Final answer:
Activation of transmitters like neurotransmitters and hormones results in the transmission of nerve impulses, regulation of body responses such as the "fight or flight" reaction, and the control of muscle contractions through complex signaling pathways.
Step-by-step explanation:
The activation of transmitters, such as neurotransmitters and hormones, plays crucial roles in various physiological processes.
Neurotransmitters like dopamine are released into the synaptic cleft, triggering a response in the post-synaptic neuron, which may involve an increase in cAMP as a second messenger when a G-protein-linked receptor is activated. This is a key step in transmitting nerve impulses across synapses, which is essential for neural communication.
Hormones are secreted by glands in response to stimuli such as signals from the nervous system or changes in the blood. Once released, hormones travel through the bloodstream and bind to receptors on the target cells to initiate a response. For example, insulin binding to its receptor can lead to phosphorylation of tyrosine residues as part of its mechanism of action. Hormones can also bind to intracellular receptors and directly affect gene transcription.
Hormones such as epinephrine and norepinephrine are involved in the body's "fight or flight" response, controlling muscle contractions, heart rate, and blood pressure during short-term stress responses.