Chapter 7 - The Neuron Flashcards
What are sensory neurons (role)?
–Carry information to the CNS from
sensory receptors
What are motor neurons (role)?
- Carry information away from CNS to an effector
What are interneurons (role)?
- Only in CNS
- Integrate and interpret sensory signals
Label the cell body, dendrites + Axon + Node of Ranvier + Schwann cell on the image. What are their roles?
Dendrites:
- Receive signals from cells
- Carry info toward the cell body of a neuron
Cell body
- Contains neuron + organelles –> maintain neuron
Axon
- Carries info away from cell body to neuron or effector
What is a nerve? (2 points)
- Parallel axons + dendrites or both from neurons
- Covered w/ tough connective tissue
What is myelin sheath? What is its role?
- Composed of the plasma membranes of glial cells
- Provides electrical insulation that increases the rate of conduction of a nerve impulse
What is saltatory conduction?
Transmission where electrical travel faster by jumping from one node to another. (Has myelin sheath)
What happens during the Threshold?
Minimum electrochemical charge that causes both channels to open
What happens during resting potential? (6 points)
- When a neuron is not conducting a nerve impulse
- Inner surface of membrane is + negative than the outer surface
- Sodium = + outside –> positive charge
- Potassium = - inside –> negative charge
- State maintained by sodium-potassium pump that uses cellular energy
- Transport sodium + potassium against their concentration gradients (low to high)
What is an action potential/nerve impulse?
Electrochemical signal involving sodium + potassium ions that cross the cell membrane through ion channels.
What happens during an action potential?
- Depolarization: Sodium channels open along the axon membrane (sodium follows a concentration gradient + rushes INTO neuron)
- Repolarization: Potassium channels open along the axon membrane (potassium follows a concentration gradient + rushes OUT of neuron)
Why does the Action Potential not travel back towards to cell body (All or nothing)?
The refractory period where the neuron cannot be stimulated again because the sodium channels are closed and can’t be reopened
Explain the release of a neurotransmitter (4 steps).
- Nerve impulse (action potential) reaches the synaptic knob of presynaptic neuron
- Calcium ions move into synaptic knob which releases neurotransmitters into synaptic cleft
- Neurotransmitter diffuses across synaptic cleft + binds w/ receptors on membrane of postsynaptic neuron causing an ion channel to open
- Once released into synapse, neurotransmitters are removed (only have temporary effects) by enzymes or pumped back into presynaptic axon terminal
What happens during an excitatory synapse?
- Neurotransmitters bind to postsynaptic neuron’s receptor which increases the chance of an action potential beginning
- Causes cell to depolarize (more sodium ions enter the cell)
What happens during an inhibitory snapse?
- Different (wrong) neurotransmitters bind to postsynaptic neuron’s receptor which decreases the chance of an action potential beginning
- Causes cell to repolarize (more potassium ions enter the cell)
