cardiac muscles and conductive system · cardiac muscles and conductive system 1.atrial muscle...

CARDIAC MUSCLES

AND CONDUCTIVE SYSTEM

1.ATRIAL MUSCLE

2.VENTRICULAR MUSCL

3.CONDUCTIVE FIBERS

A.SA NODE

B.AV NODE

C.INTERNODAL FIBERS

D.AV FIBERS (BUNDLE OF HIS)

E.LEFT AND RIGHT BUNDLE BRANCH

F.PURKIINJE FIBERS

Fig. 9-7, p. 247

Sinoatrial

(SA) node

Right

atrium

Internodal

pathway

Right

branch

of bundle

of His Right

ventricle Purkinje

fibers

Left

ventricle

Left

branch

of bundle

of His

Left

atrium

Atrioventricular

(AV) node

Interatrial

pathway

Histology of cardiac muscle

Pacemaker activity of cardiac

autorhythmic cells

Direction of ventricular

excitation

ACTION POTENTIAL OF DIFFERENT PARTS OF THE

HEART

•1.PACE MAKER OF THE HEART SANODE

•2.ATRIAL ACTION POTENTIAL

•3.ACTION POTENTIAL OF THE VENTRICLES

•4.DELAY IN THE AV NODE

•5.HIGH VELOCITY IN THE PURKINJE FIBERS

•6.REFRACTORY PERIOD

•A.ABSOLUTE

•B.RELATIVE

-90

0

0

1 2

3

4

TIME

PHASE 0 = Rapid Depolarization

(inward Na+ current)

1 = Overshoot

2 = Plateau

(inward Ca++ current)

3 = Repolarization (outward K+ current)

4 = Resting Potential

Mechanical Response

ME

MB

RA

NE

P

OT

EN

TIA

L (

mV

)

0 0

-50 -50

-100 -100

SAN VENTRICULULAR CELL

ACTION POTENTIALS

0

1 2

3

4

4

0 3

CONTROL OF EXITATION AND

CONDUCTION

1-SYMPATHETIC

2-PARASYMPATHETIC

3-IONS