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The most common functional imaging signal is the blood-oxygen-level dependent signal (BOLD), which primarily corresponds to the concentration of deoxyhemoglobin. [13] The BOLD effect is based on the fact that when neuronal activity is increased in one part of the brain, there is also an increased amount of cerebral blood flow to that area which ...
Hypoxemia (also spelled hypoxaemia) is an abnormally low level of oxygen in the blood. [1] [2] More specifically, it is oxygen deficiency in arterial blood. [3] Hypoxemia is usually caused by pulmonary disease. Sometimes the concentration of oxygen in the air is decreased leading to hypoxemia.
Other variables include the pH of extracellular fluid, the concentrations of sodium, potassium, and calcium ions, as well as the blood sugar level, and these need to be regulated despite changes in the environment, diet, or level of activity. Each of these variables is controlled by one or more regulators or homeostatic mechanisms, which ...
Potassium resides mainly inside the cells of the body, so its concentration in the blood can range anywhere from 3.5 mEq/L to 5 mEq/L. [14] The kidneys are responsible for excreting the majority of potassium from the body. [14] This means their function is crucial for maintaining a proper balance of potassium in the blood stream.
Pulmonary (lung) circulation undergoes hypoxic vasoconstriction, which is a unique mechanism of local regulation in that the blood vessels in this organ react to hypoxemia, or low levels of dissolved oxygen in blood, in the opposite way as the rest of the body. While tissues and organs tend to increase blood flow by vasodilating in response to ...
Oxygen saturation is the fraction of oxygen-saturated haemoglobin relative to total haemoglobin (unsaturated + saturated) in the blood. The human body requires and regulates a very precise and specific balance of oxygen in the blood. Normal arterial blood oxygen saturation levels in humans are 96–100 percent. [1] If the level is below 90 ...
A long-term deficiency in vitamin B 12 can lead to megaloblastic anemia, characterized by large fragile red blood cells. Pernicious anaemia results from autoimmune destruction of gastric parietal cells, precluding the synthesis of intrinsic factor and, by extension, absorption of vitamin B 12. Pernicious anemia also leads to megaloblastic anemia.
Bicarbonate in the red blood cell (RBC) exchanging with chloride from plasma in the lungs. The underlying properties creating the chloride shift are the presence of carbonic anhydrase within the RBCs but not the plasma, and the permeability of the RBC membrane to carbon dioxide and bicarbonate ion but not to hydrogen ion.