Nervous Systems Flashcards
Axon Hillock
connection of a neuron to an axon where AP is created
Axon
nerve fibers
Neurons
generate bioelectric signals to transmit information
Glial Cells
“support” cells of the neuron that assist in signaling; produce cerebrospinal fluid
Synapse
connection between the axon terminal and effector cells
Effector
can be a neuron, muscle cell or any other kind of cell
Afferent neurons
receive and carry information to the central nervous system; sensory output
Efferent neurons
carry information away from the central nervous system; motor output
Potential
difference of electrical charge between regions
Current
flow of electrical charge from region to region
Membrane Potential
unequal charge distribution across the cell membrane
Resting Membrane Potentials
the different concentrations between the inside & outside of the cell membrane; measured when the neuron is inactive
Electronic Potentials
move along the surface, can depolarize/hyperpolarize, small changes
Action Potentials
-very sudden, large changes happening in the axon
-all or nothing transient
-use voltage gated ions to move
-move through the membrane
-don’t stop once they start
Leak Channels
specific types of ion channels in the cell membrane that are always open **they can have their own permeability
Polarized cells
Cells that have distinct regions or specialized functions (- inside the cell)
Depolarized Cells
inner membrane becomes less negative, Na+ flows into cell (more + inside the cell); membrane potential increases
Hyperpolarized Cells
making the membrane potential of a cell more negative inside
Repolarization
the inner membrane becomes negative: K+ flows out of the cell; Membrane potential decreases restoring the membrane potential
Myelin
a mixture of proteins & lipids that surround nerve fibers, speeding up conduction of impulses and preventing ions from crossing the cell membrane
Refraction Period
when a neuron is unable to fire an action potential
Spiking Frequency
amount of APs created, carries information
Salatory Conduction
jumping from node to node to reach terminals
Nodes of Ranvier
allow exchange of ions for speedy electrical transmission
Electrical synapses
excitatory signals seen in invertebrates
-vital for fight or flight
-rapid flow of current
-large axon diameter= faster transmission
-no neurotransmitters involved
-they rely on ion transmission through gap junctions
EPSP (excitatory postsynaptic potential)
A small, temporary increase in the membrane potential of a neuron, making the inside of the cell less negative (depolarized); increases chance of firing a signal
IPSP (inhibitory postsynaptic potential)
A small, temporary decrease in the membrane potential of a neuron, making the inside of the cell more negative (hyperpolarized); decreases chance of firing a signal
Temporal Summation
multiple signals (typically EPSPs or IPSPs) are generated at the same synapse in rapid succession over time
Spatial Summation
signals from multiple synapses (different locations on the postsynaptic neuron) are combined
EPSP-IPSP Cancellation
(IPSP) and (EPSP) happen at the same time or close in time at a neuron, effectively canceling each other out.
Chemical synapses
slower than electrical synapses
-no gap junctions
-uses neurotransmitters
-synaptic cleft
synaptic cleft
separates the pre and post synaptic neurons by a gap
synaptic vesicles
where neurotransmitters are stored within the presynaptic neuron. When an action potential reaches the synapse, these vesicles fuse with the membrane and release neurotransmitters into the synaptic cleft
Integration
sum of hyper and depolarization
Neurotransmitter
chemical signals that allow neurons to communicate and control various processes in the body; they bind to a receptor protein in the postsynaptic membrane
Mechanoreceptors
-respond to mechanical deformation of the plasma membrane
-mechanically gated
-located in the dendrites of sensory neurons
-make the muscles flex
Thermoreceptors
responds to changes in cold & heat
Nocioreceptors
respond to pain (tissue damage)
Electromagnetic Receptors
respond to electrical & magnetic fields
Photoreceptors
respond to light stimuli
Chemoreceptors
respond to various chemicals
Stretch receptors
non-neuronal, mechanically gated Na+ channels, deformation depolarizes the membrane
Hair cells
-non neuronal
-found in organs of balance (ears) in many inverts & all verts
-mechanically gates K+ channels
-in organs of sound
-can hyperpolarize and depolarize
