The products of the digestive system are actually tied directly to the circulatory system in that the organs of the digestive system are used to turn ingested food into products that can be absorbed by the blood and then carried to other organs for use as energy or other functions.There are also several links between the digestive system and the respiratory system in that there are organs and muscles that serve both, for example the diaphragm which works to force air into and out of the lungs as well as to force waste products out of the digestive system.<span>All of the systems have to work together as well, without the intake of oxygen and exhalation of carbon dioxide, the function of the digestive system would grind to a halt. Without the production of glycogen and other things necessary for muscular function, produced by the digestive system and then distributed by the circulatory system, all three functions would cease.</span>
I cannot found the exercise anywhere, so I will just explain how the toxin works.
A toxin is a toxic substance made by a living organism such as a bacterium, a fungus, a plant or an animal.
Labil toxins are toxins which are by easily degraded. among these toxins, there is the toxin of Escherichia coli and the cholera toxin of <span>Vibrio cholerea.
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The intracellular target of cholera toxin is adenylate cyclase, one of the most important eukaryotic cell regulatory systems. This enzyme is involved in the conversion of ATP into a cyclic AMP (cAMP), a crucial intracellular messenger in a wide variety of cellular processes.
Cholera toxin catalyzes the transfer of ADP-ribose from NAD (Nicotinamide Adenine Dinucleotide) to a specific arginine residue of the Gsa protein, resulting in the activation of adenylate cyclase and consequently the increase of the intracellular level cAMP. AMPc activates a cAMP-dependent protein kinase, which leads to phosphorylation of the protein, modification of ion transport and finally diarrhea.
In biochemistry, aligand is a substance that forms a complex with a biomolecule to serve abiological purpose. In protein-ligandbinding, the ligand is usually a molecule which produces a signal by binding to a site on a target protein.
Receptor mediated endocytosis is an endocytotic mechanism in which specific molecules are ingested into the cell. The specificity results from a receptor-ligand interaction. Receptors on the plasma membrane of the target tissue will specifically bind to ligands on the outside of the cell. An endocytotic process occurs and the ligand is ingested.
A very well studied example of receptor mediated endocytosis involves the metabolism of cholesterol.
