1,721,221 research outputs found
Blood gas transport at high altitude
Full text linkAs a model of human hypoxia, exposure to high altitudes causes a number of ventilatory, circulatory and hemopoietic adaptations. A review of the literature on blood gas transport responses to hypoxia indicates that they are influenced not only by altitude, but also by factors related to acclimatization. In addition, it appears that the need to oxygenate tissues conflicts with the need to maintain H+ homeostasis. Thus, the final situation represents a compromise between the respiratory adjustment aimed at increasing blood alkalosis in order to optimize the oxygen transport system, and the metabolic readjustment aimed at reestablishing normal blood pH. there are factors like red cell 2,3-diphosphoglycerate, a compound that decreases the hemoglobin affinity for oxygen, that can influence that balance by affecting arterial oxygen saturation through mechanisms independent of respiration
Hypoxia-dependent protein expression: Erythropoietin
No full textNormal cell homeostasis relies on the ordered flow of nutrients and substrates through metabolic pathways. Any perturbation of this flow eventually leads to dysfunction, impairment of defense mechanisms, loss of viability and death. High altitude and pathological hypoxia represent a serious and frequent cause for the loss of cell viability. Although organisms customarily respond by triggering adaptive or maladaptive mechanisms, all forms of life eventually succumb to hypoxia if it is severe enough, irrespectively of the primary cause. This paper reviews one of the mechanisms by which organisms respond to hypoxia: erythropoiesis. Although such response is not always beneficial, the discovery of the biochemical mechanisms underlying erythropoiesis has triggered an active field of research that is actually applying lessons learned in the mountains to a more clinical environment
PREDICTION OF THE OXYGENATION OF HUMAN ORGANS AT VARYING BLOOD-OXYGEN CARRYING PROPERTIES
No full textThe oxygenation of some human organs (brain, heart, kidney, and legs) is correlated to the oxygen carrying characteristics of blood by predicting the PvO2 vs Ȯ relationship at a given metabolic level of the organ. The effect of moderate shifts of the oxygen equilibrium curve [≈2 Torr (0.27 kPa), comparable to the shifts caused by non-massive transfusions of blood with altered 2,3-diphosphoglycerate (DPG) concentration] is evaluated in terms of the efficiency of organ oxygenation. The results indicate the following. (1) An increase of the P50 from 27.9 to 30.0 Torr (3.71 to 3.99 kPa), that is the consequences of an increase of the [DPG]/[Hb] ratio from 0.8 to 1.04 M/M, is advantageous for all organs, because the normal metabolic level can be maintained with a considerable reduction of Q̇ (≈10%). (2) This reduction is similar to that caused by an increase of [Hb] from 160 to 182 g/L, but without increasing the blood viscosity and the vascular resistance. (3) This advantage is different for the various organs, as a function of their blood supply and metabolic level characteristics. These features were also observed at any PaO2 in the range 60-300 Torr (7.98-39.9 kPa), and when simulating acidemia or alkalemia, as well as a pH gradient across the organ
Acid-base equilibrium in the blood of sheep
No full textThe acid-base equilibrium in the blood of sheep is different from that of human blood mainly because of a lower concentration of 2,3-DPG. A nomogram relating pH, pCO2, total CO2 content and base excess has been developed
Oxygen affinity and acid-base balance in sheep blood ; Affinita per l'ossigeno ed equilibrio acido base del sangue di pecora
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