Neuro-Pathology I: Neurodegenerative Disorders
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Questions and Answers

What is the primary function of negative feedback mechanisms in the nervous system?

  • To downregulate excessive neuronal stimulation (correct)
  • To promote the release of hormones indiscriminately
  • To increase the excitability of the axon hillock
  • To amplify neuronal signals for faster processing

    • Which of the following is NOT a brain structure predominantly involved in providing negative feedback responses?

  • Limbic Cortex
  • Cerebellum (correct)
  • Hypothalamus
  • Basal Ganglia

    • What is the primary effect of decreased D1 receptor activation in the direct pathway of Parkinson's Disease?

  • Decreased inhibition of the striatum. (correct)
  • Increased activation of the supplemental motor cortex.
  • Increased activity of the GPe.
  • Decreased GABA release onto the thalamus.

    • In the indirect pathway, how does reduced dopamine availability affect the globus pallidus externa (GPe)?

    <p>It decreases GABA release onto the subthalamic nucleus. (B)</p> Signup and view all the answers

    What does 'idiopathic' mean in the context of Parkinson's Disease?

    <p>Having no known distinct or singular cause. (D)</p> Signup and view all the answers

    The axon hillock is highly excitable primarily because of its role in:

    <p>Initiating action potentials. (C)</p> Signup and view all the answers

    What is the consequence of increased Gpi activity in Parkinson's disease?

    <p>Increased GABA release onto the thalamus. (B)</p> Signup and view all the answers

    What is the direct result of diminished dopamine production on the thalamus in Parkinson's disease?

    <p>Decreased activation due to increased GABA release from Gpi (D)</p> Signup and view all the answers

    Which group has a slightly higher, but statistically insignificant, predilection for Parkinson's Disease, according to the content?

    <p>Hispanic males (C)</p> Signup and view all the answers

    What pathological protein structure is associated with advanced Parkinson's disease?

    <p>Lewy Bodies (C)</p> Signup and view all the answers

    Which of the following environmental factors is NOT strongly associated with an increased risk of Parkinson's Disease?

    <p>Living in areas with low air pollution (D)</p> Signup and view all the answers

    A history of repeated traumatic brain injuries (TBI) is most associated with which of the following?

    <p>Possible association with chronic traumatic encephalopathy (CTE) (A)</p> Signup and view all the answers

    Which of the following is NOT considered a component of the basal ganglia?

    <p>Cerebellar Nuclei (D)</p> Signup and view all the answers

    Which cortical area is most directly involved with motor speech production?

    <p>Broca's Area within the frontal cortex (D)</p> Signup and view all the answers

    The striatum primarily modulates signals to the thalamus and motor areas by the actions of which two neurotransmitters?

    <p>GABA and Glutamate (A)</p> Signup and view all the answers

    Which of the following best describes the role of the basal ganglia?

    <p>Modulation of motor coordination (B)</p> Signup and view all the answers

    A patient's family history is significant for Parkinson's disease where his father had the diagnoses. How much more likely is a male offspring to also develop the disease?

    <p>Two to three times more likely (A)</p> Signup and view all the answers

    Which of the following cortical centers is NOT part of the Basal Ganglia's network of connections?

    <p>Visual cortex (D)</p> Signup and view all the answers

    What is the primary function of carbidopa when used in conjunction with levodopa?

    <p>To prevent the peripheral breakdown of levodopa, increasing its bioavailability in the brain (B)</p> Signup and view all the answers

    Which of the following motor symptoms is NOT typically associated with Parkinson's Disease?

    <p>Hyperkinesia (A)</p> Signup and view all the answers

    What is the primary rationale for using levodopa in treating Parkinson's Disease?

    <p>It is a precursor to dopamine which can cross the blood-brain barrier (A)</p> Signup and view all the answers

    Which non-motor symptom is associated with both Parkinson's disease AND its pharmacologic therapy?

    <p>Dementia (A)</p> Signup and view all the answers

    A PET scan showing increased microglial activity within the basal ganglia and substantia nigra is most suggestive of which condition?

    <p>Parkinson's Disease (B)</p> Signup and view all the answers

    What is a significant concern associated with the use of bromocriptine, a dopaminergic agonist, in the management of Parkinson's Disease?

    <p>It has a significantly more concerning side effect profile and is typically used only as a last resort (C)</p> Signup and view all the answers

    Lewy bodies, associated with certain neurodegenerative diseases, are able to translocate to which areas of the brain, leading to dementia?

    <p>Cerebrum and limbic cortex (D)</p> Signup and view all the answers

    Which of these BEST describes the gait abnormality typically seen in individuals with Parkinson’s Disease?

    <p>Shuffling gait with reduced arm swing (A)</p> Signup and view all the answers

    Which of the following best describes the mechanism of action of MAO-B inhibitors in the context of Parkinson's Disease?

    <p>They reduce the breakdown of dopamine, leading to increased dopamine levels. (A)</p> Signup and view all the answers

    What is a unique mechanism of action of Amantadine in treating Parkinson's Disease?

    <p>It both enhances dopamine release and inhibits glutamatergic effects. (D)</p> Signup and view all the answers

    What is the primary way that caffeine is thought to have a protective effect against Parkinson's Disease?

    <p>By antagonizing adenosine A2A receptors and increasing dopaminergic activity. (D)</p> Signup and view all the answers

    True or False, a statistically significant correlation has been found between nicotine and reduced risk of Parkinson's Disease?

    <p>False, randomized clinical trials have not shown statistically significant trends (B)</p> Signup and view all the answers

    What is the significance of the CAG trinucleotide repeats in the context of Huntington's Disease?

    <p>A higher number of repeats typically leads to an earlier onset and more severe disease. (B)</p> Signup and view all the answers

    Which of the following is an example of a potential protective factor against Parkinson's Disease, as described in the text?

    <p>Regular exercise and caffeine consumption. (A)</p> Signup and view all the answers

    How is Huntington's Disease inherited genetically?

    <p>Autosomal dominant pattern, carrying one copy of the mutated gene is sufficient to pass it on. (D)</p> Signup and view all the answers

    What is the typical impact of an increase in the number of CAG trinucleotide repeats in the HTT gene on the onset of Huntington's disease?

    <p>Earlier onset of the disease. (C)</p> Signup and view all the answers

    Which demographic is most commonly affected by sporadic Amyotrophic Lateral Sclerosis (ALS)?

    <p>Caucasian males in their 70s (A)</p> Signup and view all the answers

    What is a primary mechanism proposed for glutamate toxicity in ALS?

    <p>Increased binding of glutamate by NMDA receptors (B)</p> Signup and view all the answers

    Which of the following is a result of mutations in the SOD1 gene in ALS?

    <p>Decreased expression of functional superoxide dismutase 1 (C)</p> Signup and view all the answers

    Which of the following best describes the function of SOD1 under normal conditions?

    <p>Destroys free radicals, thus reducing oxidative stress (B)</p> Signup and view all the answers

    What effect does mitochondrial dysfunction have on axonal transport?

    <p>Decreases axonal transport (A)</p> Signup and view all the answers

    What is the consequence of an increased calcium influx within neurons due to glutamate toxicity?

    <p>Activation of pro-apoptotic enzymes (B)</p> Signup and view all the answers

    An individual with a history of working in which of the following occupations has a slightly higher risk of developing ALS?

    <p>Construction or electrician work (C)</p> Signup and view all the answers

    What clinical phenotype is observed in Amyotrophic Lateral Sclerosis?

    <p>Both upper motor neuron and lower motor neuron symptoms (D)</p> Signup and view all the answers

    Study Notes

    Neuro-Pathology I: Neurodegenerative Disorders

    • Neurodegenerative disorders cause a loss of functional neurons in the central and peripheral nervous systems.
    • Key characteristics include demyelination, impairment of neurotransmitter transmission, impairment of inter-neuronal connections, and chronic imbalance in electrolyte concentrations.
    • Multiple factors are often involved in the development of neurodegenerative diseases.

    Demyelination of Neurons

    • Myelin is a protein-lipid-based structure that insulates axons.
    • Myelin allows for faster transmission of nerve impulses.
    • Demyelination slows down or prevents the transmission of nerve impulses.
    • Several causes of demyelination include infectious agents, vascular issues, and inflammatory/autoimmune conditions. These can include HIV/AIDS, JC Virus, herpesviruses, Epstein-Barr virus, Borrelia Burgdorferi, Treponema Pallidum, Measles and vascular damage.
    • Demyelination leads to decreased electrical transmission and reduced activation of myelinated structures.

    Causes of Demyelination

    • Infectious agents (mostly viruses, but parasites and bacteria are implicated)
    • Vascular damage (ischemic events).
    • Inflammatory/autoimmune (Guillain-Barre Syndrome, Acute Disseminated Encephalomyelitis).
    • Metabolic/vitamin deficiencies (Vitamin B12 deficiency and diabetes mellitus).
    • Illicit drug use (chronic alcohol, heroin, and opioids).
    • Pharmacologic agents (isoniazid and chemotherapy drugs).

    Impaired Neurotransmitter Transmission

    • Neurotransmitter release is critically dependent on calcium.
    • Communication between neurons occurs at the synapse through neurotransmitter release.
    • The synaptic cleft contains enzymes that regulate neurotransmitter concentration.
    • Aberrations in any of these three components can impair neurotransmitter transmission. These can include destruction of pre-synaptic neurons, and destruction of NT receptors.

    Impairment of Inter-Neuronal Connections

    • Axodendritic, axosomatic, and axoaxonic connections are crucial for neuronal communication and coordination.
    • Dysfunctional connections can affect many aspects of nervous system function, including motor control, and cognition.

    Failure of Homeostatic Feedback Mechanisms

    • Homeostatic feedback mechanisms are critical for maintaining proper CNS and PNS function.
    • Dysfunction in the hypothalamus, pituitary gland, and certain cortical/subcortical areas can cause problems regulating neural processes.

    Important Neurodegenerative Diseases to Focus On

    • Parkinson's Disease
    • Huntington's Disease
    • Amyotrophic Lateral Sclerosis (ALS)

    Parkinson's Disease, General

    • Neurodegenerative disorder affecting both motor and non-motor functions.
    • Mean age of diagnosis is 70, slightly more common in Hispanic males.
    • Both genetic and epigenetic factors contribute to the disease.
    • Environmental factors (air pollution, pesticides, and others) have also been linked to Parkinson's Disease.

    Parkinson's Disease, Pathophysiology

    • Characterized by a loss of dopamine-producing neurons in the substantia nigra pars compacta.
    • Lewy bodies (aggregates of alpha-synuclein) are a key pathological feature.
    • Loss of dopamine leads to problems with pathways regulating movement. This results in issues such as bradykinesia, resting tremors and postural instability.

    Parkinson's Disease, Clinical Phenotypes

    • Motor findings: bradykinesia, rigidity, resting tremors, and gait abnormalities.
    • Non-motor findings (generally appearing in advanced disease): masked facial expressions, swallowing issues, impaired cognition.

    Parkinson's Disease, Management

    • Pharmacologic treatment aims to replace lost dopamine or enhance dopamine signalling.
    • Common treatments include levodopa/carbidopa, dopamine agonists, and MAO-B inhibitors. Management also includes lifestyle interventions to support motor function and mitigate non-motor symptoms.

    Huntington's Disease, General

    • Neurodegenerative disease inherited in an autosomal dominant manner.
    • Characterized by trinucleotide repeats (CAG) in the HTT gene.
    • More CAG repeats correlate with earlier onset and increased disease severity.
    • More common in males, but females can have more severe clinical manifestations.

    Huntington's Disease, Pathophysiology

    • The increased CAG repeats lead to the production of an abnormal protein called huntingtin.
    • This abnormal protein negatively impacts neuronal function leading to neurological issues.
    • Damage to the striatum (caudate and putamen) is a key characteristic.
    • Damage typically occurs in cortex and limbic areas later.

    Huntington's Disease, Management

    • Currently, there is no cure or effective disease-modifying treatment.
    • Pharmacologic management (such as tetrabenazine and antipsychotics) is used to address specific symptoms as appropriate.

    Amyotrophic Lateral Sclerosis (ALS), General

    • Progressive neurodegenerative disease affecting upper and lower motor neurons.
    • Disease is characterized by the degeneration of neurons.
    • Approximately 90–95% of cases are sporadic.
    • More common in men than women, mostly impacting people aged 70.

    Amyotrophic Lateral Sclerosis (ALS), Pathophysiology

    • ALS involves the death of motor neurons of both the brain and spinal cord.
    • Possible mechanisms include glutamate toxicity, mitochondrial dysfunction, and axonal transport impairments.
    • Presence of SOD1 proteins, among other mechanisms, contributes to the disease and its development

    Amyotrophic Lateral Sclerosis (ALS), Management

    • Pharmacologic approaches include: Riluzole and Edaravone.
    • These drugs target specific aspects, like decreasing glutamate activity, and free radical damage to attempt to slow progression of the illness.

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    Description

    Explore the impact of neurodegenerative disorders and their effects on neuronal function. Learn about demyelination, its causes, and how it impairs nerve impulse transmission. This quiz delves into the complexities of these disorders and their implications for the nervous system.

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