Anatomy and Physiology chapter 11 & 12

Are unipolar neurons in a tissue sample of the PNS more likely to function as sensory neurons or motor neurons?

Most sensory neurons of the PNS are unipolar, so these neurons most likely function as sensory neurons.

What factors account for the local currents associated with graded potentials?

Movement of sodium ions parallel to the inner and outer surfaces of the ploasma membrane- after passing through open chemically gated sodium channels- accounts for the local currents associated with graded potentials.

Identify the neuroglia of the peripheral nervous system.

Neuroglia of the peripheral nervous system are satellite cells and schwann cells.

The axon nerve impulse is self-propagating and occurs in the direction towards the cell body. A) True B) False

false: The direction of conduction within a dendrite is towards the soma.

The levels of which neurotransmitter are affected by the mood-elevator, cocaine? A) serotonin B) GABA C) norepinephrine D) acetylcholine

norepinephrine

The _______________ are the types of neuroglial cells that provide myelin in the central nervous system. A) astrocytes B) oligodendrocytes C) microglia D) ependyma

oligodendrocytes

The portion of the brain involved in understanding speech and using words is located in the ____________ of the cerebrum. A) frontal lobe B) parietal lobe C) occipital lobe D) temporal lobe

parietal lobe

A neuron will not respond to any stimulus during its absolute refractory period. A) True B) False

true: A nerve can be made to respond again during the relative refractory period.

The ion that always moves in a membrane direction opposite to sodium is K+. A) True B) False

true: Because of the sodium-potassium membrane pump, Na+ is always exchanged for K+.

Calcium channels open during synaptic transmission. A) True B) False

true: Calcium channels allow calcium to move across a neuron membrane during synaptic transmission; some researchers consider calcium to be a neurotransmitter.

A damaged CNS nerve could not regenerate as easily as a PNS fiber. A) True B) False

true: Correct Answer: PNS fibers are surrounded with the Schwann cells that enable regeneration.

Define action potential.

An action potential is a propogated change in the transmembrane potential of excitable cells, initiated by a change in the plasma membrane's permeability to sodium ions.

Describe a synapse.

A synapse is the site of communication between a neuron and some other cell; if the other cell is not a neuron, the term neuromuscular junction or neuroglandular synapse is often used.

Classify neurons according to their function

According to function, neurons are classified as sensory neurons, motor neurons, or interneurons.

Classify neurons according to their structure

According to structure, nuerons are classified as anaxonic, bipolar, unipolar, or multipolar.

Define excitatory postsynaptic potential (EPSP) and inhibitory postsynaptic potential (IPSP).

An excitatory postsynaptic potential (EPSP) is a graded depolarization of a postsynaptic membrane by a chemical neurotransmitter released by a presynaptic cell. An inhibotory postsynaptic potential (IPSP) is a graded hyperpolarization of a postsynaptic membrane after the arrival of a neurotransmitter.

Which glial cell protects the CNS from chemicals and hormones circulating in the blood?

Astrocytes protect the CNS from circulating chemicals and hormones by maintaining the blood-brain barrier.

Identify the neuroglia of the central nervous system.

Central nervous system neuroglia are ependymal cells, astrocytes, oligodendrocytes, and microglia.

Identify the three types of gated channels, and state the conditions under which each operates.

Chemically gated channels operate when they bind specific chemicals (such as ACh); voltage-gated channels operate in response to change in the transmembrane potential; and mechanically gated channels operate in response to physical distortion of the membrane surface.

Define continuous propogation and saltatory propagation.

Continuous propotation is the propagation of an action potential along an unmyelinated axon, wherein the action potential affects every portion of the membrane surface. Saltatory propagation is the relatively rapid propagation of an action potential between successive nodes of myelinated axon

What effect would decreasing the concentration of extracellular potassium ions have on the transmembrane potential of a neuron?

Decreasing the concentration of extracellular potassium ions would cause more potassium to leave the cell, which would make the transmembrane potential of the neuron more negative.

Describe depolarization, repolarization, and hyperpolarization.

Depolarization is a shift from the resting potential in which the transmembrane potential becomes less negative. Repolarization is the return of the trnasmembrane potential to the resting potential after the membrane has been depolarized. Hyperpolarization is a shift from the resting potential in which the transmembrane potential becomes more negative.

An effector is usually a muscle or motor nerve. A) True B) False

False:Correct Answer: An effector is usually a muscle or gland.

Elderly nursing home residents are often called by their first names, rather than by their last names. Why is this the case? A) Nursing homes are friendly places and residents like to be on a first-name basis with their caretakers. B) First names are easier for caretakers to remember. C) First names are stored in the residents' long-term memories and are remembered while last names are less likely recalled. D) Elderly residents often remarry and change their last names; calling them by first names avoids confusion.

First names are stored in the residents' long-term memories and are remembered while last names are less likely recalled

Define gated channels

Gated channels are active channels in the plasma membrane that typically open in respoonse to specific stimuli.

Contrast an electrical synapse with a chemial synapse.

In chemical synapses, a neurotransmitter crosses a narrow synaptic cleft, whereas in electrical synapses the membranes of the presynaptic and postsynaptic cells are joined together by gap junctions.

if a single EPSP depolarizes the initial segment from a resting potential of -70mV to -65mV, and threshold is at -60mV, will an action potential be generated

No action potential will be generated, because the depolarization did not reach threshold.

The following statements all regard reflexes. Choose the statement that is incorrect. A) Reflexes are automatic, subconscious responses. B) Reflexes involve at least three neurons and all arc through the spinal cord. C) The knee-jerk reflex is an example of a monosynaptic reflex. D) Sometimes reflexes are carried out properly because of reciprocal innervation.

Reflexes involve at least three neurons and all arc through the spinal cord.

Cut neurons possess limited capabilities for regeneration. The type of neuroglial cell that aids regeneration by forming a regeneration tube to help reestablish the former connection is the _______________. A) Schwann cell B) astrocyte C) microglial cell D) ependymal cell

Schwann cell

name the structural componenets of a typical neuron.

Structural components of a typical neuron include a cell body (including the nucleus and perikaryon, plus neurofilaments and neurotubules), an axon (including the axon hillock, axoplasm, axolemma, telodendria, collateral branches, an synaptic terminals), and dendrites (including dendritic spines).

What is synaptic fatigue, and how does the synapse recover?

Synaptic fatigue occurs in a synaptic know when intensive stimulation exceeds the knob's ability to keep pace with the demand for neurotransmitter. It is reversed and eliiminated by the resynthesis of the neurotransmitter.

What determines the frequency of action potential generation?

The degree of sustained depolarization at the axon hillock determines the frequency of action potential generation.

List teh events involved in the generation of an action potential.

The events involved in the generation of action potentials are (1) depolarization to threshold, (2) activation of sodium channels and rapid depolarization, (3) inactivation of sodium channels and activation of potassium channels, and (4) closing of potassium channels.

The greater the degree of sustained depolarization at the axon hillock, the _______(higher or lower) the frequency of generation of action potentials.

The greater the degree of sustained depolarization at the axon hillock, the HIGHER the frequency of generation of action potentials.

Describe the parts of a chemical synapse.

The parts of a chemicla synapse- the site where a neuron communicates with another neuron or with a cell of a different type- are a presynaptic cell and a postsynaptic cell, whose plasma membranes are separated by a narrow gap called the synaptic cleft.

Compare the central and peripheral nervous systems

The peripheral nervous system or PNS contains the nerves, which leave the brain and the spinal cord and travel to certain areas of the body. The peripheral nervous system's main job is to send information gathered by the body's sensory receptors to the CNS as quickly as possible

What is the relationship between myelin and the propogation speed of action potentials?

The presence of myelin greatly increases the propagation speed of action potentials.

Compare the absolute refractory period with the relative refractory period.

The refractory period is the time between the initiation of an action potential and the restoration of the normal resting potential. The absolute refractory period is the portion of the refractory period during which the membrane cannot respond to further stimulation, no matter its magnitude. The relative refractory period is the time during which the membrane can respond only to a larger-than-normal stimulus.

Define resting potential.

The resting potential is the transmembrane potential of an undisturbed (nonstimulated) cell.

What happens at the sodium-potassium exchange pump?

The sodium-potassium exchange pump maintains the cell's resting potential by ejecting three sodium ions from the cell for every two potassium ions it revovers from the extracellular fluid.

Select the incorrect statement about nerve impulse conduction. A) Saltatory conduction involves Schwann cells and occurs at greater speed than on unmyelinated fibers. B) Nerve impulses occur in an all-or-none manner. C) The neuron cannot be stimulated during the absolute refractory period. D) The strength of impulses carried along a single nerve fiber can vary with the strength of their stimulus.

The strength of impulses carried along a single nerve fiber can vary with the strength of their stimulus.

Motor neurons usually have one axon and several dendrites. A) True B) False

True: All fibers have only one axon but motor neurons are also called multipolar because they have several dendrites.

In which part of the nervous system does wallerian degeneration occur?

Wallerian degeneration occurs in the PNS, where schwann cells participate in the repair of damaged nerves.

Define graded potential.

a graded potential (also called a local potential) is a change in the transmembrane potential that cannot spread from the site of stimulation.

Which types of neurons are likely to increase muscular activities? A) accelerator neurons B) inhibitory neurons C) bipolar neurons D) sensory neurons

accelerator neurons

Myasthenia gravis reflects a deficiency in communication by _______________ because receptors for this neurotransmitter have been destroyed. A) acetylcholine B) norepinephrine C) GABA D) dopamine

acetylcholine

The most common neurotransmitter in the body is _____. A) serotonin B) dopamine C) acetylcholine D) norepinephrine

acetylcholine

Nerves impulses always travel to the brain through _____ fibers. A) neuron B) dendrite C) nerve D) axon

axon

The embryonic hindbrain gives rise to what structures in the brain? A) cerebrum and basal ganglia B) diencephalon C) midbrain D) cerebellum, pons, and medulla oblongata

cerebellum, pons, and medulla oblongata

Fibers that originate from different parts of the nervous system and lead to the same neuron are exhibiting _____________. A) facilitation B) convergence C) divergence D) neuromodulation

convergence

Branched nerve fibers that convey impulses toward the cell body of a neuron are called _____________ A) axons B) dendrites C) axon collaterals D) axon terminals

dendrites

The ___________ is the outermost meninx, and forms supportive and protective partitions between some portions of the brain. A) dura mater B) arachnoid mater C) pia mater D) denticulate mater

dura mater

Which type of neuroglial cells help regulate the composition of cerebrospinal fluid? A) astrocytes B) oligodendrocytes C) microglia D) ependyma

ependyma

A synapse is a junction between two dendrites. A) True B) False

false: A synapse usually occurs either between an axon and dendrite or axon and soma.

Convergence is a way of amplifying a stimulus through a neuronal pool. A) True B) False

false: Divergence would be a better arrangement to spread out or amplify the significance of a stimulus.

Somatic afferent fibers would carry sensory impulses away from the brain, towards areas such as the eye. A) True B) False

false: Impulses are carried in these somatic afferent fibers, away from the eye.

Gray matter most significantly contains cell bodies and dendrites. A) True B) False

false: It is more significant that gray matter contains synapses and cell bodies.

Neurotransmitters are usually released into the synaptic vesicles during depolarization. A) True B) False

false: Neurotransmitters are stored in the axon vesicles.

Nodes of Ranvier are only found on motor axons. A) True B) False

false: Nodes of Ranvier can also be found on dendrites.

Sodium moves out of an axon as it is depolarizing. A) True B) False

false: Sodium rushes in and potassium moves out during depolarization.

The all-or-none response means that a subthreshold stimulus can never stimulate a nerve. A) True B) False

false: The all-or-none law can be satisfied even if two nerves that are both releasing subthreshold stimuli cause summation to occur.

A damaged phrenic nerve would heal more slowly than a severed spinal nerve. A) True B) False

false: The phrenic nerve is a PNS nerve with a Schwann cell neurolemma and would heal faster than a CNS spinal cord fiber without one.

The action potential is around -70 mv. A) True B) False

false: The resting potential is -70 mv, and the action potential is +30mv

There is a higher concentration of K+ outside of a resting neuron than Na+. A) True B) False

false: There is a higher concentration of Na+ outside of a fiber at rest because of the Na+-K+ pump.

Sub-threshold stimuli can never evoke an action potential. A) True B) False

false: Two or more sub-threshold stimuli could result in summation.

Which tract would be most likely to carry sensory impulses from the skin and joints to the brain? A) fasciculus gracilis B) corticospinal tracts C) reticulospinal tracts D) rubrospinal tracts

fasciculus gracilis

When a person thinks and solves problems, which area of the cerebrum is involved? A) frontal lobe B) parietal lobe C) occipital lobe D) temporal lobe

frontal lobe

In which portion of the spinal cord do the interneurons lie? A) cervical enlargement B) lumbar enlargement C) gray matter D) white matter

gray matter

In response to a stimulus, if the membrane potential becomes more negative than the resting potential, we say the membrane is _______________. A) hyperpolarized B) depolarized C) unpolarized D) polarized

hyperpolarized

The _________________ is a portion of the brain that maintains homeostasis by linking activities of the endocrine and nervous systems together. A) thalamus B) hypothalamus C) infundibulum D) mammillary body

hypothalamus

What effect would a chemical that blocks voltage-gated sodium channels in a neruon's plasma membrane have on its transmembrane potential

if the voltage-gatedsodium channels in a neuron's cell membrane could not open, sodium ions could not rush into the cell, and its transmembrane potential would not change.

The _____ cells are capable of removing a blood clot from the brain. A) astrocyte B) oligodendrocyte C) microglia D) ependymal

microglia

Which type of neuroglia would occur in increased numbers in the brain tissue of a person with a CNS infection?

microglia, small phagocytic cells, occur in increased numbers in infected (and damaged) areas of the CNS.

When a neuron reaches action potential, it depolarizes and repolarizes in an amount of time on the order of ________________. A) seconds B) milliseconds C) microseconds D) nanoseconds

milliseconds

Why is a CNS neuron not usually replaced after it is injured?

most CNS neurons lack centrioles, which organize the microtubules of the spindle apparatus during mitosis, so these cells cannot divide and replace themselves.

A neuron with many nerve fibers arising from its cell body and that carries impulses away from the brain would be classified as __________________. A) multipolar B) bipolar C) unipolar and sensory D) multipolar and motor

multipolar and motor

Which of these cells does not belong with the others? A) microglia B) neuron C) astrocyte D) oligodendroglia

neuron

Describe the role of regulatory neurons.

regulatory neurons facilitate or inhibit the activaties of presynaptic neurons by affecting the plasma membrane of the cell body, or by altering the sensivity of synaptic knobs

The myelin sheath around a neuron is actually produced by the: A) neuron B) axon C) dendrite D) Schwann cell

schwann cell

Myelin sheaths on the outsides of many axons are contributed by ______________. A) the axon itself B) secretory vesicles C) Schwann cells D) the cell bodies of the neuron

schwann cells

The cells that conduct messages towards the brain are the: A) motor neurons B) sensory neurons C) interneurons D) neuroglia

sensory neurons

Excessive sleeping is most likely due to the presence of too much of which neurotransmitter? A) GABA B) norepinephrine C) serotonin D) dopamine

serotonin

At resting potential, the ion distribution inside and outside of a neuron is such that __________ ions are most abundant on the outside of the cell, while __________ ions are most abundant on the inside of the cell. A) potassium; sodium B) sodium; potassium C) calcium; phosphate D) sulfate; potassium

sodium; potassium

Which items should not be grouped together? A) spinal nerve B) cranial nerve C) spinal cord D) PNS

spinal cord

Which term does not belong with the others? A) brain B) spinal cord C) CNS D) spinal nerve

spinal nerve

Compare temporal summation with spatial summation.

temporal summation is the additon of a rapid succession of stimuli occurring at a single synapse. Spatial summation involves the addition of simultaneous stimuli applied at different locations; that is, it involves multple synapses that are active simultaneously.

Describe the neurilemma

the neurilemma is the outer surface of a schwann cell encircling an axon.

Which of these is true when a neuron is at rest? A) the outside is positive B) the outside is negative C) there is no voltage D) the inside is positive

the outside positive

Drugs that hyperpolarize an axon would make the nerve less sensitive to stimulations. A) True B) False

true: Hyperpolarization causes the resting potential to be greater than -70mv, such as -80mv, thereby making it more difficult to depolarize a neuron.

Food additives, such as MSG (monosodium glutamate) derived from glutamic acid, could act as neurotransmitters. A) True B) False

true: Many chemicals such as monosodium glutamate could stimulate nerves.

Most brain tumors arise from neuroglial cell overgrowth. A) True B) False

true: Neuroglial cells are the only nervous tissue cells that can divide.

Oligodendrocytes can be found within the brain. A) True B) False

true: Oligodendrocytes produce myelin in the CNS

Having myelin increases the velocity of conduction. A) True B) False

true: Saltatory conduction is made possible because of the myelin sheath.

Local potential changes are graded. A) True B) False

true: The amount of stimulation is directly related to its intensity.

Norepinephrine, epinephrine, dopamine and serotonin are classed as monoamine neurotransmitters. A) True B) False

true: These all have an amine, NH2 group in them; the first terms also can be called catecholamines except serotonin.

Vesicles are intracellular accumulation of neurotransmitter. A) True B) False

true: Vesicles store neurotransmitters until they are released.

Nervous tissue includes areas of connective tissue. A) True B) False

true:There are connective tissue fibers that surround nerve fibers.