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