Neurons Flashcards
Describe the cytoskeleton in an axon
What is a perikaryon?
A neuron’s cell body or soma
What are the myelin generating cells of the CNS and PNS?
Oligodendrocytes and Schwann Cells respectively
How fast is slow anterograde transport in axons? What travels by this method?
2-4mm/day (effectively diffusion). cytosolic proteins, cytoskeletal elements are transported like this
How fast is fast anterograde transport in axons? What travels by this method?
100-400 mm/day, as mediated by kinesins
organelles and particles travel in this fashion
What protein is used for retrograde transport in axons?
dynein
How fast do unmylinated nerves conduct signals?
0.6-2 m/s
How fast do mylinated nerves conduct signals?
5-120 m/sec
Can axons regenerate?
Yes, but only in the PNS. Seems to be heavily restricted by extrinsic factors
What is the function of astrocytes?
Structural support
Physical isolation of neurons
Buffer of extracellular ions (f.e.sink for K+)
Uptake /clearance of of neurotransmitters
Metabolic functions to support neurons
Secretion of growth factors
Response to injury
Blood-brain barrier
What is the function of microglia?
Macrophages of the brain
What is the function of radial glia?
tracks for neuronal migration during brain development
What is saltatory conduction?
The propagation of action potentials alongmyelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials. This also has the happy effects of making the signal unidirectional and saving energy
What triggers synaptic exocytosis and neurotransmitter release?
Depolarization-dependent opening of Ca++ channels in nerve terminals
What is the target of the proteolytic action of tetanus and botulinum toxins?
The SNARE machinery. These toxins potently block synaptic transmission.
What part does clathrin-mediated endocytosis play in synapse function?
It allows for the recovery and recycling of neurotransmitters and synaptic vesicle membranes from the synapse.
Divide these neurotransmitters into excitatory and inhibitory categories: ACh, Amines, GABA, Glutamate, Glycine
GABA & glycine: inhibitory
Glutamate, ACh and Amines: excitatory
Generally, these neurotransmitters are seperated into different synapses
What is the function of neuropeptides? Where are they stored?
They have slow modulatory effects, and are stored in large dense core vesicles
What is the response of ionotropic neurotransmitter receptors to binding their respective neurotransmitters?
Opening connected ion channels (generally sodium at excitatory synapses, chloride at inhibitory synapses)
What are metabotropic receptors?
They function in much the same way as ionotropic receptors, but use a signal transduction, often a G-protein moiety (but also tyrosine kinases and guanylyl cyclases), to more slowly modulate the potential in the postsynaptic neuron
What are the 3 different shapes of neurons?
A multipolar neuron has multiple dendrites extending from the cell body and a single axon extending in the opposite direction.
A bipolar neuron has a single dendrite that extends from the cell body, opposite the side from which the single axon extends.
A pseudounipolar neuron is unique in that a single stem comes off the soma; this stem then splits into a single dendrite and axon
There are 3 types of sensory nerve receptors (mentioned in the nervous system lab). What are the?
Exteroceptors carry sensations of pain, temperature, touch, and pressure from the skin and connective tissue. They may be encapsulated or unencapsulated.
Proprioceptors carry impulses of stretch and position from the muscles, tendons, and joints.
Visceroreceptors carry stimuli from the internal organs and circulatory system
What is the typical shape of a motor neron
multipolar
What are the 3 layers of the cerebellar cortex?
an outer molecular layer with nerve cell processes, a layer of Purkinje cells, and an inner granular layer with several other types of neurons. Purkinje cells are very large neurons that possess a tree of branching dendrites that extend into the molecular layer.
What are Ependymal cells?
Ependymal cells line the ventricles of the brain and the central canal of the spinal cord. These are derived from epithelial cells and produce cerebrospinal fluid.
