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2nd Shifting PHA6131 LEC > Toxic Responses of the Nervous System > Flashcards

Toxic Responses of the Nervous System Flashcards

1
Q

Three basic functions of the nervous system

A

Relays information, motor functions, Integrates thought processes, learning and memory

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2
Q

two fundamental anatomical divisions of the nervous system

A

central and peripheral nervous system

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3
Q

It is the control center, composed of brain and spinal cord

A

Central nervous system

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4
Q

T/F: the central nervous system analyzes information received from sensory receptors, and in response, it issues motor commands to control body functions

A

True

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5
Q

What are the two types of nerves under the peripheral nervous system?

A

Afferent nerves and efferent nerves

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6
Q

Modified T/F: Efferent nerves relays sensory information to the CNS. Afferent nerves relays motor commands from the CNS to the various muscles and glands

A

BOTH FALSE. Afferent nerves relays sensory information to the CNS. Efferent nerves relays motor commands from the CNS to the various muscles and glands

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7
Q

Efferent nerves are further organized into two systems, which are:

A

Somatic nervous system and Autonomic nervous system

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8
Q

Modified T/F: Somatic nervous system carries motor information to smooth muscles, cardiac muscles, and various glands. Autonomic nervous system is also known as the voluntary system, which carries motor information to the skeletal muscles.

A

BOTH FALSE. Autonomic nervous system carries motor information to smooth muscles, cardiac muscles, and various glands. Somatic nervous system is also known as the voluntary system, which carries motor information to the skeletal muscles.

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9
Q

T/F: Skeletal muscles, smooth muscles, cardiac muscles, and glands are effectors

A

True

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10
Q

What is the major difference between the somatic and autonomic nervous system?

A

conscious control

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11
Q

The nervous system is protected from the adverse effects of many potential toxicants by an anatomical barrier between the blood and the brain, or a ____________________

A

blood-brain barrier (BBB).

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12
Q

To gain entry to the nervous system, molecules must pass into the __________________ of endothelial cells of the brain rather than ________________ endothelial cells, as they do in other tissues.

A

cell membranes; between

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13
Q

among the unique properties of the endothelial cells in the nervous system is the presence of __________________ between the cells, this is why molecules cannot easily penetrate between them

A

tight junctures

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14
Q

T/F: the BBB contains xenobiotic transporters, which transports xenobiotics that have diffused through the endothelial cells back into the blood

A

True

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15
Q

If not actively transported into the brain, the penetration of toxicants or their metabolites is largely related to their _______________.

A

lipid solubility

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16
Q

The _______________, ______________, and a small number of other sites within the brain are not protected by blood-tissue barriers.

A

Spinal ganglia; autonomic ganglia

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17
Q

Neurons are highly dependent on ________________ because they use the energy to maintain proper ion gradients

A

aerobic metabolism

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18
Q

These lead to early signs of neuronal dysfunction

A

Cyanide and CO poisoning

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19
Q

neuronal dysfunction can be a combination of direct toxic effects on neurons and secondary damage from ________________________

A

systemic hypoxia or ischemia

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20
Q

It is a toxicant-induced irreversible loss of neurons, including its cytoplasmic extensions, dendrites, axons, and the myelin ensheathing the axon.

A

neuronopathy

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21
Q

This is where the axon degenerates while neuronal cell body continues to survive.

A

axonopathy

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22
Q

Modified T/F: Neuronopathy is characterized by loss of cell body and all of its processes with no potential for regeneration. Axonopathy includes loss of myelin surrounding the axon

A

BOTH TRUE

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23
Q

This is a functional assessment where sensory-specific information on nerve conduction velocity and integrity is assessed.

A

electrophysiological tests

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24
Q

This is an observation with regards to behavior. This is under functional assessments

A

Functional observational studies

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25
Q

Other types of functional observational studies

A

Irwin screens, tests of motor activity, and expanded clinical observations

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26
Q

Individual neurotoxic compounds typically target the _______, the _______, the myelinating cell, or the ___________________ system.

A

neuron; axon; neurotransmitter

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27
Q

Modified T/F: A large number of compounds are known to result in toxic neuronopathies. All of these toxicants share certain features.

A

BOTH TRUE

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28
Q

T/F:

Neuropathy pathway: apoptosis or necrosis –> initial injury to neurons –> permanent loss of neurons

A

False. Initial injury to neurons –> apoptosis or necrosis –> permanent loss of neurons

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29
Q

The neurotoxic effect of this neurotoxicant is the degeneration of the dorsal root ganglion cells, and axonal degeneration in the PNS

A

doxorubicin

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30
Q

The neurologic finding in this neurotoxicant includes ataxia, constriction of visual fields, paresthesias in adults, and psychomotor retardation (fetal exposure)

A

methylmercury (organic mercury)

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31
Q

The neurologic findings of this neurotoxicant includes tremors, and hyperexcitability in experimental animals

A

trimethyltin

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32
Q

T/F: doxorubicin, which is an antimitotic in cancer chemotherapy, exerts its effects on the neurons in the PNS, particularly, the dorsal root and autonomic ganglia by intercalating with the DNA and interfering with the transcription

A

True

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33
Q

This neurotoxicant targets neurons of the visual cortex; massive degeneration can lead to blindness and marked ataxia for adults

A

Methylmercury (organic mercury)

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34
Q

This neurotoxicant targets irreversible limbic-cerebellar syndrome in humans and similar behavioral changes in primates

A

trimethyltin

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35
Q

The children affected will usually have developmental deficits, retardation and even cognitive deficits

A

methylmercury (organic mercury)

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36
Q

this neurotoxicant may be found in plasticizers, antifungal agents, or pesticides

A

trimethyltin

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37
Q

The accumulation of methylmercury in the body from eating fish from bodies of water connected to chemical factories may lead to ________________

A

Minamata disease

38
Q

The cellular basis of neurotoxicity of this neurotoxicant includes loss of hippocampal neurons, and on amygdala pyriform cortex

A

Trimethyltin

39
Q

The cellular basis of neurotoxicity of methylmercury (organic mercury)

A

Neuronal degeneration in visual cortex, cerebellum, and ganglia. Spongy disruption in the cortex and cerebellum

40
Q

These are chemicals associated with neuronal injury (neuropathies)

A

doxorubicin, methylmercury (organic mercury), and trimethyltin

41
Q

primary site of axonopathies

A

axons

42
Q

These are chemicals associated with axonal injury (axonopathies)

A

acrylamide, carbon disulfide, n-hexane, B,B’-Iminodipropionitrile, and organophosphorous compounds (NTE inhibitors)

43
Q

Neurotoxicant: Acrylamide

Neurologic findings: peripheral neuropathy, which is often _________

Basis: axonal degeneration where the axon terminal is affected in its _________ stages

A

sensory

earliest

44
Q

Neurotoxicant: Carbon disulfide

Neurologic findings: Acute ____________ and chronic _____________

Basis: axonal degeneration, early stages include _______________________

A

psychosis; peripheral neuropathy

neurofilamentous swelling

45
Q

Neurotoxicant: n-Hexane

Neurologic finding: peripheral neuropathy, severe cases have ________

Basis: axonal degeneration, early neurofilamentous swelling (_________ and _________)

A

spasticity

PNS and spinal cord

46
Q

Neurotoxicant: B,B’-Iminodipropionitrile

Neurologic finding: No data in humans; ___________________ in rats

Basis: ___________ axonal swellings, degeneration of _____________ epithelial cells and _________________ cells

A

excitatory movement

proximal; olfactory; vestibular hair

47
Q

Neurotoxicant: Organophosphate compounds (NTE inhibitors)

Neurologic findings: acute _____________ and peripheral neuropathy

Basis: Axonal degeneration

A

abdominal pain

48
Q

identify the neurotoxicant

These are classified as gamma-diketones

A

n-hexane and 2-hexanone

49
Q

identify the neurotoxicant

distal axonopathy; covalent cross-linking of neurofilaments which can also lead to aberrations in mood and signs of diffuse encephalopathic disease

A

Carbon disulfide (CS2)

50
Q

This syndrome is specifically for rats as there is not much record of its effect on humans. It exhibits excitement, circling, head twitching, or over-alertness which indicates that there is already degeneration of vestibular hair cells

A

Waltzing syndrome

51
Q

Identify the neurotoxicant

Causes Waltzing syndrome

A

B,B’-Iminodipropionitrile (IDPN)

52
Q

identify the neurotoxicant

distal axonopathy characterized by multiple axonal swellings

A

Acrylamide

53
Q

T/F: the critical difference between central nervous system and peripheral nervous system axonal degeneration, is that in PNS, it can regenerate but for central axons, they cannot regenerate

A

True

54
Q

Factors why central axons cannot regenerate

A

inhibitory factors that are secreted by oligodendrocytes, and astrocyte scarring, and glial interference

55
Q

Modified T/F: Myelin provides electrical insulation of neuronal processes. In its absence, there is slowing of conduction and aberrant conduction of impulses between adjacent processes

A

BOTH TRUE

56
Q

This myelinopathy is caused by alterations in transcript levels of myelin basic protein mRNA, where there is separation of myelin lamellae

A

Intramyelinic edema

57
Q

This myelinopathy may result from progressive intramyelinic edema or from direct toxicity to myelinating cell, where there is selective loss of myelin

A

Demyelination

58
Q

______________ in the PNS are capable of remyelinating the axon.

A

Schwann cells

59
Q

Acute, massive exposures to lead would result in severe ____________, and intramyelinic edema

A

cerebral edema

60
Q

Chronic lead intoxication usually leads to ________________, gastritis, or _________

A

peripheral neuropathy; anemia

61
Q

Examples of chemicals associated with myelinopathies

A

hexachlorophene and tellurium

62
Q

Neurotoxicant: Hexachlorophene

Neurologic findings: ____________, confusion, and ___________

Basis: _________ swelling, intramyelinic edema in _____ and _____, and _____ axonal degeneration

A

irritability; seizures

brain; CNS and PNS; late

63
Q

Neurotoxicant: Tellurium

Neurologic finding: _____________, and hind limb paralysis in experimental animals

Basis: Demyelinating neuropathy, and ________________ in experimental animals

A

hydrocephalus

lipofuscinosis

64
Q

Identify the neurotoxicant

When absorbed by the skin, it enters the nervous system and causes neurotoxicity by forming vacuoles that would create spongiosis in the brain

A

Hexachlorophene

65
Q

Are primary means of defense in the CNS following exposure to neurotoxicants.

A

astrocytes

66
Q

Modified T/F: Astrocytes also serves as spatial buffering system for osmotically active ions. They are also depot for metabolic processing of exogenous molecules only.

A

1st TRUE
2nd FALSE. depot for metabolic processing of endogenous molecules and xenobiotics

67
Q

This causes astrocytic swelling and morphological changes

A

ammonia

68
Q

The inhibition of neuronal glutamate precursor synthesis (changes in neurotransmitter uptake: glutamate) is a result of …?

A

increased intracellular ammonia

69
Q

Organic nitrates, Dinitrobenzenes (DNB), and Metronidazole are classified as

A

Nitrochemicals

70
Q

This nitrochemical creates gliovascular lesions that target astrocytes in the gray matter of the brainstem and deep cerebellar roof nuclei

A

dinitrobenzenes (DNB)

71
Q

Prolonged treatment with this drug is associated with peripheral neuropathy; effects include paresthesia, headache, glossitis, urticaria or pruritus

A

metronidazole

72
Q

This is an irreversible inhibitor of astrocyte-specific enzyme glutamine synthase in which there would be a large increase of glycogen levels that would lead to swollen and damaged astrocytic mitochondria

A

Methionine sulfoximine (MSO)

73
Q

T/F: Although neurotransmitter-associated actions may be well understood for some agents, the specificity of the mechanism should not be assumed.

A

True

74
Q

This neurotoxicant bind to nicotinic cholinergic receptor

A

nicotine

75
Q

T/F:

Nicotine toxicity pathway: rapid rise after acute OD → excessive stimulation of nicotinic receptors → ganglionic paralysis (nausea, rapid heart rate, perspiration, somnolence, coma)

A

True

76
Q

Cocaine blocks ____________, _____________, and ___________ reuptake at the nerve terminal in the CNS; causes release of dopamine from storage vesicles

A

dopamine; norepinephrine; serotonin

77
Q

Modified T/F: Cerebrovascular defects, stroke, and intracranial hemorrhage are common effects of cocaine. The PRIMARY EVENT that is responsible for the addictive properties and euphoric feelings during cocaine intoxication is the blockade of the dopamine reuptake transporter (DAT)

A

BOTH TRUE

78
Q

This neurotoxicant is involved in catecholamine neurotransmission in the CNS

A

amphetamines

79
Q

This causes higher energy and sensation in adults

A

MDMA (methylenedioxymethamphetamine; ecstasy)

80
Q

The most pronounced effects of amphetamines is on __________________, but can also damage serotonin axons and axon terminals.

A

dopaminergic neurons

81
Q

These chemicals are associated with damages in the astrocytes

A

Ammonia, nitrochemicals, and methionine sulfoximine (MSO)

82
Q

These chemicals are associated with neurotransmission-associated neurotoxicity

A

Cocaine, amphetamines, and nicotines

83
Q

Neurotoxicant: amphetamine and metamphetamine

Neurologic findings: tremor, restlessness (acute), __________________ and hemorrhage, and _______________ disturbances

Basis: Bilateral infarcts of _______________, abnormalities in dopaminergic, serotonergic, and dopaminergic systems. Also acts at ________________ receptors in the PNS

A

cerebral infarctions; neuropsychiatric

globus pallidus, adrenergic

84
Q

Neurotoxicant: Cocaine

Neurologic findings: Increased risk of stroke and ______________ in chronic users, increased risk of cardiac death; movement and psychiatric abnormalities especially during ______________

Decreased ____________ in fetal exposures (newborns)

Basis: Infarcts and hemorrhages, alteration in __________ dopamine neurotransmission

A

cerebral atrophy; withdrawal

head circumference

striatal

85
Q

Neurotoxicant: Nicotine

Neurologic findings: nausea, vomiting, ____________

Basis: binds to nicotinic receptors (____________) low-dose stimulation; high-dose blocking

A

convulsions

cholinergic

86
Q

Generalized depression of CNS function is produced by a variety of volatile solvents. Give examples

A

Ethanol, organics, and anesthetics

87
Q

Mechanism of generalized depression: interactions with ____________ ion channels as well as ____________ calcium channels.

A

ligand-gated; voltage-gated

88
Q

Modified T/F: Calcium is involved in motor function and control. Interactions with these compounds possibly induces NS depression

A

BOTH TRUE

89
Q

Goal for future studies of neurotoxicology: replace standard _________ assessments with high throughput in vitro assays and ___________________________ to predict adverse outcomes.

A

In vivo; Quantitative Structure-Activity Relationships (QSARs)

90
Q

T/F: The nervous system is the most complex system of the body.

A

True

91
Q

T/F: There are still many gaps in understanding how many neurotoxins act, yet research is discovering their possible effects on the body’s structures and functions which may all be due to a lot of considerations.

A

True

92
Q

T/F: It is important to understand that the most potent toxins are common kitchen ingredients, with extremely minute amounts sufficient to cause death.

A

False. Most potent toxins are neurotoxins

2nd Shifting PHA6131 LEC (6 decks)

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