PCB4843 Week 2 - Questions with Correct Answers
(Verified Update)
24 questions with answers
Topic: PCB4843 Week 2
1. what is information transmission analagous to
Answer: transmission of electrical signals down a telephone wire the main ditterence is that
neurons are "leaky" so ions escape
2. membrane potential
Answer: voltage across a membrane, negative at rest
3. action potential
Answer: a signal that makes membrane potential briefly positive fixed in amplitude
4. composition of cytosol and extracellular fluid
Answer: made of water and ions
5. what causes resting potential
Answer: the phospholipid bilayer maintains concentrations of ions so they don't fluctuate
6. ion channels and their selectivity 4-6
Answer: protein subunits that form a pore for ions to pass through number, shape, and
arrangement of subunits provides ion selectivity passive transportneeds a driving force as
well (either concentration or electrochemical gradients) one side is hydrophobic (in the
membrane) and the other is hydrophilic (in the cytosol)
7. equation that describes how easily ions can flow given a potential difference
Answer: R = 1 / g R = resistance g = conductance
8. resistance equation with and without channels
Answer: without: no conductance (g approaches 0, so R increases) with: increased
conductance (g increases, so R decreases)
9. how is membrane potential measured
Answer: electrodes measure the distance in mV between the inside and the outside of a cell
10. what happens when a K+ channel is added to a membrane
Answer: K+ will go out through the membrane (down the concentration gradient), which
alters the electrical gradient
11. what happens when an Na+ channel is added to a membrane
Answer: Na+ will go inside through the membrane (down the concentration gradient) which
alters the electrical gradient
12. equilibrium potential
Answer: electrical potential ditterence that balances the ionic concentration gradient
13. where does each important ion lie at rest relative to the membrane
Answer: Na+ outside K+, Ca2+, Clinside
14. what is the ionic driving force
Answer: the membrane potential - equilibrium potential
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(Verified Update)
24 questions with answers
Topic: PCB4843 Week 2
1. what is information transmission analagous to
Answer: transmission of electrical signals down a telephone wire the main ditterence is that
neurons are "leaky" so ions escape
2. membrane potential
Answer: voltage across a membrane, negative at rest
3. action potential
Answer: a signal that makes membrane potential briefly positive fixed in amplitude
4. composition of cytosol and extracellular fluid
Answer: made of water and ions
5. what causes resting potential
Answer: the phospholipid bilayer maintains concentrations of ions so they don't fluctuate
6. ion channels and their selectivity 4-6
Answer: protein subunits that form a pore for ions to pass through number, shape, and
arrangement of subunits provides ion selectivity passive transportneeds a driving force as
well (either concentration or electrochemical gradients) one side is hydrophobic (in the
membrane) and the other is hydrophilic (in the cytosol)
7. equation that describes how easily ions can flow given a potential difference
Answer: R = 1 / g R = resistance g = conductance
8. resistance equation with and without channels
Answer: without: no conductance (g approaches 0, so R increases) with: increased
conductance (g increases, so R decreases)
9. how is membrane potential measured
Answer: electrodes measure the distance in mV between the inside and the outside of a cell
10. what happens when a K+ channel is added to a membrane
Answer: K+ will go out through the membrane (down the concentration gradient), which
alters the electrical gradient
11. what happens when an Na+ channel is added to a membrane
Answer: Na+ will go inside through the membrane (down the concentration gradient) which
alters the electrical gradient
12. equilibrium potential
Answer: electrical potential ditterence that balances the ionic concentration gradient
13. where does each important ion lie at rest relative to the membrane
Answer: Na+ outside K+, Ca2+, Clinside
14. what is the ionic driving force
Answer: the membrane potential - equilibrium potential
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