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BIO 264: Exam 2 Review Latest Update
Graded A+
Which ion has greatest influence on resting membrane potential? ✔✔Potassium (potassium has more leak channels on the membrane than sodium, which is why potassium has a higher permeability value and has more impact of resting membrane potential)
Concerning resting membrane potential, the inside of the membrane is _______ compared to the ________ charged outside. ✔✔negative, positively.
T or F:
The diffusion of K+ and Na+ down their chemical gradients contributes to the resting membrane potential ✔✔F
At resting membrane potential, ______________________. ✔✔extracellular sodium levels are high
During the hyper polarization phase... ✔✔K+ leaves the cell
Which is not a characteristic of a graded potential?
A) Spreads in a decremental fashion
B)Can result from changes in voltage across the membrane
C) Can summate
D) Size is inversely proportional to stimulus strength ✔✔D
As the stimulus strength and size of the graded potential _____________ the action potential frequency ___________. ✔✔increases; increases
The outside of a cell during resting membrane potential is _________ in relation to the inside of the cell. ✔✔Positively charged
If at resting membrane potential (RMP), the plasma membrane became more permeable to K+, the cell would _________________________. ✔✔hyperpolarize
Which ion has greatest influence on resting membrane potential? ✔✔K+
Which statement is true?
A) ATP is required to move Na+ extracellularly
If a plasma membrane becomes more permeable to K+ the charge difference across the plasma membrane will _________, or (AKA) _________. ✔✔increase, hyperpolarize
If the extra cellular fluid around a muscle cell is replaced with an isotonic saline solution that contains less K+ than the normal extra cellular fluid, the result would be: ✔✔a hyperpolarized membrane
The resting membrane potential of a cell is = -60mV, and the intracellular and extracellular Cl- concentrations are [Cl-]inside = 7 mM and [Cl-]outside = 105 mM, respectively. Which of the following statements is FALSE?
A) The Cl- electrical gradient is inward
B) The Cl- concentration gradient is inward
C) Both a and b are True statements
D) Both a and b are False statements ✔✔A
T or F:
Simple diffusion is based on the fact that molecules are in constant, random motion. Because of collisions with each other, and anything else in the particles way, they eventually disperse- or are evenly distributed throughout the system. ✔✔T
The "All-or-None" principle ✔✔whether the stimulus is just strong enough to reach threshold or if it is so strong to surpass the threshold, the action potential will proceed without stopping
Repolarization results ✔✔from the increase in potassium moving out of the cell
Refractory period ✔✔from beginningof action potential, return to resting state, during whichmembrane will not respond normally to additional stimuli
Absolute refractory period ✔✔sodium channels open or inactivated no action potential possible
Opening of sodium gates typically leads to ________. ✔✔depolarization of the plasma membrane
Action potentials are constant in ___________. (Hint: all-or-none principle) ✔✔Magnitude
Which statements are true? ✔✔-The purpose of the Na+, K+ ATPase pump is to maintain concentration gradients of Na+ and K+.
-The brain prefers to use action potentials, but can function using other forms of communication like ketones.
-If a graded potential does not hit threshold it will never become an action potential.
Which statement is true regarding ion concentrations across a resting membrane? ✔✔K+ concentration is greater intracellularly and Na+ concentration is greater extracellularly.
When a cell is in the depolarization phase... ✔✔a new action potential is possible provided the repolarization potential value is lower than threshold
How is a cell repolarized after stimulation? ✔✔by K+ flowing out of the cell
Which is true regarding voltage-gated K+ channels? ✔✔-They only have one gate.
-They are slower to open than Na+ channels. -They stay open until repolarization is complete.
-They only allow K+ ions to flow through them.
What occurs during depolarization? ✔✔There is a rapid influx of Na+ ions.
Define threshold ✔✔the critical level of depolarization that must be achieved to fire an action potential
What is an action potential? ✔✔An action potential is an electrical impulse that travels down the axon, leading to neurotransmitter release
Define membrane potential ✔✔difference in electrical charge between the inside and outside of a cell
Define resting potential ✔✔steady membrane potential of -70mV, and in this state with the - mV charge built up across its membrane it is said to be POLARIZED
less then -70 mV ✔✔DEPOLARIZED
More than -70 mV ✔✔HYPERPOLARIZED
competition
saturation
tonicity
specificity ✔✔tonicity
Small pieces of matter, and even whole cells, can be transported across the plasma membrane in ✔✔vesicles
Which is true in regard to concentration gradients? ✔✔The greater the difference between areas of high concentration and low concentration, the greater the rate of diffusion.
The rate of diffusion increases if the ✔✔viscosity of a solution decreases.
