Neurons differ most strongly from other body cells in their ____.
The two basic kinds of cells in the nervous system are _____.
Water, oxygen, and ____ most freely flow across a cell membrane.
Which scientific work did Cajal apply to his study of infant brains?
The structure that contains a cell’s chromosomes is called the ____.
What do neurons have that other cells do not?
Small, charged molecules can cross the cell membrane through ____.
Santiago Ramon y Cajal demonstrated that ____.
What structure is composed of two layers of fat molecules that are free to flow around one another?
The cell membrane is composed of two layers of _____.
Dendrites ____.
The branching fibers that form the information-receiving pole of the nerve cells are called _____.
Many dendrites contain short outgrowths called spines that _____.
Protein channels allow ____ molecules to cross the cell membrane.
As compared to dendrites, axons usually ____.
The surface of a dendrite is lined with specialized junctions through which the dendrite receives information from other neurons. What are these junctions called?
The endoplasmic reticulum is a ____.
The insulating material that covers many vertebrate axons is called the ____.
The tree-like branches of a neuron that receive information from other neurons are called _____.
Ribosomes are the part of a cell that ____.
Nodes of Ranvier are ____.
If you were to accidentally touch a hot stove with your hand, you would quickly pull your hand away. The information carried to the muscles in your arm to make them contract was carried by ____.
A presynaptic terminal is also known as ____.
What type of neuron in the pons receives information only from other cells in the pons and sends information only to other cells in the pons?
Neurons typically have one ____, but many ____.
An axon has many branches, each of which swells at its tip. These are known as ____.
Gaps in the insulating material that surrounds axons are known as ____.
As a general rule, axons convey information ____.
If all of a neuron's dendrites or axons were contained within the spinal cord, it would be considered a(n) ____ neuron.
Chemicals are released by axons ____.
____ in the brain and spinal cord and ____ in the periphery are specialized types of glia that build the myelin sheaths that surround neurons.
Which type of glia remove waste material in the nervous system?
What type of glial cells myelinate axons in the brain and spinal cord?
Which type of glia release chemicals that modify the activity of neighboring neurons?
Glial cells ____.
are less numerous than neurons in the human brain.
occupy about ten times more space in the brain than do neurons.
transmit information over long distances within the central nervous system.
are smaller but more numerous than neurons in the human brain.
Which type of glia builds myelin sheaths around axons in the periphery of the body?
Glial cells whose function most closely resembles that of the immune system are called ____.
Radial glia ____.
What type of glia helps to synchronize the activity of axons?
What mechanism prevents or slows some chemicals from entering the brain, while allowing others to enter?
Why do neurons rely so heavily on glucose as their source of nutrition?
Molecules that can cross the blood-brain barrier are usually ____.
The membrane of a neuron is composed of ____ with ____ embedded in them.
Why does the brain need thiamine?
What happens to a virus that manages to cross the blood-brain barrier and enter the brain?
Korsakoff's syndrome ____.
What is the main source of nutrition for vertebrate neurons?
Glucose enters the brain via which type of transport?
The major disadvantage of a blood-brain barrier is that ____.
What leads to Korsakoff's syndrome?
What term describes the difference in voltage that typically exists between the inside and the outside of a neuron?
Which of the following describes selective permeability?
When the neuronal membrane is at rest, the sodium channels ____.
The resting potential is mainly the result of ____.
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.
The resting potential of a neuron refers to the ____.
When the neuronal membrane is at rest, the potassium channels ____.
The idea that a neuron's membrane is polarized refers to a difference in electrical potential between ____.
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.
What is the approximate resting potential of the inside of a neuron's membrane, relative to the outside?
Electrical gradients lead to the ____.
Which event will increase the concentration gradient of sodium?
The concentration gradient for potassium tends to ____.
What is one major cause for the resting potential of a neuron's membrane?
When the neuron is at rest, what is primarily responsible for moving potassium ions OUT of the cell?
The concentration gradient refers to the ____.
Under which conditions would the sodium-potassium pump likely be far less effective in creating a concentration gradient?
When a neuron is at rest, what is primarily responsible for moving potassium ions into the cell?
The net effect of each cycle of the sodium-potassium pump is to ____.
When a membrane is at rest, what attracts potassium ions to the inside of the cell?
When a membrane is at rest, what attracts sodium ions to the inside of the cell?
Which action will produce a hyperpolarization of a neuron?
Which action would depolarize a neuron?
Ordinarily, stimulation of a neuron takes place ____.
What action tends to open the sodium gates across a neuron's membrane?
Which of the following is an advantage of having a resting potential?
What occurs when depolarization is less than the cell's threshold?
A membrane produces an action potential whenever the potential across it reaches what level?
What occurs when a stimulus shifts the potential inside a neuron from the resting potential to a more negative potential?
The action potential of a neuron depends mostly on what movement of ions?
At what point do the sodium gates begin to close, shutting out further entry of sodium into the cell?
When the potential across a membrane reaches threshold, the sodium channels ____.
After the peak of an action potential, what prevents sodium ions from continuing to enter the cell?
In the normal course of an action potential, ____.
What causes potassium ions to leave the axon just after the peak of the action potential?
A drug will prevent an action potential if it ____.
lowers the threshold of the membrane
blocks the movement of potassium across the membrane
blocks the movement of sodium across the membrane
increases the movement of sodium across the membrane
Voltage-activated channels are channels for which a change in the voltage across the membrane alters their ____.
A drug that blocks the sodium gates of a neuron's membrane will ____.
decrease the threshold
block the action potential
cause repeated action potentials
eliminate the refractory period
At the peak of the action potential, the electrical gradient of potassium ____.
Local anesthetic drugs attach to the sodium channels of the membrane, which ____.
The speed of an action potential down an unmyelinated axon is best described as ____.
The function of a myelin sheath is to ____.
prevent action potentials from traveling in the wrong direction
increase the velocity of transmission along an axon
increase the magnitude of an action potential
provide a store of nutrients for the neuron
The primary feature of a neuron that prevents the action potential from traveling back from where it just passed is the ____.
concentration gradient
refractory period
sodium potassium pump
phospholipid bilayer
According to the all-or-none law, ____.
What will most affect the speed of an action potential?
In what direction does a local neuron transmit information?
During the relative refractory period, the ____.
sodium gates are firmly closed
sodium gates are reverting to their usual state
sodium gates are wide open
potassium gates are firmly closed
Which of the following describes the transmission of information in a local neuron?
The all-or-none law states that ____.
a neuron produces an action potential of maximal strength, or none at all
all neurons fire or none at all
all neurons in a pathway fire at the same time, or none do
all ions move in the same direction, or none do
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What are nerve cells and nerve impulses? - Exams 1aThe difference in voltage in a resting neuron is called the resting potential.
Neurons receive information and transmit it to other cells.
Glial cells serve many functions.
Glial cells transmit information across long distances.
The blood-brain barrier is made up of closely packed glial cells.
The difference in voltage in a resting neuron is called the resting potential.
Increasing the electrical gradient for potassium will reduce the tendency for potassium ions to exit the neuron.
Dendrites contain the nuclei, ribosomes, mitochondria, and other structures found in most cells.
A prolonged increase in the permeability of the membrane to sodium ions would interfere with a neuron's ability to have an action potential.
An afferent axon brings information into a structure.
Neurons are distinguished from other cells by their shape.
Both dendrites and cell bodies are capable of producing action potentials.
At the resting potential, the potassium channels are completely closed and the sodium channels are almost closed.
Schwann cells build the myelin sheaths in the periphery of the body.
An efferent axon carries information away from a structure.
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What are nerve cells and nerve impulses? - Exams 1bNeurons differ most strongly from other body cells in their ____.
The two basic kinds of cells in the nervous system are _____.
Water, oxygen, and ____ most freely flow across a cell membrane.
Which scientific work did Cajal apply to his study of infant brains?
The structure that contains a cell’s chromosomes is called the ____.
What do neurons have that other cells do not?
Small, charged molecules can cross the cell membrane through ____.
Santiago Ramon y Cajal demonstrated that ____.
What structure is composed of two layers of fat molecules that are free to flow around one another?
The cell membrane is composed of two layers of _____.
Dendrites ____.
The branching fibers that form the information-receiving pole of the nerve cells are called _____.
Many dendrites contain short outgrowths called spines that _____.
Protein channels allow ____ molecules to cross the cell membrane.
As compared to dendrites, axons usually ____.
The surface of a dendrite is lined with specialized junctions through which the dendrite receives
.....read more What are nerve cells and nerve impulses? - Exams 1cExplain the function and process of a neuron’s refractory period.
Describe how the brain transports essential chemicals.
Describe the key aspects of the resting potential.
Provide a summary of the all-or-none law of action potentials.
Describe the structure of the blood-brain barrier and explain why it is important.
Although the electrical potential across the membrane is returning from its peak toward the resting point, it is still above the threshold. Why doesn’t the cell produce another action potential during this period? (If it did, of course, it would endlessly repeat one action potential after another.) Immediately after an action potential, the cell is in a refractory period during which it resists the production of further action potentials. In the first part of this period, the absolute refractory period, the membrane cannot produce an action potential, regardless of the stimulation. During the second part, the relative refractory period, a stronger-than-usual stimulus is necessary to initiate an action potential. The refractory period depends on two facts: The sodium channels are closed, and potassium is flowing out of the cell at a faster-than-usual rate. In most of the neurons that researchers have tested, the absolute refractory period is about 1 millisecond (ms), and the relative refractory period is another 2 to 4 ms.
The brain has several transport mechanisms. Small, uncharged molecules, including oxygen and carbon dioxide, cross freely. Water crosses through special protein channels in the wall of the endothelial cells. Also, molecules that dissolve in the fats of the membrane cross easily. Examples include vitamins A and D and all the drugs that affect the brain—from antidepressants and other psychiatric drugs to illegal drugs such as heroin. How fast a drug takes effect depends partly on how readily it dissolves in fats and therefore crosses the blood– brain barrier.
For a few other chemicals, the brain uses active transport, a protein-mediated process that expends energy to pump chemicals from the blood into the brain. Chemicals that are actively transported into the brain include glucose (the brain’s main fuel), amino acids (the building blocks of proteins), purines, choline, a few vitamins, iron, and certain hormones.
All parts of a neuron are covered by a membrane about 8 nanometers (nm) thick (just less than 0.00001 mm), composed of two layers (free to float relative to each other) of phospholipid molecules (containing chains of fatty acids and a phosphate group). Embedded among the phospholipids are cylindrical protein molecules through which various chemicals can pass. The structure of the membrane and its proteins controls the flow of chemicals between the inside and outside of the cell. When
.....read more What is the function of synapses? - Exams 2aOnly sensory neurons are found in a reflex arc.
The amount of temporal summation depends on the rate of stimulation.
At synapses, the cell that receives the message is called the presynaptic neuron.
Electrical communication between neurons is faster than chemical communication within neurons.
Transmission of information between neurons occurs in the same way as transmission along an axon.
Most of the known neurotransmitters are synthesized from amino acids.
Inhibitory synapses actively suppress excitatory responses.
Neurotransmitter levels in the brain can be affected by changes in diet.
Gases can be used as neurotransmitters.
Spatial summation is the result of synaptic inputs from different locations arriving at the same time.
Most neurons release more than one kind of neurotransmitter.
Most of the brain’s excitatory ionotropic synapses use the neurotransmitter glutamate.
Generally speaking, a neuron will release a greater number of neurotransmitters than what it will respond to with its own receptors.
Metabotropic synapses use a large variety of transmitters.
Whether or not a neurotransmitter is excitatory depends on the response of the postsynaptic receptor.
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