Cells of the Nervous System 1 Flashcards
Neurones supported by?
Neuroglia
Abundance of neuroglia compared with neurones?
9:1 neuroglia more abundant
Neuronal components? (6)
Cell body Dendrites Axon Axon terminals Synapse Neuronal cytoskeleton
Neuronal cell body (soma) features?
Consider its high involvement in protein manufacture, packaging and secretion.
Large nucleus and prominent nucleolus Abundant rough ER and free ribosomes Well developed Golgi Large number of mitochondria Large number of lysosomes Highly organised cytoskeleton
Neuronal dendrite features?
Spread from soma
Branch frequently
Increase surface area of the neurone
Covered in protrusions called DENDRITIC SPINES
Difference in diameter further away from cell body between axons and dendrites?
Dendrites = diameter decreases further away from cell body Axons = diameter does not change no matter how far from cell body
Neuronal axon features?
Emerge at axon hillock
Usually only one per cell but may branch extensively after leaving cell body/at target cell
Prominent microtubules and intermediate filaments (neurofilaments)
Can be myelinated or unmyelinated
Consists of 3 domains
Function of dendrites?
Input - Major area of reception of incoming information to the cell body
Function of axon?
Output - Conducts impulses away from the cell body
Where are action potentials generated in the neurone?
Axon hillock
Domains of the axon?
Node - consists of Na+ channels
Paranode - next to the node
Juxtaparanode - next to the paranode, consists of K+ channels
What do axons form near their target?
Terminal branches
Synaptic terminals - Bouton/Varicosities
Features and location of Bouton synaptic terminals?
Large, bulb-like structures at the end of the terminal branches (pre-synaptic knob)
Features and location of varicosities (synaptic terminals)?
Swelling-like structures along the axon (multiple in an axon)
Form along smooth muscle so one axon can stimulate contraction of multiple smooth muscle cells
How are synaptic vesicles packaged and transported?
Packaged in Golgi and transported by FAST ANTEROGRADE transport
Synapse features?
Specialised mechanism for association of synaptic vesicles with plasma membrane (release of neurotransmitters)
Abundant mitochondria
Neuronal cytoskeleton components?
Microfilaments
Intermediate filaments
Microtubules
Neuronal cytoskeleton functions?
Maintain axon tensile strength
Transport of proteins
Types of intracellular transport in neurones?
Fast axonal transport
Anterograde transport - both FAST and SLOW
Fast retrograde transport
Fast axonal transport function, mechanism and speed?
Transport of MEMBRANE to different compartments
Vesicles with associated motors move along the axon
100-400mm per day
Anterograde transport definition?
Transport of materials needed for neurotransmission and survival away from cell body
Fast anterograde transport components, speed, and mechanism?
Synaptic vesicles, transmitters, mitochondria
400mm per day
Moves materials along microtubular network using specific molecular motors - requires ATP
What is slow anterograde transport?
Cytoplasmic flow of soluble constituents away from cell body
What is fast retrograde transport?
Return of organelles and transport of substances from extracellular space
Uses different molecular motors
Anterograde moving vesicles and retrograde moving vesicles, same or different?
DIFFERENT - morphologically and biochemically different
Morphological subtypes of neurones?
Pseudounipolar
Bipolar
Golgi type I multipolar
Golgi type II multipolar
Location, shape and function of pseudounipolar neurones?
Dorsal root ganglia sensory neurones
Two fused axonal processes with a soma branching off
Act as a continuous cable carrying action potentials from peripheral receptor organ to central terminal in spinal cord (sensory organ to spinal cord)
Shape and location of bipolar neurones?
Two axonal processes extending from central soma
Found in cerebral cortex, retina
Features of Golgi Type I multipolar neurones?
Highly branched dendritic trees
Long axons
Pyramidal cerebral cortex cells - output
Features of Golgi Type II multipolar neurones?
Highly branched dendritic trees
Short axons
Excitatory input to cortical pyramidal cells
Functional subtypes of neurones?
Sensory
Motor
Interneurones
Features of sensory neurones?
Commonly pseudounipolar
Conducts impulses from sensory receptors to CNS
Features of motor neurones?
Generally multipolar with large soma
Conduct impulses from CNS to effectors (muscles and glands)
Features of interneurons?
Cell bodies and processes remain within CNS
Make up majority of neurones within CNS
Large multipolar or small bipolar
Functions of interneurons?
Modification, coordination, integration facilitation and inhibition between sensory input and motor output
CNS functional neurone groups?
Nucleus Laminae Ganglion Fibre tracts Nerves
What is a nucleus group of neurones?
Group of UNENCAPSULATED neuronal cell bodies within CNS
What are laminae?
Layers of neurones of similar type and function (cerebral cortex/cerebellar grey matter)
What is a ganglion?
Group of ENCAPSULATED neuronal cell bodies in the peripheral nervous system
What are fibre tracts?
Groups or bundles of axons in the CNS
Mixture of myelinated and unmyelinated
What are nerves, functions?
Discrete bundles of axons
Often mixed sensory and motor neurones
Bring information to CNS from sensory receptors
Bring axons from CNS to effector organs
