Okay why does my 'fro do this?

I have a 'fro that im currently workin on cause I wanna get twists. you know they kinda look like dreads but they are thinner. like those:: look down





My mama said that she know how to do em so she'll do em for me. But I 've always wondered this but never took the time to find out, see my hair is naturally curly, like really tight curls. Therefo it dont grow straight up you know wut im saying? So like, if i pick/comb it out, it doesnt stick up all the way it could. After I pick my hair out I can pull strands up and standing straight up it like 3 or 4 times higher. So often my mom will have to hot comb or use that comb that has a blo dryer on it to make it stick up. but like when my hair get wet from sweat when i play bball it flattens, So im askin is there any like chmical or gel i can use to make my hair maintain a straight stand up?