P4 - Cockroach Mechanoreceptors

Question 1

What is the Na+/K+-ATPase pump?

Answer 1

• Transports Na+ out of the cell and K+ into the cell
• The sodium potassium pump
• requires an input of ATP energy

Question 2

What does the resting membrane potential arise from?

Answer 2

• membrane is more permeable to K+ than to Na+
• K+ diffuses out of the cell faster than Na+ into the cell
  (- More K+ leakages out of the cell than Na+ leakages into the cell)
• the inside of the cell thus has a lower electrical voltage than the outside

Question 3

How do action potentials arise?

Answer 3

• stimulus-gated ion channels open; Na+ flows into cell
• if depolarisation threshold of -50mV; voltage-gated Na+ channels open and flood of Na+ ions diffuse into cell (cell membrane permeability to Na+ suddenly increased

Question 4

How is the resting membrane potential restored after action potential (depolarisation of inside of cell)

Answer 4

• Na+ channels inactivated

- K+ voltage-sensitive K+ channels are activated, and K+ flows out of the cell

Question 5

How are action potentials from a single neuron recorded?

Answer 5

Intracellular recording

Question 6

What is an extracellular recording?

Answer 6

• insert a recording and reference electrode in close proximity outside a group of cells to measure the combined electrical activity of all nearby cells
• -> recording of the difference in voltage or potential between the two electrodes
• to know that an action potential has occurred and to measure the entire electrical activity of a group of cells
• action potentials recorded in such a way are known as compound action potentials (CAPs)

Question 7

What is the difference between the recording and the reference electrode

Answer 7

• proximal electrode = reference electrode (-)
  (closest to the stimulus)
• distal electrode = recording electrode (+)
  (furthest from the stimulus)

–> voltage will be recorded as it is observed from the distal electrode (recording) in comparison to the proximal electrode (reference)