Sanglot is an itneresting word with a murky etymology. Meyer-Lübke gives *singultus and *singluttus as possible Vulgar Latin words of origin. Both meaning 'schlucken; to gulp, swallow, guzzle'. No doubt related to glottus 'throat, gullet'. Gamillscheg gives *subgluttus 'schluchzen; sob'. Nothing to do with blood as one might think.