The phrase "jerk up" can mean a sudden movement or jolt, and there are several synonyms to describe this action. Words such as boost, elevate, hoist, lift, and heave signify an upward movement with a sudden force. Additionally, terms like yank, tug, pull, and wrench convey a more abrupt and forceful jerk. These synonyms can be used in various contexts, such as lifting heavy objects, adjusting posture, or sudden emotional reactions. Whether it's physical or emotional, "jerk up" can be appropriately replaced with any of these phrases depending on the situation and desired tone.