4-neurotransmitters Flashcards
Define neurotransmitters ?
Chemical substance transmit activity through synapses
classified ?
Chemical structure & rapidity of action
Rapid acting transmitters act by ?
Activation of ion channels
Rapid acting transmitters responsible for ? (2)
Transmission of
- sensory impulse to brain
- motor signals to muscle
Rapid acting transmitters synthesized in ?
Presynaptic terminals
Rapid acting transmitters stored in ?
Transmitters vesicles
Rapid acting transmitters released in?
Large quantities
Rapid acting transmitters removed by (2) ?
Active reuptake
Enzymatic destruction
Rapid acting transmitters class 1 ? (1)
Acetylcholine
Rapid acting transmitters class 2 amines (5) ?
- norepinephrine
- epinephrine
-dopamine - serotonin
- histamine
Rapid acting transmitters class 3 a.as ?(4)
- GABA
- glycine
-glutamate
-aspartate
Rapid acting transmitters class 4 ? (1)
Nitric oxide
Neuropeptides act by ?
2nd messenger
Neuropeptide synthesized in ————-?
Released in ———quantity & —————?
- by neurons
Small quantity but more potent
Neuropeptide synthesized by ———- in ————-?
Ribosomes in neural cell body
Neuropeptide synthesis in steps (3) ?
1- ribosomes
2- enter golgi appartus ( split & packed )
3 - transported to tip of nerve fibers by axonal streaming
Properties of synaptic transmission ?
1) unidirectional conduction
2) synaptic delay
3) synaptic fatigue
4 ) change in composition of ECF
5) effect of drug
Unidirectional conduction is ?
Impulse only conducted from presynaptic to post synaptic
Unidirectional conduction prevent ?
Anti-dromic impulse
Synaptic delay is ?
The time needed for conduction of impulse (0.5m.sec )
In synaptic delay Time is needed for?
1- release of transmitters
2- diffuse through synaptic cleft
3- combination with postsynaptic receptor
4- Na influx = EPSP
5- summation of EPSP
synaptic delay can be used to know ?
Number of synapses
Synaptic fatigue is?
when presynaptic neuron is stimulated repettied at rapid rate, discharge from postsynaptic will gradually decrease.
Synaptic fatigue is due ?
Rate of release of neurotransmitters > grater than rate of reformation
Synaptic fatigue is protective mechanism how ?
In people with epileptic shock stops it after 2-3 min
Inhibitory condition? (4)
- acidosis = coma
- hypoxia
- hypoglycemia
-hypocalcemia
Inhibitory drugs ?
Anesthetics & sedative (inc threshold to stimuli )
Excitatory conduction?(3)
- alkalosis = convulsion
- hypercalcemia
- hyperthyroidism
excitatory drugs?
- xanthines
- strychnine
