Bohr effect

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Oxyhaemoglobin Dissociation Curve. Dotted red line corresponds with shift to the right caused by Bohr

Bohr effect is a property of haemoglobin first described in 1904 by the Danish physiologist Christian Bohr (father of physicist Niels Bohr), which states that in the presence of carbon dioxide, the oxygen affinity for dissociation of respiratory pigments, such as haemoglobin, decreases; because of the Bohr effect, an increase in blood carbon dioxide level or a decrease in pH causes haemoglobin to bind to oxygen with less affinity.

This effect facilitates oxygen transport as haemoglobin binds to oxygen in the lungs, but then releases it in the tissues, particularly those tissues in most need of oxygen. When a tissue's metabolic rate increases, its carbon dioxide production increases. The carbon dioxide is quickly converted into bicarbonate molecules and acidic protons by the enzyme carbonic anhydrase:

CO₂+ H₂O $\rightleftharpoons$ H⁺ + HCO₃⁻

This causes the pH of the tissue to decrease, and so increases the dissociation of oxygen from haemoglobin, allowing the tissue to obtain enough oxygen to meet its demands.

The dissociation curve shifts to the right when carbon dioxide or hydrogen ion concentration is increased. This facilitates increased oxygen dumping. This makes sense because increased CO₂ concentration and lactic acid build-up occur when the muscles need more oxygen. Changing haemoglobin's oxygen affinity is the body's way of adapting quickly to this problem.

In the Hiroshima variant haemoglobinopathy the Bohr effect is diminished so the haemoglobin has a higher affinity for oxygen and tissue may suffer minor oxygen starvation during high work.

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There is no Latic acid being formed in the tissue, speccially muscle, since pK of -COOH from de lactate is +-2.86, so in pH =7.4 for exaple does not existe H3C-CHOH-COOH does existe only H3C-CHOH-COO^-

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Impact of training

v • d • e Respiratory system, physiology: respiratory physiology

Volumes	lung volumes - vital capacity - functional residual capacity - respiratory minute volume - closing capacity - dead space - spirometry - body plethysmography - peak flow meter - thoracic independent volume - bronchial challenge test

Airways	ventilation (V) (positive pressure) - breath (inhalation, exhalation) -respiratory rate - respirometer - pulmonary surfactant - compliance - hysteresivity - airway resistance

Blood	pulmonary circulation - perfusion (Q) - hypoxic pulmonary vasoconstriction - pulmonary shunt

Interactions	ventilation/perfusion ratio (V/Q) and scan - zones of the lung - gas exchange - pulmonary gas pressures - alveolar gas equation - hemoglobin - oxygen-haemoglobin dissociation curve (2,3-DPG, Bohr effect, Haldane effect) - carbonic anhydrase (chloride shift) - oxyhemoglobin - respiratory quotient - arterial blood gas - diffusion capacity - Dlco

Control of respiration	pons (pneumotaxic center, apneustic center) - medulla (dorsal respiratory group, ventral respiratory group) - chemoreceptors (central, peripheral) - pulmonary stretch receptors (Hering-Breuer reflex)

Insufficiency	high altitude - oxygen toxicity - hypoxia