Download 1. Dendrites receive messages from other neurons that are either

 Steps of Neurotransmission 1. Dendrites receive messages from other neurons that are either excitatory or inhibitory. 2. If the input reaches the threshold, the neuron conducts a neural message. 3. The messages travels down the axon in an action potential that depolarizes and repolarizes the axon. a. The inside of the axon has a negative charge at rest and the message makes it positive for a brief time. b. Myelin sheath speeds up the message propagation. i.
Multiple sclerosis is a disease where myelin sheath degenerates. 4. Once the message reaches the terminal branches of the axon, neurotransmitters (chemical messengers) are released to the receiving cell across the synaptic cleft. 5. The sending neuron then reabsorbs excess neurotransmitters in a process called reuptake. Neurotransmitters ● Acetylcholine: enables muscle action, learning, and memory. a. Lack of → Alzheimer’s disease ● Dopamine: influences learning, movement, attention, and emotion. a. Excess → Schizophrenia b. Lack of → Parkinson’s disease ● Serotonin: affects mood, hunger, sleep, arousal. a. Lack of → Depression ● Norepinephrine: alertness and arousal a. Lack of → lethargy and depressed mood ● GABA: inhibitory a. Lack of → seizures, tremors, insomnia ● Glutamate: excitatory, involved in memory a. Excess → overstimulation of the brain (migraines, seizures)