Practice Set 4B Flashcards
Which best describes an electrical current?
The movement of charged particles like ions
Which term is used to refer to a cell membrane across which there is a separation of electrical charge, so that one side is more positive and the other side is more negative?
Polarized
Which term refers to the voltage difference (electrical potential) across the plasma membrane of a neuron when it is at rest and not engaged in electrical signaling?
Resting membrane potential
At rest, K+ diffuses out of the cell through leak channels, resulting in a slight local accumulation of positive charge on the outside of the membrane (due to excess K+) and a slight local accumulation of negative charge on the inside of the membrane (due to decreased K+). This describes the basis of the ________ membrane potential.
resting
An electrical potential is a form of what type of energy?
Potential energy
Which term refers to the flow of charged particles from one point to another?
Current
Which of the following contributes to the development of the resting membrane potential in neurons?
K+ is more concentrated in the ICF than in the ECF.
True or false: As long as there is an electrical potential across a cell membrane, we say that the membrane is polarized.
True
Which is most likely to be the resting membrane potential of a neuron?
-70 mV
At rest, K+ diffuses out of the cell through leak channels in the plasma membrane. Why does K+ diffusion result in a negative membrane potential?
It creates a slight local accumulation of K+ on the outside of the membrane relative to the inside.
Which best describes an electrical potential?
A form of potential energy that can produce current
Which ion has the greatest influence on the resting membrane potential of most neurons?
Potassium
Which term is used to refer to a cell membrane across which there is a separation of electrical charge, so that one side is more positive and the other side is more negative?
Polarized
Which term refers to the voltage difference (electrical potential) across the plasma membrane of a neuron when it is at rest and not engaged in electrical signaling?
Resting membrane potential
Choose all of the following statements that are true about sodium?
Na+ is about 12 times as concentrated in the ECF as in the ICF.
The resting plasma membrane is much less permeable to Na+ than to K+.
Choose all statements that are true regarding the Na+-K+ pump.
It moves Na+ out of the cell and K+ into the cell.
It helps maintain the proper ion distribution across the membrane.
It requires the use of ATP.
Choose all that are characteristics of local potentials.
Graded
Decremental
A negative membrane potential indicates which of the following?
The inside of the membrane is negatively charged relative to the outside.
Why is sodium more concentrated in the ECF than in the ICF of most neurons?
Sodium is actively pumped out of the cell by transporter proteins
Choose all that are true regarding the Na+-K+ pump.
It accounts for about 70% of the energy (ATP) required by the nervous system.
It helps maintain the proper ion distribution across the membrane, compensating for ion leakage.
Which ion has the greatest influence on the resting membrane potential of most neurons?
Potassium
Which term refers to decremental changes in electrical potential along a dendrite or the soma?
Local potentials
Which term refers to the upward change in membrane potential during an action potential?
Depolarization
A shift in membrane voltage to a value that is more negative than the resting membrane potential is called which of the following?
Hyperpolarization
Choose all that are characteristics of local potentials.
Decremental
Graded
Place these events into the order in which they occur during a single action potential.
Local potential depolarizes membrane
Threshold is reached
Depolarization
Repolarization
Hyperpolarization
During which part of the action potential do most voltage-gated sodium channels open?
Depolarization
In order for local potentials to trigger an action potential, the membrane must depolarize up to a level called which of the following?
Threshold
Which term refers to the period of time after a nerve cell has responded to a stimulus in which it cannot be excited by a threshold stimulus?
Refractory period
Resting membrane potential
Depolarization begins
Repolarization begins
Both types of voltage-gated channels are closed.
Voltage-gated Na+ channels open; voltage-gated K+ channels open more slowly.
Voltage-gated Na+ channels inactivate; voltage-gated K+ channels remain open longer.
The all-or-none law of action potentials states which of the following?
A neuron will fire at maximum voltage if a stimulus depolarizes it to threshold.
After a nerve cell responds to a stimulus, the period of time when the cell can not respond again except to an unusually strong stimulus is called what?
Relative refractory period
The refractory period in which no stimulus of any strength will trigger a new action potential is the ______ refractory period.
absolute
What is a quick, involuntary, stereotyped response to a stimulus is called?
Reflex
In order for local potentials to trigger an action potential, the membrane must depolarize up to a level called which of the following?
Threshold
After a nerve cell responds to a stimulus, the period of time when the cell can not respond again, regardless of the strength of stimulus, is called the _____ refractory period.
absolute
The refractory period in which it is possible to trigger a new action potential, but only with an unusually strong stimulus is the ______ refractory period.
relative
Choose all that are components of a monosynaptic somatic reflex arc?
Receptor in skin, muscle or tendon
Efferent nerve fiber
Skeletal muscle
Afferent nerve fiber
Which stimulus causes a muscle to reflexively contract?
Increased stretch
Which are true regarding the absolute refractory period? Select all that apply.
No stimulus of any strength will trigger a new action potential.
It refers only to a small patch of the membrane; other parts of the neuron can still be stimulated while a small area of it is refractory.
It occurs during the depolarization and repolarization phases of the action potential.
In which reflex is there a quick contraction of flexor muscles in response to a painful stimulus?
Flexor
A reflex in which a contralateral extensor muscle is contracted is called a __________ extension reflex.
crossed
Place the components of a reflex arc in order.
Receptor
Afferent nerve fiber
Integration center
Efferent nerve fiber
Effector
In response to stretching, a muscle reflexively does which of the following?
Contracts
A quick contraction of flexor muscles in response to a painful stimulus is called a _______ reflex.
flexor
A reflex that occurs in response to excessive tension on a tendon is called a(n) ______________.
flexor reflex
Which is usually under involuntary control?
Autonomic nervous system
Which nervous system has two nerve fibers connecting the CNS to an effector?
Autonomic
What does the axon of a postganglionic neuron synapse with?
An effector
Which reflex occurs in response to excessive tension on a tendon?
Tendon
Which nervous system regulates conscious, voluntary movements of the skeletal muscles?
Somatic nervous system
From where do all preganglionic nerve fibers of the sympathetic nervous system arise?
Thoracic and lumbar regions of the spinal cord
Which nervous system transmits only excitatory signals to effector cells?
Somatic nervous system
Which efferent pathway has a single nerve fiber extending from the CNS to effector?
Somatic
Where are the cell bodies of sympathetic preganglionic fibers located in the spinal cord?
Lateral gray horn
Which nervous system has two nerve fibers connecting the CNS to an effector?
Autonomic
The division of the ANS that has relatively short preganglionic fibers and long postganglionic fibers is which division?
Sympathetic
Which describes a preganglionic neuron in the ANS?
It has its cell body in the spinal cord or the brainstem and its axon terminates in a ganglion
Which type of neurons make up the adrenal medulla?
Postganglionic sympathetic
The nerves of the sympathetic nervous system arise from which regions of the spinal cord?
Thoracic
Lumbar
The division of the ANS that develops from the same embryonic tissue as the adrenal medulla is the ________ division.
sympathetic
Regarding the length of fibers, the parasympathetic nervous system has ______ preganglionic fibers and ______ postganglionic fibers.
long, short
Choose all the regions of the CNS that the nerves of the parasympathetic nervous system arise from.
Sacral division of spinal cord
Brainstemc
Within the ANS, the effects of the ______ division are often general and widespread, while in the _______ division the effects are more specific and local.
sympathetic, parasympathetic
What is the alternative name for the craniosacral division of the ANS?
Parasympathetic division
The ganglia of the sympathetic division are located ______.
near the spinal column
The neurotransmitter ______ binds to cholinergic receptors.
acetylcholine
The sympathetic division of the ANS is also called the ______ division as it arises from the thoracic and lumbar regions of the spinal cord.
thoracolumbar
The division of the ANS that develops from the same embryonic tissue as the adrenal medulla is the __________ division.
sympathetic
Which receptors bind to ACh?
Cholinergic
The nerves of the sympathetic nervous system arise from which regions of the spinal cord?
Lumbar
Thoracic
Which type of receptor can either be inhibited or excited by the binding of acetylcholine?
Muscarinic
What are two receptors that bind norepinephrine?
Alpha-adrenergic
Beta-adrenergic
What is the alternative name for the craniosacral division of the ANS?
Parasympathetic division
The neurotransmitter ______ binds to cholinergic receptors.
acetylcholine
What effect does the parasympathetic system have on the respiratory system?
Bronchoconstriction
Which receptors are cholinergic receptors that are found at the synapses of all autonomic ganglia, on cells of the adrenal medulla, and at neuromuscular junctions?
Nicotinic
Receptors for epinephrine and norepinephrine are called _________ receptors.
adrenergic
Choose all the regions of the CNS that the parasympathetic division of the ANS arise from.
Brain
Sacral spinal cord
Choose all that are effects of the parasympathetic division on the digestive system.
Increased gastric motility
Increased pancreatic enzyme secretion
Increased gastrointestinal secretion
The type of innervation that refers to the fact that many structures in the body are innervated by nerve fibers from both the sympathetic and parasympathetic divisions of the ANS is called __________ innervation.
dual
The neurotransmitter norepinephrine binds to ______ receptors.
adrenergic
The neurotransmitter norepinephrine binds to ______ receptors.
adrenergic
What is the alternative name for the craniosacral division of the ANS?
Parasympathetic division
Which division of the ANS causes a decrease in gastrointestinal secretions, pancreatic enzymes, and pancreatic insulin?
Sympathetic
An organ that receives both sympathetic and parasympathetic fibers is said to have what?
Dual innervation
Which receptors are cholinergic receptors that are found at the synapses of all autonomic ganglia, on cells of the adrenal medulla, and at neuromuscular junctions?
