2. Cardiovascular Physiology Flashcards
How does the heart function effectively?
Heart contracts between 50 and 200 times per minute depending on the load
Contraction must be precisely timed so that atria contract first followed by a delay which allows ventricles to fill, with a subsequent contraction of ventricles form the base
What happens during systole?
Ventricles contract
Why is it significant that the S.A. node is automatic?
It will depolarise itself
When do the atria contract?
When the S.A node is activated
Where does the electrical signal travel?
Septum
down LHS then turn RHS and depolarises left centricles
What does the T wave indicate?
The heart repolarising
What is sinus arrhythmia?
Speeding up of the heart when you breathe in
What does the vagus heart do to the nerve?
Slows the heart down
What happens to the vagus nerve when you breathe in?
It is turned off and heart rat
What is a heart block?
Ventricles and atria beat at own rate separately, atria beat with S.A. rate and ventricles beat with bundle of his
What does a heart block result in?
Results in stokes adam syndrome
What is a first degree heart block?
Extensive delay between atria and ventricles
What is meant by circus movements? read up on this
Situation in the heart where the current is going round in a circle rather than apex to base
What is Wolff Parkinson White syndrome?
Where there is a genetic abnormality conducting electricity between the ventricles and the atria
What are ectopics?
Where parts of the heart that normally don’t initiate and impulse do causing extrasystoles
What happens in late diastole?
AV valves open, blood flows in to the atria and ventricles passively
What happens in atrial systole?
Atrial contraction primes the main pump. 70% of ventricular filling is passive
Contraction of muscles around great veins minimise backflow along with inertia of blood
A wave of atrial pressure and JVP trace
How long into the cardiac cycle does atrial systole occur?
0-0.1
What happens in ventricular systole?
Isovolumetric contraction; ventricles contract against closed valves until P vent > P art. This builds up pressure head
Aortic and pulmonary valves burst open, giving the ventricular ejection phase
C wave of atrial and JV pressures
How long into the cardiac cycle does ventricular systole occur?
0.1-0.4
What happens in early diastole?
Protodiastole, ventricles stop contracting, blood still flows out through the momentum imparted by ventricular contraction.
Aortic and pulmonary valves close and we get isovolumetric relaxation until pressure falls to below atrial pressure
V wave on JVP and atrial pressure trace from blood flowing into atria
Then AV valves open
How far into the cardiac cycle does early diastole occur?
0.4-0.6 into cycle
What are the difference in systolic and diastolic murmurs?
Systolic murmurs are on the beat and diastolic murmurs off the beat
