A&P - Nerves

Which ion triggers synaptic vesicles to discharge neurotransmitter into the synaptic cleft? sodium potassium calcium magnesium

calcium

The sodium-potassium exchange pump stabilizes resting potential of the neuron membrane at about __________. -70 mV -20 mV +66 mV -90 mV

-70 mV

What is the value for the resting membrane potential for most neurons? +30 mV -90 mV -70 mV

-70 mV

What is the primary role of the enzyme acetylcholinesterase (AChE) at a cholinergic synapse? AChE degrades acetylcholine in the synaptic cleft. AChE binds to ACh receptors, causing them to open. AChE depolarizes the postsynaptic cell. AChE releases acetylcholine into the synaptic cleft.

AChE degrades acetylcholine in the synaptic cleft.

During propagation of the action potential, __________. local currents depolarize a spot adjacent to the active zone the axon hillock depolarizes the initial segment after threshold is reached, sodium channels open rapidly All of the listed responses are correct.

All of the listed responses are correct.

Which of the following best describes the role of calcium in synaptic activity? Calcium breaks down acetylcholine. Calcium influx into the synaptic terminal causes vesicle fusion with the plasma membrane and the release of neurotransmitter. Calcium influx into the axon causes an action potential to propagate into the synaptic terminal. Calcium diffuses across the synaptic cleft and binds to chemically gated channels on the postsynaptic cell.

Calcium influx into the synaptic terminal causes vesicle fusion with the plasma membrane and the release of neurotransmitter.

The concentration of _____ is higher outside than inside the cell.

Na+

The concentrations of which two ions are highest outside the cell. Na+ and A- (negatively charged proteins) K+ and Cl- Na+ and Cl- K+ and A- (negatively charged proteins)

Na+ and Cl-

Where on the neuron is the action potential initiated? Choose the best answer. Cell body Initial segment Dendrite Axon

Initial segment

In which cell does a graded potential occur? adipocytes epithelial cells neurons It occurs in all the cell types listed.

It occurs in all the cell types listed.

The concentration of _____ is higher inside than outside the cell.

K+

The membrane is more permeable to _____.

K+

The membranes of neurons at rest are very permeable to _____ but only slightly permeable to _____. K+; Cl- Na+; Cl- K+; Na+ Na+; K+

K+; Na+

The resting membrane potential is maintained by Na+-K+ pumps that actively transport _____ into and _____ out of the cell.

K+; Na+

Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel? Ligand-gated channels Sodium-potassium ATPases Leak channels Voltage-gated channels

Leak channels

The Na+-K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped? Na+ is pumped out of the cell and K+ is pumped into the cell. K+ is pumped out of the cell and Na+ is pumped into the cell. Both Na+ and K+ are pumped out of the cell. Both Na+ and K+ are pumped into the cell.

Na+ is pumped out of the cell and K+ is pumped into the cell.

What prevents the Na+ and K+ gradients from dissipating? Na+-K+ ATPase Na+ and K+ leaks Na+ cotransporter H+-K+ ATPase

Na+-K+ ATPase

What is the role of neurotransmitter at a chemical synapse? Neurotransmitter binds to receptors on the postsynaptic cell membrane. Neurotransmitter causes vesicles to fuse with the presynaptic membrane. Neurotransmitter causes an action potential in the presynaptic cell. Neurotransmitter causes calcium to enter the presynaptic cell.

Neurotransmitter binds to receptors on the postsynaptic cell membrane.

Ions are unequally distributed across the plasma membrane of all cells. This ion distribution creates an electrical potential difference across the membrane. What is the name given to this potential difference? Resting membrane potential (RMP) Threshold potential Action potential Positive membrane potential

Resting membrane potential (RMP)

What happens just after an axon is depolarized to threshold? All sodium channels open. Some potassium channels open. All potassium channels open. Some sodium channels open.

Some sodium channels open.

When you take a pain reliever, which of the following best describes, in general terms, how this affects the threshold of neurons? Taking a pain reliever decreases the threshold. Taking a pain reliever affects the all-or-none principle of neurons. So, neurons reaching threshold send an action potential at 50%. Taking a pain reliever does not affect the threshold of neurons. Taking a pain reliever increases the threshold.

Taking a pain reliever increases the threshold.

On average, the resting membrane potential is -70 mV. What does the sign and magnitude of this value tell you? The outside surface of the plasma membrane is much more negatively charged than the inside surface. There is no electrical potential difference between the inside and the outside surfaces of the plasma membrane. The inside surface of the plasma membrane is much more negatively charged than the outside surface. The inside surface of the plasma membrane is much more positively charged than the inside surface.

The inside surface of the plasma membrane is much more negatively charged than the outside surface.

Josh and a bunch of friends decided to see how many people they could squeeze into a small car for a charity event. Once inside, Josh felt it get hot, smelly, and like the air was getting squished out of his lungs. He also noticed aches and pains in his joints. Which of the following statements best describes the type of sensory neurons involved? His interoceptors were monitoring his respiratory system. His exteroceptors were bringing in information from the outside world. The proprioceptors were monitoring the position of his skeletal muscles and joints. The interoceptors, exteroceptors, and proprioceptors were all monitoring his condition.

The interoceptors, exteroceptors, and proprioceptors were all monitoring his condition.

The resting membrane potential depends on two factors that influence the magnitude and direction of Na+ and K+ diffusion across the plasma membrane. Identify these two factors. The presence of concentration gradients and Na+-K+ pumps The presence of concentration gradients and voltage-gated channels The presence of concentration gradients and leak channels The presence of a resting membrane potential and leak channels

The presence of concentration gradients and leak channels

Which answer best describes the relative refractory period in the neuron? Choose the correct answer. The neuron's membrane potential is -70 mV. The neuron cannot generate another action potential under extreme stimulation. Potassium ions are entering the neuron through open membrane channels. The resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

The resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

The plasma membrane is much more permeable to K+ than to Na+. Why? The Na+-K+ pumps transport more K+ into cells than Na+ out of cells. There are many more K+ leak channels than Na+ leak channels in the plasma membrane. Ligand-gated cation channels favor a greater influx of Na+ than K+. There are many more voltage-gated K+ channels than voltage-gated Na+ channels.

There are many more K+ leak channels than Na+ leak channels in the plasma membrane.

Female gymnasts can contort their bodies in many different ways and land on a 4" beam with accuracy. Which fiber type is responsible for this ability? Type A fibers Type B fibers Type C Type D fibers

Type A fibers

Which of the following channels is most directly responsible for the properties of the axon that lead to action potential generation? Choose the best answer. Voltage-gated potassium channels Leak sodium channels Leak potassium channels Ligand-gated potassium channels Voltage-gated sodium channels Ligand-gated sodium channels

Voltage-gated sodium channels

What type of channel in the postsynaptic membrane binds neurotransmitter? a chemically gated channel a mechanically gated channel a leakage channel a voltage-gated channel

a chemically gated channel

Which of the following is an example of a presynaptic cell? a muscle cell a secretory cell a Schwann cell a neuron

a neuron

When a person has a stroke, blood leaks into the brain tissue. Which type of neuroglia cells would repair the damage? ependymal cells satellite cells astrocytes oligodendrocytes

astrocytes

During depolarization, which gradient(s) move(s) Na+ into the cell? only the chemical gradient only the electrical gradient Na+ does not move into the cell. Na+ moves out of the cell. both the electrical and chemical gradients

both the electrical and chemical gradients

Events that occur at a cholinergic synapse are listed here, but they are arranged in an incorrect order. Choose the correct order of these events below. (a) Calcium influx triggers exocytosis of ACh. (b) An action potential depolarizes the synaptic terminal. (c) ACh is removed by AChE. (d) ACh binds to receptors on the postsynaptic membrane. b→ a→ d→ c c→ d→ b→ a a→ b→ d→ c b→ a→ c→ d

b→ a→ d→ c

Demyelination disorders such as Multiple Sclerosis and Guillain-Barre Syndrome are particularly dangerous because they __________. facilitate retrograde action potential transmission block sodium channels and thus interfere with action potential transmission reduce the size of the axon diameter decrease the speed of action potential transmission

decrease the speed of action potential transmission

What mechanism releases neurotransmitter from presynaptic neurons? endocytosis pinocytosis phagocytosis exocytosis

exocytosis

When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron, ion channels in the plasma membrane of the receiving neuron open. the receiving neuron becomes more positive inside. the receiving neuron becomes more negative inside. ion channels in the plasma membrane of the sending neuron open. vesicles in the synaptic terminal fuse to the plasma membrane of the sending neuron.

ion channels in the plasma membrane of the receiving neuron open.

Rabies illustrates a negative consequence to otherwise healthy retrograde flow within axons. Which of the following components will not be involved in retrograde flow? axon hillock neuronal cell body axoplasm kinesin

kinesin

Saltatory propagation occurs in _________ axons, in which action potentials _________. myelinated; move from one node of Ranvier to another myelinated; move continuously along the axon toward the axon hillock unmyelinated; move from one node of Ranvier to another unmyelinated; spread by depolarizing the adjacent region of the axon membrane

myelinated; move from one node of Ranvier to another

A molecule that carries information across a synaptic cleft is a receiving neuron. neurotransmitter. sending neuron. synaptic cleft. synapse.

neurotransmitter.

Demyelination results from issues associated with myelin producing cells. Which of the following is an example of a myelin producing cell in the central nervous system (CNS)? oligodendrocytes schwann cells astrocytes ependymal cells

oligodendrocytes

Which type of ion channel is always open? mechanically gated chemically gated passive voltage-gated

passive

The most abundant intracellular cation is __________ while the most abundant extracellular anion is __________. sodium; chloride sodium; protein anions potassium; chloride potassium; protein anions

potassium; chloride

Neuroglia perform all of these functions EXCEPT __________. regulate extracellular fluid composition secrete CSF provide supportive framework release neurotransmitters

release neurotransmitters

What separates the presynaptic and postsynaptic cells at a chemical synapse? calcium channels chemically gated ion channels vesicles filled with neurotransmitter synaptic cleft

synaptic cleft

The small space between the sending neuron and the receiving neuron is the synaptic terminal. calcium channel. synaptic cleft. vesicle. neurotransmitter.

synaptic cleft.

If a signal from a sending neuron makes the receiving neuron more negative inside, the receiving neuron is less likely to generate an action potential. the sending neuron becomes more positive inside. the receiving neuron is more likely to generate an action potential. the sending neuron becomes more negative inside. the receiving neuron immediately generates an action potential.

the receiving neuron is less likely to generate an action potential.

When calcium ions enter the synaptic terminal, they cause an action potential in the sending neuron. the inside of the receiving neuron becomes more positive. neurotransmitter molecules are quickly removed from the synaptic cleft. they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron. the inside of the receiving neuron becomes more negative.

they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron.

Tumors that originate within the central nervous system (CNS) are due to __________. a lack of centrioles within neuronal cell bodies uncontrolled division of neurons in adults uncontrolled divisions of neuroglia all of the above

uncontrolled divisions of neuroglia

The generation of an action potential in a neuron requires the presence what type of membrane channels? leakage channels voltage-gated channels chemically gated channels membrane channels are not required

voltage-gated channels