Shared Flashcard Set

Details

Cells of the Nervous System
Cells of the Nervous System
52
Medical
Graduate
10/21/2009

Additional Medical Flashcards

 


 

Cards

Term
SYNAPSE
Definition

Can be electrical  or chemical

Term
CENTRAL NERVOUS SYSTEM (CNS)
Definition

1. Comprises brain and spinal cord

2. Derived from neural tube

Term
PERIPHERAL NERVOUS SYSTEM (PNS)
Definition

1. Includes sensory and autonomic neurons and their associated glia

2. Derived from neural crest

3. Divided into somatic and autonomic

Term
SOMATIC NERVOUS SYSTEM
Definition

Associated with skin and striated muscle

Term
AUTONOMIC NERVOUS SYSTEM
Definition

Associated with cardiac and smooth muscle glands

1. Sympathetic ("fight or flight")

2. Parasympathetic ("rest & digest")

Term
ENTERIC NERVOUS SYSTEM
Definition

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

Term
NEURON DOCTRINE
Definition

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

Term
CELL COMMUNICATION
Definition

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

Term
LEVELS OF ORGANIZATION OF NERVOUS SYSTEM
Definition

1. Hierarchical

2. Parallel

3. Serial modes

Term
NEURON CLASSIFICATION
Definition

1. Number of processes

2. Connections

3. Neurotransmitter content

Term
TYPES OF NEURONAL PROCESSES
Definition

1. Pseudounipolar (sensory ganglion cell)

2. Bipolar (retinal neuron)

3. Multipolar (spinal motor neuron)

Term
NEURITES
Definition

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

Term
AFFERENT NEURONS
Definition

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

Term
EFFERENT NEURONS
Definition

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

Term
LOCAL CIRCUIT NEURONS
Definition

Process information locally

Term
PROJECTION NEURONS
Definition

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

Term
MYELIN
Definition

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

Term
INTERNEURON
Definition

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

Term
FOUR FUNCTIONAL DOMAINS OF NEURONS
Definition

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)

Term
NISSLE SUBSTANCE
Definition

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

Term
DENDRITIC SPINES
Definition

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

Term
DENDRITES
Definition

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)

Term
MICROTUBULE ASSOCIATED PROTEINS (MAPS)
Definition

Regulate the stability and packing density of microtubules

1. MAP2

2. tau

Term
MAP2
Definition

Microtubule associated protein specifically localized to dendrites

Term
TAU
Definition

Microtubule associated protein specifically localized to axons

Term
NEUROFILAMENT
Definition

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

Term
ACTIN MICROFILAMENTS
Definition

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

Term
AXON HILLOCK
Definition

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)

Term
AXON
Definition

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

Term
AXON TERMINAL
Definition

1. MTs don't extend into terminal

2. Contains higher concentration of mitochondria

3. Numerous synaptic vesicles containing NTs (synaptic bouton)

 

Term
SYNAPSES
Definition

1. Axodendritic, Axosomatic, or Axoaxonic

2. Electrical or Chemical

Term
ELECTRICAL SYNAPSE
Definition

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

Term
CHEMICAL SYNAPSE
Definition

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

Term
AXONAL TRANSPORT
Definition

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

Term
ANTEROGRADE TRANSPORT
Definition

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)

Term
RETROGRADE TRANSPORT
Definition

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)

Term
SLOW AXONAL TRANSPORT
Definition

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

Term
FAST AXONAL TRANSPORT
Definition

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

Term
LEAKAGE CHANNELS
Definition

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

Term
ELECTRICALLY-GATED CHANNELS
Definition

1. Voltage dependent

2. Ion selective

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

Term
CHEMICALLY GATED CHANNELS
Definition

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

Term
MECHANICALLY GATED CHANNELS
Definition

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

Term
GLIA VS. NEURONS
Definition

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

Term
TYPES OF GLIA
Definition

1. Oligodendrocytes (CNS)

2. Astrocytes (CNS)

3. Microglia (CNS)

4. Ependymal cells (CNS)

5. Schwann cells (PNS)

Term
INTERNODE
Definition

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

Term
SCHWANN CELLS
Definition

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

Term
OLIGODENDROCYTES
Definition

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

Term
MYELINATION OF PNS VS. CNS
Definition

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

Term
ASTROCYTE FUNCTIONS
Definition

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

Term
MICROGLIA
Definition

1. Brain's immune system

2. Derived from mesoderm

3. Represent the primary phagocytic cells of CNS

Term
EPENDYMAL CELLS
Definition

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

Term
TUMORS OF CNS
Definition

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

Supporting users have an ad free experience!