AbstractsBiology & Animal Science

The function of a valve is to alter or regulate a flow or movement, and/or render it unidirectional. The body's valve mechanisms would constitute a fascinating study in themselves if for no other reason than for the variety of which Mother Nature has availed herself. Some are thought of commonly in terms of 2-way flow (laryngeal cords, lips, nasal turbinates) while most are thought of as being associated with 1-way flow (iris, external nares, cricopharyngeal or upper esophageal sphincter, all the heart valves, venous valves, pylorus, sphincter of Oddi, ileo-caecal valve, urethral sphincters). Some are active (anal sphincters) and some passive (valve of the coronary sinus). [...]