Excitation/Inhibition 1
Excitatory neurons produce/secrete what neurotransmitter?
glutamate
Inhibitory neurons produce/secrete what neurotransmitter?
GABA
Name the 3 glutamate ionotropic/rapid response receptors and list them from most complex to least complex.
NMDA, AMPA, Kainate
What are the 4 primary somatic sensations?
tactile, position, pain, temperature
In regards to Pacinian corpuscles, the (greater/lesser) the stimulus intensity, the greater the receptor potentials. The (greater/lesser) the magnitude of receptor potentials, the higher the frequency of action potentials in the axon.
greater
greater
For an excitatory neuron, what happens to the resting membrane potential when the neuron is activated? What molecule/s cause this change in RMP?
depolarization
Na+ and K+
For an inhibitory neuron, what happens to the resting membrane potential when the neuron is activated? What molecule/s cause this change?
hyperpolartization
Cl-
A recurrent synapse to an inhibitory neuron close by (shuts off/turns on) the excitatory neuron.
shuts off
Reduced or attenuated response to a constant stimulus is called ______.
This occurs due to what 2 characteristics of Pacinian corpuscles.
adaptation
Their physical properties (fluid filled) and nerve fiber accommodation
List the hierarchy of how information flows through neuronal pathways.
spinal cord, myelencephalon, pons, midbrain, thalamus, cortex
ACH receptors in the muscle are (inhibitory/excitatory). ACH receptors in the heart are (inhibitory/excitatory).
excitatory
inhibitory
Explain the concept of long term potentiation.
A single stimulus elicits a single response. A train of stimuli (for example tetanus causing muscle spasms) elicits a large response. Later, a single stimulus can produce a large response that lasts for a period of time (days or months)
What receptors does strychnine block?
What major symptom does this substance cause?
glycine
strong muscle spasms that once they reach the lungs, cause asphyxiation
During receptor desensitization, what happens to the special gates on the ion channels upon sustained pressure?
they close
In what area of the brain is the primary somatosensory cortex located?
forebrain
List the drivers of the PNS.
acetylcholine and norepinephrine
Explain how astrocytes control excitotoxicity via g-coupled metabotropic glutamate receptors.
Astrocytes buffer glutamate synapses. They only allow glutamate into the synapse by surrounding the synapse. This prevents glutamate toxicity.
Explain the experiment that shows the significance of LTP.
Knockout mice lacking the NMDA receptor were put in a pool of water with a platform. The knockout mice swam around trying to find the platform every time, but the non-knockout mice swam directly to the platform after the first few times once they learned where the platform is. They concluded that learning and memory are hippocampal LTP dependent.
Describe the structure of a Pacinian corpuscule.
An axon with an unmyelinated tip, encapsulated by concentric layers of connective tissue forming a capsule. Viscous fluid fills the spaces between membrane layers. The nerve fiber before the axon hillock is the unmyelinated tip and the rest of the axon is myelinated.
Using your iPad or a whiteboard, draw the pathway of tactile somatosensory transmission to the CNS.
Check your answer using slide 17 of lecture 2 (it won't let me add pictures)
List the drivers and modulators of the CNS.
Drivers: glutamate, GABA
Modulators: acetylcholine, dopamine, norepinephrine, serotonin, ...
NMDA receptors require what molecule as a co-agonist?
They can let what molecules in/out through they receptors?
How are NMDA receptors gated?
Mg2+ blocks the NMDA channel at negative potentials What does this indicate about NMDA receptor activation?
Name at least 1 (of 6) NDMA antagonists.
glycine
Na+, K+, Ca++
ligand gated and voltage gated
glutamate binding alone cannot activate NMDA receptors
methadone, nitrous oxide, ketamine, ethanol, dextrorphan, dextromethorphan
Explain how tetanus works.
The toxin is distributed in the blood. Motor neurons pick up the toxin and send it to inhibitory cells retrogradely. Glycine can't be secreted so this causes muscle spasms.
What are the 7 tactile somatosensory receptors?
Explain the mechanism of action for Pacinian corpuscles.
Pressure on the nerve ending causes a deformation of the capsule. The fluid is compressed and deforms the nerve membrane. Mechanically gated Na+ channels in the nerve terminal open. Local depolarization occurs. Local current flow develops and a action potential is generated at the axon hillock where there are a lot of Na+ voltage gated channels.