Neurons Flashcards
What are the two major divisions of the nervous system?
CNS - brain and spinal cord - surrounded by bone
PNS - nerves and neurons - not surround by bone
2 classes of cells
Glial cells and neurons
Glial cells are _____ of NS, 4 functions, *
Structural units like glue Firmness and structure Form myelin Provide nutrients to neurons Scavengers - remove debris * no function in electrical transmission
Neurons are ____ of NS, 5 parts and functions
Functional units/basic signaling units of NS
Dendrites/branching - input mechanism
Cell body/soma - integrative centre of neurons
Axon hillock - site of action potential generation
Axon/conducting unit - myelin and nodes of ranvier to have signals go faster
Terminal branch - output mechanism from collaterals
Where do neurons make connections
At synapses with one another
Synapse
Area where neurons communicate with another cell
Presynaptic neuron
Neuron that sends msg
Post synaptic neuron
Cell that receives msg
Synaptic cleft
Fluid filled gap separating pre and post synaptic membranes
3 different types of synapses
Axo dendritic synapse - between axon of presynaptic neuron and dendritic branch of postsynaptic neuron
Axo somatic - between axon of presynaptic neuron and cell body of postsynaptic neuron
Axo axonic - between axon of presynaptic neuron and axon of postsynaptic neuron
Agonist
Contraction for movement
Antagonist
Action opposing agonist
Synergist
Works with agonist
Homonymous
Same muscle for sensory and contracting
Concentric
Muslce shortens
Eccentric
Muscle lengthens
Motor nerve - efferent or afferent?
Efferent
Sensory nerve - efferent or afferent?
Afferent
Single axon rule
If a neuron has an axon, then it has only one
3 structural classification of neurons for mammalian
Pseudounipolar
Bipolar
Multipolar
Pseudounipolar
Single process emerges from soma, splits into two processes
Goes to periphery and spinal cord
Sensory neuron that travels to the dorsal root ganglia
Bipolar
Soma give rise to 2 processes - 1 actual axon
Special sense organs
Multipolar
Most common
Single axon and many dendritic branches
Motor neurons controlling skeletal muscles
3 functional classification of neurons
Sensory
Motor
Inter neurons
Sensory neurons - 2
respond to stimuli
input neurons of NS
Motor neurons
Sends signals to cells outside of NS
output neurons of NS
Interneurons
Carry information between sensory and motor neurons
Cell membrane consists of? What’s selectivity?
Lipd/protein belayer to separate intra/extra cellular environments, semipermeable to some ions
What dictates the electrical signalling properties of neurons?
Relative concentration of ions between intra and extra cellular environments - membrane potential
What exists across a neuron’s cell membrane?
Electrical potential
What is a potential difference?
Difference in electrical potential across the membrane where electrical potential reflects ionic concentration (Na, K, Cl, Ca)
Membrane potential
Voltage value describing the potential difference across the membrane at any point of time
What ions are outside?
Sodium and chloride
What ions are inside?
Potassium and aspartame
Neuron resting membrane potential
-65mV
Muscle cell RMP
-90mV