What is the function and location of smooth muscles?

Function:

- Control the diameter of blood vessels (adjusting blood flow)

- Propels substances along internal body passages (via peristalsis)

- Control the size of various body openings (sphincters)

- Facilitate involuntary movements in many organs (e.g., the gastrointestinal tract, respiratory tract, reproductive system, and urinary system).

Location:

- Walls of hollow internal organs (e.g., the stomach, intestines, uterus, and bladder).

- Blood vessel walls (arteries and veins).

- Muscles associated with hair follicles (arrector pili muscles).

- Sphincter muscles (e.g., the pyloric sphincter in the stomach, the esophageal sphincter, and the anal sphincter).