When blood pressure in the afferent and efferent arterioles is insufficient, cells in the juxtaglomerular apparatus called _____ cells secrete renin, which indirectly causes a(n) _____ in systemic blood pressure and indirectly _____.

3000+ review questions on anatomy and physiology. 

Anatomy refers to the internal and external structures of the body and their physical relationships, whereas physiology refers to the study of the functions of those structures.