This question has already been answered. Please see the link below.
The chapter is coherent both internally and in the overall narrative. The internal coherence of the chapter is given by the consistent focus on the hairs of the different family members. In addition the sketch, the second of the book, adds details on the narrator's family members that were introduced by the first vignette. "Hairs" also introduces the theme of gender roles and the narrator's search for a community of women (the book is dedicated "A las Mujeres, To the Women") in her description of her mother's comforting and reassuring hair. In addition, the narrator's own hair which "never obeys barrettes or bands" symbolyzes her own yearning for freedom and independence.