Blood Cells and the Circulatory System

DNA and Developmental Programs 1901 1. Blood Cells and the Circulatory System... 

The average adult contains about 60% water by mass, and the average infant about 75%. About 60% of the body s water is contained within the cells as intracellular fluids the other 40% makes up extracellular fluids, which include the interstitial fluid in tissue and the plasma in the blood. These external fluids carry nutrients and waste materials between the cells and the circulatory system. 

These unusually shaped sickle cells clog the circulatory system, reducing blood flow. Therefore, oxygen supply to nearby tissues is reduced. Sickle cell disease causes pain, anemia, stroke, and susceptibility to infection. 

Removal of senescent red blood cells from the circulation has been attributed to desialylation of the membrane glycoproteins. In vitro removal of sialic acid from human red blood cells and introduction of the modified cells into the circulatory system result in drastic shortening of their life span. However, aging and removal of red blood... 

Experimentally there are two important ways of detecting anti-tumour activities of Vinca alkaloids. One way deals with healthy animals. Products with potencies in cell growth inhibition may first suppress fast growing cells. For this purpose the cells of the circulatory system may serve as subject cells. In healthy mice, rats, guinea pigs, rabbits, or other small animals, the normal blood cell count (red and white cells) is easily established. Any significant drop in the blood cell count after single or repeated doses of substances with possible anti-tumour activities can indicate that these substances are worth further study. The second step involves evaluation of these substances in experimental tumours. One of the most useful models is the P 1534 leukemia in DBA/2 mice, which has... 

A thrombus is a mass of cells and protein composed principally of platelets and fibrin, but also containing red and white blood cells. A thrombus which forms in the circulatory system can become occlusive in that the thrombus can physically block flowing blood. 

The principal function of the circulatory system is to supply oxygen and vital metabolic substrates to cells throughout the body, as well as removal of metabolic waste products. Circulatory shock is a life-threatening condition whereby this principal function is compromised. When circulatory shock is caused by a severe loss of blood volume or body water it is called hypovolemic shock, the focus of this chapter. Regardless of etiology, the most distinctive manifestations of hypovolemic shock are arterial hypotension and metabolic acidosis. Metabolic acidosis is a consequence of an accumulation of lactic acid resulting from tissue hypoxia and anaerobic... 

The surface area in the luminal side of the small intestine per unit length of the serosal (blood) side is enormous in the proximal jejunum, and steadily decreases (to about 20% of the starting value [62]) in the distal portions of the small intestine. The surface area is increased threefold [69] by ridges oriented circumferentially around the lumen. Similar folds are found in all segments of the GIT, except the mouth and esophagus [66]. Further 4—10-fold expansion [62,69] of the surface is produced by the villi structures, shown schematically in Fig. 2.4. The layer of epithelial cells lining the villi structures separate the lumen from the circulatory system. Epithelial cells are made in the crypt folds of the villi, and take about... 

Symptoms of intoxication in humans caused by accidental ingestion of Kou-Wen plants have been described as follows. The effect on the digestive system starts with loss of appetite and turn of the stomach, and continues to severe abdominal pain and intestinal bleeding. The effect on the respiratory system presents as breathing difficulties which finally lead to death by respiratory failure. The effect on muscle innervation usually results in generalized muscular weakness and paralysis of the limbs. The effect on the circulatory system starts with heartbeat disorders and a drop in blood pressure, but heart failure is not a common cause of death. In addition to dilation of pupils, a drop in body temperature and proliferation of white blood cells have also been obseryed (70). 

With this background there is an obvious call for novel strategies to follow changes of complex molecular patterns of different stress-related diseases over days, weeks, months, and years as an effect of lifestyle and the psychosocial environment to reflect the effects of unhealthy environments. The molecular interactions between the brain and the immune system in health and disease are reflected in the circulatory system as the white blood cells, the lymphocytes, mimic ongoing activities in the brain. By using lymphocytes from patients with psychosomatic-psychiatric diseases we can find detailed information about protein-peptide translational modifications and transformation essential for the development of new approaches that can prevent and treat major psychiatric diseases. 

Internal structure of the tube worm Riftia pachyptila. (a) Oxygen, sulfide, and carbon dioxide are absorbed through the plume filaments and transported In the blood to the cells of the trophosome. (b) The chemicals are absorbed into these cells, which contain dense colonies of sulfur bacteria, where they are converted to organic compounds and (c) passed back into the circulatory system to act as an energy source for the worms. Source-. From Childress, J. J., et al. (1987). Scientific American, 256, 114-121. 

Waste products (cells only five for hours to days) pass back to the blood, where they are carried through the fiver, which is the other major chemical reactor in the circulatory system. Here enzymes bound to surfaces in the fiver further react the decomposition product molecules into even smaller molecules that can pass through the body s major filter, the kidneys. Liquid wastes and excess water then are stored in the bladder until needed. 

Except for lymphocytes, each specialized blood cell Is a workhorse at the end of its road each remains in the circulatory system or In a tissue and then dies, perhaps as a result of doing its job. Red ceiis (erythrocytes) have lost their nucleus, and platelets are fragments of precursor cells. Because they have no nuclei, human red cells and platelets cannot divide. 

In endocrine signaling the hormone is synthesized in specific signaling, or endocrine, cells and exported via exocytosis into the extracellular medium (e.g. blood or lymphatic fluid in animals). The hormone is then distributed throughout the entire body via the circulatory system so that remote regions of an organism can be reached. 

Transport of oxygen (02) and carbon dioxide (C02) in the circulatory system. In most tissues 02 is released and C02 is withdrawn by the red blood cells in the lungs these processes are reversed. 

Once in the blood, substances are transported throughout the circulatory system and enter other organs and tissues via passage across the membranes of the cells composing the organs and tissues. Hence, a critical determinant of a substance s bioavailability is its ability to cross cellular membranes. 

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