Physiology Ch. 8a-8b

Synaptic Transmission and Neural Integration

Function of an electrical synapse in the nervous system

direct, rapid communication which allows for synchronous activity and bidirectional communication

chemical synapses are ______

unidirectional

location of chemical synapses

axodendritic, axosomatic, axoaxonic, and dendrodendritic

Two types of receptors in the post-synaptic neuron

ionotrpic (for ions) and meotropic (G-Protein)

three ways to get rid of a neurotransmitter

send it somewhere else away from synapse, enzyme degrades it, recycle back to pre-synapse

functional anatomy of a a synapse:

Action potential—> voltage-gated Ca2+ channels open—>Ca2+ entry triggers vesicle docking and secretion—>neurotransmitter diffuses and binds to receptor—>response in cell—→degradation by enzymes —> neurotransmitter reuptake into presynaptic terminal (degraded or recycled)—→ diffusion out of synaptic cleft

channel-linked or ionotropic receptors are ____ than metabotropic receptors

faster

the channel ____ as soon as the neurotransmitter leaves

closes

why are metobotropic receptors slower than ionotropic

they need G-protein to activate the channel to open

Direct coupling means

the G-protein immediately activates the channel for the neurotransmitter

Second type of g-protein coupling?

Second messenger (G-protein activates the second messenger that opens the channel)

excitatory postsynaptic potential (EPSP) is what part of the action potential and what gates open

depolarization; more NA+ gates open to make the cell more +

Inhibitory postsynaptic potential is what part of the action potential

hyperpolarization (more negative)

membrane stabilization is when

the wave stops somewhere near the RMP

(EPSP)activation of metabotropic receptor with g-protein and cAMP second messenger closes what channel

K+ channel closed, NA+ still leaks in

IPSP opens what channles

either K+ or Cl- to make K+ leave or Cl- come in to make the cell more negative

Cl- stabilizes what?

membrane potential

K+ when exited ____ the gate and when inhibited ____ the gate

close; open

when the Cl- channel is opened what happens

cation diffuses into cell, increase of Cl- electrochemical gradient, anions and cations balanced, membrane stabilization

Divergence means

synapse with multiple neurons

convergence means

receive from multiple neurons

Two types of summations are

temporal and spatial

temporal summation is

adding 2 graded potential of the same neuron

spatial summation is

adding 2 graded potentials of different neurons

The higher the frequency of the action potential means the ____ will be stronger which means there were will be more _____

signal; neurotransmitters released

______ influences frequency of action potentials

summation

the higher the action potential the _____ the neurotransmitters

higher

modulation is

the regulation of communication across a synapse

the two types of axoaxonic synapses are

presynaptic facilitation and inhibition

Presynaptic facilitation makes action potential more _____ by ______ the likelihood of threshold stimulus

effective; increasing

presynaptic inhibition makes the action potential ______ and ______ the likelihood of threshold stimulus

less effective; decreasing

Axoaxonic is _____

selective

axoaxonic excites or inhibits __ synapse

one

axodendritic and axosomatic are _____

nonselective

axodendritic and axosomatic are excite or inhibit _________

postsynaptic neuron membrane potential

Acetylcholine is the most_____ neurotransmitter in the PNS

abundant

the somatic branch of acetylcholine is what kind of movement?

voluntary

the autonomic branch of acetylcholine is what kind of movement?

involuntary

what is acetylcholine’s enzyme for synthesis

choline acetyl transferase (CAT)

acetycholine is made where in the neuron?

axon terminal

acetylcholine is what kind of receptors?

cholinergic receptor and they can be either ionotropic or metabotropic

Which is slower: inotropic (nicotinic) or metabotropic (muscarimic)?

metabotropic (muscarimic) because of G-protein

What enzyme breaks down acetylcholine after it has been used?

acetylcholinesterase (AChE)

Where does acetylcholine breakdown occur?

in the synaptic cleft

Ionotropic (nicotinic) cholinergic receptors have what cation channels?

NA+ and K+

What is signal transduction

what happens on the other side

metabotropic (muscarinic) cholinergic receptors have what kind of channel and what type of messenger?

G protein slow ligand gated ion channel and G protein second messenger

Biogenic amines are derived from and synthesized where?

amino acids that are synthesized in cytosol of axon terminal

catecholamines are derived from

tyrosine

dopamine is primarily located where and has what receptor?

CNS; dopaminergic receptors

Norepinephrine is located where and has what kind of receptors?

CNS; adrenergic receptors e

epinephrine is located where and has what type of receptors

CNS, PNS, and hormone; adrenergic receptors

Serotonin is derived from?

tryptophan

where is serotonin located at in the CNS

brainstem

histamine is derived from?

histidine

histamine is located where in the CNS

primarily hypothalamus

biogenic amines has how many neurotransmitters?

5

what two enzymes are responsible for biogenic amines breakdown

monoamine oxidase (MAO) and Catechol- O- methyltransferase (COMT)

chemicals that inhibit re-uptake? Specific to which NT

selective serotonin reuptake inhibitors (SSRI). specific to serotonin

are adrenergic slow or fast receptors?

slow because they are G protein coupled and generally linked to second messengers

the amino acid NT aspartate and glutamate are located where?

at excitatory synapses

the amino acids NT glycine and GABA are located where?

at inhibitory synapses

both glycine and GABA open what type of channels and why

Cl- channels to make the cell more negative

What do you need first before Cl- channels can open

ATP to increase the difference in and out

ATP is a type of ____?

Purine

ATP is found where in the body?

enteric nervous sytem, CNS, and PNS

Other types of purines

GTP, ADP, and AMP

P2X receptors, or ______, are fast

ionotropic receptors

P2Y, receptors or ______, are slow

metabotropic

Neuropeptides are?

short chains of amino acids

What is substance P used as?

a neurotransmitter for pain

Nitric Oxide is considered a ?

unique neurotransmitter

is nitric oxide stored?

No.

What is nitric oxide’s release determined by?

rate of synthesis by nitric oxide synthetase

How does Nitric oxide diffuses and where may it NOT be?

diffuses ti target and may not be at a synapse

endocannabinoids are considered what?

unique nuerotransmitters

synthesis of endocannabinoids depends on what?

calcium or other chemicals

Endocannabinoids are stimulated by?

increased cytosl Ca2+ concentration

How do endocannabinoids diffuse?

diffuse out of cell

CB1 receptors are?

metabotropic

what is the active component of cannabis?

Tetrahydrocannabional (THC)

Types of disorders that tie into THC

parkinson’s anxiety, PTSD, and epilepsy

ionotropic is for_____

ions to open and close = faster

synaptic delay means what?

slow connection

Which ion has a higher electrochemical gradient?

NA+ because it has two forces pushing it into cell

To balance out Cl- to make the cell more negative (inhibit) you need to do what?

use active diffusion (low to high) and then pump all of the Cl- back into the cell

presynaptic modulation happens in what kind of synapse?

axoaxonic synapses

what are the two types of adgrenergic receptors?

alpha and beta receptors