Synapses & Neural Integration pt 2 Flashcards
what is neural integration
nervous system communication involving more than one presynaptic and postsynaptic cell at any one time
what are the types of neural integration
- divergence/convergence
- axon hillock and threshold
- summation
- frequency coding
describe axon divergence
axon has many collaterals that communicate with many other neurons
describe axon convergence
any given neuron receiving communication from tons of neurons
describe axon hillock in relevance to threshold
AH of postsynaptic neuron acts as an integrator which sums signals of all active synapses
why is summation needed for neural integration
single EPSP is generally not enough to depolarize post synaptic neuron to threshold
what are the types of neural summation
temporal (one at a time) and spatial (several at the same time)
describe frequency coding
considers number of action potentials (affected by summation) to find the degree of depolarization at the axon hillock
what is presynaptic modulation
regulation of communication across another synapse
what are the two possible effects of presynaptic modulation
release of NT can be enhanced or suppressed
what is presynaptic facilitation
release of neurotransmitter can be enhanced
what is presynaptic inhibition
release of neurotransmitter can suppressed
what are the classes of the neurotransmitters
choline derivative, biogenic amines, amino acids, purines, neuropeptides, unique molecules
what are examples of purines
ATP, ADP, adenosine
what are examples of unique molecules
nitric oxide, endocannabinoids
what are examples of choline derivatives
acetylcholine
what are examples of amino acids
glutamate, aspartate, glycine, GABA
what are examples of biogenic amines
serotonin, histamine, catecholamines (dopamine, epinephrine, norepinephrine)
what are examples of neuropeptides
TRH, vasopressin, oxytocin, substance P, cholecystokinin, endogenous opioid (enkephalins, endorphins), orexin
describe acetylcholine; where is it found, stored, released
- most abundant NT in PNS, also found in CNS
- stored in synaptic vesicles once synthesized in cytosol
- action potentials trigger its release thru exocytosis
what are the 2 types of acetylcholine receptors
nicotinic and muscarinic cholinergic receptors
describe nicotinic cholinergic receptors
found in PNS (autonomic neurons on skeletal muscle cells) and CNS, ionotropic
describe muscarinic cholinergic receptors
found on some effector organs for ANS, this is the dominant cholinergic receptor type found in CNS, metabotropic
why are unique NT molecules considered unique
appear to function as neurotransmitters but are not stored in synaptic vesicles nor released by exocytosis
