Generation & Conduction of Nerve Impulse MCQ - Practice Questions with Answers

Generation and Conduction of Nerve Impulse

• OUR NERVES ARE POLARISED (Has opposite charges)

• TWO TYPES OF ION CHANNELS ARE PRESENT IN NERVES

1. Open or leaky channels : These channels are open always 

2. Voltage gated channels : These open or close depending on the voltage applied 

FOLLOWING EVENTS TAKE PLACE DURING CONDUCTION OF NERVE IMPULSE

1. RESTING POTENTIAL OR POLARISED STATE
2. DEPOLARISED STATE 
3. RE POLARISED STATE
4. HYPER POLARISED STATE

1. RESTING OR POLARISED STATE

• NO IMPULSE 
• LEAK CHANNELS ARE FUNCTIONAL
• VOLTAGE GATED CHANNELS ARE NOT FUNCTIONAL 
• AT RESTING STAGE THE MEMBRANE IS MORE PERMEABLE TO K IONS THAN Na
• Na-K PUMP OPERATES TO MAINTAIN THIS
• THIS TRANSPORTS 3Na+ OUTWARDS AND 2K+ INWARDS AT THE COST OF 1 ATP
• THUS OUTER IS MAINTAINED POSITIVE AND INNER IS NEGATIVE 

2. DEPOLARISED STATE

• AS ACTION POTENTIAL REACHES THE NEURONS, THE VOLTAGE GATED CHANNELS OPEN
• FIRST THE Na+ GATED CHANNELS OPEN 
• THUS Na+ MOVES WITHIN THE AXON
• THUS THE POLARISATION IS TEMPORARILY DISTURBED
• THIS IS DEPOLARISATION
• INNER BECOMES MORE POSITIVE 
• Na+ CHANNELS CLOSE WITHIN 0.5 msec

3. REPOLARISED STATE

• AFTER THIS K+ CHANNELS OPEN AND THESE START MOVING OUT AND THIS RESTORES THE RESTING POTENTIAL. THIS IS REPOLARISATION

4. HYPERPOLARISED STATE

• K+ CHANNELS REMAIN OPEN FOR LONGER TIME AND THIS IS HYPERPOLARISATION