The action potential generated at the motor end plate region spreads along the membrane of skeletal muscle cell and into the T tubules. The T tubules contain dihydropyridine receptors that connect to the Ca++ channels of sarcoplasmic reticulum. Depolarization of T tubules opens the sarcoplasmic reticulum Ca++

Small Intestinal Motility

The small intestine is divided into duodenum, jejunum, and ileum, with the duodenum and jejunum being the major site of digestion and absorption. Chyme takes 2 to 4 hours to move through the 5 m of the small intestine. Segmentation, which mixes intestinal contents and enhances contact

Neurological Disorders Affecting Muscles

Botulism poisoning is caused by a neurotoxin produced by the bacterium Clostridium botulinum. The toxin prevents release of ACh from the terminal boutons of somatic motor axons. Without prompt treatment with an antitoxin, death may result from paralysis of breathing muscles. Poisoning results from eating improperly canned

Colonic Motility

The colon reabsorbs salts and water. About 1500 mL of fluid enters the colon each day, but only 50 to 100 mL of fluid is excreted in feces. Anatomically, the colon is divided into the cecum, ascending colon, transverse colon, and descending colon. Segmental contraction of the

Divisions of The Nervous System

Although the nervous system functions as a coordinated whole, it is divided into anatomical and functional divisions as an aid in understanding this complex organ system. Anatomical Divisions The nervous system has two major anatomical divisions. The central nervous system (CNS) consists of the brain and spinal