Ch 12: Biological Processes in the Brain Flashcards
Neurons with one dendrite are termed _______; those with many dendrites are __________.
bipolar
multipolar
What is the difference between a neuron and a nerve?
A neuron is a single cell. A nerve is a large bundle of many different axons from different neurons.
The resting membrane potential is approximately ___ __, with interior of the cell __________ charged with respect to the exterior of the cell.
-70 mV
negatively
What two primary membrane proteins are required to establish the resting membrane potential?
the Na+/K+ ATPase pump and the potassium leak channels
The Na+/K+ ATPase pumps _ sodium ions out of the cell for every _ potassium ions into the cell with the __________ of one ATP molecule.
3
2
hydrolysis
Leak channels are channels that are open all the time.
There are relatively few sodium leak channels in the cell membrane; the ratio of K+ leak channels to Na+ leak channels is about _____.
100:1
The threshold potential is approximately _____.
-50 mV
In an action potential, which of these events happens first?
a. ) voltage-gated K+ channels close
b. ) voltage-gated Na+ channels open
c. ) voltage-gated Na+ channels inactivate and voltage-gated K+ channels open
b.) voltage-gated Na+ channels open
Repolarization happens for a number of reasons:
- ) voltage-gated Na+ channels inactivate very quickly after they open, shutting off the flow of sodium into the cell. These channels remain ___________ until the membrane potential nears resting values again.
- ) voltage-gated potassium channels open ____ ______ than the voltage-gated sodium channels and stay open longer. Voltage-gated K+ channels open in response to membrane DEpolarization. As K+ leaves, it actually overshoots the resting potential by about 20 mV (to -90 mV). At that point, the voltage-gated K+ channels close.
inactivated
more slowly
In the PNS, the myelin sheath is created by _______ cells. In the CNS, this job is done by ___________.
Schwann
oligodendrocytes
p. 348
The rapid jumping conduction in myelinated axons is called _________ __________.
saltatory conduction
p. 348
The equilibrium potential for sodium is approximately _____. What does this mean?
+50 mV (+65mV according to Sketchy)
Na+ ions are driven into the cell by their concentration gradient. But if the interior of the cell is too positive, the positively-charged ions are repelled. In other words, the electrical gradient would drive sodium out. These forces, the chemical gradient driving sodium in, and the electrical gradient driving sodium out balance each other at about +50mV.
In contrast, K+ has an equilibrium potential of _____.
-90 mV
The equilibrium potential for any ion can be predicted by the ______ equation.
Nernst equation
E ion = (RT/zF) {ln [X outside]/[X inside]}
During the ________ __________ ______, a neuron will not fire another action potential no matter how strong a membrane depolarization is induced.
absolute refractory period
p. 350
Electrical synapses occur when the cytoplasms of two cells are joined by ___ _________.
gap junctions
p. 351
* Note: Electrical synapses are not common in the nervous system although they are quite important in propagating action potentials in smooth muscle and cardiac muscle.
There are many steps involved in the transmission of a signal across a chemical synapse in the nervous system. The first 3 of 8 are here:
- ) an action potential reaches the end of an axon, the ________ ____.
- ) depolarization of the presynaptic membrane opens voltage-gated calcium channels.
- ) calcium influx into the presynaptic cell causes __________ of neurotransmitter stored in secretory vesicles.
synaptic knob
exocytosis
There are many steps involved in the transmission of a signal across a chemical synapse in the nervous system. Steps 4 and 5 of 8 are here:
- ) Neurotransmitter molecules diffuse across the narrow _______ _____ (small space between cells).
- ) Neurotransmitter binds to receptor proteins in the postsynaptic membrane. These receptors are ______-_____ ion channels.
synaptic cleft
ligand-gated
p. 351
There are many steps involved in the transmission of a signal across a chemical synapse in the nervous system. Steps 6-8 of 8 are here:
- ) the opening of these ion channels in the postsynaptic cell alters the ________ __________.
- ) If the membrane depolarization of the postsynaptic cell reaches the threshold of voltage-gated sodium channels, an action potential is initiated.
- ) Neurotransmitter in the synaptic cleft is ________ and/or removed to terminate the signal.
membrane polarization
degraded
p. 351
If a neurotransmitter opens a channel that depolarizes the postsynaptic membrane, then that neurotransmitter is termed __________.
Neurotransmitters that induce hyperpolarization of the postsynaptic membrane are called __________.
Note, however, that it is ultimately not the neurotransmitter that determines the effect on the postsynaptic cell, it is the RECEPTOR for that neurotransmitter and its associated ion channel. The same neurotransmitter can be excitatory in some cases and inhibitory in others.
excitatory
inhibitory
p. 352
True or false, postsynaptic neurons may have many different receptors, allowing them to respond to many different neurotransmitters.
TRUE
p. 352
One form of summation is ________ summation in which a SINGLE presynaptic neuron fires action potentials so rapidly that the EPSPs or IPSPs pile up on top of each other.
temporal
p. 352
The other form of summation is ________ summation, in which the EPSPs and IPSPs from ALL of the synapses on the postsynaptic membrane are summed at a given moment in time. If the total sum causes the postsynaptic membrane to reach the threshold voltage, an action potential will be fired.
spatial
p. 352
Receiving information is the sensory function of the nervous system carried out by the ______ nervous system. Processing the information is the integrative function carried out by the ______ nervous system, and acting on it is the motor function also carried out by the ______ nervous system.
peripheral
central
peripheral
p. 353
A muscle stretch reflex involving only two neurons and one synapse is known as….
….a monosynaptic reflex arc.
p. 353
The terms afferent and efferent pertain to function of the _______ and _______ branches of the peripheral nervous system.
somatic and autonomic
p. 355
