PSL201Y1 Lecture Notes - Lecture 3: Collecting Duct System, Pancreatic Islets, Zygote
Document Summary
Gap junctions are formed by connexins and link adjacent cells together. Connexins form connexons which allow ions and small molecules to pass directly from one cell to another. Movement of ions through gap junctions couples cells electrically. Electrical signals in one cell are directly transmitted to neighbouring cell. Most often, cells communicate in the form of ligands. Occurs when one cell releases a chemical into the interstitial fluid by secretion. Target cell responds to the chemical messenger after its receptors recognise it. Response is produced through a variety of mechanisms (=signal transduction) Paracrines are chemicals that communicate with neighboring cells. Neurotransmitters are chemicals released into interstitial fluid by neurons. Released by the axon terminal into synaptic junction. Communication by neurotransmitters is called synaptic signalling. Hormones are chemicals released from endocrine glands into the interstitial fluid. Diffuse and travels in blood to target cells. Water soluble and can thus dissolve in plasma. Not lipid soluble so cannot pass plasma membrane.
