Circulatory system, physiology

The human body can be considered to be made up of a series of anatomically discrete compartments connected to each other through the circulatory system and by physiological and biochemical links. When... 

The most distensible vessels in the circulatory system are the veins. As with arteries, this feature of the veins also has important physiological implications because it allows them to serve as blood reservoirs. The veins are so distensible that they are capable of holding large volumes of blood at very low pressures. In fact, under resting conditions, 64% of the blood volume is contained within these vessels. 

After highlighting the present top ten pharmaceuticals, let us now cover a number of other important drugs, both prescription and over-the-counter. We will attempt to categorize them by physiological action but will emphasize chemical structure and synthesis where appropriate. Our first type will be drugs affecting the heart. Cardiovascular agents are used for their action on the heart or on other parts of the vascular system. They modify the total output of the heart or the distribution of blood to certain parts of the circulatory system. 

The physiology of drug absorption from the GI tract has a direct effect on the bioavailability (F) of a drug. Bioavailability is defined as the fraction of the dose of a drug that enters the general circulatory system, that is ... 

Vitamins and hormones are minor organic biomolecules, but both of them are required by animals for the maintenance of normal growth and health. They differ in that vitamins are not synthesized by animals and must be supplied in diets while hormones are secreted by specialized tissues and carried by the circulatory system to the target cells somewhere in the body to initiate/stimulate specific biochemical or physiological activities. Vitamins (Dyke, 1965) can be classified as water-soluble (B vitamins and vitamin C) or fat-soluble (vitamins A, D, E, and K) and act as cofactors for numerous enzyme catalyzed reactions or cellular processes. Hormones (Nornam and Litwack, 1997) can be classified structurally as follows ... 

Human serum albumin (HSA) is an important transporter of fatty acids, metabolites, drugs, and organic compounds in the circulatory system [93, 94], It is a single polypeptide chain consisting of 585 amino acids. Under physiological conditions (pH 7), HSA adopts a heart-shaped three-dimensional (3D) structure with three homologous domains I—III (Fig. 14) each domain contains two subdomains A and B, which consist of four and six a-helices, respectively [95, 96]. The X-ray structure shows that two halves of the albumin molecule... 

Considerable losses of body water may occur rather suddenly via hemorrhage or more slowly via severe diarrhea or vomiting. Excessive losses of blood volume cause shock, which may set in when 25-30% of the blood volume is lost. The physiologic mechanism to correct for blood loss involves the rapid movement of interstitial fluid into the circulatory system, into which as much as 50% of the interstitial fluid may thus be transferred within a matter of a few hours. The interstitial fluid is, in turn, partially replaced by intracellular fluid however, this is a much slower process, and 1 or 2 days is required to reestablish a fluid equilibrium in the organism. The lost fluids and electrolytes must eventually be replaced through diet or intravenous feeding. 

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