Answer
Muscles perform four key kinds of functions:
1. Production of body movements: walking, swimming, nodding the head, riding a bike etc.
2, Stabilization of body positions: as in standing and sitting.
3. Storing and moving substances: fluids and food in the digestive tract, blood in the CV system, urine in
the bladder etc.
4. Generation of heat: during contraction of skeletal muscles.
Work Step by Step
There are several circular muscles that function as sphincters ( band or ring) that control entrances and exits into or out of structures/organ.; Examples of these sphincters are obicularis oculi (eye); esophageal sphincters; pyloric sphincter, sphincter of Oddi (common bile duct and pancreatic duct);
urethral sphincter(urethra), and anal sphincters(internal and external).
