Human muscle contraction relies on the action of the motor proteins actin and myosin. Muscles contract through the sliding of myosin and actin filaments along one another.

The sarcoplasmic reticulum (SR) is a specialized type of smooth endoplasmic reticulum in striated muscle tissue. The SR has a different function than the smooth ER. The SR is involved in calcium ion storage that is critical in contraction while the smooth ER synthesizes new molecules.

During embryogenesis, the process of myogenesis forms myocytes and muscle tissue.

The sarcoplasm in muscle cells is comparable to the cytoplasm in other types of cells. The sarcoplasm is specialized in the high amount of myoglobin present. Its specialized regulation of calcium ion concentrations controls muscle contractions.

Intercalated disks are structures that connect cardiac muscle cells, allowing them to work together and communicate within the heart. Intercalated disks are made up of different types of cell junctions and are observable under the microscope. This makes cardiac muscle tissue distinguishable.

Muscle tissue can be divided into red—fast twitch—and white—slow twitch—muscle types. Red muscles have many capillaries, mitochondria, and myoglobin. Red muscles also perform aerobic activity.

Myofibrils are the basic units of all muscle tissue that are composed of chains of myocytes. Myocytes contain thin and thick filaments of proteins that organize into sarcomeres.

The calcium ions bind to troponin, which causes the release of the tropomyosin from actin as a result of the troponin-tropomyosin complex detaching. This makes the binding site on actin available for myosin to attach to. The sarcoplasmic reticulum stores calcium for its quick release to facilitate muscle contraction.

Skeletal muscle fibers come in 3 types: red (type I), intermediate/pink (type IIA), and white (type IIB). Red muscle fibers produce slow movement and do not fatigue quickly; these muscles mainly utilize oxidative phosphorylation as an energy source. White muscle fibers work the fastest, but also fatigue much more rapidly; these muscles mainly utilize glycolysis as a source of energy. Intermediate muscle fibers consist of both red and white muscle fibers. All muscles contain some degree of intermediate muscle fibers, however the pectoralis major muscle is an example of a muscle group primarily composed of white muscle fibers. Cardiac muscle is found in the heart only, and smooth muscle is involuntary.

The correct answer to this question is lactic acid fermentation.

Lactic acid fermentation occurs in human muscle cells when oxygen is not available. Alcohol fermentation only occurs in yeast, fungi, and some bacteria. The other answers are unrelated to cramps and instead just are other concepts of respiration.