Summary: Fysiologie

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• 1 Fysiologie

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• what are  Peripheral ganglia?

  groups of nerve cells concentrated into small clumps that are located outside the CNS

• what is and what is the function of myelin?

  Myelin consists of coiled glia cell membranes that wrap around the nerve axon.
  without myelin the electrical message of the axon travels slowly, but with myelin segments the message jumps over the myelin segments to a node of ranvier and so on. so much faster impulse conduction. this is called saltatory conduction.

• what is a synapse?

  the junction formed between the presynaptic terminal and its target.
   it consists of the presynaptic terminal,membrane of the target cell(postsynaptic membrane) and the space between them (synaptic cleft).

• what are dendritic spines?

  small projections to amplify the range of the postsynaptic surface  that is available for receptors.

• in which way can neurons be seen as endocrine cells? and polarized cells?

  endocrine because they package and store hormone-like molecules which they release fast into extracellular space by exocytosis in response to a external stimulus.
  not via blood but only local.
  polarized cells because they have some properties of the epithelial cells, like they have different populations of membrane proteins at each distinct domain of the neuronal plasma membrane. So, the design of the nervous system permits information transfer across synapses in a selective and coordinated way that serves the need of an organism and summates to produce complex behavior.

• which 2 major classes of MAPs are found in the brain?

  - the high-molecular-weight-proteins, like MAP-1 and MAP-2(2 only found in dendrites and cell body)
  - the lower molecular weight tau proteins. (dephosphorylated tau proteins only found in axons)

• in which way do microtubules help to create morphological and functional divisions in neurons?

  Axons- the microtubules assemble with their plus ends pointed away from the cell body(sort of polarization)this orientations is helping to define what should and shouldn't be in the axonal cytoplasm.
  dendrites- the microtubules haven't got a consistent orientation, which gives them structural and functional similarities with the cell body.

• which 3 types are there by axoplasmic transport? and how is this transport functioning? ad what materials are transported?

  - fast anterograde~400mm/day, saltatory movement along microtubules by the motor molecule Kinesin(ATP dependent). mitochondria, vesicles containing peptide and other neurotransmitters, some degradative enzymes.
  - fast retrograde~200-300mm/day, saltatory movement along microtubules by the motor molecule Dynein(ATP dependent). degraded vesicular membrane, absorbed exogenous material(toxins, viruses, growth factors).
  - slow anterograde~0.2-8mm/day, not clear, possible by molecular motors. Cytoskeletal elements(neurofilament and microtubule  subunits), soluble proteins of intermediary metabolism, Actin.

• what is anterograde and retrograde?

  anterograde is moving material to the synaptic terminal
  retrograde is the opposite direction

• what are projection neurons?

  neurons with long axons that connect with other parts of the nervous system.