"Hemorrhagic Shock (Part I)" (出血性ショック（前編) Shukketsusei Shokku (Zenpen)?) is the 12th and penultimate episode of the Cells at Work! anime adaption. It is based on the 17th chapter of the manga titled "Hypovolemic Shock (Part I)".
In the human body, AE3803 is in the pulmonary alveoli depositing CO2 to be turned into oyxgen. AA5100 is happy that AE3803 is working hard and getting used to the work. AA5100 tells her to train NT4201, a rookie red blood cell. AE3803 is surprised but remembers that other blood cells helped nurture her, and AA5100 tells her to think of it as repaying them. AE3803 is impressed by how calm and collected NT4201 is, before realizing that she is confusing her kouhai.
AE3803 tries to find her notes but ends up embarrassing herself. She then tries to teach her the basics but NT4201 apparently knows everything from the start, which causes her even more embarrassment. They then begin their job; AE3803 is unsure of what to say to her, while NT4201 knows that AE3803 is inefficient. As they descend the lift, AE3803 tries to go towards the lymphatic vessels, only to get yelled at by Killer T Cell.
Returning to the original path, NT4201 states that she did not mind her senpai taking a wrong turn, but was more concerned with Killer T's aggression towards them. As they walk, they find U-1146 battling a germ. AE3803 states that the white blood cells are friendly, but NT4201 states that they confuse justice with violence, surprising her, as the Neutrophil are quite friendly when they aren't killing. AE3803 thanks U-1146 for his work; he is surprised to see that AE3803 has taken a kouhai before noticing that the germ is still alive and starts battering it again while explaining the roles of the many white blood cells in the body.
U-1146 kills the germ and causes blood to splatter; NT4201 shoves AE3803 out of the way, forcing them to take a temporary detour to a shower area to rinse off the germ's blood. AE3803 goes off to get drinks for both, but NT4201 reminds her that she needs to give her a towel. They arrive at a delivery spot and AE3803 tries to show NT4021 the procedure, but end up annoying the cell in the process.
Later on, AE3803 introduces NT4201 to Eosinophil and the Platelets, though NT4021 is unimpressed and stops AE3803 from stepping on a fibrin net. They later make their way to Dendritic tree, where they meet Dendritic Cell and a Macrophage; Dendritic Cell is impressed that AE3803 has started to train rookie blood cells. NT4201 reminds AE3803 of their delivery, and she goes off, only to be reminded by her that she is going the wrong way. They later stop at a glucose center to refill. NT4201 finds B Cell and Mast Cell arguing over the cedar incident and try to get Memory Cell into the argument, but he is too obsessed with the legends and has forgotten everything.
AE3803 keeps going the wrong way, having been reminded by NT4201, which tires and disappoints her. U-1146 drops down by a vent and finds AE3803 depressed, wondering if she is treating her kouhai right. AE3803 examines a map and finds the right direction, though NT4021 is unimpressed that she finds a simple map complex.
The day passes by as the various cells perform their jobs, until one day when a large explosion rattles the body. The shockwave is much stronger than expected, and AE3803 wakes up to find the city ruined with many casualties. NT4201 has also survived and is shocked by the devastation. They are met by U-1146 who is carrying a Platelet. He is unsure of what has happened, but tells them that all blood cells are to head to the center of the body. Before they are able to move however, a tide of red blood survivors (blood pressure) sweeps them away.
The cells are grouped around the center of the body, waiting for the announcement. In another area, a high level emergency meeting conducted by the cells ends in a state of emergency, as the tissue and blood vessels near the head have been critically damaged (hemorrhagic shock). All cells are to immediately stop the wound; NT4201 is nervous, but AE3803 states that they need to do their jobs now as it is not the time to hesitate.
The body temperature keeps increasing, so a cold sweat is applied to cool the body down. NT4201 notices the change but AE3803 tells her that they need to keep working. In another area, various antigens attempt to invade, but are cut down by U-1146, who surmises that he is near the wound area. Upon arriving, he is shocked to find that there are no red blood cells in the area.
When U-1146 somewhat introduced himself to the newer red blood cell, all of the blood stains vanished. Yet when he turned to find out the bacteria is still moving, the strains reappear in the same shot. Worst off, the next shot, the stains disappear again. In fact, the stains disappear and reappear continuously in the brief scene.