MICROANATOMY

Detailed explanation-1: -Blood that has lost its oxygen is dark bluish-red. People whose blood is low in oxygen tend to have a bluish color to their skin. This condition is called cyanosis. Depending on the cause, cyanosis may develop suddenly, along with shortness of breath and other symptoms.

Detailed explanation-2: -The colors of arterial and venous blood are different. Oxygenated (arterial) blood is bright red, while dexoygenated (venous) blood is dark reddish-purple.

Detailed explanation-3: -Central cyanosis is caused by a decrease in arterial oxygen saturation (SaO2) and begins to show once the concentration of deoxyhemoglobin in the blood reaches a concentration of ≥ 5.0 g/dL (≥ 3.1 mmol/L or oxygen saturation of ≤ 85 %).

Detailed explanation-4: -Patients with cerebral ischemia or brain tumor have been reported to exhibit an increase of deoxygenated hemoglobin (deoxy-Hb) together with an increase of oxygenated hemoglobin (oxy-Hb). However, the physiological mechanisms underlying this hemodynamic response pattern are unclear.