A hemodialysis system includes: a peristaltic blood pump; a first peristaltic dialysate pump; a second peristaltic dialysate pump; and a fluid cassette including an upper portion and a lower portion, a blood pumping tube extending linearly from the upper portion to the lower portion, the blood pumping tube actuated by the peristaltic blood pump, a first dialysate pumping tube extending linearly from the upper portion to the lower portion, the first dialysate pumping tube actuated by the first dialysate pump, and a second dialysate pumping tube extending linearly from the upper portion to the lower portion, the second dialysate pumping tube actuated by the second dialysate pump.