Neuronal Function Flashcards
excitable cells that are important in signaling
(electrical and chemical), coordination and movement (cell body, dendrites and axon)
Neurons (Nerve Cells)
3 types of neurons and their functions
Sensory - Transmit information and respond to stimuli
Interneurons - Connect other neurons within the CNS
Motor - Carry signals to effector organ
Components of the nervous system
Neurons and Neuroglia
These are the supporting cells in the nervous system
Neuroglia (glial cells)
Parts of the neuron and their functions
Soma - Cell Body; Responsible for metabolic maintenance of cell
Dendrites - Receives signals from other neurons
Axon - conduct signals away from the body
include the astrocytes, oligodendrocytes, microglia, and ependymal cells
Glial cells
Steps in transmission of signals in a single neuron
- Dendrites and cell body receive and integrate information.
- Axon hillock is the trigger zone. Action potentials travel from hillock to terminals.
- Action potentials move along the axon’s surface.
- Action potentials in axon terminals trigger neurotransmitter release, transmitting signals to other cells.
collect from and send out information to other neurons
Sensory Neurons (Afferent Neuron)
Axons of afferent neurons are called?
Afferent Fiber
Lie inside the Central Nervous System and carry information between other neurons
Interneurons
Specialized location where information is passed
Synapses
Neurons that carry the information out to the effectors
Motor (Efferent) Neurons
potential difference across the membrane
(separation of charges across the membrane)
Membrane Potential (Vm)
What governs the electrical properties of the membrane
Unequal distribution key ions between the ICF and ECF and their selective movement through the plasma membrane
Different parts of the membrane potential graph and what they mean (3)
Depolarization - Decrease in potential; les negative
Repolarization - Return to resting potential post depolarization
Hyperpolarization - Increase in potential; membrane more negative
passive movement of current across the cell
membrane
electrotonic conduction
Passive change in Vm depends on
K+ leak channels
hindrance to electrical
charge movement/ measure of
impermeability to ions
Resistance
measure of the amount of
charge that can be maintained across an
insulating gap
Capacitance
spread by passive current flow and are impeded by resistances; die out over short distances
Graded Potentials
Active change in Vm depends on
The opening or closing of gated ion selective
channels
voltage difference across cell membrane
- Ion concentration gradient in and out of the cell
- Selective permeability of ion channels
Electrochemical Potentials
concentration gradient and electrical potential difference are balanced/equal
Electrochemical Equilibrium
potential difference across the membrane that balances the concentration gradient
Equilibrium Potential
used in calculating equilibrium potential for single ions
Nernst Equation
used in calculating equilibrium potential for multiple ions
Goldman Equation
Potential difference at equilibrium (non-excited or resting state), Vrest
Resting Potentials
Factors affecting Vrest
- Selective Ion channel
- Unequal distribution of ions in and out of cell
Rapid, brief, large changes in membrane potential (Vm) that are propagated along axons
Action Potentials
Factors affecting Action potentials
- Unequal concentrations across membranes caused by active transport of ions
- Electrochemical gradient across membranes
- Selective gating of ion channels
membrane potential that triggers AP (-50 to -55mV); critical all-or-none event
Threshold potential
States that an excitable membrane either responds to a triggering event with a maximal action potential that spreads non-decrementally through-out the membrane, or it does not respond with an action potential at all.
All-or-none Law
Types of conduction
Contiguous and Saltatory
spread of the AP along every patch of membrane down the length of the axon
Contiguous Conduction
(contiguous means “touching” or “next to in sequence”)
new action potential cannot be initiated by normal events.
Prevents backward flow
Limits AP frequency
Refractory Period
membrane is completely refractory (unresponsive) to further stimulation
Absolute Refractory Period
Second Action Potential can be produced by strong triggering event
Relative Refractory Event
Action potential are speeded up by myelination, this is done by these two myelin forming cells
Oligodendrocytes (CNS) and Schwann Cells (Non-CNS)
Conduction in myelinated fiber, impulse “jumps” from node to node
Saltatory Conduction
Non-gated ion channels
Leak Channels
Ion Channels that open or close in response to specific triggering events
Gated Channels
Two basic forms of electrical signal
Graded (Short distance/decay over time) and Action Potential (longer distance/no decay)
Portion of the Membrane potential graph vs time graph where the membrane potential becomes positive
Overshoot
Portion of the membrane potential vs time graph where the membrane potential is more negative than the resting potential
Hyperpolarization
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