Biology Ch9 →Cell Communication

Functional Classification of Chemical Messengers
•Paracrines
•Autocrines
•Neurotransmitters
•Hormones
•Neurohormones
•Cytokines

Paracrines
Released by cell, moves to target cell by diffusion
Paracrines- act on neighboring cells

Example of Paracrine ~Histamine
Released with tissue damage and causes dilation of local blood vessels.
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Autocrines
Act on cells that release it

Neurotransmitters
•Messenger of nervous system = neurotransmitter
–Released from neuron by exocytosis
–Diffuses to very close target cell

Hormones
•Messenger of endocrine system = hormone
–Released from endocrine gland into blood
–Transported in blood to target
•Target cell = cells in body with receptors specific to the hormone

Neurohormones
•Messenger = neurohormone
–Released from neuron into blood where it acts in manner similar to hormones

Cytokines
•Cytokines = peptides or proteins
•Can be transported in blood
•Released by most cell types
•Involved in cell development, differentiation, and immune response
•Often act on a wide range of targets