Flashcards in Anatomy and Physiology VII Deck (25)
What is the function of the direct pathway of the basal ganglia?
To facilitate movement (stimulatory) (p.416)
What is the function of the indirect pathway of the basal ganglia?
To inhibit movement (p.416)
Which dopaminergic receptors correspond to the direct and indirect pathways respectively?
Direct- D1; Indirect- D2 (p.416)
Describe the excitatory pathway through the basal ganglia.
Cortical inputs stimulate the striatum (putamen). This stimulates release of GABA. GABA release disinhibits the thalamus via the Gpi/SNr nuclei. This works to increase motion (p.416)
Describe the inhibitory pathway through the basal ganglia.
Cortical inputs stimulate the striatum (putamen). This disinhibits STN via the Gpe nucleus. STN then stimulates the Gpi/SNr nuclei to inhibit the thalamus. This decreases motion (p.416)
What is Parkinson's disease?
A degenerative disorder of the CNS associated with Lewy bodies and loss of dopaminergic neurons (p.416)
What are Lewy bodies composed of?
A-synuclein intracellular inclusions (p.416)
What changes occur in the substantia nigra pars compacta due to loss of dopaminergic neurons in Parkinson's disease?
What area of the brain is most affected by loss of dopaminergic neurons in Parkinson's disease?
The substantia nigra pars compacta of the basal ganglia (p.416)
Name four clinical features of Parkinson's Disease.
Resting tremor ("pill rolling tremor"); cogwheel rigidity; Akinesia (or bradykinesia); Postural instability (p.416)
What is the inheritance pattern of Huntington's disease?
Autosominal dominant; trinucleotide repeat of CAG (p.417)
What neurotransmitters are decreased in the caudate nucleus of patients with Huntington's disease?
GABA, Ach (p.417)
What are the clinical findings associated with Huntington's disease?
Chorea, aggression, depression, dementia (p.417)
What is the pathophysiology associated with Huntington's disease?
Neuronal death via NMDA-R binding and glutamate toxicity.
What imaging findings can be seen in a patient with Huntington's?
Atrophy of the striatal nuclei (main inhibitors of movement) (p.417)
Name eight disorders of movement.
Hemiballismus; Chorea; Athetosis; Myoclonys; Dystonia; Essential Tremor (postural tremor); Resting tremor; Intention tremor (p.417)
What is the characteristic presentation of Hemiballismus?
Sudden, wild flailing of 1 arm +/1 the ipsilateral leg (half of body typically affected) (p.417)
What is the characteristic presentation of Chorea?
Sudden, jerky, purposeless movements (dance-like) (p.417)
What is the characteristic presentation of Athetosis?
Slow, writhing movements, especially seen in fingers (p.417)
What is the characteristic presentation of Myoclonus?
Sudden, brief, uncontrolled muscle contraction (common in metabolic abnormalities) (p.417)
What is the characteristic presentation of Dystonia?
Sustained, involuntary muscle contractions (p.417)
What is the characteristic presentation of Essential Tremor (postural tremor)?
Action tremor; exascerbated by holding posture/ limb position; genetic predisposition (p.417)
What is the characteristic presentation of Resting Tremor?
Uncontrolled movement of distal appendages (most notable in hands) which is alleviated by intentional movement (p.417)
What is the characteristic presentation of Intention tremor?
Slow, zigzag motion when pointing/ extending towards a target (p.417)