send-up n.

Middle English senden, from Old English sendan "dispatch (as a messenger, on an errand); order or cause to go or pass (from one place to another);" also "send forth, emit; throw, propel, cause to be delivered or conveyed."

This is reconstructed to be from Proto-Germanic *sond- "make to go" (source also of Old Saxon sendian, Old Norse senda, Old Frisian senda, Middle Low German and Middle Dutch senden, Dutch zenden, German senden, Gothic sandjan), causative form of *sinþan "to go, journey" (source of Old English sið "way, journey," Old Norse sinn, Gothic sinþs "going, walk, time"). This in turn is from the PIE root *sent- "to head for, go" (source also of Lithuanian siųsti "send"), for which see sense (n.). For the linguistic connection of "go" and "sense," compare German sinnen (past tense sann) "go over in the mind, review, reflect upon." 

The meaning cause (someone) to go into some specified state (send to sleep, etc.) is by 1831. The slang sense of "to transport with emotion, delight" is by 1932, in American English jazz slang. To send word "transmit or dispatch a message" (to someone) is from c. 1200. To send for "summon, send a message or messenger for" is by late 14c.

Old English up, uppe, from Proto-Germanic *upp- "up" (source also of Old Frisian, Old Saxon up "up, upward," Old Norse upp; Danish, Dutch op; Old High German uf, German auf "up"; Gothic iup "up, upward," uf "on, upon, under;" Old High German oba, German ob "over, above, on, upon"), from PIE root *upo "under," also "up from under," hence also "over."

As a preposition, "to a higher place" from c. 1500; also "along, through" (1510s), "toward" (1590s). Often used elliptically for go up, come up, rise up, etc. Up the river "in jail" first recorded 1891, originally in reference to Sing Sing, which is up the Hudson from New York City. To drive someone up the wall (1951) is from the notion of the behavior of lunatics or caged animals. Insulting retort up yours (scil. ass) is attested by late 19c.