Neurophysiology Flashcards
basic functions of neurons
To transduce different types of energy of the world into electrochemical energy inside the body (Sensation)
-Afferents
To faithfully carry info (encoded in electrochemical energy) rapidly throughout the body
- Interneurons - Efferents
afferents do what?
Sensation (interoception, exteroception, proprioception)
interneurons do what?
Circuit modification (adds properties to synapses)
efferents do what?
Motor control (skeletal muscle, smooth muscle, cardiac muscle, glands)
what do we see on a slide of alzheimer neurons?
the soma show “tangles” (Neurofibrillary Tangles) and “plaques” (Beta-amyloid Plaques) which are diagnostic of Alzheimer’s disease in the Hippocampus (part of the cerebrum where neuronal changes mediate memory formation)
plaques
accumulation of proteins in the neuron that play ar role in neurodegenerative processes
Location and function: neurons, dendrites, synapses
gray matter
collect, integrate, transmit information; synthesize macromolecules
Location and function: axons
white matter
conduct information
Location and function: oligodendrocytes & schwann cells
white matter
form myelin sheaths
Location and function: protoplasmic astrocytes
gray matter
provide mechanical and metabolic support, response to injury
also part of the blood-brain barrier
Location and function: fibrous astrocytes
white matter
provide mechanical and metabolic support, response to injury
where do we usually find pyramidal cells?
cortex
ependymal cells
Line the ventricles of the brain
Characterized by cilia, are usually cuboidal, move cerebrospinal fluid through the brain
-Together with blood supply and pia mater, make up choroid plexus
Longstanding debate of whether or not they are neural stem cell progenitors
2 important areas:
- Subventricular zone (SVZ)
- Subgranular zone (SGZ)
Different ependymal cell types move cilia at different rates.
- Dependent on Ca2+
- Alcohol can slow ciliary movement
choroid plexus
ependymal cells + blood supply + pia mater together
what happens at a synapse
A single AP triggers opening of v-gated Ca2+ channels, resulting in small vesicle fusion with the terminal membrane, releasing small amounts of small-molecule neurotransmitter into cleft. Vesicles can either stay fused or be recycled in the terminal.
A train of AP’s triggers opening of more v-gated Ca2+ channels, resulting in many small vesicles fusing with the terminal membrane, releasing large amounts of small-molecule neurotransmitter into cleft. Large Dense Core Vesicles may also co-release neuropeptide into the cleft.
Post-synaptic neurons and glia compute the combinatorics of transmitter release
Small molecule transmitters bind to post-synaptic ionotropic receptors
Reuptake of unbound transmitter into presynaptic terminal
Reuptake of unbound transmitter by astrocytes
Inactivation of transmitter
Small molecule transmitter or neuropeptides bind to post-synaptic metabotropic receptors
Unbound transmitter can diffuse out of the cleft
synapses are tri-partite
Pre-synaptic: transmitter released in “quanta”
Glia- post-synaptic neuron has metabotropic AND ionotropic responses
The quantity of transmitter in the synapse must be tightly controlled.
what does ionotropic mean?
it’s a fast action. open up a channel, some current is going to flow through.
metabotropic
activates G proteins, take a while (slower)
Multiple Action Potentials Result in more complex post-synaptic signaling
Hi frequency action potential stimulation co-releases neuropeptides with small molecule neurotransmitters
Neuropeptides can bind to post-synaptic metabotropic receptors (GPCR’s)
GPCR’s are also used for some small molecules
- Change conductance
- ↑ or ↓Receptor #
- ↑ or ↓Receptor Opening
- Activate 2nd messenger cascade
- Alter gene expression
The post-synaptic effects of small molecule neurotransmitters are modulated by the actions of neuropeptides
what is conductance?
the permeability of the neuron
neurons speak in
electrochemical signals.
electric potential traveling down calcium channels being the exciting thing at the end that leads to... neurotransmitter release (chemical)
