3A Synaptic and Junction Transmission Ch.46 Central Nervous System Synapses section (Guyton and Hall) Flashcards
two major types of synapses
chemical and electrical
utilizes neurotransmitters
chemical
utilizes gap junctions
electrical
one important characteristic of the chemical synapses that makes them highly desirable for transmitting nervous signals
transmits signal in ONE DIRECTION
neuron that transmits the neurotransmitter
presynaptic neuron
neuron on which the transmitter acts
postsynaptic neuron
phenomenon in chemical synapses that transmits signals in one direction only
PRINCIPLE OF ONE-WAY CONDUCTION
the membrane of presynaptic terminal contains large numbers of what channel
voltage-gated calcium channels
relationship between the quantity of neurotransmitter that is released from the terminal to the number of calcium ions that enter
DIRECTLY RELATED OR DIRECTLY-PROPORTIONAL
neurotransmitter receptors that directly gate ion channels
ionotropic receptors
receptors that act through second messenger systems
metabotropic receptors
ion channel that mostly allow sodium ions to pass
cation channel
mainly allow chloride ions to pass
anion channel
neurotransmitter that opens cation channels (excites neuron)
excitatory transmitter
neurotransmitter that opens anion channels (inhibits neuron)
inhibitory neurotransmitter
prolonged postsynaptic neuronal excitation or inhibition is achieved by what chemical system
second messengers
most common second messenger type
utilizes G proteins
space where neurotransmitters are released from presynaptic terminal and binds to the receptors in the postsynaptic neuron
synaptic cleft
keeps inactivity of the g protein
GDP attached to the alpha subunit
synapse in which the action potential from presynaptic neuron will also induce the action potential in the postsynaptic neuron
one to one synapse
give an example of a one to many synapse
Renshaw cell (an inhibitor interneuron found in the gray matter of the spinal cord
occurs when one action potential in the presynaptic cell is not enough to make postsynaptic terminal fire an action potential
many to one synapse
organ that uses many to one synapse mechanism
brain (formation of the intermediate memory)
impulses travel from the junction of one neuron to another. this junction is called?
synapse
a plaque like structure composed of intramembrane protein particles with six subunits around central channel
gap junctions
this synapse is usually seen in reflex pathways, wherein there is a need for rapid transmission of signals
electrical synapse
retinal adaptation in a dark place
Electrical or chemical?
electrical synapse
entire hexagonal unit of a gap junction
connexon
each subunit of a connexon
connexin
2 important components of RECEPTOR PROTEIN
- binding component
2. intracellular component
directly gating ion channels
ionotropic receptors
second messengers
metabotropic receptors
ligand-gated ion channel
ionotropic
allows passage of ions through the membrane
ionotropic
FAST synaptic potentials produced
ionotropic
two types of inotropic receptor
cation and anion channels
allows passage of sodium, potassium, and calcium
cation channels
lined with negative charges that attract the positively charged na ions into the channel
cation channel
opened by EXCITATORY neurotransmitters
Cation channels
Na, K, Ca cations are blocked since their hydrated ions are too large to pass
anion channels
opened by INHIBITORY neurotransmitters
anion channels
activates secondary messengers via G protein
metabotropic receptors
prolonged effect in the euron even after the inital neurotransmitter is gone
metabotropic
common type of secondary messenger system
G Protein complex
inactive state of G Protein complex activity is consist of guanosine diphosphate (GDP) + what three components
Alpha, beta, and gamma
what is the activator portion of the G protein
alpha
what keeps the inactivity of protein
GDP attached to alpha subunit
NAQ
possible effects of G protein activation is the activation of gene transcription
ok
a model that can be used to describe the process of chemical transmission
neuromuscular junction
a chemical synapse between a motor neuron and a skeletal muscle fiber
neuromuscular junction
mechanism of neuromuscular junction
page 4 of trans
formed from the condensation of acetylcoa and choline via the enzyme choline acetyltransferase
acetylcholine
