PSYC 312 Ch. 1 quiz
An axon releases chemicals:
into the junction between neurons.
When a neuron's membrane is at rest, the concentration gradient tends to move sodium ____ the cell and the electrical gradient tends to move it ____ the cell.
into, into
Where do the metabolic activities occur that provide energy for all of the other activities of the cell?
mitochondria
What receives excitation from other neurons and conducts impulses to muscle or gland cells?
motor neurons
What disease is related to the destruction of myelin sheaths?
multiple sclerosis
The insulating material which covers many vertebrate axons is called the:
myelin sheath.
What type of glial cells myelinate axons in the brain and spinal cord?
oligodendrocytes
If there is a depolarizing effect on a neuron, the result will be that the neuron will fire:
only if it reaches threshold.
The sodium-potassium pump pumps sodium ions ____ and potassium ions ____.
out of the cell; into the cell
When a neuron's membrane is at rest, the concentration gradient tends to move potassium ____ the cell and the electrical gradient tends to move it ____ the cell.
out of, into
At the peak of the action potential, the electrical gradient of potassium:
pushes potassium out of the cell.
The presence of an all-or-none law suggests that neurons can only convey different messages by changing their:
rate or pattern of action potentials.
Compared to passive transport, the major disadvantage of active transport is that it:
requires expenditure of energy.
One of the most distinctive features of neurons compared to other types of cells is their:
shape
When a neuron's membrane is at rest, which of the following molecules crosses through it MOST slowly?
sodium
Chemicals than cannot flow freely across a cell membrane enter a neuron through:
specialized protein channels.
Ribosomes are the part of a cell that:
synthesizes new proteins.
When you state that the neuron's membrane is polarized, you are referring to a difference in electrical potential between:
the inside and the outside of the membrane.
What structure is composed of two layers of fat molecules that are free to flow around one another?
the membrane
Concentration gradients lead to what kind of movements?
the movement of ions to areas of their lowest concentrations
What is the point from which an axon releases chemicals into the synapse?
the presynaptic terminal
What is to prevent an action potential from exciting the area behind it and starting a "rebound" action potential traveling the opposite direction?
the refractory period
What is one major cause for the resting potential of a neuron's membrane?
the sodium-potassium pump
When the neuron is at rest, what is responsible for moving sodium ions out of the cell?
the sodium-potassium pump
Which function is NOT performed by glia?
transmitting information
The risk of having part of the brain unprotected by the blood-brain barrier is:
viruses or toxic chemicals are more likely to damage it.
What is the approximate resting potential of the inside of a neuron's membrane, relative to the outside?
-70 millivolts
How does glucose enter the brain?
It is pumped in by an active transport system.
What happens once an action potential starts?
It is regenerated at other points along the axon.
Just after the peak of the action potential, what movement of ions restores the membrane to approximately the resting potential?
Potassium ions leave the cell.
Which type of glia builds myelin sheaths around axons in the periphery of the body?
Schwann cells.
Stimulus A depolarizes a neuron just barely above the threshold. Stimulus B depolarizes a neuron to 10 mV beyond threshold. What can we expect to happen?
Stimulus A and stimulus B will produce the same response in the neurons.
Which of the following is an advantage of having a resting potential?
The cell is prepared to respond quickly to a stimulus.
Prior to the work of Santiago Ramon y Cajal, what did many investigators believe?
The tip of an axon physically merged with the next neuron.
Which of the following is NOT true of axons?
They carry information toward the soma.
When the neuron is at rest, what is responsible for moving potassium ions OUT of the cell?
a concentration gradient
What causes potassium ions to leave the axon just after the peak of the action potential?
a continuing concentration gradient and the opening of the potassium gates
Compared to dendrites, axons usually:
are covered with myelin.
Sensory neurons:
are specialized at one end to be highly sensitive to particular types of stimulation.
Where do most action potentials begin?
at the axon hillock
At what point do the sodium gates begin to close, shutting out further entry of sodium into the cell?
at the peak of the action potential
Ordinarily, stimulation of a neuron takes place:
at the synapse.
The information sender of the neuron, conveying an impulse toward either other neurons or a gland or muscle is called the:
axon
A drug that blocks the sodium gates of a neuron's membrane would:
block the action potential.
The net effect of each cycle of the sodium-potassium pump is to:
decrease the number of positively charged ions within the cell.
The tree-like branches of a neuron that receive information from other neurons are called:
dendrites
What is the result if a stimulus shifts the potential inside a neuron from the resting potential to a potential slightly closer to zero?
depolarization
Drugs can cross the blood-brain barrier if they are soluble in:
fats
What is the result if a stimulus shifts the potential inside a neuron from the resting potential to a more negative potential?
hyperpolarization
Under what conditions is it impossible for a stimulus to produce an action potential?
if the membrane is in its absolute refractory period
