Introduction Flashcards
Cell Theory
Idea that the entire body is made of cells except for the brain.
Theorized by Theodore Schwann in 1839.
Golgi Stain
Silver nitrate solution that sparsely labeled neurons.
Discovered by Camillo Golgi
Reticular Theory
Idea that the brain is a network of nerve fibers rather than distinct cells
Theorized by Camillo Golgi
Neuron Doctrine
Idea that the brain is discrete neurons that form dynamically polarized signaling units
Information flows in one direction
Theorized by Ramon Cajal and discovered using Golgi stain
Dendrites
Tapered extensions of the cell body
Collect information from other neurons
Soma
Aka cell body
Composed of one axon and many dendrites
Responsible for synthesis and signal integration
Axon
Aka boutons
Cylindrical in shape and sometimes myelinated
Sending/conducting information
Axon terminal
Vesicle-filled space
Transmitting information to other neurons
Neuron types are defined by…
- morphology
- physiology
- gene expression
Unipolar neuron
Composed of cell body and axon
Exist in early development; rare in adults
Pseudounipolar neuron
Composed of dendrite, cell body, and axon (cell body branches off)
Present in sensory neurons at the spinal cord
AP isn’t propagated at the cell body
Bipolar neuron
Composed of dendrite, cell body, and axon (cell body is in line with dendrite and axon)
Found in the retina and nose
Multipolar
Composed of multiple dendrites branching off of cell body and one axon
Most common type of neuron
Ex. motor neuron, cortical pyramidal cells, interneurons
Synapses can be…
- axodendritic
- axosomatic
- axoaxonic
- dendrodendritic
Glutamate
Abbrev = Glu
Neurotransmitter
Responsible for CNS excitation
GABA
Neurotransmitter
Responsible for CNS inhibition
Key Neurotransmitters
Glutamate - CNS excitation
Aspartate - brain, spinal chord excitation
GABA - CNS inhibition
Glycine - rapid spinal chord inhibition
Acetylcholine - muscle and autonomic activation, attention (present at NMJ)
Key Neuromodulators
Dopamine - reward and movement
Norepinephrine - arousal and smooth muscle activation
Serotonin - relaxation, mood, and sensory processing
Substance P - pain signaling
Neuropeptide Y - appetite control
Opioids - pain modulation
Adenosine triphosphate - misc.
Neuromodulator
A transmitter that works by slow signaling to alter neuron excitability (often through GPCR pathways)
Ionotropic receptors
Works via ion flow
Timescale of ms (fast)
Ex. Glu, GABA
Used mainly by NTs
Metabotropic receptors
Works via signaling pathways
Timescale of 100ms to s (slow)
Ex. DA, 5-HT
Used by NMs and NTs
Glial cells
Majority of cells in brain
Generally no axons, dendrites, or APs
Capable of cell division
Important to brain function and homeostasis
Astrocytes
Buffering the extracellular environment
Metabolic regulation
Blood flow regulation
Oligodendrocytes
Make myelin
Have synaptic potential
