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

Neuroendocrine Positive-Feedback Mechanism Controlling Labor

During the latter stages of pregnancy, the blood concentration of estrogens become increasingly greater than that of progesterone, as noted earlier. Whereas progesterone inhibits uterine contractions, estrogens promote them. Therefore, there is an increasing tendency toward the onset of uterine contractions as the pregnancy approaches full term.

Nervous Tissue

The nervous system consists of organs composed primarily of nervous tissue supported and protected by connective tissues. There are two types of cells that compose nervous tissue: neurons and neuroglia. Neurons Neurons, or nerve cells, are the structural and functional units of the nervous system. They are