Intro to Nervous System Flashcards
Describe the importance of the neuron. 3 ideas
The neuron is the basic structural and functional unit of the nervous system.
The Neuron is the to Nervous System as the Muscle Fiber is to the Muscle System.
Somal, axonal, dendritic, and synaptic changes occur throughout life due to demand driven change derived from Neural Plasticity.
What is the Basic function and number of the following cell types?
Neurons
Glial Cells
Neuron: Processing information and signaling other elements within the human body.
100 billion neurons in CNS
100 Trillion connections
Glial Cells: Role supporter to the neurons.
Perhaps 1 Trillions in human nervous system.
What are the 2 types of Neural connections? How do they compare for speed? How does the most common type of connection transfer signals between neurons
Electrical: an extremely rapid process within the neuron.
Chemical: Comparatively slower process, transfers signals between neurons.
What are the 4 types of synaptic connection?
Axodendritic–Axon to dendrite. Most common
Axosomatic–Axon to soma
Axoaxonic–Axon to axon or axon to axon hillock
Dendrodendritic–Dendrite to dendrite
Why don’t axons use diffusion?
What needs to be moved around the cell?
What is used instead?
Axons are too long for diffusion.
Macromolecules and organelles need to go to axon.
Used organelles and chemicals need to be returned to the soma.
Axonal transport is therefore used.
Define Anterograde and Retrograde.
What are the two speed classifications of axonal transport?
Anterograde–Transport away from the Soma.
Retrograde–Transport toward the Soma.
Fast transport
Slow transport…When both transorts are occuring, they happen at the same speed. The difference in speed occurs when in slow transport, the chemistry units “get on and off the train through the system.” Fast doesn’t stop.
What types of cargo does Fast Transport move?
At what rate do they move?
What is the railroad track?
(membrananous cargoes (membrane associated substances)) Mitochondria Lysosomes Vesicles of neurotransmitter precursors Membrane components.
Rates of 50mm – 400mm per day. Usually 100mm –200mm/day.(2 - 16”/day = fastest. Could be 3 or 4 days in longest nerves)
Microtubules.
Microtubules serve as railroad tracks for Fast Transport…
What are the Microtubules made of? Polarization?
Name the 2 enzymes that haul cargo. What is their fuel?
Tubulin is a structurally polarized molecule oriented longitudinally with the positive end pointing away from the soma. (Negative pointed toward cell body.)
Kinesin (ATPase) bridges between microtubules and moves towards the + end of the axon (anterograde).
Dynein (ATPase) Moves come components in the retrograde direction along microtubules. (Move toward soma for rebuilding.)
Distinguish between Microtubules and Actin Meshwork.
Microtubules are longitudinally arranged within the axon cytoplasm and dendritic cytoplasm.
Actin Meshwork is found on the interior membranous lining of the axon.
What are the 3 anatomical parts of a Kinesin?
What are the 3 anatomical parts of Dynein?
Tail–carries transport vesicle
Stalk–twisted like a twist tie.
Head–two feet that do the walking.
Light and Intermediate chains–cargo transport.
Base–contains chains
Head–two large feet for walking.
What does Slow Transport carry?
2 types of cargo.
3 cargo in 1
2 cargo in 2
How far do they travel?
(Non-membranous cargoes)
Cytoskeletal polymeres ("stop and go" method)
Neurofilaments
Microtubules
Actin
Soluble Proteins (Cytosolic Proteins)
Cytoskeletal Proteins
Cytoplasmic enzymes
Only move a few mm/dayHow is Slow Transport cargo transported?
Dynein is also found tethered to the inner surface of the actin meshwork.
Microtubules can be moved along the actin meshwork as it is passed along the Dynein motoes. (The heads[feet] are up in the cytoplasm. They crowd surf molecules (cargo) along the way.)
What are Neurofilaments and how are they transported?
Neurofilaments–tethers for microtubules. Known to be moved on microtubule tracts.
Example: Several kinesin may carry neurofilament in an anterograde direction.
How are Cytosolic Proteins transported?
The 2 Cytosolic proteins piggyback on Cytoskeletal polymers already being transported within the axon…Neurofilaments, Microtubules, Actin
What are the 2 ways neurons are classified?
Neurons are classified by size, shape, and structure (Pseudounipolar, bipolar, multipolar, anaxonic(looks like it doesn’t have an axon but does).)
Neurons also classified by function or connections.
Afferent (sensory)
Efferent (motor)
Interneuron
Define Sensory neuron (afferent)
Motor neuron (efferent)
Interneuron
Sensory–sensitive to stimuli, may also receive direction connections from non-neuronal receptor cells.
Motor–end directly on muscles or glands. ANS also has motor neurons. stimulation.
Interneurons–relar neurons, association neurons, connector neurons or local circuit neurons.
(These connect to NEARBY neurons. Do not include long projection neurons, form connections between other neurons, are neither motor nor sensory neurons.)
Distinguish why grey matter and white matter are abundant in different areas of the CNS.
Most areas of CNS contain either mostly Neuronal Cell Bodies or Axons.
High numbers of Soma are “Grey matter”.
High numbers of Axons are “White matter.”
What are neuronal Nissl Bodies?
Where are they found?
What do they make?
Stacks of Rough Endoplasmic Reticulum (RER) and clusters of free ribosomes. Prominent in large neurons. They are embedded in the cytoplasm. They Synthesize proteins.
Describe the 3 Protein Polymers found in the Neuronal Soma.
Microtubules (25nm) cylindrical assemblies of 13 strands.
Neurofilaments (10nm) intermediate, twisted, ropelike assemblies. (too small for microscope)
Microfilament (7nm) twisted pairs of actin filaments.
Why are mitochondria abundant in dendrites?
What is a dendritic spine?
Mitochondria are an energy source near synaptic areas to facilitate energy demands.
Studded protuberance areas are called dendritic spines (preferred sites for synaptic contact)
