Exam 1 Review Flashcards
Types of Glial Cells
- Astrocytes: most numerous, for support & repair
- Oligodendrocytes: myelinate axons (so in white matter)
- Microglia: macrophages in CNS
- Ependymal cells: circulate CSF in choroid plexus
Feed Forward/Back
Neuronal Types
- Multipolar: most common CNS neuron, all peripheral motor neurons
- Bipolar: one dendrite, one axon; always special sensory
- Pseudounipolar: axon & dendrite fuse, split into CNS “central process” and PNS “peripheral process”; peripheral sensory neurons
Action Potential Process & NT Release
Cell is at an electrical charge at rest due to Na/K pump, electrical, and chemical forces at selectively-permeable non-gated ion channels. When cell membrane’s voltage changes via integrated input from other neurons, AP gets propagated (energy is released through activation of gated ion channels). NA ions rapidly influx into the cell, depolarizing it, then K+ rushes in to hyperpolarize back to negative mV. This then propagates. AP opens voltage-gated calcium (Ca) channels, permitting influx of Ca++ ions into axon terminal which triggers fusion of synaptic vesicles with the presynaptic membrane. NTs are released into synaptic cleft via exocytosis.
Myelencephalon
Medulla
Metencephalon
Pons + cerebellum
Mesencephalon
Midbrain
Diencephalon
Thalamus + hypothalamus + 3rd ventricle
Rostral
Anterior and towards the head
Caudal
Posterior and towards the tail
Gray Matter
- 80% glial cells (Astrocytes, oligodendrocytes, microglia)
- Exterior: cortex, cerebellum, diencephalon
- Interior: spinal cord, brainstem
White Matter
- Myelinated axons
- Fascicles > funiculi > peduncles
Branchiomotor Cranial Nerves
SVE
Efferent
- From CNS to effectors/muscles
- Motor
Afferent
- Towards the CNS from somewhere else
- Sensory
Spinnal Nerves & Vertebrae
- Cervical: 7 vertebrae, 8 nerves
- Thoracic: 12 vertebrae, 12 nerves
- Lumbar: 5 vertebrae, 5 nerves
- Sacral: 5 vertebrae, 5 nerves
- Coccygeal: 1 vertebrae, 1 nerve
Dorsal vs Ventral Root
- Dorsal
- Sensory
- Ventral
- Motor
- Both combine at the spinal nerve and separate into dorsal/ventral rami with both components (motor, sensory) for dorsal and both components for ventral
- Exit via intervertebral foramen
GVE
- Autonomic nervous system; works to maintain homeostasis
- Preganglionic sympathetic: spinal nerves T1-L2
- Preganglionic parasympathetic: spinal nerves S2-S4
CN that moves the jaw
CN 5
CN that keeps the face wet
CN 7
Conus Medullaris end location
L1/L2
Epithalamus
Pineal body = melatonin
Dural sac end location
S2
Lumbar cistern and puncture locations
- Cistern: L1/L2 - S2
- Puncture: L3/L4, L4/L5, or L5/S1
CBF: inverse/same
- Same for CO2
- Inverse for BP, O2, pH, viscosity
- Sympathetic = vasoconstriction
BBB Selectivity
- Diffusion of lipid-soluble substances
- Substances with high lipid solubility (ethanol, nicotine) enter brain rapidly
- Low/no solubility (sodium, dopamine) enter slowly or not at all
- Receptor-mediated transport (proteins)
- Facilitative and energy-dependent receptors
- Specific water-soluble substances only
- Ion channels
Segmental v radicular v medullary arteries
- Segmental artery: provides branches to both ventral, dorsal rootlets
- Radicular artery: segmental artery that fuses with roots
- Medullary artery: radicular artery that fuses with ASA/PSA
Rhombencephalon
- Metencephalon + myelencephalon
- Medulla + pons
Anencephaly
- Failure of the anterior neuropore to close
- Results in major portion of the brain, skull, and scalp being absent
- Incompatible with life
Rachischisis
- Failure of the posterior neuropore to close
- Results in motor and sensory deficits, chronic infections, and disturbances in bladder function
Types of Spina Bifida
- SB: incomplete formation of vertebrae and meninges surrounding SC
- SB Occulta: vertebrae deficit
- Meningiocele: meninges lie beneath skin
- Meningomyelocele: meninges and SC lie right beneath skin
Main Spinal Cord Support
Dural sheath on spinal roots
Laminar vs Nuclei Gray Matter Organizations
Laminar: cell structure
Nuclei = function
GSA, GSE, GVA, GVE spinal cord organization
Reflex SC Segments
- Bicep: C6
- Triceps: C7
- Knee-jerk: L3
- Ankle-jerk: S2
Prosencephalon
Telencephalon + diencephalon
GVE innervation
paramedian branches
(basilar if 4th ventricle or above)
(ASA if below 4th ventricle)
Trigeminal Sensory Complex receives which CNs
GSA (5, 7, 9, 10)
NTS receives which CNs
GVA, SVA
(7, 9, 10)
Slow adapting receptors
- Merkel’s disks, Ruffini endings
- Produce continual APs over duration of stimulus
- Eventually adapt after several minutes
Fast-adapting receptors
- Paciian corpuscles, Meissner’s corpuscles
- Diminish in response very quickly
- Respondt o changes in stimulus intensity
Peripheral vs Central sensitization
- Peripheral = DRG level
- Primary hyperalgesia
- Central = upper pathway
- Secondary hyperalgesia
UMN Signs
- Paresis (weakness)
- Hypertonia
- Hyperreflexia
- Appearance of neonatal reflexes
LMN Signs
- Weakness, paralysis
- Decreased or abolished reflexes
- Muscle atrophy
- Hypotonia (flaccidity)
LMN signs always trump UMN signs!
