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Section 2: Review Questions
Terms in this set (24)
Actions are said to be "all-or-none" which means ___
local potentials have to be strong enough to reach the threshold potential which is the limit that will open the voltage-gated sodium ion channels
Graded potentials are called graded because ___
the magnitude of the potential can vary; larger stimulus equals a larger effect on membrane potential
In efferent neurons, the dendrites and cell body are always in the ___
In afferent neurons, the cell bodies and the axons are found in the ___
Newly defined glial cells are called ___
What is responsible for maintaining the ionic difference between the ECF and the ICF?
Sodium / potassium pumps
Why does the sodium-potassium pump have to keep going?
The ions leak through the membrane and disrupt the membrane potential
What is the log of 1?
What is the log of 10?
What is the log of 0.1?
(Q1 part 1) In a very small area of a neuron membrane, if we open a sodium ion channel for a very brief (<1 msec) time, what will happen to the membrane potential?
A few sodium ions will flow into the cell and slightly depolarize the membrane at that site?
(Q1 part 2) What will happen to the surrounding membranes if the membrane becomes slightly depolarized at that site?
The local current will depolarize adjacent regions
Graded potentials are often initiated by ___ channels
Grade potentials are ___ voltage changes
Grade potentials travel ___ distances
Action potentials are ___ voltage changes
Action potentials travel ___ distances
What are the major types of cells that are affected by action potentials?
Nerve, muscle, and endocrine
What is the first step in generating an action potential?
A depolarizing stimulus opens a few voltage-gated sodium ion channels
What is the second step in generating an action potential?
A positive feedback mechanism occurs which causes more sodium ion channels to open allowing more ions to flow into the cell once the threshold potential is reached
What is the third step in generating an action potential?
Sodium flows into the cell rapidly until the membrane potential becomes positive (+30 mV)
What is the fourth step in generating an action potential?
Sodium gates close when the membrane reaches +30 mV and potassium gates open which initiates repolarization
What is the fifth step in generating an action potential?
Repolarization occurs until the cell membrane reaches a hyperpolarized state
What is the sixth step in generating an action potential?
Potassium gates all close and the sodium/potassium pump maintains the RMP at -70 mV
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