Histologia do Cerebelo Flashcards
Constituição do Sistema Nervoso
Sistema Nervoso Periférico (SNP)
Sistema Nervoso Central (SNC)
- Nervos cranianos (12 pares)
- Nervos espinhais/raquidianos (31 pares) e gânglios associados
- Encéfalo
- Medula espinhal/Espinhal Medula
Regiões do Encéfalo
Anterior:
- Diencéfalo:
» Tálamo
» Hipotálamo
- Tranco Cerebral:
» Mesencéfalo
» Ponte ou protuberância
» Bulbo raquidiano
Posterior:
- Cérebro
- Corpo caloso
- Cerebelo
Anatomia do Cerebelo
- Lobo anterior
- Lobo posterior
- Vermis
- Folhas
- Hemisfério cerebeloso
- Matéria branca (arbor vitae)
- Matéria cinzenta
Funções do Cerebelo
- Coordenação musculaar
- Controlo da motricidade fina
- Controlo do tónus muscular
- Manutenção da postura e equilíbrio
- Aprendizagem motora
- Envolvimento nas emoções, processamento de estímulos tácteis, perceção espacial e linguagem
Cerebellar Comparator Function
(1) Action potencials from the motor cortex descend into the spinal cord to initiate voluntary movements
(2) At the same time, action potencials are carried from the motor cortex to the cerebellum to give the cerebellar neurons information representing the intended movement
(3) In addiction, action potencials from proprioceptive neurons ascend through the spinocerebellar tracts and simultaneously arrive at the cerebellum. Proprioceptive neurons innervate the joints and tendons of the structure being moved, such as the elbow or knee, and provide information about the position of the body or body parts. These action potencials give the cerebellar neurons information from the periphery about the actual movements
(4) The cerebellum compares the action potencials from the motor cortex with those from the moving structures. That is, it compares the intended movement with the actual movement
(5) If a difference is detected, the cerebellim sends action potencials to the motor cortex, via the thalamus, and to the spinal cord to correct the discrepancy
(6) The result is smooth, coordinated movements
Disfunção do Cerebelo
- Atraso no movimento
- Erros na amplitude dos movimentos
- Erros nos movimentos padronizados
- Ataxia
Ataxia
Grupo de doenças neurodegenerativas.
Origem
> Genética:
- Autossómica dominante (Ataxias espeinocerebelosas (SCAs))
- Autossómica recessiva (ex.: Ataxia de Friedreich; Ataxia-telangiectasia)
- Ligada ao X (ex.: Síndrome de tremor/ataxia associado ao X frágil)
- Mitocondrial
> Não-Genética (ex.: Degeneração cerebelosa paraneoplásica)
Ataxia — Manifestações Clínicas
- Vascular
- Inflamatória
- Traumática
- Metabólica
- Desenvolvimental
- Causado por toxinas ou drogas
- (Para)neoplásica
- Infeções
Ataxia Espinocerebelosa
- Cognitive impair
- Ocular dysmetria and slow saccades
- Muscle cramps
- Ataxia
- Bradykinesia and rigidity
- Dysarthria
- Dysphagia
Células do Sistema Nervoso
- Neurónios
- Células da Glia (Neuróglia)
> Astrócitos
> Microglia
> Oligodendrócitos - Células ependimárias
- Células estaminais neurais
Neurónios
Neurónio não-mielizado:
- Dendrite
- Corpo celular
- Cone de implantação
- Axónio
- Terminal axónico
Neurónio mielinizado
- Dendrite
- Corpo celular
- Cone de implantação
- Axónio
- Nódulo de Ranvier
- Bainha de mielina
- Terminal axónico
Histologia do Cerebelo
- Molecular layer
- Purkinje cell layer
- Granular layer
> Purkinje cells
Basket cell
Climbing fibre
Inferior olive
Pontine nuclei
Mossy fibre
Granule cell
Golgi cell
Parallel fibre
Stellate cell
Basic structure of the cerebellar cortex
There are two main afferents to the cerebellar cortex: climbing fibres, which make direct excitatory contact with the Purkinje cells, and mossy fibres, which terminate in the granular layer and make excitatory synaptic contacts mainly with granule cells, but also with Golgi cells. In some cases, the stem axons of climbing and mossy fibres also provide collaterals to the cerebellar nuclei en route to the cerebellar cortex. The ascending axons of the granule cells branch in a T-shaped manner to form the parallel fibres, which, in turn, make excitatory synaptic contacts with Purkinje cells and molecular layer interneurons — that is, stellate cells and basket cells. Typically, parallel fibres extend for several millimetres along the length of individual cerebellar folia. With the exception of the granule cells, all cerebellar cortical neurons, including the Purkinje cells, make inhibitory synaptic connections with their target neurons.
Cerebellum Histology
The cerebellar cortex contains five types of neurons organized into three layers. A vertical section of a single cerebellar folium illustrates the general organization of the cerebellar cortex. The detail of a cerebellar glomerulus in the granular layer is also shown. A glomerulus is the synaptic complex formed by the bulbous axon terminal of a mossy fiber and the dendrites of several Golgi and granule cells. Mitochondia are present in all of the structures in the glomerulus, consistent with their high metabolic activity
Planos Anatómicos e Termos descritivos
A. Rostral-causal and dorsal-ventral axes
B. Medial- lateral axis
C. Section planes
> Horizontal plane
> Coronal plane
> Sagital plane
