Rhythmical Excitation of the heart Flashcards
system of heart does what things in order to produce rthymical self excitation and repetitive conduction
- Generates electrical impulse to initiate the rhythmically contraction of the heart
- Conducts these impulses repeatedly through the heart
What features are shown because of this system of rhythmical contraction and repetitive impulses
- The atria contracts 1/6th of second ahead of ventricle this allows filling of ventricle before they pump blood from lungs and peripheral circulation
- Both the atria contacts together
WHat happens in ischemia and why ischemia happens
Happen because of inadequate amount of coronary blood flow and causes bizarre rhythmical contractions of heart, the pumping effectiveness of the heart is affected
SA node
normal rhythmical impulses are generated in SA node
internodal pathways
that take the impulse from the SA node to AV node
AV node
the node in which the impulses are delayed from the atrial to ventricle
AV bundle
the bundle which conducts impulses from atrium to ventricle
Purkinje fibers
purkinje bundle branches of right and left conducts impulses to all parts of the ventricles
Describe SA node
it is a small, flattened, ellipsoid specialized cardiac muscle. 15mm long, 3mm wide and 1mm thick
location of SA node
Present in superior posterolateral wall of right atrium below and slightly lateral to where the superior vena cave enters
Function of SA node
SA node fibers are connected directly to Muscle fibers of atrium so the action potential can be spread immediately
Resting membrane potential of SA node between discharge is
-55 to -60
Resting membrane potential of ventricles between discharge is
-85 to -90
Why resting membrane potential Of SA node is less than ventricle
due to the natural leakage of Na and calcium ions.
