27 lines
2.8 KiB
Markdown
27 lines
2.8 KiB
Markdown
---
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title: Physiology of Scuba Diving
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created_date: 2024-11-02
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updated_date: 2024-11-02
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aliases:
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tags:
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---
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# Physiology of Scuba Diving
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The understanding of partial pressure in the physiology of scuba diving is crucial. What determines the functional state of the body is that the cells receive enough oxygen to continue functioning. Oxygen is transported across membranes into cells mainly by diffusion, meaning its going from a higher concentration to a lower concentration to balance out the concentrations.
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In summary, the transport of oxygen from the blood to tissues is a diffusion-driven process, guided by concentration gradients and modulated by physiological factors that ensure efficient oxygen delivery to meet cellular demands.
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## Partial Pressure
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The gradient of partial pressure of Oxygen (pO2) is the driving force behind the diffusion. The cells have a low partial pressure of Oxygen, because [[Mitochondria]] use it in aerobic respiration for the [[ATP]] production. Therefore, this makes sure there is always a low concentration of oxygen within the cell.
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Across the membrane and interstitial fluid we have blood with oxyhemoglobin thus presenting a high partial pressure of oxygen. Since there is a high gradient, the oxygen will diffuse.
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Both the Bohr-effect (increase in pCO2 results in lowering affinity of hemoglobin to Oxygen resulting in decomposition of oxyhemoglobin into oxygen and hemoglobin) and the temperature decrease the affinity between hemoglobin and oxygen, thus promoting the diffusion process from arteriole into the cells.
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The same happens in the lungs, only that the diffusion happens from lungs into the blood.
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Since only the partial pressure is relevant scuba divers can breathe an air mix with only 1% oxygen when breathing it under high pressure (e.g 21 bars =200m depth) resulting in a partial pressure of oxygen of 0.21 bars which is very similar to what we have on the surface of the earth.
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> [!Important]- Carbon Monoxide (CO) Toxicity
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> Carbon Monoxide (CO) is a colorless and odorless gas. Carbon Monoxide poisoning occurs when CO reacts with haemoglobin at the site of oxygen binding. Haemoglobin has an affinity for CO that is 210x greater than its affinity for oxygen. This means that once carbon monoxide binds to haemoglobin, it is **irreversible.**
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> Symptoms of CO poisoning are headache, nausea and tiredness. Interestingly, respiration rate is usually spared as the partial pressure of oxygen dissolved in the blood is maintained at normal levels. Haemoglobin bound to CO has a **cherry-red colour** and this may be visible in nails beds and mucous membranes of patients with CO poisoning. Treatment is with 100% oxygen and referral for **hyperbaric oxygen** treatment. CO poisoning is considered **fatal** when 70-80% of haemoglobin is bound with carbon monoxide
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