Sedation Physiology - Cardiovascular Flashcards
list the 4 main valves in the heart and their location
- tricuspid – between the right atrium and ventricle
- pulmonary – between the right ventricle and the pulmonary circulation
- mitral (bicuspid) – between the left atrium and left ventricle
- aortic – between the right ventricle and the systemic circulation
what is the function of the coronary arteries?
supplies arterial blood to the myocardium
where do the coronary veins drain into?
The right atrium
What percentage blood volume is involved in pulmonary circulation?
20% blood volume
What percentage blood volume is involved in systemic circulation?
80%
Describe what occurs during pulmonary circulation
Deoxygenated blood leaves the right ventricle of the heart, enters the lungs and becomes oxygenated and comes back to the left atrium.
Describe what occurs during pulmonary circulation
Describe what occurs during systemic circulation
Oxygenated blood leaves the left ventricle of the heart, supplies the whole body and and returns to the right atrium.
What are the cardiac muscle contractions controlled by?
controlled by electrical signals fired from nodes
List the 3 main nodes that control muscle contractions within the heart.
• Sino-atrial node = natural pacemaker which defines the cardiac rhythm
• Atrio-ventricular node
• Purkinje system
- Bundle of his
- Left bundle branch
- Right bundle branch
What innervation does the heart receive?
Autonomic innervation via the;
parasympathetic NS - from vagus nerve
Sympathetic NS
Describe the effect that the parasympathetic NS has on the heart and how this is achieved.
Acts on SA node and AV node - Via muscarinic cholinergic receptors
= Negative chronotropic and dromotropic effect
= slowing down the pacemaker (SA node) and increasing the delay (hence reducing conduction velocity)
Where does the parasympathetic NS act on?
– Acts on SA node and AV node Via muscarinic cholinergic receptors
Where does the sympathetic NS act on? (3) and with what receptors?
SA Node, AV Node and myocytes
- Act mostly Via B1 adrenoreceptors (also B2 present
Describe the effect that the sympathetic NS has on the heart. (2)
Positive chronotropic, dromotropic and Positive inotropic effect = increasing heart rate, conduction velocity as well as contractility.
– The effect on the myocytes will increase the rate of relaxation.
List the 5 stages in the cardiac cycle.
atrial systole
ventricular contraction
ejection
ventricular relaxation
ventricular filling
What occurs during the ventricular contraction stage of the cardiac cycle? (3)
Isovolumetric contraction = contraction but there is no volume change in the ventricular chamber
- closure of the respective valve that filled the ventricle from the respective atrium.
- There is an increase in ventricular pressure which forces the atrio ventricular valves, tricuspid and mitral, to close and avoid reflux of the blood.
Describe what occurs in the ejection phase.
allows the opening of the pulmonary and aortic valves and ejects the blood towards the pulmonary and system circulation