|The Tiny Platelets|
|Czech Title||Krevní destičky|
|Original (French) Title||Les Petites Plaquettes|
|The Blood||The Heart|
The Tiny Platelets is the sixth episode of Once Upon a Time... Life. Its plot has the job to explain the function of platelets.
The narrator shows the bone marrow and introduces the hematopoiesis of Platelets. After the scene, a group of newborn Platelets arrives to bloodstream and enter the bloodstream. They begin to wonder if they actually have a purpose in the body. Some of older Platelets meet them and they introduce the young Platelets to their purpose.
However, some of the old Platelets begin to rant about how boring their lives are and begin to question is it true that Lieutenant Claire meant they are useful. She arrives and greets the young ones. In a blood vessel, a group of Platelets finds a damaged tissue and begins to cling onto it. Globus explains that the tissue is result of damage by fatty acids. The young Platelets and old Platelets group check out the process and and the latter find out that, once a Platelet joins the reparation of tissue, it stays like that. They witness an Antibody neutralizing a pathogen. Then, two Neutrophils check out some, unbeknownst to them, disguised Viruses, that begin an infection. However, the Antibodies successfully neutralize them.
The old Platelet guide decides to tell the young ones a story of how, in one of his former lives, Antibodies were attacking the Platelets instead of protecting them. Then, the doctor decided to create a Trojan Horse in appearance of toxic Platelets, that were killing the malicious Antibodies. Claire and Captain Peter meet them and tell them that they have to return to the bloodstream. The young platelets distress a bit when they see a swarm of Antibodies.
In the meantime, in a vein with the same tissue damage, Platelets quickly start to pile up to the tissue. Then, the Fibrin Enzymes toss their ropes over. As Globin and Hemo approach them, one of the Enzymes grabs Globin by the lasso and Hemo jumps after her to put her down. Globus arrives and scolds the Enzymes, who tell him off wanting to have fun. Platelets, knowing there are plenty of veins, think there's nothing wrong with doing this, but when Globus reveals that the tissue of the vein can die, they start thinking again. However, the Enzymes keep wrapping the Platelets. Meanwhile, Hemo struggles to pull Globin out of lasso.
In the nucleus of a nearby cell, Maestro is alarmed and his assistants register the forming blood clot. In an attempt to stop them, Maestro requests for Prostaglandin squad to dissolute the blood clot. They use their guns to destroy the Fibrin ropes and the heap finally comes undone, along with Globin and Hemo. She gives him a kiss for trying to save her.
In the outside world, Peter and Jumbo are practicing archery but run out of arrows. Peter decides to make some using a knife by carving some branches. His mother tries to convince him not to do it, but he promises he'll be careful and that it'll be for a short while. After some time, she begs him with his sister to give her the knife. Saying he's nearly done making the arrow, he makes two more strikes before cutting his thumb on accident. The narrator zooms in on the knife, filthy of wood and stained with some blood, and then into a huge swarm of Staphylococci.
The vein suddenly collapses and breaks into a ravine, causing a massive waterfall of blood, beginning the hemorrhage. As Staphylococci climb up, their leader leads them further into the tissue. Metro soon notices them and defeats some of the germs, but not enough. Lieutenant Jumbo manages to catch himself by the edge of the tissue and requests help. Young and old Platelets are walking through the bloodstream as they and body sentinels receive an announcement from the system:
"Your attention, please! This is a general emergency. All engineers and combat troops must report to the right thumb immediately. The veins have been cut! The body is losing blood, and we've been invaded by a powerful force of Staphylococcus Germs. All specialized cells are ordered to step up Antibody manufacture with an immediate effect."As Captain Peter calls the Lymphocytes, the Platelets make their way to the cut veins. Globin and Hemo make their way to surface, but latter quickly grabs Globus and pulls him to safety. The three observe as the Platelets make their way to shrink the rivers of blood. However, Heparin agents, anticoagulant units, begin to interrupt them. Soon, specialized Enzymes begin to destroy them. A lot of leukocytes and Antibodies are heading to the hemorrhage site as well.
In the Chromosome room, an Enzyme is having trouble while trying to prepare mRNA. Annoyed by the sass of the nitrogenous bases, he begins to cry and Maestro is disappointed with what is happening. He contacts the chief who orders to qucikly perform transcription procedure. Antibodies soon leave the cells and enter the bloodstream. Meanwhile, Trombin Enzymes are collecting fibrinogen for Fibrin Enzymes to use. They quickly throw lassos to strengthen the dams made of Platelets. The young and old Platelets make their way and achieve their purpose as they make bridges. Police units are still battling Staphylococci.
A bit later, Red Corpuscles cheerfully begin to walk on the good-as-new bridge made of Platelets. The Staphylococcus leader and some of his remain colleagues are soon finished off by a Macrophage. The scene zooms out to where Peter's Mum takes Peter to disinfect the cut. The episode ends as the narrator tells the viewers that they now know what's the purpose of Platelets.
- This is the first episode to feature a hemorrhage and the second episode to feature a massive combat between the leukocytes and pathogens.
- It's revealed that Platelets shrink with age.
- This is the second episode to show the body's sentinels act like attackers (in a flashback); the first time was in The Bone Marrow.
- This is the second episode to center around a type of blood cell; the first one being The Body's Sentinels.
- In the beginning of the episode, a cluster of newborn Platelets was shown building up and then bursting, which refers to megakaryocytes.
- Peter's Sister, who was cured of leukemia thanks to Peter, in this episode sounded ungrateful for taunting him when he accidentally hurt himself.
- Platelets, also known as thrombocytes, are small, without nucleus, disc-shaped blood cells. They usually live from 8 to 14 days, after which they are devoured by macrophages in the spleen.
- Platelets are very small compared to the other blood cells; about 2 to 4 micrometers.
- The episode's name acts like a nod to this.
- Platelets are created in hematopoiesis by dissolving megakaryocytes, large hematopoietic clusters in the bone marrow.
- The purpose of platelets is to stop bleeding (or hemorrhaging) by making a thrombocyte cork and causing blood clotting.
- Platelets themselves aren't able to stop the bleeding on their own. That's where they get the assistance:
- Coagulation begins when prothrombin, an inactive blood protein, transforms into thrombin. Thrombin further transforms the inactive fibrinogen to fibrin by dissolving them to monomers, that soon create a net that the blood cells stick to.