Human metabolism anabolic processes

Most of the reported metabolic effects of the thyroid hormone do not satisfactorily explain the hormone s mode of action either because the effects occur too late after the administration of the hormone or because serious discrepancies between in vivo and in vitro observations exist. Therefore, the effect of the hormone is reinvestigated each time a new biochemical pathway is elucidated. The biosynthetic pathways for proteins have not escaped this intrusion by the thyroid endocrinologist. Researchers have known for a long time that human myxedema is associated with a slowing down of the anabolic processes, including reduction in the rate of protein synthesis. Anabolic pathways of hypothyroids are normalized by thyroid hormone administration. Similarly, the rate of protein synthesis as measured by amino acid incorporation is reduced in thyroidectomized rats, and the ratio of DNA to RNA is decreased. Thyroxine administration restores to normal amino acid incorporation and the RNA DNA ratio. 

These are the first studies of zinc absorption reported In a large group of normal subjects. Results of these studies are Important as a basis for comparison with data from patients with various diseases who may exhibit abnormalities of zinc absorption. Zinc absorption has been shown to decrease with age In normal humans, but whether this Is related to decreased anabolism with reduced demand for zinc or to some physiological or pathological process associated with aging Is unclear. The decreased absorption of zinc taken with food Is Important with respect to the design of studies of zinc metabolism. In the determination of zinc bloavallablllty and nutritional requirements of the trace metal and In treatment of subjects who may require zinc replacement. 

Complex molecules are broken down into smaller ones through catabolism, and simple molecules are used to build bigger ones through a process called anabolism. A metabolio pathway is a series of linked chemical reactions that occur within a cell and result in a specific product. The major metabolic pathways fcr mcst crganisms are very similar. So, one can study the metabolic pathways in simple crganisms to get information about the reactions in organisms that are more complex, including humans. 

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