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What are neurotransmitters?
- discharged from the synaptic vessicles
- rapidly removed by enzymes or are involved in reuptake by the presynaptic neuron
What are the 7 neurotransmitters?
What is Acetylcholine?
the major muscle neurotransmitter
Is acetylcholine inhibitory or excitatory?
Where is acetylcholine found? What does it do there?
- found at neuromuscular junctions
- initiates muscle contraction
What is unique about acetylcholine?
it is the only neurotransmitter that is degraded in the synapse... others have reuptake
What is acetylcholine responsible for?
- much of the stimulation of muscles, including muscles of the digestive tract
- has a part in scheduling REM (dream) sleep
What are some things that work against acetylcholine?
- plant poisons: curare and hemlock cause paralysis by blocking the acetylcholine receptor cites of muscle cells
- the poison botulin works by preventing the vesicles in the axon ending from releasing acetylcholine, also causing paralysis
What disease affects acetylcholine? how so? explain.
Alzheimers Disease: there is something on the border of a 90% loss of acetylcholine in the brains of people with Alzheimer's, which is a major cause of senility
What is Norepinepherine?
- neurotransmitter associated with emotions, dreaming, and waking
- strongly associated with bringing our nervous system to "high alert"
Is norepinepherine inhibitory or excitatory?
What does norepinepherine do?
- increases heart rate and blood pressure
- also important in forming memories
What releases norepinepherine?
our adrenal glands release it into the bloodstream along with its relative ephinepherine (adrenaline)
What decreases our store of adrenaline?
What increases it?
- Stress decreases it
- Exercise increases
What is dopamine?
A neurotransmitter that is strongly associated with reward mechanisms in the brain
Is dopamine inhibitory or excitatory?
What happens with dopamine in the body?
When it finds its way to its receptor cites, it blocks the tendency of that neuron to fire
What increases dopamine levels?
- drugs like cocaine, opium, heroin, and alcohol
- nicotine does too
- if it feels good, dopamine neurons are probably involved
What happens if you have excessive amounts of dopamine? Where would you have it?
If you have excessive amounts of dopamine in the frontal lobes you may have schizophrenia because you will see things that aren't there
What happens if you have too little dopamine? in what areas?
too little dopamine in the motor areas in the brain are responsible for Parkinson's disease, which involves uncontrollable muscle tremors
What also may low dopamine be related to?
it has been reported that low dopamine may be related not only to the unsociability of schizophrenics, but also to social anxiety
What is Seratonin?
a neurotransmitter that has been found to be intimately involved in emotion and mood
Is Seratonin inhibitory or excitatory?
What happens when you have too little seratonin?
- too little seratonin has been shown to lead to depression, problems with anger control, OCD, and suicide
- too little also leads to an increased appetite for carbs (starchy foods) and trouble sleeping which are also associated with depression and other emotional disorders
What is too little seratonin also tied with?
- irritable bone syndrome
- fibromyalgia- constant joint pain
What else does seratonin play a role in?
- hallucinogens such as LSD, mescaline, psilocybin, and ecstasy work by attaching to seratonin receptor cites and thereby blocking transmissions in perceptional pathways
What are Endorphines?
Endogenous morphine neurotransmitters
What is the structure of endorphins?
structure very similar to the opoids (opium, morphine, heroin) and has similar functions
Are endorphins inhibitory or excitatory?
What are endorphins involved in?
pain reduction and pleasure
What role do endorphins play in other animals?
- it is a neurotransmitter that allows bears and other animals to hibernate
- Consider: heroin slows heart rate, respiration, and motabolism in general- exactly what you need to hibernate
- ---> of course sometimes slows it all down to nothing... permanent hibernation
What increases endorphin levels? What happens with a lot of endorphin?
- long aerobic exercise has been associated with an increase in endorphin levels
- causes "Runner's High"
What is GABA?
A neurotransmitter related to stopping anxiety
Is GABA an inhibitory or excitatory neurotransmitter?
What does GABA do?
it acts like a brake to the excitatory neurotransmitters that lead to anxiety
What happens when you have too little GABA?
people with too little GABA tend to suffer from anxiety disorders
What drugs are used for GABA
- Drugs like Valium enhance the effects of GABA
- Lots of other drugs influence GABA receptors including alcohol, and barbiturates
What happens if GABA is lacking in certain parts of the brain?
result is epilepsy- seizures
What is Glutamate?
- a relative neurotransmitter of GABA
- most common neurotransmitter in the CNS
Is Glutamate inhibitory or excitatory?
How many Glutamate neurons are in the brain?
as many as 1/2 of all neurons in the brain are glutamate
What does glutamate do?
especially important in regards to memory
What happens if you have too much glutamate?
- glutamate is toxic to other neurons and excessive amounts of it will kill them
- Lou Gehrig's disease (ALS) is also a result
- many people also believe too much glutamate may also be responsible for many disease of the nervous system
What can lead to excessive amounts of glutamate?
a stroke or brain damage will sometimes lead to excess amounts in the end with many more brain cells dying than from the original trauma