Can be electrical  or chemical

1. Comprises brain and spinal cord

2. Derived from neural tube

1. Includes sensory and autonomic neurons and their associated glia

2. Derived from neural crest

3. Divided into somatic and autonomic

Associated with skin and striated muscle

Associated with cardiac and smooth muscle glands

1. Sympathetic ("fight or flight")

2. Parasympathetic ("rest & digest")

Intrinsic nervous sytem to the gastrointestinal system (techincally a part of the autonomic) and referred to as the "little brain"

Composed of an individual signaling element, the neuron, which, although a separate structural, functional and genetic unit, acts as part of an assembly

Neurons interact with each other by means of electrical conduction and chemical transmission via the synapse. This communication is polarized

1. Hierarchical

2. Parallel

3. Serial modes

1. Number of processes

2. Connections

3. Neurotransmitter content

1. Pseudounipolar (sensory ganglion cell)

2. Bipolar (retinal neuron)

3. Multipolar (spinal motor neuron)

Processes of neurons grown in culture that do not contain the specific organization of either dentrites or axons

Carry information to target structures from somewhere elase (e.g., to CNS from skin)

Carry information away from one structure to targets (e.g. motor neurons to muscles)

Process information locally

Relay information long distances (e.g., motor neurons and pyramidal cells)

Lipid coating secreted by glial cells that surrounds axons of projection neurons to increase speed of transmission

Any neuron interposed between two others-can be local or can project long distances

1. Input domain (soma, dendrites)

2. Integrative (trigger) zone (axon hillock or near peripheral termination of the peripheral process in pseudounipolar neurons)

3. Conductile domain (axon)

4. Output domain (synaptic endings)

Characteristic accumulation of RER in parallel stacked arrays near the nucleus that is prominent in projection neurons and found in soma (cell body)

Small protuberances in shaft of dendrites that further increase surface area for synaptic input

1. Highly branched outgrowths from cell  body that function to increase surface area of neuron and receive synaptic connections

2. Proximal cytoplasm contains RER, but no Nissl substance

3. Distal cytoplasm contains only polysomes (no RER)

Regulate the stability and packing density of microtubules

1. MAP2

2. tau

Microtubule associated protein specifically localized to dendrites

Microtubule associated protein specifically localized to axons

Represents intermediate filament of neurons that consists of individual long protein molecules

Found throughout the neuron but are particularly prevalent in the growth cones of growing axons or dendrites

1. The initial segment of the axon

2. The site of AP generation (except in pseudounipolar sensory neurons where AP is generated near peripheral end of axon)

3. High density of voltage-gated sodium and potassium channels

4. Notable lack of RER and ribosomes

5. Microtubules and neurofilaments change orientation as they enter axon hillock (MTs gather into thick bundles)

1. Speed at which AP traverses length of axon depends on axonal diameter

2. Axons larger than 1 micrometer are myelinated

3. High concentration of microtubules, neurofilaments, mitochondria, and vesicles

1. MTs don't extend into terminal

2. Contains higher concentration of mitochondria

3. Numerous synaptic vesicles containing NTs (synaptic bouton)

1. Axodendritic, Axosomatic, or Axoaxonic

2. Electrical or Chemical

A gap junction where current (ions) flows directly from one cell to the next

Invasion of synaptic bouton by AP results in increase in calcium within the bouton that starts a cascade in which NT-containing vesicles fuse with terminal plasma membrane and release contents extracellularly into synaptic cleft where they diffuse to activate receptors on postsynaptic cell

1. Transports proteins to axon and synapse (since they don't contain ribosomes or RER)

2. Transport of organelles, trophic (signaling) molecules, viruses, and neurotoxins

1. Substances and organelles transported from the cell body to the ends of the axon or dendrites

2. Kinesin motor proteins involved (transports vesicles from minus to plus end along MTs)

1. Substances transported from distal ends of cell back to the cell body

2. Dyenin motor proteins involved (from plus end to minus end of MTs)

1. 2-4mm/day

2. Occurs only in anterograde direction and is responsible for transporting cytoskeletal elements

3. Maintains intergrity of the neuron

4. The rate limiting step for axonal regeneration

1. 100-400mm/day

2. Occurs in both anterograde and retrograde direction

3. Transports membrane associated materials, metabolic enzymes, and trophic factors

4. Maintains metabolic homeostasis of neuron

1. Always open or ungated

2. Can be selective for anions or cations

3. Distributed along the entire plasma membrane of neuron

4. Responsible for neuronal resting membrane potential

1. Voltage dependent

2. Ion selective

3. Voltage-gated Na+ and K+ channels (axon hillock) and voltage-gated Ca++ channels (synaptic bouton)

1. Open or close in response to binding of ligand to specific receptor

2. Responsible for postsynaptic cell's ability to respond with a change in membrane polarization to a NT released by a presynaptic cell

3. In soma or terminal regions of axon

4. Calcium-gated channels

Opened or closed by physicial deformation (typically associated with sensory endings)

1. Glial cells retain capacity to divide in adult

2. Glia do not fire APs or form synapses

3. Glia mainly contribute to brain function by supporting neuronal functions

1. Oligodendrocytes (CNS)

2. Astrocytes (CNS)

3. Microglia (CNS)

4. Ependymal cells (CNS)

5. Schwann cells (PNS)

1. The interval between adjacent nodes

2. Length and thickness of internode (and diameter of axon) is proportional to the speed of conduction of AP

The only glial cell in the PNS that performs the basic functions of glial cells and also fills interneuronal space and becomes phagocytic in response to inflammation or injury

Located in white matter of spinal cord, and form myelin in CNS

1. One Schwann cell contributes myelin to one axon, while oligodendrocyte can contribute myelin to several axons

2. Schwann cells synthesize basal lamina, but oligodendrocytes do not

1. Form end feet that cover basal lamina around blood vessels to selectively take up materials from blood

2. Homeostasis-takes up and metabolizes glucose from blood, transports as lactate to neurons for energy

3. Neurotransmitter recycling

4. Buffering-of extracellular potassium

5. Development-radial glia guide neuronal migration

1. Brain's immune system

2. Derived from mesoderm

3. Represent the primary phagocytic cells of CNS

Line ventricals of the brain and central canal of spinal cord (certain cells can secrete CSF)

1. Neurons lost capacity to divide, so brain tumors in adults are not neuronal in origin

2. Primary tumors of CNS are of glial origin

3. Astrocytomas, ependymomas, meningiomas, oligodendrogliomas

5. Glioblastoma multiform