Cardiac ion channels i Voltage gated ii Ligand

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Cardiac ion channels: i. Voltage gated ii. Ligand gated b) Nodal tissue- RMP &

Cardiac ion channels: i. Voltage gated ii. Ligand gated b) Nodal tissue- RMP & AP Action potential m. V 0 ICa. L -40 -60 ICa. T Pacemaker potential IK

m. V SYMPATHETIC STIMULATION: 0 -60 Sympathetic stimulation m. V PARASYMPATHETIC STIMULATION: 0 -60

m. V SYMPATHETIC STIMULATION: 0 -60 Sympathetic stimulation m. V PARASYMPATHETIC STIMULATION: 0 -60 Vagal stimulation

3) CONDUCTIVITY: i. SA node: ii. Internodal pathways: iii. AV node: iv. Bundle of

3) CONDUCTIVITY: i. SA node: ii. Internodal pathways: iii. AV node: iv. Bundle of HIS: v. Purkinje fibres:

i. SA (SINO-ATRIAL) NODE: Transtitional cells P - cells

i. SA (SINO-ATRIAL) NODE: Transtitional cells P - cells

SA node

SA node

ii. INTERNODAL PATHWAYS: • Anterior internodal tract: • Middle internodal tract: • Posterior internodal

ii. INTERNODAL PATHWAYS: • Anterior internodal tract: • Middle internodal tract: • Posterior internodal tract:

SA node Internodal pathways Anterior Middle Posterior

SA node Internodal pathways Anterior Middle Posterior

SA node Internodal pathways Anterior Middle Posterior AV node

SA node Internodal pathways Anterior Middle Posterior AV node

iii. AV (ATRIO-VENTRICULAR) NODE: N AN NH HIS bundle

iii. AV (ATRIO-VENTRICULAR) NODE: N AN NH HIS bundle

iv. BUNDLE OF HIS: • Left bundle branch: • Right bundle branch:

iv. BUNDLE OF HIS: • Left bundle branch: • Right bundle branch:

SA node Internodal pathways Anterior Middle Posterior AV node HIS bundle Rt. branch Lt.

SA node Internodal pathways Anterior Middle Posterior AV node HIS bundle Rt. branch Lt. branch

v. PURKINJE FIBRES: SA node Internodal pathways Anterior Middle Posterior Purkinje fibres AV node

v. PURKINJE FIBRES: SA node Internodal pathways Anterior Middle Posterior Purkinje fibres AV node HIS bundle Rt. branch Lt. branch

Conduction speeds of different parts (m/sec) Rate of discharge of impulses (impulses/sec) Time taken

Conduction speeds of different parts (m/sec) Rate of discharge of impulses (impulses/sec) Time taken for impulse to travel different tissues: 0. 03 sec SA node 0. 13 sec AV Bundle branches node 0. 03 sec Purkinje fibers Ventricular endocardial & epicardial surfaces

STEPS IN SPREAD OF ELECTRICAL ACTIVITY: 1. Atrial activation: 2. Septal activation: 3. Activation

STEPS IN SPREAD OF ELECTRICAL ACTIVITY: 1. Atrial activation: 2. Septal activation: 3. Activation of: Ventricular myocardium- anteroseptal portion Ventricular myocardium-major portion 4. Late activation of: Left ventricle-posterobasal portion Pulmonary conus Uppermost portion of septum

1. Atrial activation: SA node AV node

1. Atrial activation: SA node AV node

A-V nodal delay • Duration – • Cause for the delay – • Significance

A-V nodal delay • Duration – • Cause for the delay – • Significance of the delay – • Effect of drugs • Regulation of A-V conduction: Vagal stimulation Sympathetic stimulation

2. Septal activation: SA node AV node

2. Septal activation: SA node AV node

3 (a) Activation of anteroseptal region of ventricular myocardium SA node AV node

3 (a) Activation of anteroseptal region of ventricular myocardium SA node AV node

3 (b). Activation of major portion of ventricular myocardium SA node AV node

3 (b). Activation of major portion of ventricular myocardium SA node AV node

4. Late activation of : Posterobasal portion of left ventricle Pulmonary conus & septal

4. Late activation of : Posterobasal portion of left ventricle Pulmonary conus & septal uppermost portion SA node AV node

SA AV

SA AV