Physiology Practice Test: Chemical Messengers — Flashcards

Chemical messengers are molecules that transmit messages between neurons, or from neurons to muscles. 

Some types of chemical messengers include:
Neurotransmitters: These are molecules used by the nervous system to transmit messages.
Hormones: These are chemicals that carry messages through your blood to your organs, skin, muscles, and other tissues.
Neuropeptides
Pheromones 

Chemical messengers can also be local or paracrine.

Autocrine agents: These are local chemical messengers that are released into the extracellular fluid and act upon the same cells that secreted them.
Paracrine chemical messengers: These are local messengers that are secreted by one cell type but affect neighboring cells of a different type.
Paracrine signaling: This is a mechanism in which one cell secretes a molecule that acts on a second cell in close proximity.