Chapter 6 Flashcards
Neural communication takes place at
Synopses an extra synaptic sites
Synapse
Where a neuron and a postsynaptic cell communicate
Can either be electrical or chemical
Electrical synapse
Occurs when two neurons are physically joined by gap junctions allowing current to spread between them almost instantaneously
Chemical synapse
Most common
Comprises of presynaptic terminal where neurotransmitters are released
Postsynaptic potentials
Local potentials that occur due to changes in ion concentration across the postsynaptic membrane
Depolarizing postsynaptic potentials
Excitatory postsynaptic potentials EPSPs
Hyperpolarizing postsynaptic potentials
Inhibitory postsynaptic potentials IPSPs
Excitatory Postsynaptic potential
Occurs when neurotransmitters bind to post synaptic Ligand gated ion channels allowing a local instantaneous flow of Na+ or Ca+ into the neuron
Less negative
Neuron releases acetylcholine ACh

Inhibitory postsynaptic potential
hyperpolarization which reduces the possibility of an action potential
More negative
Involves a local flow of Cl- and or K+
Summation of EPSPs
May result in action potential generation
Summation of IPSPs
Well inhibit action potential generation
Presynaptic facilitation
Allows more neurotransmitters to be released
Occurs when the presynaptic terminal of the second neuron is depolarized opening a voltage gated calcium channels
Presynaptic inhibition
Allows less neurotransmitters to be released
Occurs when the presynaptic terminal of the second neuron becomes hyperpolarized
Fast transmission
Occurs when neurotransmitters cause changes in postsynaptic neurons on a millisecond to minute time scale
Slow transmission
Occurs when a Neuro transmitters cause changes that take hundreds of milliseconds to days to manifest
Due to activation of G protein coupled receptors
G proteins
Sometimes activate ion channels
Activates second messengers
Affect long acting systems that regulate mood, pain perception, movement, motivation, cognition
Second messengers can initiate
Activation of genes
Opening of membrane ion channels
Release calcium to regulate metabolism and other cellular processes
Cotransmitters
When two or more neurotransmitters are released at the same synapse
Acetylcholine
Major conveyor of information in the PNS
All lower motor neurons use ACH to elicit fast acting effects via ligand gated ion channels
Nicotinic receptors
Fast acting
Respond to ACH
Selective activation of these receptors by nicotine
Are found at the neuromuscular junction and autonomic ganglia and then some areas of the CNS are
Muscarinic receptors
Slow acting
ACH has slow acting affect in the PNS that regulates heart rate and other autonomic functions via GPCRs
Regulation of cardiac muscle, smooth muscle, glandular activity
Glutamate
Main excitatory transmitter of the CNS
Has powerful excitatory affects on every region of the brain
Activates a class of GPCRs known as metatrophic glutamate receptors : Mediate slow transmission
Excess can case seizures (excitatory)
Receptor : NMDA
GABA
Major inhibitory neurotransmitter in the CNS
Prevent excessive neural activity
Binds to 2 receptors: GABAa GABAb
Glycine
both inhibitory and excitatory signaling
Glycine receptors are chloride ion channels that cause inhibition of postsynaptic membrane primarily in the basal ganglia, brain stem, spinal cord
Amines
Amine neural transmitters include dopamine, norepinephrine, serotonin, histamine
Dopamine
Affects motor activity, cognition, motivates behavior
Norepinephrine
vital role in active surveillance by increasing attention to sensory information
Associated with Vigilance
Essential in a fight or flight response
Released by neurons in the sympathetic nervous system
Receptors: Alpha and beta
Serotonin
Affect sleep, general arousal level, cognition, perception, pain, motor activity, mood
Highest levels of serotonin occur with alertness
Low levels associated with REM sleep
5-HT receptor of serotonin
SSRIs
Block reuptake of serotonin
L Dopa
Supplement drug for dopamine
Diminishes hallucinations, delusions, and disorganized thinking
Side effects: involuntary movements
Dopamine agonist
Opioids
inhibit neurons in the CNS that are involved in the perception of pain
Ex. Endorphins, enkephalins, dynorphins
Substance P
Released by injured tissue
Stimulates nerve endings at site of injury
Serves key role in perceiving pain
Agonists
Drugs that mimic the action of neurotransmitters
Antagonists
Drugs that block the ability of neurotransmitter to interact with its receptor
ACh agonist
Nicotine
Muscarinic ACh receptor antagonist
Atropine
Botulinum toxin
Botox
Interferes with ACh signaling
Used to improve movement abnormalities (ppl with cerebral palsy)
Nitric oxide
Regulates vascular system in the periphery and active in the brain
Involved in cell death and excitotoxicity
Role of calcium in neurotransmitters
Allows neurotransmitters to be released
Lambert-Eaton Syndrome
Antibodies destroy voltage gated Ca2+ channels in presynaptic terminal
Occurs in people with small cell cancers of lung
Myasthenia gravis
Antibodies attack and destroy nicotine receptors on muscle cells
Ptosis, muscle weakness, affected respiration, affected limb movements
Ptosis
Drooping of the upper eyelid
Myasthenia gravis treatment
Removal of thymus gland
ACh inhibitors
Plasmapheresis
TENS
transcutaneous electro nerve stimulation
Interrupts pain signals and relieves pain
