Cardiovascular System Part 2

Question 1

Neurons

Answer 1

• Lipid bilayer membrane that surrounds a neuron is impermeable to ions
• To enter or exit, ions must pass through ion channels (proteins) spanning the membrane
• Some ion channels need to be activated to open and allow ions to pass into or out of the cell
• These ion channels are sensitive to the environment and can change their shape
• A neuron at rest (resting membrane potential) is negatively charged
• Inside of the cell is approximately 70 millivolts more negative than the outside (-70mV)

Question 2

Voltage-gated ion channels

Answer 2

• Ion channels that change their structure in response to voltage changes
• Structural changes in protein channel allow or prevent ion movement

Question 3

Leak channels

Answer 3

• Generally open but it may open and close at random
• There is no actual even that opens the channel; it has an intrinsic rate of switching between the open and closed states

Question 4

Resting membrane potential

Answer 4

• Na+ and K+ each have a concentration gradient across the neuron plasma membrane
• In most neurons, [K+] is higher inside the cell; [Na+] is higher outside the cell at RMP
• Gradients maintained by sodium-potassium pump actively transporting Na+ outside the cell and K+ inside the cell
• RMP is unequal distribution of ions across cell membrane but it is stable.