Volume, total circulating blood

Blood consists of cellular elements (red blood cells, white blood cells, and platelets) as well as plasma, the fluid in which the blood cells are suspended. Normally, total circulating blood volume is about 8% of body weight (about 5 1 in women and 5.5 1 in men). Adipose tissue is relatively avascular and therefore contains little blood compared to other tissues. 

For a drug that is confined solely to the circulation (blood volume is 80 mb kg ) the volume of distribution will be 0.08 L kg . Distribution into total body water (800 mb kg ) results in a volume of distribution of 0.8 b kg . Beyond these values the number has only a mathematical importance. For instance a volume of distribution of 2 b kg means only, that less than 5 % of the dmg is present in the circulation. The drug may be generally distributed to many tissues and organs or concentrated in only a few. 

The lungs are covered extensively by a vast network of blood vessels, and almost all the blood in circulation flows through lungs. Deoxygenated blood is supplied to the lungs by the pulmonary artery. The pulmonary veins are similar to the arteries in branching, and their tissue structure is similar to that of systemic circulation. The total blood volume of the lungs is about 450 mL, which is about 10 percent of total-body blood volume.118... 

Diuretics work by increasing the amount of sodium and fluids excreted by the kidneys. Less fluid means less total blood volume and improved circulation and blood pressure. There are five main classes of the drug loop diuretics, thiazide diuretics, potassium-sparing diuretics, osmotic diuretics, and carbonic anhydrase inhibitors. 

Normal values for total blood volume vary depending on the methods used for its determination and the basis of reference (sex, age, weight, surface area). In a healthy adult or normal body habitus, the circulating blood comprises 6-8% of the body weight, or 63-80 mL/kg. Blood consists of cellular elements suspended in a solution containing a host of proteins and low molecular weight substances. There are three types of cells in blood the red cells (erythrocytes), the white cells (leukocytes), and platelets (thrombocytes). Only the white cells possess... 

The differences between the transfused and nontransfused cases observed by Flear and Clarke (F2) appeared to be related to the adequacy of the circulating red cell mass and the total blood volume during the early stages after injury and its treatment. They suggest that blood loss and an adequate circulating blood volume are major etiologic factors of posttraumatic metabolic changes. The concept of a fixed pattern of response to injury involves an oversimplified approach and may lead to... 

Figure 1. Block diagram of a model for the control of erythropoiesis (HbO), oxyhemoglobin concentration Vi, viscosity factor (HbO), effective oxyhemoglobin concentration R, rate of erythropoietin release (E), plasma erythropoietin concentration E0, normal plasma erythropoietin concentration V , distribution volume for erythropoietin P, rate of hemoglobin production MT, erythrocyte maturation time L, rate of hemoglobin loss TH, total circulating hemoglobin (Hb), blood hemoglobin concentration Vb, blood volume Vp, plasma volume Vp0, normal plasma volume Vpf, steady-state hypoxic plasma volume MCV, mean corpuscular volume MCH, mean corpuscular hemoglobin k, constant...

Total circulating blood volume was calculated by summing plasma volume and total circulating red blood cell volume. Plasma volume changes in the model are represented by an empirically derived relationship. Upon application of a stimulus, plasma volume changes from the control value to an experimentally determined steady-state value in an exponential manner with a time constant of 1.5 days (2). 

Total circulating red blood cell volume was calculated from experimentally determined values for mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV) (2) and the model predictions of total circulating hemoglobin. In response to stimulus, MCH is assumed to remain constant while MCV changes from the control value to a steady-state value (predetermined from the data) in a linear manner during the first 5 days of stimulus. 

Contraction of veins forces reserved blood into circulation, which increases diastolic pressure, while the increased circulating blood volume, coupled with arteriolar constriction (which increases the total peripheral resistance), increases systolic pressure. The drug simultaneously causes norepinephrine to be released from sympathetic nerve terminals, which increases cardiac output and antagonizes the effects of vagal compensation. 

Chapter 6). Prolonged or excessive losses of fluid via the GI tract will affect packed cell volume (hematocrit), plasma total protein, albumin, electrolytes, acid-base balance, and osmolality values as the circulating blood volume adjusts to the fluid loss. Excessive and prolonged salivation may also cause electrolyte perturbations, but to a much smaller extent. Hypo- or hypernatremia may occur depending on the proportional losses of electrolyte to water these electrolyte changes are also reflected by plasma osmolality. There may be significant differences between the measured and calculated plasma osmolality in the presence of hyperlipidemia and hyperproteinemia. 

The geometrical parameters of the canine systemic and pulmonary circulations are summarized in Table 56.1. Vessel diameters vary from a maximum of 19 mm in the proximal aorta to 0.008 mm (8 m) in the capillaries. Because of the multiple branching, the total cross-sectional area increases from 2.8 cm in the proximal aorta to 1357 cm in the capillaries. Of the total blood volume, approximately 83% is in the systemic circulation, 12% is in the pulmonary circulation, and the remaining 5% is in the heart. Most of the systemic blood is in the venous circulation, where changes in compliance are used to control mean circulatory blood pressure. This chapter will be concerned with flow in the larger arteries, classes 1 to 5 in the systemic circulation and 1 to 3 in the pulmonary circulation in Table 56.1. Flow in the microcirculation is discussed in Chapter 59, and venous hemodynamics is covered in Chapter 60. 

The average adult male has a total blood volume of 5.0 L. After drinking a few beers, he has a BAC of 0.10 (see Exercise 4.65). What mass of alcohol is circulating in his blood ... 

The total blood volume is unevenly distributed. About 84 percent of the entire blood volume is in the systemic circulation, with 64 percent in the veins, 13 percent in the arteries, and 7 percent in the arterioles and capillaries. The heart contains 7 percent of blood volume and the pulmonary vessels 9 percent. At normal resting activities heart rate of an adult is about 75 beats/min with a stroke volume of typically 70 mL/beat. The cardiac output, the amount of blood pumped each minute, is thus 5.25 L/min. It declines with age. During intense exercise, heart rate may increase to 150 beats/ min and stroke volume to 130 mL/beat, providing a cardiac output of about 20 L/min. Under normal conditions the distribution of blood flow to the various organs is brain, 14 percent heart, 4 percent kidneys, 22 percent liver, 27 percent inactive muscles, 15 percent bones, 5 percent skin, 6 percent ... 

Blood is a complex non-Newtonian fluid that consists of several kinds of cells carried through the circulation in an isotonic aqueous medium, the plasma. Plasma contains a large number of proteins, salts, lipids, and various other nutrients and components. The cellular components normally account for 45% of the total blood volume. They include erythrocytes, leukocytes, and platelets. Erythrocytes constitute most of the total cell volume 1% is accounted for by leukocytes, which include several types of cells. The major blood cell types and their concentrations are shown in Table 1. About 52% of total blood volume is water and the remaining 3% is contributed by dissolved solids, including protein and nonprotein components. The normal pH of plasma is 7.4. 

Relative hypovolemia can occur when a large portion of the body s fluids escape into the tissues, most often owing to low oncotic pressures as a result of decreased protein. The circulating blood volume is decreased, which reduces venous return and results in symptoms similar to those of inadequate intake or fluid loss from the body. Symptoms of hypovolemia can occur when the total volume of fluid in the body is adequate. If an excess amount of fluid volume remains in the tissues, decreased volume in the blood vessels will result. 

Here Rq, tot is ml O2 (STP) consumed per hour, and M is body mass in grams. Other important properties, for example blood volume per unit mass and decrease of total oxygen content per unit volume of blood on passing through the arterial system, are invariant b is zero. It follows that average blood circulation time... 

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