chapter 39 ~ neurons Flashcards
Cells in the nervous system that send and receive electrical signals are called….
Neurons
Which component of a neural signaling pathway sorts and interprets messages?
Integration
Which sequence of the neural signaling pathway is correctly arranged from the earliest to the latest event as it occurs in the nervous system?
Reception, transmission, integration, transmission, response
Which cells serve as electrical insulators in the central nervous system?
Oligodendrocytes
Which type of neuron directly stimulates a muscle or gland?
Efferent neurons only
A frog sees a fly and immediately sticks his tongue out to catch it. Which type of cell transmitted the visual signal from his eye to his brain?
Afferent neuron
A trapeze artist loses her grip and falls off the trapeze, causing her heart rate to increase in response to the rear of falling (despite the net below to prevent injury). Which type of neurons is directly responsible for this increase in heart rate?
Efferent neuron
In humans, and some primates, the most abundant neurons are the…
Interneurons
Which part of the neuron conducts the electrical signals away from the cell body of a neuron?
Axon
Which gilal cell(s) is/are only found in the peripheral nervous system?
Schwann cells
In the context of the nervous system, what does the term “nucleus” mean?
A cluster of neurons in the CNS with a related function
Where is a ganglion found?
Peripheral nervous system
Which cells assist and nourish neurons that transmit electrical signals?
Glial cells
Which category of organic macromolecule allows myelinated sheaths to act as electrical insulators?
Lipids
Otto Loewi demonstrated that neurons transmit signals across synapse by _______.
Chemical signals
Which process is responsible for the release of neurotransmitters from the presynaptic neurons into the synapse?
Exocytosis
Electrical synapses are most common in the….
Retina
If a drug inhibits the uptake of an excitatory neurotransmitter after it has been released into the synaptic cleft, what is the most likely result?
An increased number of EPSPs
If a drug binds irreversibly to a postsynaptic receptor to prevent the binding of an excitatory neurotransmitter, what is the most likely result?
A decreased number of EPSPs
If a drug binds to a receptor, which normally triggers the opening of a Na+ channel, causing it to open in the absence of neurotransmitter release, what is the most likely result?
An increased number of EPSPs
In an effort to determine the mechanism of neuronal signaling, Otto Loewi isolated_____.
Frog brains
For a neuron at rest, there is a higher concentration of ______ outside the cell than inside.
Na+
When measuring membrane potential, the tip of a microelectrode is inserted into a(n) _______.
Axon
What is the typical resting potential of an isolated neuron?
-70 mv
The nernst equation is used to calculate the _______.
Equilibrium potential
Calculate the ENa for a neuron that has an extracellular concentration of Na + of 78 mM and an intracellular concentration of Na+ of 6 mM
68.0 mv
An abrupt and transient change in membrane potential is called a(n)
Action potential
When a neuron membrane potential becomes less negative, it is said to be_______.
Depolarized
The minimum level of depolarization required to initiate an action potential in an excitable cell is called the ____ potential.
Threshold
When a neuron membrane potential goes below its resting value it becomes______.
Hyperpolarized
The refractory period of a neuronal plasma membrane is important because it _______.
Ensures that an impulse will travel in a one-way direction.
During an action potential, the membrane potential can reach as high as______.
+30 mv
When threshold potential is reached______.
The activation gates of Na+ channels open
As the action potential peaks….
The inactivation gates of Na+ channels close
If the K + channels of an excitable plasma membrane were blocked by the action of a drug, which process(es) would be disrupted?
Repolarization and hyper polarization
Depolarization of the neuronal plasma membrane occurs due to…
The diffusion of Na+ into the cell
At which point in this action potential diagram are Na+ inactivation gates opening?
D
Answer the question using the accompanying figure. At which point in this action potential diagram are many Na+ activation gates open and K + activation gates closed?
A
Answer the question using the accompanying figure. At which point in this action potential diagram does the onset of Na+ channel inactivation stop the inward flow of Na+?
B
Answer the question using the accompanying figure. At which point in this action potential diagram does the K+ channel close to stabilize the membrane potential?
E