Final answer:
The pathway involving norepinephrine functions both as a neurotransmitter and a hormone affecting mood and stress responses, using adrenergic receptors, while the glutamate pathway is primarily involved in excitatory neurotransmission and cognitive processes through ionotropic and metabotropic receptors.
Step-by-step explanation:
Difference Between Norepinephrine and Glutamate Pathways
The pathways involved with norepinephrine and glutamate differ significantly in terms of their roles within the central nervous system (CNS), receptor types, and mechanisms of synaptic transmission. Norepinephrine, derived from tyrosine, is a part of the adrenergic system and interacts with alpha and beta receptors. It is associated with the regulation of mood, attention, and the body's fight or flight response. Norepinephrine is removed from the synapse via transporter proteins and can function both as a neurotransmitter when released from nerve terminals and as a hormone when released into the bloodstream from the adrenal gland.
In contrast, glutamate is the main excitatory neurotransmitter in the CNS, responsible for synaptic plasticity and cognitive functions such as learning and memory. Synthesized from glutamine, glutamate is stored and released by glutamatergic neurons, and after release, it is taken up by excitatory amino acid transporters (EAATs). Glutamate acts on ionotropic receptors like AMPA, NMDA, and kainate receptors that are involved in fast synaptic transmission, as well as on metabotropic glutamate receptors (mGluRs) that modulate slower, longer-lasting synaptic responses through G-protein coupled mechanisms.