The autorhythmic fibers of the heart a constitute approximat

The autorhythmic fibers of the heart

a. constitute approximately 90% of the cardiac muscle fibres

b. depolarize to threshold spontaneously
c. depolarize more slowly than other cardiac muscle fibres

d. are found in the fibrous skeleton of the heart

e. depolarize only in response to neurotransmitters or hormones

PLease expalain why the answer is one of these. Thanks

Solution

Auto rhythmic fibres constitute 1% of cardiac muscle they depolarize slowly. Depolarization is followed by repolarization forming influx of Ca ++ and thus inhibit rapid sequential depolarization. Hence answer c is correct