Neurobiology (Exam 1) Flashcards
Membrane Potential
- Voltage difference across the membrane (v or mv)
- Arises from unequal distribution of ions
- Changes w/ selective movement of ions across the membrane
- Rate of ion movement is proportional to the difference between membrane and equilibrium potential (driving force)
- The larger the difference, the stronger the driving force
Equilibrium Potential
- Membrane potential when the net flow of an ion is zero
- When concentration gradient and electrochemical gradients are equal and opposite to one another
What is the resting membrane potential of neurons?
~70mV
Resting Membrane Potential
- Relies heavily on K+ leak current
- Neurons maintain concentration gradients via active transport
- Na/K pump, leaky channels, and ions all contribute to this
Graded Potentials
- Short distance signals that occur in dendrites and cell bodies
- Vary in magnitude and duration
- Based on strength of stimulus
- Created by ligand-gated channels
- Decay over short distances
Action Potentials
- Long distance all-or-none signals that maintain the same magnitude, duration, and amplitude
- Move from the axon hillock to axon terminal only
- Due to the inactivation of voltage-gated Na+ channels
- Weak stimulus leads to a low frequency of action potentials
- Strong/supra-threshold stimulus leads to high frequency of action potentials
Types of Neurons
Multipolar, bipolar, unipolar, efferent, afferent, interneuron
Steps of Neurotransmitter Release
- Voltage-gated Ca2+ channels open, Ca2+ flows into the cell and pushes vesicles toward the plasma membrane
- Ca2+ ions change the conformation of SNARE proteins, which causes the vesicles to fuse with the plasma membrane
- Neurotransmitter is released and binds to receptor on post-synaptic cell
Multipolar
Several processes off of cell body
Bipolar
Two processes off of cell body
Unipolar
One process off of cell body + branches
Efferent Neuron
- Carries info from CNS to PNS
- Motor neuron (multipolar)
Afferent Neuron
- Carries info from PNS to CNS
- Sensory neuron (unipolar)
Interneuron
- Carries info from one neuron to another
- Multipolar
Temporal Summation
Converts a rapid series of weak pulses from a single source into one large signal
Spatial Summation
Several weak signals from different locations into one large signal
Types of Neurotransmitters
- Amino acids
- Neuropeptides
- Biogenic amines
- Acetylcholine
Ionotropic Receptors
- Receptors + channel is the same protein
- Neurotransmitter binds, channel opens, ions flow through
Inhibitory Neurotransmitters
Generates IPSPS (hyperpolarization)
Excitatory Neurotransmitters
Generates EPSPS (depolarization)
What causes depolarization (action potential graph)?
Ligand-gated channels open at threshold, Na+ enters
Metabatrophic Receptors
- Receptor + channel are different proteins
-Neurotransmitter binds + activates pathway to open a separate channel
What enables the transition from absolute to relative refractory period?
Opening of the inactivation gate
Absolute Refractory Period
Time during which no new AP can occur, occurs from onset of AP until the end of Na+ channel inactivation
What causes repolarization (action potential graph)?
Voltage-gated K+ channels open and K+ leaves
What results from hyper-polarization (action potential graph)?
Voltage gated K+ channels close
Relative Refractory Period
When a larger depolarization is needed to reach the threshold due to hyper-polarization
Neuron
- Fundamental unit of the nervous system
- Uses changes in membrane potential to communicate signals across long distances
What Quickens the Action Potential Conduction Velocity
- Quicker when the axon is heavily myelinated
- Quicker when the axon has a large diameter
- Current spreads farther + decays slower
Dendrites Function
Receives information from other neurons
Rough ER Function
Protein synthesis
Cell Body (soma) Function
Keeps cell functional
Axon Hillock Function
Generates impulse in the neuron
Myelin Sheath Function
Increases speed of signal
Nodes of Ranvier Function
APS jump between these (saltatory conduction)
Axon Function
Transfers signals to other cells; stimulus must surpass threshold potential here
Axon terminal Function
Forms junctions with other cells
Synapse Function
Transmits info; neurotransmitter carries message to next cell
