Types of Signalling

• Cells communicate via various types of signalling by which chemicals travel to target sites in order to elicit a response
• Different types of cell signalling include autocrine, paracrine and endocrine signalling
• Autocrine signalling occurs when the chemicals released by a cell stimulate the cell itself
• An example of autocrine stimulation

  the proliferation of T lymphocytes following cytokine release from an activated T lymphocyte
• Paracrine signalling occurs when the chemicals released by a cell stimulate a neighbouring cell
• An example of paracrine signalling

  the stimulation of post-synaptic neurons by neurotransmitters released from a pre-synaptic neuron
• Endocrine signalling occurs when a chemical released by a cell travels in the bloodstream to activate distant cells
• An example of endocrine signalling

  the release of hormones from endocrine glands to activate distant target tissue