Carla 7

Which of the following is TRUE of a graded potential? A. A stimulus causes ion channels to open which changes membrane permeability. B. The potential is propagated with a constant magnitude. C. The potential is all-or-none. D. No summation of potentials occurs.

A stimulus causes ion channels to open which changes membrane permeability.

Which of the following is NOT true about changes in the membrane potential? A. An increase in the movement of potassium out of the cell creates a hyperpolarization B. An increase in the movement of calcium ions into the cell creates a hyperpolarization C. An increase in the movement of sodium ions into the cell causes depolarization D. An increase in the movement of chloride ions into the cell causes hyperpolarization

An increase in the movement of calcium ions into the cell creates a hyperpolarization

What type of membrane channels are non-gated and responsible for the permeability of the membrane at rest? A. Na+ / K+ ion pump B. Leak channels C. Ligand-gated ion channels D. Voltage-gated ion channels E. None of the above

Leak channels

At the normal resting potential of a typical neuron, its ion exchange pump A. exchanges 1 intracellular sodium ion for 2 extracellular potassium ions. B. exchanges 2 intracellular sodium ions for 1 extracellular potassium ion. C. exchanges 3 intracellular sodium ions for 1 extracellular potassium ion. D. exchanges 3 intracellular sodium ions for 2 extracellular potassium ions. E. exchanges 3 extracellular sodium ions for 2 intracellular potassium ions.

exchanges 3 extracellular sodium ions for 2 intracellular potassium ions.

The ion needed to initiate the release of acetylcholine into the synaptic cleft is A. sodium. B. potassium. C. calcium. D. chloride. E. zinc.

calcium

The axon is connected to the soma or cell body at a region called the A. telodendria. B. synaptic knobs. C. collaterals. D. hillock. E. synapse.

hillock

Cells responsible for information processing and transfer are A. neuroglia. B. Schwann cells. C. neurons. D. astrocytes. E. microglia.

neurons

13. The brain and spinal cord comprise the A. autonomic nervous system. B. peripheral nervous system. C. central nervous system. D. efferent nervous system. E. afferent nervous system

central nervous system

Branches that sometimes occur along the length of an axon are called A. action potentials. B. synaptic knobs. C. collaterals. D. hillock. E. synapse.

collaterals.

Opening of sodium channels in the membrane of a neuron results in A. depolarization. B. repolarization. C. hyperpolarization. D. increased negative charge inside the membrane. E. none of these.

depolarization

The sodium-potassium exchange pump A. pumps calcium ions along their concentration gradient B. transports sodium ions into the cell during depolarization. C. transports potassium ions out of the cell during repolarization. D. moves sodium and potassium in the direction of their chemical gradients. E. requires ATP to function.

requires ATP to function

Voluntary control of skeletal muscles is provided by the A. sympathetic nervous system. B. parasympathetic nervous system. C. afferent nervous system. D. somatic nervous system. E. autonomic nervous system.

somatic nervous system

The site of intercellular communication between neurons is A. dendrite. B. synaptic knob. C. collateral. D. hillock. E. synapse.

synapse

Neurotransmitters are released from the A. dendrites. B. synaptic terminals/knobs. C. collaterals. D. hillock. E. synapse.

synaptic terminals/knobs

The following is a series of events that occur at a typical cholinergic synapse. Place the events in the correct sequence. 1. Calcium ions enter the cytoplasm of the synaptic knob and ACh release occurs. 2. Arriving action potential depolarizes the synaptic knob and the presynaptic membrane. 3. Depolarization ends as ACh is broken down into acetate and choline by AChE. 4. ACh release ceases because calcium ions are removed from the cytoplasm of the synaptic knob. 5. The synaptic knob reabsorbs choline from the synaptic cleft and uses it to resynthesize ACh. 6. ACH diffuses across the synaptic cleft and binds to receptors on the postsynaptic membrane. 7. Sodium channels on postsynaptic surface are activated, producing a graded depolarization. The correct sequence of events is A. 2, 1, 6, 7, 4, 3, 5. B. 2, 6, 8, 1, 3, 5, 7. C. 1, 3, 5, 7, 2, 4, 6. D. 1, 2, 4, 5, 3, 6, 7. E. 7, 4, 5, 6, 2, 3, 1.

2, 1, 6, 7, 4, 3, 5.

The following are the main steps in the generation of an action potential. 1. Sodium channels are inactivated. 2. Potassium channels open and potassium moves out of the cell initiating repolarization. 3. Sodium channels regain their normal properties. 4. A graded depolarization brings an area of an excitable membrane to threshold. 5. A temporary hyperpolarization occurs. 6. Sodium channel activation occurs. 7. Sodium ions enter the cell and depolarization occurs. The proper sequence of these events is A. 4, 6, 7, 3, 2, 5, 1 B. 4, 6, 7, 1, 2, 3, 5 C. 5, 7, 4, 1, 2, 3, 5 D. 2, 4, 6, 7, 1, 3, 5 E. 4, 2, 5, 6, 7, 3, 1

4, 6, 7, 1, 2, 3, 5

Tetradotoxin is a toxin that blocks the sodium channels from opening. What effect would this have on the function of neurons? A. Neurons would depolarize more rapidly. B. Action potentials would lack a repolarization phase. C. The refractory period would be shorter than normal. D. The neurons would not be able to propagate action potentials. E. none of these

The neurons would not be able to propagate action potentials

During saltatory conduction, A. action potentials move in all directions along an axon. B. action potentials occur between successive nodes along the length of the stimulated axon. C. local currents depolarize adjacent areas of membrane so that action potentials continue to form along the membrane. D. action potentials produce a local current that is strong enough to spread along the length of the axon. E. local potentials produce a continuous outward flow of potassium ions.

action potentials occur between successive nodes along the length of the stimulated axon.

If the sodium-potassium pumps in the cell membrane fail to function, A. the extracellular concentration of potassium ions will increase. B. the intracellular concentration of sodium ions will increase. C. the membrane will lose its capacity to generate action potentials. D. the inside of the membrane will have a resting potential that is more positive than normal. E. all of these will occur.

all of these will occur

The all-or-none principle states that A. all stimuli will produce identical action potentials. B. all stimuli great enough to bring the membrane to threshold will produce identical action potentials. C. the greater the magnitude of the stimuli, the greater the intensity of the action potential. D. only sensory stimuli can activate action potentials. E. only motor stimuli can activate action potentials.

all stimuli great enough to bring the membrane to threshold will produce identical action potentials.