A cochlear implant sends electrical signals straight to the hearing nerve, bypassing the inner-ear receptor region that normally changes vibration into impulses. Which structure does it stand in for?

A prosthetic valve opens and closes between the left atrium and the left ventricle so blood moves only toward the pumping chamber. Which native structure is it replacing?

A powered lower-limb prosthesis bends and straightens where the thigh would normally meet the leg during walking. Which joint's motion is being replaced?

An automated pump releases insulin when glucose rises, substituting for endocrine cell clusters in an abdominal gland. Which structure's function is being replaced?

A retinal prosthesis stimulates remaining nerve layers after loss of the light-detecting cells at the back of the eye. Which cells is it substituting for?

An implanted pump moves blood from the chamber that sends blood into the aorta when that chamber cannot eject strongly. Which heart chamber's action is supported?

An electronic speech aid makes vibrations in the throat after removal of the sound-producing tissue in the voice box. Which structure's function does it replace?

A myoelectric hand opens and closes around objects after loss of the finger bones beyond the palm. Which structures does it replace?

A scaffold seeded with chondrocytes fills a worn smooth covering at the end of the femur, and new cartilage spans the defect. At which level of organization is the repair?

A viral vector delivers a working CFTR gene into microscopic units of the airway lining so each can make a chloride channel. At which level is the intervention acting?

A printed mandible segment is anchored where a portion of jaw bone was removed, restoring the shape of one bone made of several tissues. At which level is this replacement?

Transplanted beta cells release insulin after blood glucose rises, replacing a missing endocrine cell population. At which level is this therapy working?

A lab-grown epithelial sheet covers a burn and forms a new surface layer over connective tissue. At which level is the main repair?

A wearable system combines heart rhythm, blood oxygen, and temperature to flag loss of whole-body homeostasis. At which level is the combined warning most useful?

A wrist monitor shines light into skin and reports a pulse each minute. Which physiological change is the sensor tracking?

A fingertip clip compares red and infrared light passing through tissue. Which quantity is the displayed oxygen number estimating?

An arm cuff inflates, then detects when blood flow through an artery stops and returns. Which vital sign is being measured?

A continuous sensor sits in interstitial fluid and sends a phone reading used to adjust insulin delivery. What is the reading tracking?

A smart inhaler records the time and number of puffs released from the canister. What does that technology measure?

Deep brain stimulation sends timed electrical pulses to motor-control nuclei. What is the intended action of the pulses?

A chest patch detects voltage changes at the skin during each heartbeat and sends a rhythm strip. Which process is it monitoring?

Stem cells from a patient's own marrow are returned after leukemia treatment. Why is immune rejection unlikely?

Gene therapy gives liver cells a working factor IX gene in hemophilia B. What physiological result should follow?

Edited hematopoietic stem cells no longer carry the sickle-causing DNA sequence before they repopulate marrow. What result should appear in new red blood cells?

Stem cells grown into a clear corneal surface are grafted onto a damaged eye. What outcome should the graft support?