lecture 5 - neurons & nerves Flashcards
What are the components of a neuron?
Dendrites, soma/cell body, axon, synapses
What is the name for the cell body of a neuron?
Soma
What is the function of neuron dendrites?
Receive signals from other neurons via synapses
What are axons?
Processes that leave a neuron’s soma to propagate an action potential for signalling to other neurons via synpases
What are the 4 morphological types of neuron?
multipolar, bipolar, unipolar, anaxonic
What is the structure of a multipolar neuron?
Multiple processes emanate from the cell body
What is the structure of a bipolar neuron?
2 processes emanate from the cell body
What is the structure of a unipolar neuron?
One process emanating from the cell body that branches into the dendrite and axon
What is the structure of an anaxonic neuron?
No distinct axon because all processes look alike
What are glia?
Non-neuronal support cells of the CNS or PNS
What are the 4 key glia types of the CNS?
oligodendrocytes, astrocytes, microglia, ependymal cells
What are the 2 key types of glia in the PNS?
Schwann cells, satellite cells
What is the function of oligodendrocytes?
Form the myelin sheath around neurons in the CNS
What is the function of astrocytes?
Provide nutrients, maintain extracellular environment and structural support to neurons in the CNS
What is the function of microglia?
Mount the immune response within the CNS
What is the function of Ependymal cells?
Circulate and produce cerebrospinal fluid in the CNS
Which cells produce CSF in the CNS?
Ependymal cells
What is the function of Schwann Cells?
Form the myelin sheath around neurons in the PNS
What is the function of Satellite Cells?
Provide nutrients and structural support to neurons in the PNS
What is the name for a unit of neurons with a nerve that is surrounded by perineurium?
Fascicle
Where does sensory information enter the spinal cord?
Dorsal root
Where does motor information leave the spinal cord?
Ventral root
What type of peripheral nerve has the fastest relative conduction velocity?
Motor neurons
What type of peripheral nerve has the slowest relative conduction velocity?
Sensory - pain/temperature, etc.
What are the characteristics of motor neurons?
Large diameter, heavily myelinated = fast conduction velocity
Which 2 factors influence the relative conduction velocity of a nerve?
Diameter, myelination
What happens to the conduction velocity of a nerve as its diameter increases?
Increases
What is the resting membrane potential inside of neurons?
~-70mV
Which factors contribute to the resting membrane potential?
Concentration gradient of ions across membrane, differential permeability of membrane to K+ vs Na+
Are cell membranes more permeable to K+ or Na+?
K+
Which ion has the greatest influence on resting membrane potential?
K+
What creates the electrochemical gradient across a cell membrane?
The difference on the concentration of ions on either side of the membrane, and the permeability of the membrane to these ions
What ion channel maintains the electrochemical gradient across a cell membrane?
Na+,K+ - ATPase
What does Na+,K+-ATPase pump, and in what directions?
3Na+ out of cell, 2K+ into it
Which equation calculates the equilibrium potential for an ion?
Nernst equation
How does the ratio of ions in/outside a cell influence the voltage across the membrane?
The greater the concentration difference between outside and inside, the greater the voltage
Which equation calculates the resting membrane potential of a cell?
Goldman-Hodgkin-Katz
What are voltage-gated ion channels?
Ion channels that provide selective permeability to certain ions due to changes in membrane potential
What are mechanically gated ions channels?
Ion channels that open when a physical stimulus causes membrane deformation
What are chemically gated channels?
Ion channels that open when a ligand binds
