Where the shape comes from
A sacrificial dish 皿 with a single drop shown above the rim — the blood of an offering caught and held up during a ritual, rather than blood in the body generally. It gives 血液, blood, and 流血, to bleed, and extends easily to 血统, a bloodline, the kinship that runs, figuratively, in the same vessel.
汉字 filed under 血
No published character on HSK Guide is filed under this radical yet. 汉字库.