Chapter+5+Chemical+messengers 2

Chemical messengers

Substances released by cells to communicate with other cells, affecting their function.

Intercellular communication

The process through which cells communicate with each other.

Paracrine signaling

A form of cell communication where the signal affects nearby target cells.

Autocrine signaling

Cell signaling where a cell secretes a chemical messenger that binds to receptors on itself.

Neurotransmitters

Chemical messengers released from neurons that transmit signals across synapses to other neurons or target cells.

Hormones

Chemical messengers produced by endocrine cells and released into the bloodstream for systemic effect on target cells.

Lipophilic messengers

Chemical messengers that are lipid-soluble and can easily cross cell membranes.

Lipophobic messengers

Water-soluble chemical messengers that cannot easily cross cell membranes.

Connexins

Proteins that form gap junctions between cells, allowing for direct intercellular communication.

Receptor agonists

Ligands that bind to receptors and induce a biological response.

Receptor antagonists

Ligands that bind to receptors but block a response, competing with agonists.

Signal transduction

The process by which a chemical messenger transmits a signal through a cell leading to a cellular response.

Hemichannel

A single connexon that allows for direct communication between neighboring cells in gap junctions.

Neurohormones

Hormones secreted by neurons into the circulatory system.

Eicosanoid messengers

A type of lipophilic messenger derived from arachidonic acid that functions in paracrine signaling.

G-protein linked receptors

Receptors that, upon activation by a chemical messenger, interact with a G-protein to trigger a cellular response.

Enzyme-linked receptors

Receptors that activate enzymatic activity inside the cell upon binding to their messenger.

Channel-linked receptors

Receptors that open ion channels in response to binding of their respective chemical messenger.

Catecholamines

A class of amine messengers derived from tyrosine, including neurotransmitters like dopamine and hormones like epinephrine.

Steroid hormones

Hormones derived from cholesterol that are lipophilic and synthesized on demand.

Signal strength

The effectiveness of a chemical messenger's signal, dependent on messenger concentration and receptor availability.