Discussion
The pacemaker potential of the SA node is generated mainly by __________.
Answer: B
The pacemaker potential is generated mainly by the funny current (If) through Na+ channels.
SA node cells have no stable resting potential. After each beat, as the membrane repolarises to about -60 mV, HCN channels open and carry an inward current, mostly of Na+. This is the 'funny' current, so named because it is activated by hyperpolarisation. It slowly depolarises the cell towards threshold, and T-type and then L-type Ca2+ channels complete the upstroke.
Fast sodium channels are largely inactivated at the SA node's resting voltage and produce the upstroke of ventricular cells, not pacemaker cells. Chloride channels and ATP depletion do not drive diastolic depolarisation.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development