Chapter 7 Quiz

Match the neurotransmitter with its action. 1. Painkillers Endogenous 2. Appetite stimulant 3. Inhibits NT release; may aid memory and learning 4. Blood vessel dilation, relax other smooth muscles 5. Promotes odor adaptation 6. Dilation of cerebral blood vessels

1. opioids 2. neuropeptide 3. endocannabinoids 4. nitric oxide 5. carbon monoxide 6. ATP

Which of the following is/are a characteristic of GABA as a neurotransmitter?

All choices are correct. -it is inhibitory -it opens Cl- channels into the cell -it helps control skeletal muscle movements

T/F? - Action potentials travel faster on thin, myelinated axons than on thick, myelinated axons.

False

T/F? - IPSPs always open K+ channels.

False

Hyperpolarization that leads to postsynaptic inhibition is a/an

IPSP

How does glycine act to control skeletal movements?

It inhibits the antagonist's action by causing IPSPs.

Acetylcholine has which effect on the postsynaptic neuron?

Ligand-gated sodium ion channels open and sodium diffuses in.

If demyelination occurs, why don't action potentials occur at regions of the axon that were previously myelinated?

These regions lack the appropriate concentration of voltage-gated sodium channels.

T/F? - If the postsynaptic membrane potential reaches threshold level, an action potential will be produced.

True

T/F? - Nicotinic receptors are also ion channels.

True

T/F? - The area between the presynaptic nerve cell and the postsynaptic muscle cell is termed the synaptic cleft.

True

T/F? - The sodium-potassium pump is involved in establishing the resting membrane potential.

True

Threshold is the minimum current required for the cell membrane to generate an action potential.

True

The period of time when a membrane cannot respond to another stimulus, no matter how strong, is the

absolute refractory period

The neurotransmitter at the neuromuscular junction is

acetylcholine

Action potentials arriving at a presynaptic terminal cause

calcium ion channels to open

The voltage-gated Na⁺ channels _________ when the cell reaches +30 mV.

close

Demyelinating diseases cause a(n) ______________ in the conduction velocity of action potentials.

decrease

An action potential generates local currents that tend to _____ the membrane immediately adjacent to the action potential.

depolarize

In the neuromuscular junction, acetylcholine...

diffuses across the synaptic cleft and binds to acetylcholine receptors on the postsynaptic muscle fiber.

What structures are involved in electrical synapses?

gap junctions

Action potentials occur ____________________________.

in the unmyelinated regions of an axon

When K⁺ diffuses out of the cell, the cell becomes ______ depolarized.

less

When Na⁺ diffuses into the cell, the cell becomes _________ depolarized.

more

Depolarization occurs because

more Na+ diffuse into the cell than K+ diffuse out of it.

The voltage-gated Na⁺ channels __________ when the cell membrane reaches threshold level as a result of a stimulus.

open

The following information best describes the _____________ phase of an action potential. • A membrane potential reading of +10 mV • Inactivated voltage-gated sodium channels • Open voltage-gated potassium channels

repolarization

When threshold is reached in a neuron, depolarization occurs with the same amplitude of potential change. This is known as _________

the All-or-None Law.

Depolarization of the postsynaptic membrane by an excitatory postsynaptic potential (EPSP) causes ____.

the sodium channels open and sodium ions pour into the intracellular fluid.

An inhibitory post synaptic potential (IPSP)...

will make the membrane potential of a neuron's inner cell membrane more negative.

Na+ diffusing into the cell causes more Na+ gates to open, which is a _______ feedback loop

positive

The convergence of many presynaptic terminals onto one postsynaptic neuron is called

spatial summation.

An action potential _____.

causes the inside of the neuron cell membrane to become positively charged in reference to the outside.

Which type of neuroglial cell supports the metabolic needs of the blood-brain barrier?

astrocytes

During depolarization, which of the following statements about voltage-gated ion channels is TRUE?

Na+ gates open before K+ gates

The neurotransmitter in the neuromuscular junction...

causes ligand gated sodium channels in the muscle fiber to increase their permeability to sodium, which depolarizes the postsynaptic membrane.

When voltage-gated sodium channels are open, sodium flows _____________ the neuron making the inside of the cell more _______________.

into; positive

The muscarinic ACh receptors are formed from only a single subunit and do not contain ___________ like the _________ACh receptors. Rather, binding of ACh to the muscarinic receptor activates a complex of proteins in the cell membrane known as __________, because their activity is influenced by GDP and GTP, guanosine nucleotides. There are 3 G-protein subunits: alpha, beta and gamma. Binding of ACh causes the _______ subunit to dissociate from the other two, which form the ____________ complex. Either the alpha subunit or the ________ complex then diffuses through the membrane until it binds to an ion channel and causes it to open or close.

ion channels; nicotinic; G-Proteins alpha; betta-gamma; beta-gamma

K⁺ diffusing out of the cell has a _________ feedback effect on the initial depolarization.

negative

What type of cells produce the myelin sheath in the central nervous system (CNS)?

oligodendrocytes

Successive EPSPs from a presynaptic terminal to a postsynaptic neuron is called

temporal summation.

Which of the following statements about the resting membrane potential is TRUE?

the exterior of the cell has a net positive charge and the interior has a net negative charge