neurotransmitters Flashcards
what are the two types of neurotransmitter transmission
1) electrical
2) neurotransmission
electrical transmission
- information is processes electricaly
- ionic current flows passively though the synaptic junction
- not able to control as easily
what is the main disadvantage of the electrical synapses
the signal transduction which occurs at a very high speed through gap junctions
neurotransmission transmission
neurons communicate with each other by secreting and responding to neurotransmitters (chemicals)
what types of channels do neurotransmitters flow through
gates channels
the movement of ions
move though synaptic membrane through channels (passive) or pumps (active).
post synaptic receptors : transport
- receptors are anchored to the post synaptic membrane
- may directly open channels or indirectly (through messenger systems)
what are the 2 main types of cannels
1) open : open all of the time (might be leaky)
2) closed ; have 2 states (open or closes/resting)
voltage gated (Ions)
- open and close in response to electrical charge across the membrane
- changes in positive or negative ions such as K+, Na+, Ca+, Cl-
example of a voltage gates channel
- pharm Ca+: voltage gated calcium channels able to treat heart disease by targeting calcium channels
- Ca+ blockers (Nifidepine); used to lower BP
modality-gated (sensory) is activated by
stretch, pressure or movement
where do modality - gated channels occur in
- touch receptors of the skin
- hearing a balance in the inner ear
- temperature changes in the skin
- chemicals such as the tongue
- pain sensations
- stretch receptors in the muscle
example of modality - gated channels in PT
TENS, hot and cold modalities
pumps
Na+ and K+ pump (active) requiring ATP
- 20-40% of the brains synapses are pumps
- moves ions against their concentration gradient
- works to maintain concentration gradients
what is a neurotransmitter
a chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and by diffusing across the synapse or junction, causes the transfer of the impulse
where are neuromodulators releases
into the extracellular fluid (NOT THE SYNAPTIC CLEFT)
how do neuomodulators work
- act on multiple neurons at the same time
- act slower and have longer lasting effects
- act in junction with NTs
Cholinergic NT
acetylcholine (ACh) - excitatory
Amino Acid NT
aminobutyric acid (GABA) - Inhibitory
Glutamate - Excitatory
Glycine - inhibitory
Aspartate - Excititory
Amine NT
Dopamine - inhibitory or excitatory
Histamine - Usually inhibitory
Norepinephrine - inhibitory or excitatory
Serotonin / Meltatonin - inhibitory
Peptide NT
Endorphines - usually inhibitory
Enkephalines - usually inhibitory
Substance P - Excitatory
Nitiric oxide
Excitatory NT
what are the 2 neurotransmitters that increase with exercise
Endorphines and Enkephalines
what is glutamate
- excitatory NT
- widespread throughout the CNS
- associated with attention, learning, functioning, and memory
- essentrial role in neuroplasticity (LTP) in the hippocampus and neocortex
what can high levels of glutamate lead to
cell death by setting off the inflammatory response called excitotoxicity with a toxic level of Ca+
what is GABA
- main inhibitory NT
- found throughout the CNS
- helps put us to sleep
what is Gabapentin or Neurontin
- anti seizure medication
- also can be used for neuropathic pain
- similar to GABA
- inhibition of nerve connunication
what is Baclofen
- anti-spasticity medication
- similar in structure to GABA
what is Valproic acid
- anti seizure medication
- similar in structure to GABA
what is acetylcholine (ACH)
- mostly excitatory or facilitatory
- neuromuscular junction
- ANS preganglionic and postganglionic neurons
receptors: Nicotinic and Muscarinic
Dopamine functions as a hormone and NT
- generally excitatory
- movement, memory, rewards and motivation (why it is often associated with addiction)
- limbiv system connection (happiness)
- retina
where is dopamine found
- brainstem
- BG
- Substantia Nigra (PD)
reward pathways with dopamine
- cocaine and other amphetamines affect reuptake leading to longer dopamine activity, producing euphoria and stereotype behaviors.
- require more of the drug to produce the same affect
treatment strategy for PD
- increasing dopamine levels by administering L-Dopa nerve grafting with dopamine containing cells and deep brain stimulation
serotonin
- generally inhibitory
- associated with mood, appetite and sleep
- often used for depression meds
- used for pain reduction (slow acting)
where is Serotonin
90% located in the GI tract; 10% in the brain
what is low levels of serotonin associated with
depression
Prozac
is a selective blocker of serotonin reuptake resulting in serotonin remaining in the synapses longer
what are the distinct pathways of norepinephrine in the brain
cerebral cortex, limbic system and the SC
what is norepinephrine
- hormone and NT
- works in the areas of the brain that relate to attention and responding
where is norepinephrine found
- smooth muscle
- ANS postganglionic sympathetic cells
- brain stem regions
ADHD ritalin meds
increase norepinephrine and increases dopamine
norepinephrine as a hormone
- effects the amygdala, were attention and responses are controlled
- underlines the sympathetic nervous system (increase HR and BP and peripheral vasoconstriction)
epinephrine as a hormone
underlines the sympathetic nervous system (increase HR and BP, peripheral vasocontriction, increase lipid breakdown, coronary dilation and bronchial dialation, convert glycogen to glucose)
where is substance P found
- excitatory / facilitory
- SC
- BG
- Limbic system
what is related to high levels of substance P
- changes the perception of pain in individuals with fibromyalgia
endorphines
- are endogenous opioid neuropeptides
- Releases positive feeling
- they are produces by the CNS and pituitary gland
- increases by exercise
- reduce the intensity of pain sensed by the brain
Brain Derived Neurotrophic Factor (BDNF)
-protein from the neurotrophin family
- acts in neurons in the CNS and PNS
- Exercise induced neurogenesis
BDNF exercises induced neurogenesis function of the brain areas
- hippocampus: associated with higher learning and memory
- cortex: facilitates nerve growth, differentiation of synapses
- Basal forebrain: long term memory
