Neurons Flashcards
What are the three stages of all neuronal circuit paths?
Sensory input
Integration
Motor Response
What is sensory input?
sensory neurons will detect stimuli and transmit a signal
like sound or touch
What is integration?
signal is transferred to interneurons for analysis/evaluation
What is motor response?
a processed signal is then relayed to motor neurons to trigger response to muscles/glands
What is the central nervous system?
interneurons that integrate and process signals, and the select an appropriate response
What is the peripheral nervous system?
carries information from the sensory neurons to the interneurons for processing, and relays processed signal from CNS to motor neurons.
Describe the structure of neurons.
Cell body: organelles are located
Dendrites: branched extensions that receive signals from other neurons
Axon: typically longer extension that transmits signals to other cells
Axon Hillock: area where electrical signals are typically generated
How do neurons interact?
Through synapses
What is a synapse?
junction between branches ends of an axon and another cell
What is a synaptic terminal
specialized end of the axon, which passes signals the neuron on the other side of the synapse, via neurotransmitters
What are neurons insulated by?
Glia
What are glia cells?
support cells for neurons that nourish, insulate, support, and help maintain neurons
What is the membrane potential for a non-signaling neuron called?
Resting potential
What are sodium-potassium pumps?
along the neuron’s membrane use ATP to actively transport Na+ and K+ against their gradients
Makes two gradients
What are the two gradients?
Na+ is higher outside the cell
K+ is higher inside the cell
How does a negative charge build up inside the cell?
diffusion imbalance between Na+ and K+
Where does voltage stabilize at?
-70mV
What is the resting potential?
the difference in charge is stored energy which can be used for impulses
the membrane is highly polarized
What are gated ion channels?
they open and close in response to stimuli, which will alter membrane permeability
causes ions to rapidly cross the membrane which leads to change in membrane potential
What does the resting potential get converted to?
action potential
What is the threshold?
voltage where enough depolarization has occurred that voltage gated ion chases are opened, causing huge Na+ influx
Describe the resting stage.
Stage 1: Resting Potential
most of the voltage gated Na+ and K+ channels are closed
negative inside
Describe the depolarization stage.
Stage 2
a stimulus opens some channels and allows Na+ to enter and depolarization to begin opening some voltage gated Na+ channels
Describe rising phase. (action potential generated)
Stage 3
the threshold is reached, and most voltage gated Na+ channels open first, to let in large amount of Na+ in
Describe the falling phase. (refractory period)
Stage 4
Most voltage gated Na+ channels are inactivated blocking Na+ inflow, stopping the Positive Feedback Loop
Voltage gated K+ Channels now open to permit K+ to leave the cell, making it negative again
Describe the undershoot phase. (Hyperpolarization)
voltage gated K+ channels remain open for a bit longer while other channels reset, which hyperpolarizes the cell, leading to an undershoot in membrane potential
resting potential is restored
How does electrical current flow?
by electrical synapses, where current flows from one neuron to another via cytoplasmic bridges (gap juntioncs)
What are chemical synapses?
a chemical neurotransmitter relays signal information across the space between cells (Synaptic Cleft)
What triggers the opening of voltage gated Ca2+ channels?
open in response to an action potential, which lets Ca2+ enter cell
Where are neurotransmitters stored?
within the presynaptic cell in synaptic vesicles
How is the action potential generated?
neurotransmitters bind to ligand gated ion channels on dendrites of the postsynaptic cell
