Biological Psychology Chapter 1 & 2 Kalat
What mechanism prevents or slows some chemicals from entering the brain, while allowing others to enter?
A blood-brain barrier
Glucose enters the brain via which type of transport?
Active transport
Adrenocorticotropic hormone (ACTH) controls secretions of the ____.
Adrenal cortex
The basic building blocks for the majority of neurotransmitters are ____.
Amino acids
A presynaptic terminal is also known as ____.
An end bulb
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
As a general rule, axons convey information ____.
Away from their own cell body
Neurons typically have one ____, but many ____.
Axon; dendrites
"Transporter" proteins transport neurotransmitters ____.
Back into the presynaptic neuron
On the basis of what evidence were the properties of synapses first inferred?
Behavioral observations
A drug that blocks the sodium gates of a neuron's membrane will ____.
Block the action potential
When a membrane is at rest, what attracts sodium ions to the inside of the cell?
Both an electrical gradient and a concentration gradient
When a neuron is at rest, what is primarily responsible for moving potassium ions into the cell?
Both the sodium-potassium pump and electrical gradient
When an action potential reaches the end of an axon, it evokes the release of neurotransmitters by opening ____ channels in the axon terminal.
Calcium
When an action potential reaches the end of an axon, the depolarization causes what ionic movement in the presynaptic cell?
Calcium into the cell
Loewi demonstrated that synapses operate by the release of chemicals by ____.
Collecting fluid from a stimulated frog's heart, transferring it to another frog's heart, and measuring that heart rate
A hormone is a chemical that is ____.
Conveyed by the blood to other organs, whose activity it influences
Activation of autoreceptors tends to ____.
Decrease further neurotransmitter release
The net effect of each cycle of the sodium-potassium pump is to ____.
Decrease the number of positively charged ions within the cell
A graded depolarization is known as an ____.
EPSP
Which statement is TRUE about the spontaneous firing rates of neurons?
EPSPs increase the frequency
COMT and MAO are ____.
Enzymes that convert catecholamines into inactive chemicals
The catecholamines include ____.
Epinephrine, norepinephrine, and dopamine
Depolarization is to ____ as hyperpolarization is to ____.
Excitation; inhibition
A neuron excretes neurotransmitters through its membrane by a process called ____.
Exocytosis
The speed of an action potential down an unmyelinated axon is best described as ____.
Faster in thick axons than in thin ones
Nodes of Ranvier are ____.
Gaps in the myelin of axons
The anterior pituitary is composed of ____ and the posterior pituitary is composed of ____.
Glandular tissue; neural tissue
What is the main source of nutrition for vertebrate neurons?
Glucose
Radial glia ____.
Guide the migration of neurons during embryonic development
What occurs when a stimulus shifts the potential inside a neuron from the resting potential to a more negative potential?
Hyperpolarization
Inhibitory synapses on a neuron ____.
Hyperpolarize the postsynaptic cell
Releasing hormones are synthesized in the ____ and released in the ____.
Hypothalamus; anterior pituitary
Vesicles are located ____.
In presynaptic terminals
Many dendrites contain short outgrowths called spines that _____.
Increase the surface area available for synapses
Chemicals are released by axons ____.
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
If all of a neuron's dendrites or axons were contained within the spinal cord, it would be considered a(n) ____ neuron.
Intrinsic
What makes nitric oxide unique among neurotransmitters?
It is a gas
What happens to acetylcholine after it attaches to a receptor on the postsynaptic cell?
It is broken down into two components
What happens to a virus that manages to cross the blood-brain barrier and enter the brain?
It remains there and may cause negative effects several years later
Glial cells whose function most closely resembles that of the immune system are called ____.
Microglia
Molecules that can cross the blood-brain barrier are usually ____.
Molecules that can dissolve in the fats of the capillary walls
Electrical gradients lead to the ____.
Movement of ions to areas having opposite electrical charges
Spatial summation refers to ____.
Multiple weak stimulations that occur at the same time
The resting potential is mainly the result of ____.
Negatively charged proteins inside the cell
The resting potential of a neuron refers to the ____.
Net negative charge on the inside of the neuron
The endoplasmic reticulum is a ____.
Network of thin tubes that transport newly synthesized proteins
The two basic kinds of cells in the nervous system are _____.
Neurons and glia
Receptor molecules for neurotransmitters that exert metabotropic effects are proteins that bind to ____ outside the membrane, and attach to ____ inside the membrane.
Neurotransmitters; G-proteins
In addition to influencing other neurons, ____ increases blood flow to a specific area of the brain.
Nitric Oxide
Which neurotransmitter is released by stimulated neurons to dilate the blood vessels?
Nitric Oxide
The structure that contains a cell's chromosomes is called the ____.
Nucleus
____ in the brain and spinal cord and ____ in the periphery are specialized types of glia that build the myelin sheaths that surround neurons.
Oligodendrocytes; Schwann cells
Voltage-activated channels are channels for which a change in the voltage across the membrane alters their ____.
Permeability
When the neuronal membrane is at rest, the potassium leak channels ____.
Permit potassium ions to pass slowly
Increased permeability to which type of ion would most likely result in an IPSP?
Potassium
An axon has many branches, each of which swells at its tip. These are known as ____.
Presynaptic terminals
Local anesthetic drugs attach to the sodium channels of the membrane, which ____.
Prevents sodium ions from entering and stopping action potential
A drug that inhibits the action of the enzyme acetylcholinesterase will have the effect of ____.
Prolonging the action of acetylcholine at its synapses
Ionotropic effects are characterized by ____.
Rapid and short-lived effects
Which event is most likely to be dependent on ionotropic effects?
Rapid muscle contraction
Which pattern of post-synaptic excitation will most likely result in an action potential?
Rapid sequence of EPSPs
Temporal summation most likely occurs with ____.
Rapid succession of sub-threshold excitation
The primary feature of a neuron that prevents the action potential from traveling back from where it just passed is the ____.
Refractory period
What term describes the difference in voltage that typically exists between the inside and the outside of a neuron?
Resting potential
Which type of glia builds myelin sheaths around axons in the periphery of the body?
Schwann cells
Compared to ionotropic effects, metabotropic effects are ____.
Slower and longer lasting
What occurs when depolarization is less than the cell's threshold?
Sodium crosses the membrane only slightly more than usual
The action potential of a neuron depends mostly on what movement of ions?
Sodium ions entering the cell
In the normal course of an action potential, ____.
Sodium remains much more concentrated outside than inside the neuron
What is the primary difference between temporal summation and spatial summation?
Spatial summation depends on contributions from more than one sensory neuron
Even at rest, most neurons have periodic production of action potentials, known as the ____.
Spontaneous firing rate
Specialized junctions between neurons are called ____.
Synapses
Which of the following is an advantage of having a resting potential?
The cell is prepared to respond quickly to a stimulus
What determines whether a neuron has an action potential?
The combined effects of EPSPs and IPSPs
What is the synaptic cleft?
The gap between the presynaptic neuron and the postsynaptic neuron
The idea that a neuron's membrane is polarized refers 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
After the peak of an action potential, what prevents sodium ions from continuing to enter the cell?
The sodium gates in the membrane close
What is one major cause for the resting potential of a neuron's membrane?
The sodium-potassium pump
Sherrington deduced that transmission at a synapse must be slower than conduction along an axon. This was based on what kind of evidence?
The speed of reflexive responses
Although slower than an action potential, synaptic transmission is still relatively fast because ____.
The synaptic cleft is very narrow
What do dopamine, norepinephrine, and epinephrine share in common?
They are all synthesized from the same amino acids
What leads to Korsakoff's syndrome?
Thiamine deficiency due to chronic alcoholism
The neuron will produce an action potential only if the depolarization exceeds the ____.
Threshold of excitation
Temporal summation is to ____ as spatial summation is to ____.
Time; location
The presynaptic terminal stores high concentrations of neurotransmitter molecules in ____.
Vesicles
A normal, healthy animal never contracts the flexor muscles and the extensor muscles of the same leg at the same time. Why not?
When the interneuron sends excitatory messages to one, inhibitory messages go to the other.
What is the approximate resting potential of the inside of a neuron's membrane, relative to the outside?
70 millivolts
Autoreceptors monitor the ____.
Amount of neurotransmitter released
Dendrites ____.
Are branching fibers that get narrower near their ends
When the neuronal membrane is at rest, the sodium channels ____.
Are closed, so there is almost no flow of sodium
As compared to dendrites, axons usually ____.
Are covered with myelin
Glial cells ____.
Are smaller but more numerous than neurons in the human brain
"Second messengers" carry their messages to ____.
Areas within the postsynaptic cell
Water, oxygen, and ____ most freely flow across a cell membrane.
Carbon Dioxide
The branching fibers that form the information-receiving pole of the nerve cells are called _____.
Dendrites
What action tends to open the sodium gates across a neuron's membrane?
Depolarization of the membrane
The concentration gradient refers to the ____.
Difference in distribution for various ions between the inside and outside of the membrane
The cell membrane is composed of two layers of _____.
Fat
A temporary hyperpolarization is known as an ____.
IPSP
Under which conditions would the sodium-potassium pump likely be far less effective in creating a concentration gradient?
If selective permeability of the membrane did not exist
The function of a myelin sheath is to ____.
Increase the velocity of transmission along an axon
Which event will increase the concentration gradient of sodium?
Increasing activity of the sodium potassium pump
Which action would depolarize a neuron?
Increasing membrane permeability to sodium
When a vertebrate animal contracts the flexor muscles of a leg, it relaxes the extensor muscles of the same leg. Sherrington considered this evidence for the existence of ____.
Inhibitory Messages
In a reflex arc, the coordination between contraction of certain muscles and relaxation of others is mediated by ____.
Interneurons
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?
Intrinsic
The insulating material that covers many vertebrate axons is called the ____.
Myelin sheath
Why do neurons rely so heavily on glucose as their source of nutrition?
Other fuels do not readily cross the blood-brain barrier
Small, charged molecules can cross the cell membrane through ____.
Protein channels
What is the proper ordering of a reflex arc?
Sensory neuron, interneuron, motor neuron.
What causes an EPSP?
The opening of sodium channels
Which of the following describes the transmission of information in a local neuron?
The signal decreases in strength as it travels
Which statement is TRUE of EPSPs?
They decay over time and space
Why does the brain need thiamine?
To enable it to metabolize glucose
Why is the speed of conduction through a reflex arc slower than the speed of conduction of an action potential along an axon?
Transmission between neurons at synapses is slower than along axons
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 ____.
Efferent neurons
The "decision" for a neuron to fire is determined by the ____.
Ratio of EPSPs to IPSPs
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
What type of glia helps to synchronize the activity of axons?
Astrocytes
Which type of glia release chemicals that modify the activity of neighboring neurons?
Astrocytes
A metabotropic synapse, by way of its second messenger, ____.
Can influence activity in much or all of the postsynaptic cell
You are eating a food containing tryptophan. What can you consume with it to increase its entry to the brain?
Carbohydrates
Neuropeptides are synthesized in the ____.
Cell body
The major disadvantage of a blood-brain barrier is that ____.
Certain required chemicals must be actively transported
Which process will most likely result in an IPSP?
Chloride ions entering the cell
An EPSP is to ____ as an IPSP is to ____.
Depolarization; hyperpolarization
The primary method for disposal of peptide neurotransmitters is ____.
Diffusion
The primary difference between an EPSP and an action potential is that ____.
EPSPs are sub-threshold events that decay over time and space
The membrane of a neuron is composed of ____ with ____ embedded in them.
Fat molecules; proteins
Glutamate opens sodium gates, enabling sodium ions to enter the postsynaptic cell. What type of effect is this?
Ionotropic
A receptor can directly open a channel and thereby exert a(n) ____ effect, or it can produce slower but longer ____ effects.
Ionotropic; metabotropic
Korsakoff's syndrome ____.
Is marked by severe memory impairments.
What is the function of the enzyme acetylcholinesterase?
It breaks acetylcholine down into components for recycling.
The main advantage of a neuron releasing more than one neurotransmitter is that:____.
It can send more complex messages
The "spontaneous firing rate" of a neuron refers to ____.
Its rate of producing action potentials even when it is not stimulated
What do neurons have that other cells do not?
Large, branching extensions
Which terms refers to a chemical that binds to another chemical?
Ligand
Ionotropic effects ____.
May depolarize or hyperpolarize the postsynaptic membrane
What type of glial cells myelinate axons in the brain and spinal cord?
Oligodendrocytes
According to the all-or-none law, ____.
Once an axon reaches threshold, the amplitude and velocity of an action potential are nearly equal each time
Which of the following describes selective permeability?
Only certain molecules are allowed to cross the membrane freely
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
Which category of chemicals includes adenosine and several of its derivatives?
Purines
The effect of a neurotransmitter on a postsynaptic neuron is determined by the ____.
Receptors on the postsynaptic membrane
To measure temporal summation in single cells, researchers ____.
Record depolarizations of the postsynaptic neuron
The amino acid tryptophan is the precursor to which neurotransmitter?
Serotonin
In general, a single neuron releases ____ neurotransmitter(s) and can respond to ____ neurotransmitter(s).
Several; many
Neurons differ most strongly from other body cells in their ____.
Shape
Hormones exert their effects ____.
Similarly to metabotropic neurotransmitters
The surface of a dendrite is lined with specialized junctions through which the dendrite receives information from other neurons. What are these junctions called?
Synaptic receptors
Ribosomes are the part of a cell that ____.
Synthesizes new proteins
A certain weak stimulus produces no reflexive response, but a rapid repetition of that stimulus may produce such a response. What is this phenomenon called?
Temporal summation
What happens when a neurotransmitter is released by a presynaptic cell?
The neurotransmitter passively spreads across the synaptic cleft
At the peak of the action potential, the electrical gradient of potassium ____.
Pushes potassium out of the cell
The all-or-none law states that ____.
A neuron produces an action potential of maximal strength, or none at all
The circuit from sensory neuron to muscle response is called ____.
A reflex arc
Avoiding foods with lecithin, such as eggs and peanuts, would affect the levels of which neurotransmitter the most?
Acetylcholine
Which type of glia remove waste material in the nervous system?
Astrocytes
What do temporal summation and spatial summation have in common?
Both enable a reflex to occur in response to weak stimuli.
Many neurons release neuropeptides mostly from the ____.
Dendrites