Download Chapter 11 Worksheet 2 The action potential: Fill in the blanks. The

Chapter 11 Worksheet 2
The action potential: Fill in the blanks.
The dendrites receive signals from messenger molecules released from adjacent neurons called
_________________________________.
These molecules bind to receptors that act as ______________ gated ion channels. When these
channels open they allow ions to flow in or out which produces small changes in the membrane around
the receptors, known as ______________________________. These changes can be
positive/_______________________ or negative/___________________________.
The threshold potential of the neuron membrane is _______ mV, which requires a change of ______ mV
from the resting membrane potential of _________ mV to generate an action potential
When enough neurotransmitter is released onto the dendrites to reach the threshold potential,
____________-gated _____ channels in the ___________________________ are opened, allowing
_______ ions to move ________ the cell, causing the membrane to become more ________________
inside which results in a/an ___________________________________.
This depolarization of the membrane causes ____________-gated _____ channels in the membrane
further down to open which causes it to depolarize. This sequential depolarization allows the action
potential to flow like a ___________ down the axon all the way to the ___________________________.
After depolarization, the membrane potential raises to _______ mV at which point the voltage-gated
____ channels close and __________ -gated ______ channels open. This allows _______ to flow
_______ of the cell which makes the inside of the neuron more ___________________ again. This
action is called __________________________________________ and brings the membrane potential
back down to ________ mV, at which point the ________-gated _______ channels close.
If the membrane potential falls below the resting membrane potential, called _____________________,
it is restored back to normal by the _____________________ leak channels and the ___-___ pump.
After an action potential, the neuron cannot generate another action potential because _____ channels
are inactivated. This period is called the ________________________________ period. This also insures
that the action potential always flows from the ___________________ to the _____________________
and not back up the axon.
When the action potential reaches the axon terminal it causes the release of _____________________.
A. Depolarization
B. Repolarization
C. Refractory period
D. Resting membrane
Potential
E. Threshold potential
F. V-G Na+ channels open
G. V-G Na+ channels close
H. V-G K+ channels open
I. V-G K+ channels close
Mark these values on the
Membrane potential axis.
-70 mV
-55 mV
0 mv
+30 mV
Membrane potential
Using the information above and your text book, label the diagram below using the terms provided
Time
Local (graded) potentials can be _____________________ (EPSP) or ________________________(IPSP)
Ion
Na+
K+
Ca2+
Cl-
Flow across membrane makes
inside more + or -
Creates Excitatory or Inhibitory
local potentials
Schwan cells produce myelin which insulates the axons in the peripheral nervous system. This insulation
allows action potentials to travel up to 30 times faster in myelinated axons compared to naked axons.
Using the textbook, describe what each of these diagrams is depicting:
Describe how myelin speeds up the action potential. What is the name given to this process?
Which is faster? A small diameter myelinated axon or a large naked axon? Why?
How does the brain code for the intensity of a stimulus if every action potential is the same height?