BI236 Chapter 14: Chapter 14.docx
Document Summary
Animals have two different but complementary systems of intracellular communication and control: nerve cells communicate with one another and with other types of cells. Arrival of an action potential ay a synapse causes the release of neurotransmitters, which in turn bind to receptors on the adjacent postsynaptic membrane: second major means of intercellular communication, the signal is transmitted by regulatory chemical messengers. Receptors located on receiving cells that can be quite distant from the secreting cell. Different types of chemical signals can be received by cells. Endocrine signals (hormones): produced at great distances from their target tissue and carried by circulatory system. Paracrine signals (growth factors): released locally and act at short range on nearby tissues: juxtarine singals require physical contact between sending and receiving cells, autocrine signals act on the same cell that produces them. Affinity: relationship between [] of ligand and # of receptors occupied. High: most receptors occupied at low [ligand]
