Ch11 Flashcards
(23 cards)
What is the process by which sensory receptors transduce changes in energy into depolarization of the plasma membrane of sensory neurons?
by the opening of Na+ channels.
What forms of energy are detected by sensory receptors?
- Light (sight)
- Sound waves (hearing)
- Kinetic energy of molecules (taste and smell)
- Distortions of sensory neuron membranes (temperature)
- Mechanical changes in sensory neuron membranes (touch)
What are the two major types of dendritic Na+ channels involved in depolarization?
Ligand-gated Na+ channels.
What factors influence the magnitude of excitatory postsynaptic potential (EPSP)?
- Amount of glutamate released from the presynaptic neural terminus
- Number of ligand-gated Na+ channels on the postsynaptic dendritic membrane
- Speed by which Na+ transverses a type of ligand-gated Na+ channel
- Rate of clearance of glutamate from the synaptic cleft.
What happens after a sensory neuron’s plasma membrane depolarizes to threshold?
A wave of depolarization flows down the axon of the neuron and enters the CNS through the spinal cord or directly into the brain.
What neurotransmitter is exocytosed by sensory neurons to depolarize subsequent neurons?
Glutamate.
What types of postsynaptic potentials can sensory neurons generate in interneurons?
- Excitatory postsynaptic potentials (EPSP)
- Inhibitory postsynaptic potentials (IPSP).
What is the significance of the summation of EPSP and IPSP in interneurons?
If the sum of depolarization reaches threshold, voltage-gated Na+ channels will open and an action potential will be initiated.
If the sum of hyperpolarization reaches threshold, voltage-gated K+ channels will open.
True or False: Decision making occurs at the interneurons’ dendrites based solely on sensory input.
False.
What are the two types of memory retained in interneuron circuits?
- Short-term memory
- Long-term memory.
Describe short term memories
Short-term memories are easily forgotten and not stored permanently within interneuron circuitry
What are the two major isoforms of dendritic glutamate-gated channels found on interneurons?
- AMPA Receptors
- NMDA Receptors.
What is the function of AMPA receptors?
They open in the presence of glutamate, allowing Na+ to enter the cytosol of the postsynaptic neuron, causing EPSP.
Describe the structure and function of NMDA channels.
NMDA channels are blocked by Mg2+ in the absence of glutamate and only allow Na+ and Ca2+ to enter after significant depolarization.
What role does the transient increase of Ca2+ in the dendritic cytosol play?
It triggers internal vesicles to fuse with the plasma membrane, releasing contents and incorporating channels into the membrane. (Exocytosis of neurotransmitters)
What happens if activation of the circuit to the postsynaptic region is not maintained?
NMDA receptors close, Ca2+ is pumped out of the cell, and AMPA receptors are endocytosed back into the cytosol.
What triggers a sustained increase in Ca2+ levels within the cytosol of neurons?
Sustained increases in Ca2+ trigger phosphorylation events that activate transcription factors and increase gene transcription.
What is the outcome of increased transcription in interneurons?
Increased synthesis of AMPA channels and remodeling of synapses.
What is the relationship between sustained activation of interneuron circuits and memory?
Sustained activation leads to long-term memory formation and synaptic remodeling.
True or False: Persistent memories and deep learning can be easily disconnected.
False.
What can lead to memories of trauma like PTSD?
Major sustained input over a short period of time.
What is the effect of studying new material over repeated periods?
It can lead to the formation of memories due to minor inputs over time.
What is the lesson for academics regarding information retention?
Stimulation and use of information over sustained periods increases the likelihood of retaining information permanently.
