Neurotransmitters Flashcards
Excitatory neurotransmitters (ESPS)
Glutamate, aspartate, ACh. Lowers post synaptic membrane potential to increase firing rate. Depolarizes the cell.
Inhibitory neurotransmitter (ISPS)
GABA, glycine. Stabilizes or raises postsynaptic potential to decrease firing rate.
Ionotrophic receptor
Activation causes ions to travel through. Very fast acting. Made up of usually 4 different subunits. Can change the activity and specificity of the receptor by changing part of its protein makeup.
Metabotrophic receptor
Activation causes a G-protein coupled response and second messenger system to be activated. Can be ligand, mechanical or voltage. Slower than ioinotrophic receptors.
Seven membrane spanning regions..
Agonist
Mimics the neurotransmitter. Can have full or partial.
Antagonist
Blocks neuro transmitter by binding to receptor
Neuromodulator
Has an enabling or disabling effect on the response to the NT by binding allosterically to the receptor. Reduces the number of receptors available.
Neurotransmitter types
- Acetylcholine
- Biogenic amines
- Catecholamines: Dopamine, norepinephrine, epinephrine
- Serotonin
- Histamine - Amino acids
- GABA
- Glycine
- Glutamine - Neuroactive peptides
Acetylcholine acts at which 2 receptors.
Acts at muscarinic (G protein coupled) or nicotinic (ion channel) receptors. Found in the PNS and CNS
Cholinergenic neurons
Neurons that use ACh as the primary neurotransmitter
Where are nicotinic receptors found
At the neuromuscular junctions of skeletal muscles.
Where is ACh produced?
IN the presynaptic axon by the enzyme choline acetyl transferase (CAT).
How is ACh degraded?
Occurs in the synaptic cleft and is done by the enzyme acetylcholinesterase (AChE). Breaks down the acetylcholine into acetate and choline.
How to block action of a NT
Block receptor, block enzyme that degrades or re uptakes the neurotransmitter
Neuromodulator
Has an enabling or disabling effect on the response to the NT by binding allosterically to the receptor. This reduces the number of receptors available.
Alzheimer’s disease
Neurons associated with the ACh system degenerate. Degreneration of cholinergic neurons. 10-15% over age 65 and 50% of people over 85 years old.
Biogenic amines
Neurotransmitters that are made from amino acids.
Catecholamines are made from which amino acids?
Tyrosine (3), tryptophan (1) and histidine (1)
Three catecholamines made from tyrosine
Dopamine, norepinephrine, epinephrine
one catecholamine made from tryptophan
Serotonin
One catecholamine made from histidine
Histamine
Enzymes that degrade the biogenic amine neurotransmitter are:
Monoamine oxidase (MAO) Catechol-o-methyltransferase
Synthesis of catecholamines derived from tyrosine
Tyrosine –> L- Dopa —> Dopamine —> Norepinephrine —> epinephrine
To create dopamine, norepinephrine, and epinephrine, you absolutely need
Tyrosine and enzymes needed to convert each molecule
Parkinsons disease
Involves the loss of dopamine releasing neurons. Symptoms include persistent tremors, head nodding and a forward bent walking posture. Slow in initiating and executing movement.
Adrenergic receptors
Utilized by the neurotransmitters norepinephrine (NE) and epinephrine (Epi).
Adrenergic receptors are G protein coupled and are generally linked to a second messenger signal transduction pathway.
2 alpha receptors
3 beta receptors
How is parkinsons disease treated?
With the drug L-Dopa in the initial stages. Not curative.
What is serotonin also known as?
5-Hydroxytryptamine or 5-HT
Main CNS location of serotonin
The brainstem
Functions of serotonin
Regulating sleep, emotions, vomiting reflex, regulates cell growth, vascular smooth muscle contraction.
