The new blood line

The renal mechanisms come into play immediately the disturbance of acid-base physiology starts. However, it takes a relatively long period for the renal mechanisms to come to maximum efficiency and for the renal retention of bicarbonate to build up the concentration throughout the body. In respiratory acidosis, it takes around three days for the subject to settle to the compensated point. This is where the subject then stays so long as the same degree of hypoventilation persists. 

When sufficient time has elapsed for the subject to have established a new steady state, the composition of the blood has changed radically. The kidney 

Most authorities use the term acidaemia to mean a low blood pH and alkalaemia to mean a high blood pH (Table 3.2). Acidosis means that the extracellular fluid contains excess of unwanted acid but there is not necessarily a low plasma pH the pH may have been returned to normal values because 

Acidosis an excess of unwanted acid in the body the pH may be normal 

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Figure 3.3. This shows the information of Figure 3.1 together with the new blood line of a subject who has completely compensated for the respiratory acidosis. Arrow BC indicates the change in blood chemistry if hypoventilation is suddenly corrected and the respiratory system is able to excrete the previously-accumulated COj.

Suppose now that, after three days, the obstruction to ventilation is removed normal respiratory exchange is resumed and over the course of minutes, the excess CO2 is washed out of the body. In Figure 3.3, the point representing the composition of the subject s blood moves down along the new blood line until the PCO2 has fallen to around normal values (point C). The bicarbonate concentration is still high, reflecting the bicarbonate retention by the kidney,s. 

In a patient in whom there is a sudden rise in the alveolar partial pressure of carbon dioxide, the change in composition of the patient s arterial blood is represented in Figure 3.1 as a move from the normal, represented by point N, along the normal blood line to point A. The increase in the x coordinate represents the rise in the PCO2 of the patient s arterial blood. The increase in the y coordinate represents the rise in bicarbonate concentration the move to a new isohydric contour reflects the increase in hydrogen ion concentration. These changes in composition of the arterial blood are summarized in Table 3.1 Column A. 

Compensation renders the situation more complex. In respiratory acidosis, for instance, compensation involves the retention of bicarbonate by the kidneys as illustrated in Figure 3.1. This results in the subject moving to a new blood line indicating the addition of a metabolic component to an initially purely respiratory effect. The compensation means that there is now a positive base excess in addition to the raised partial pressure of carbon dioxide. So in compensated respiratory acidosis, there are both resjnratory and metabolic components. The respiratory component is the primary disorder and the metabolic component is the secondary effect. The primary respiratory component is in the direction of acidaemia and the secondary metabolic response component is in the direction of restoration of pH, i.e. in the direction of alkalaemia. In compensation, therefore, as shown in Table 4.4B, both the partial pressure of carbon dioxide and the base excess are raised. 

The characteristics of a synovium affected by RA are (1) the presence of a thickened, inflamed membrane lining called pannus, (2) the development of new blood vessels, and... 

Red blood cells are amongst the most numerous of the human cell lines an average healthy 70 kg male having a total of approximately 25 x cells in his 51 of blood. A typical red cell contains in excess of 600 million haemoglobin molecules which equates to a total of about 300 g of haemoglobin, an amount that is far greater than for any other protein in the body. The lack of a nucleus clearly indicates that red cells cannot divide and at the end of their life, worn out RBCs are removed by the cells of the reticuloendothelial system. Approximately 2% (5 x 1011) of the red cell number are removed and replaced by new ones each day. Haem synthesis is outlined later in this chapter and its catabolism is discussed in Chapter 6. 

The effects of tretinoin on keratinization and desquamation offer benefits for patients with photo damaged skin. Prolonged use of tretinoin promotes dermal collagen synthesis, new blood vessel formation, and thickening of the epidermis, which helps diminish fine lines and wrinkles. A specially formulated moisturizing 0.05% cream (Renova) is marketed for this purpose. 

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