Physiology of neuronal activity

Question 1

Action Potential

Answer 1

• intracellular resting potential is -70mv. When transmitting an action potential this rises to -55mV
• at -55mV the Na+ channels open
• subsequent influx of Na+ causes membrane potential to rise to +40mV
• at+40mV the Na+channels close and the voltage gated K+ channels open
• K+ ions move out of the axon and the cell membrane gets polarised

Question 2

Chemical synapses

Answer 2

• presynaptic neuron releases a chemical molecule on stimulation
• can be either excitatory or inhibitory

Question 3

Facilitation

Answer 3

-post-synaptic changes induced by an excitatory synapse may not be sufficient to induce an action potential but may help increase the likelihood of generating an action potential with further stimulation

Question 4

Spatial summation effect

Answer 4

-additional imput from several other presynaptic cells through other synapses may lead to a spatial summation effect leading to an action potential

Question 5

Temporal summation effect

Answer 5

-recurrent stimulation by the same synapse can result in temporal summation and leads to an action potential

Question 6

Electrical synapses

Answer 6

-bring responses by electrical communication without chemical exchange

Question 7

Conjoint synapses

Answer 7

-both have electrical and chemical properties