Research the causes of these diseases that are similar to, or related to, Autoimmune Urticaria: 1  Idiopathic urticaria without angioedema. 2  Chronic urticaria.  Occult infection (e.g., sinusitis, oral infection, cholecystitis, vaginitis, prostatitis, hepatitis, HIV, tinea manus or pedis)
The sarcoplasmic reticulum is known for its storage of calcium ions in muscle cells.
Making the world better, one answer at a time. During skeletal muscle contraction calcium ions expose myosin binding sites on to the actin. When a nerve sends a signal to a muscle to do some action the release of acetylcholine at the neuromuscular junction triggers calcium to be released into the cytoplasm. At rest, the cell has a low concentration of calcium.