MBB1 Week 1 Part 1

Nucleus: collection of nerve cell bodies in CNS

Ganglion: collection of nerve cell bodies in PNS

• 1. Focal
• 2. Diffuse (functional systems with a selective vulnerability)
• 3. Multifocal

• 1. Acute: minutes - hours
• 2. Subacute: weeks - months
• 3. Chronic: years

• V: Vascular (stroke)
• I: Infectious
• T: Traumatic
• A: Autoimmune
• M: Metabolic/Toxic/Endocrine/Nutrition
• I: Iatrogenic
• N: Neoplastic

• D: Degenerative
• E: Episodic/Paroxysmal
• C: Congenital/Developmental

• 1. Multipolar
• 2. Bipolar

• -dendrites and axons
• -Intrinsic: short axon
• -Projection: long axon

-first order neurons in the sensory systems (activated by receptors, not another neuron)

• -extensions of the neuron cell body that:
•       1. increase surface area
•       2. increase synapses
•       3. organization and heirarchy to synapses
• -dendritic spines are dynamic --> plasticity

• 1. Fast anterograde: newly synthesized materials
• 2. Slow anterograde: cytoskeletal elements/proteins
• 3. Retrograde: materials for degradation or reuse

• -bulk of CNS gray matter
• -filled with neuronal processes, synapses and glia

• 1. Astrocytes
• 2. Oligodendrocytes
• 3. Ependymal Cells
• 4. Microglial Cells

• -structural support
• -repair
• -maintain ionic environment
• -electrical insulation of synapses
• -prevent NT diffusion out of synapse

• -axon ensheathment
• -myeling formation in CNS

• -line ventricles: Brain-CSF barrier
• -specialize to become CSF-secreting cells of the choroid plexus

-phagocytes

• -CNS: many ensheathed, most myelinated
• -PNS: all ensheathed, most myelinated

***different myelin with different antigens --> autoimmune disorders that only affect CNS or PNS

-ensheath and myelinate in the PNS

-ensheath and myelinate in the CNS

• 1. RMP: K leak channels open at rest = -90mV
•               small number of Na leak channels = -70mV
• 2. Depolarization: if reaches threshold of -55mV opens voltage gated Na channels, depolarize to +20mV, followed by Na channel inactivation
• 3. Repolarization: voltage gated K channels take longer to open and stay open longer leading to repolarization.

4. Refractory Period: prevents backwards depolarization

• -increases speed of conduction
• -saltatory conduction: jumps from node to node

-electrotonic conduction on: dendrites, cell body, nerve terminal

-saltatory conduction on: axon

1. depolarization on nerve terminal opens voltage gated Ca channels

2. Calcium triggers binding of NT vescicles to membrane

3. NT binds receptors on post synaptic membrane causing an EPSP ro IPSP

4. All EPSPs and IPSPs summate

• -afferent axon: conduct APs toward cell body
• -efferent axon: conduct APs away from cell body

Pseudounipolar: AP propagates over the cell body

presentation of sensory information in terms of spatial and temporal patterns of nerve cell activity

labeled line code: sensory event represented by activity of a specific group of cells

increased stimulus intensity coded by increased firing rate

topographic maps

-block voltage gated Na channels

-unprotonated form diffuses through active channel into cell where it is protonated

-protonated form binds to inactive channel

• Effectiveness:
• 1. decreased with acidosis (protonated form can't enter cell)
• 2. enhanced with more membrane depolarization (more inactive channels to bind)

• -smaller diameter fibers are more sensititve
• -unmyelinated fibers more sensitive
• = pain fibers are the most sensitive

• -duration of action determined by systemic absorption
• -prolong duration of action with a vasoconstrictor (epi)

-function of blood level

• 1. CNS effects
• 2. Cardiovascular depression
• 3. Hematologic effects
• 4. rarely hypersensitivity

• 1. DA
• 2. NE/Epi
• 3. 5-HT
• 4. ACh
• 5. GABA
• 6. Glycine
• 7. Glutamate

• -DA, NE, Epi
• -metabotropic (GPCR)
• -metabolism: MAO-A, MAO-B, COMT
• -reuptake: NET, DAT

• -metabotropic (GPCR)
• -metabolised by MAO
• -reuptake by SERT

• -metabotropic
• -degraded by AChE

-ionotropic

• 1. Inhibitory: GAGA, glycine
• 2. Excitatory: glutamate

• From: locus ceruleus and pontine nuclei
• To: cerebral cortex, brain and spinal cord

Regulates: mood, arousal, food intake, body temp regulation, reward and BP

• 
• From: median raphe
• To: cerebral hemispheres, diencephalon, cerebellum, spinal cord

Regulates: mood, anxiety, sleep, sexual fxn, appetite, migraine

• 1. Tuberoinfundibular
• From: arcuate nucleus (hypothalamus)
• To: Pituitary
• Regulates: DA inhibits prolactin release from pituitary

• 2. Nigrostriatal
• From: Substantia Nigra
• To: Striatum (caudate and putamen)
• Regulates: motor systems

• 3a. Mesolimbic
• From: Ventral tegmental area of midbrain
• To: Medial limbic system
• Regulates: emotion and cognition

• 3b. Mesocortical
• From: VTA of midbrain
• To: neocortex (prefrontal cortex)
• Regulates: emotion and cognition

• D1: excitatory
• D2: Inhibitory