Central Nervous System Flashcards
Gray matter
Contains the cell bodies of neurons
Cortex and deep grey matter
White matter
Contains myelinated axons
Below the cortex and running along tracts in the brain
Diencephalon
The posterior part of the forebrain
Contains hypothalamus, thalamus, epithalamus, ventral thalamus and third ventricle
Relay and processing center
3 things that make up the basal ganglia (and 3 functions)
Caudate nucleus
Putamen
Globis palladis
These supply inhibitory stimuli to skeletal muscles, coordinate skeletal muscle contractions, and block unwanted muscle contractions
4 lobes of the cerebrum and what are they responsible for
Frontal: controls movement, behavior, emotions, higher intellectual functions
Parietal: integrates sensory inputs like touch and controls language (ability to understand words)
Temporal: hearing, smelling, memory and expression (ability to express words)
Occipital: vision
Thalamus
Important for integrating sensory stimuli (like pain and touch) and determinant of conciousness
Gray and white matter in brain vs spinal chord
In the spinal chord the gray matter is internal and the white matter is external
In the brain the gray is on the outside and the white is on the inside
Hypothalamus
Connects many different parts of the brain and regulates many body functions like appetite, thirst and temperature
Controls the pituitary by secreting factors that regulate hormonal release
Functions of each part of the brainstem
Midbrain: visual, auditory reflex centers
Medulla oblongata: cardiac, vasomotor, respiratory centers
Pons: contains bundles of axons carrying info to and from the brain
Cerebellum
Coordinated voluntary movement
Controls ability to stand upright without falling over
Controls muscle toone
3 inputs to the cerebellum
- Sensory info carried by the spinal chord
- Vestibular organ in the inner ear
- Motor impulses from cerebral cortex
What type of neurons synapse in the dorsal versus anterior horn of the spinal chord?
Dorsal: sensory neurons
Anterior: motor neurons (lower motor neurons)
3 layers of the meninges
- Dura: outer layer
- Arachnoidae: middle layer
- Pia: innermost layer
Another word for neuronal cell body
Perikaryon
4 types of glial cells
Astrocytes: support cells
Oligodendrocytes: wrap around axons and form myelin sheaths
Microglia: resident macrophages
Ependymal cells: line ventricles and make CSF
Dysgraphic disorders
Incomplete fusion of the neural tube and defective formation of meninges, calvaria, or vertebras
Malformations in
- Ancephaly
- Meningocele
- Spina bifida
- Myelomeningocele
- No brain
- Vertebrae doesn’t form and meninges protrude through bony defect
- No vertebral arches, resulting in exposure of meninges or spinal cord to outside
- Same as 2, but along with a bit of the spinal cord protruding
Epidural Hematomas
Between skull and dura
Rupture of middle meningeal artery (fracture related)
Tight space, so hematoma takes hours to develop and its localized
Coma can result; lethal if unrecognized because arterial bleeding will continue
Subdural hematomas
Between dura and arachnoid Caused by blunt trauma Ruptured bridging veins Venous bleeding occurs slowly, so may be asymptomatic Can produce headache, coma, death
Subarachnoid hemorrhages
Located between arachnoid and pia
Caused by traumatic contusion of the brain and/or the rupture of congenital aneurysms (in the circle of Willis)
Intracerebral hemorrhages
Rupture of intracerebral vessels
Common complication of head trauma, gunshot wounds
Nontraumatic forms include stroke
Common with poor clotting, so blood spreads easily
Stroke
Sudden persistent loss of brain function from a vascular cause
Risk factors include hypertension, smoking, diabetes, high cholesterol
Global ischemia
If many vessels are narrowed they can develop small infarcts, which over time can lead to dementia
Hypoperfusion from cardiac arrest or peripheral bleeding
Watershed infarcts (systemic hypotension lowers the perfusion from both sides and the area in the border zone becomes hypoxic)
Laminar necrosis from hypoperfusion
Cerebral infarct
Caused by thrombotic occlusion, thromboemboli
Pale or hemorrhagic infarct (reperfusion)
Surrounding brain tissue: edematous
Fluid filled cavity
Never heals (damage is permanent)
Clinical presentation depends on site of occlusion
Acute stroke can kill
MCA stokes result in contralateral hemiplegia and sensory loss, global aphasia in the dominant hemisphere
Intracerebral hemorrhage
Most caused by arterial hypertension Others from vascular malformations Basal ganglia, cerebellum and pons Well-circumscribed Clinical features often severe, high mortality
Multiple Sclerosis
Demyelinating, chronic disease (presumed autoimmune)
Women > men
Most common neurological disease in young adults
Mediated by helper lymphocytes, macrophages, and B cells/plasma cells
Exacerbation and remission episodes
Sensory and motor abnormalities
Unpredictable course
Oligoclonal T cells
Oligoclona proliferations of sensitized T cells is considered to be the basis of MS lesions
Macrophages also found in the lesions
2 possible courses for MS
Relapsing remitting type: works well with therapy (beta interferons, etc), during remission function returns to normal, dampens down symptoms of inflammation
Chronic: permanent due to neurodegeneration
What is found in early vs late lesions in MS
Early: contain demyelinated axons surrounded by lymphocytes and foamy macrophages
Late: demyelinated axons and astrocytes
Wernicke-Korsakoff syndrome (deficiency in, symptoms)
Vitamine B1 (thiamine) deficiency W part is more acute (abnormal eye movements) and K part is more chronic (loses short term memory)
Vitamin B12 deficiency
Leads to loss of sensation and motor function with uncoordinated movements plus psychiatric symptoms
Leads to subacute combined degeneration of the ascending tracts of the spinal cord
Pellagra
deficiency in, symptoms
Nicotinic acid deficiency
Dermatitis, diarrhea, delirium/dementia
Myelopathy vs neuropathy
M: damage to spinal cord
N: damage to peripheral nerves
Both can be a direct effect of alcoholism
Alzheimers Disease
Sporadic neurodegenerative disease
Genes increase levels of beta-amyloid and apoE4
Atrophy greatest in frontal and temporal lobes
Dementia
Requires nursing care, death due to physical deterioration or infection
Can see histological changes in cortex, neuritic plaques, neurofibrillary tangles
Parkinson’s Disease
Subcortical neurodegenerative disorder
Decreased number of dopaminergic neurons in the substantial nigra (appears pale)
Disturbances of movement, TRAP
Depression, dementia common
Presence of Lewy bodies (with alpha synuclein)
TRAP
Tremor, rigidity, brady or akinesia, postural instability
In Parkinson’s disease
Huntington’s Disease
Autosomal dominant, familial
Gene is huntingtin gene on chromosome 4 with CAG trinucleotide repeat expansion
Disease only occurs when the repeats exceed a threshold
Involuntary, gyrating movements, progressive dementia
Atrophy of cortex, caudate, putamen
Loss of neurons and reactive gliosis
Amyotrophic Lateral Sclerosis
Neurodegenerative disease, most sporadic
10% have mutations in copper-zinc superoxide dismutase (SOD1) gene
Loss of motor neurons in cortex, brainstem and spinal cord and of corticospinal tracts in spinal cord
Weakness and wasting of muscles, fasciculations, slurred speech
Incurable and progressive disease
Epilepsy (2 types)
Generalized: discharges all over the brain - leads to aura, tonic clonic seizures and post ictal drowsiness, can be controlled
Focal: one spot that can be detected - many causes - drugs or surgery
One differences between malignant tumors in the CNS and malignant tumors everywhere else
Malignant tumors in the CNS do NOT metastasize, they just grow rapidly
Astrocytomas
Solid cerebral tumors in adults, cystic cerebellar tumors in children
Well-differentiated astrocytes
Progress into lesions
Cannot distringuish from glioblastoma multiforme
Glioblastoma Multiform
Most common CNS tumor
Lateral hemispheres
Gross appearance: parts are necrotic/yellow, hemorrhagic/red, or white, irregularly shaped, poor demarcations, butterfly appearance
Cells are very atypical
Oligodendrogliomas
Cerebral hemispheres
Well circumscribed, partially cystic, calcified
Well-differentiated
Possible progression to GBM
Ependymomas
Children: ventricles, adults: spinal cord
Ependymoma or filum terminale
Tumor cells line papillary structures or form rosettes
Medulloblastoma
Cerebellum
Childhood
Cells are primitive neuroectodermal cells
Cells may enter CSF and metastasize to other sites in the CNS
Poor prognosis
Meningiomas
Arise from meninges and are dural based
Mostly benign
Most located near midline, base of brain, along spinal cord
Cause epileptic seizures or motor deficits
Excellent prognosis - surgery is curative unless malignant or in unreachable location
Neurofibromatosis type 1 vs 2
1: produces multiple peripheral neurofibromas
2: produces acoustic schwannomas as well as multiple meningiomas
3 most common cancers to metastasize to brain
Lung
Breast
Melanoma
