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Biology 252 (Anatomy) Exam 1 Study and Revision Questions Chamberlain College.
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Biology 252 (Anatomy) Exam 1 Study and Revision Questions Chamberlain College.
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Biology 252 (Anatomy) Exam 1 Study andRevision Questions Chamberlain College.
Action potentials can only be generated and propagated in ______ and
_______.
Correct Answer -Neurons (only at the axon) and muscles. Why?
________ channels are found mainly on the axon and axon hillock (trigger
zone).
Correct Answer -Voltage gated channels
Sodium voltage gated channels have two gates. Describe these.
Correct Answer -At resting state:
- Na+ activation gate: closed
- Na+ inactivation gate: open
- K+ inactivation gate: closed
Upon depolarization the gates change their status.
- Na+ activation gate: Opens quickly
- Na+ inactivation gate closes slowly
- K+ gate opens slowly
At the peak, Na+ channels close and slower K+ channels open.
Hyperpolarization causes Na activation gate to close completely and K+ to
open completely
,Voltage gated K+ channels close and returns to normal.
At what point does an action potential become an all or none process?
Correct Answer -Upon reaching the threshold
What allows action potentials to continue and not die out?
Correct Answer -Voltage gated channels !!
How do action potentials move through the cell?
Correct Answer -Formation of one AP in one site generates AP in the next
site and so forth (domino effect)
Absolute Refractory Period
Correct Answer -Na+ channels have not yet reset to the resting positions. A
new AP CANNOT be generated. (before the peak)
Relative refractory period
Correct Answer -Some Na+ channels have reset to their resting position, so
if the stimulus in strong enough, a new AP can be generated. (after the
peak)
What is another function of the myelin sheath?
Correct Answer -It provides faster propagation aka saltatory conduction
"leaps."
, What are the spaces in between the myelin sheath?
Correct Answer -The Nodes of Ranvier. They contain the voltage gated
channels, leak channels, Na+/K+ pump, etc.
Where does continuous conduction occur?
Correct Answer -Along unmyelinated axons
What is multiple sclerosis and cellist died from it?
Correct Answer -Jacqueline du Pre'
When there is an immune attack on the myelin. When myelin is lost, the
ions will not propogate as fast, some well leak out or get lost, and never
reach the target cell like the muscle. Results in loss of functional muscles.
The _________ the diameter of an axon, the _______ the resistance and
the _______ the impulse.
Correct Answer -The LARGER the diameter of an axon, the LOWER the
resistance and the FASTER the impulse.
The plasma membrane is ______ is the resting state.
Correct Answer -Polarized
______ gated channels generate local, graded potentials.
Correct Answer -Chemically gated channels generate local potentials.
What are the three types of synapses with a POST synaptic neuron?
Correct Answer -Axodendritic synapses (interact with dendrites)
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