Smooth muscle cells are non-striated, involuntary muscle cells found in various tissues throughout the body, including the dermal layer of the skin where hair follicles reside. They play a crucial role in regulating blood flow and the contraction of hair follicles, which can influence hair growth and loss. In the context of hair biology, the contraction of these cells can affect the hair's position and the cycle of hair growth, making them relevant in understanding conditions like alopecia and other hair loss disorders. Key distinguishing characteristics of smooth muscle cells include their spindle-shaped structure and the ability to contract slowly and rhythmically, unlike skeletal muscle cells.