Neurobio End

Question 1

Dale’s Law

Answer 1

• neuron releases same NT at all of its axon terminals
  
  • fundamentally true but NTs in axon terminal are often exhibiting “colocalization” - so may be another NT
    
    • ex. Dopamine often colocalized w/BABA or w/peptide or GHRH
  • depends on where this is located ex. in brain can be one set, in another tissue is a diff one
  • secondary NT can vary at axon terminals so can have diff secretory vesicles
  • primary NT is same

Question 2

Electrical Synapses - common in cardiac tissue, GI and CNS maybe

Answer 2

• electrical synapses have cells connected by gap junctions
• local current moves from one cell to next set up by electrical current
• advantage of electrical synapse -
  
  • decrease delay time from cell to cell b/c no nt release
  • can syncronize electrical activity in group of cells
  • can be bidirectional b/c no nt release; about current flow
    
    • in heart anatomy prevents this
• in general, nervous system is “one way” b/c we use primarily chemical synapses adn they are one way

Question 3

Learning and Memory in CNS

Answer 3

• procedural memory - things you do physically
• declarative memory - cognition, learning what we learned here

Question 4

Synaptic Plasticity - essential to learning

Answer 4

• you change what happens at synapse either pre or post
  
  • this improves/makes more efficient the signal
• facilitation:
  
  • AP comes down axon and depolarize terminal and what follows is
  • can > Ca2+ at presyn terminal which makes easier to stimulate NT release and > efficiency of post syn event
    
    • ex. aplysia w/sensory neuron
    • “habituation” you become desensitived to some type of input like don’t feel your clothes
  • can also modify presyn neuron by ennervating it w/another neuron ex is cannbinoid system
  • can also change things at post-syn level like remove hippocampus to stop repeated seizures

Question 5

Post synap membrane example: NMDA receptor

Answer 5

• NMDA receptor (for glutamate which is stimulatory NT)
• pt w/epilepsy so seizures in hippocampus
  
  • when destroy pts hippocampus, doesn’t stop seizures and can’t form long term memory
• see hippocampus key to learning and memory
  
  • has neurons loaded w/NMDA receptors for glutamate which is stimulatory
• post synp membrane has AMPA and NMDA receptors for glutamate
  
  • when 1st release glutamate it binds AMPA and > conductance of Na+ and K+ in post syn area to generate local current flow
  • there’s Mg stuck in ion channel of NMDA
  • if enough LCF can dislodge Mg2+ block at NMDA
  • now glutamate can bind to NMDA and Ca2+ enters teh ccell
• Ca2+ binds to calmodulin and this complex stimulates a kinase that will phosphorylate specific post synp cell (have something to do w/set up long term memory

Question 6

Autonomic NS

Answer 6

• sympathetic division arises from spinal cord in thoracic region and lumbar region and its actions that we see are fight or flight response
• parasymp arises from cranial and bottom of spinal cord (sacral) and its actions are rest and digest (GI ennervated via parasympathetic system)

Question 7

Components of autonomic NS

Answer 7

• basic mechanics
• 2 neuron chain:
• preganglionic axon - synapse - post ganglionic axon
• parasymp ganglion usually goes to heart so neurons/axons: long pre-gang; short post-gang
• sym: short pre-gang and long post-gang
• NT diff:
  
  • para = uses Ach as NT for pre and post
  • symp = uses Ach as pre but at end of organ (post) uses NE as NT
  • a few symp neurons that release Ach at end too but few