineae = strands in the heart which anchor the atrioventricular valves
What is the function of the papillary muscle? What happens if the papillary muscles do not work?
they are able to contract independently of the heart
during ventricular systole, the papillary muscles pull on the chordae tendineae to close the atrioventricular valves
- prevents inversion and/or prolapse of the valves
if they do not work then the valves can invert/prolapse due to the high pressure in the ventricles
during diastole, the papillary muscles relax allowing the valves to open
Why is the inside face of the ventricular chambers not smooth as one might expect?
are covered in ridges called trabeculae carneae and papillary muscles
What are the features of the inside of the atria that might predispose a patient to stroke?
blood clots in the atria predispose a patient to stroke
- it can travel up to the brain
Where is the moderator band located and what two anatomical structures does it link?
the moderator band is located in the right ventricular apex
- it links the interventricular septum and the anterior papillary muscle
What are the two possible roles of the moderator band?
acts as a primary conduction pathway from the right bundle branch of the atrioventricular bundle in the interventricular septum
- carries impulses to the papillary muscle
= purpose is to make sure the papillary muscles contract before the ventricles in order to prevent the valves opening during ventricular systole
= ensures equal conduction time in the left and right ventricles
prevent over distension of the right ventricle
Where does the contraction start in the ventricles?
the ventricles contract from the bottom upwards to ensure all the blood is squeezed from the ventricles
- at the apex of the heart
What is the ductus arteriosus?
patent ductus arteriosus (PDA) is a persistent opening between the two major blood vessels leading from the heart
- aorta and the pulmonary artery
the opening (ductus arteriosus) is a normal part of a baby's circulatory system in the womb that usually closes shortly after birth - if it remains open, it's called a patent ductus arteriosus.
Where are the mitral and tricuspid valve located?
What are the names of the two semi lunar valves?
are known as the atrioventricular valves mitral valve - left side tricuspid - right side
the semilunar valves are known as the aortic and pulmonary valves
What is the function of the fibrous ring?
the fibrous skeleton provides structural and functional support for the valves of the heart
- by enabling them to stay open and provides a point of attachment for the valves to the myocardium (wall of the heart)
the fibrous skeleton of the heart acts as an insulator for the flow of electrical current across the heart
- it stops the flow of electricity between the different chambers of the heart so that electrical impulses do not flow directly between the atria and ventricles
