Pathology. Pathology is the precise study and diagnosis of disease. The word pathology is from Ancient Greek ÏÎ¬Î¸Î¿Ï, pathos which may be translated into English as either experience or suffering. and -Î»Î¿Î³Î¯Î±, -logia, An account of or the study of.
Red cells contain a special protein called hemoglobin, which helps carry oxygen from the lungs to the rest of the body and then returns carbon dioxide from the body to the lungs so it can be exhaled. Blood appears red because of the large number of red blood cells, which get their color from the hemoglobin.
Each hemoglobin protein is made up subunits called hemes, which are what give blood its red color. More specifically, the hemes can bind iron molecules, and these iron molecules bind oxygen. The blood cells are red because of the interaction between iron and oxygen. When the iron is oxygenated(Fe+3), it becomes red. When the iron is deoxygenated(Fe+2), it becomes blue. This is why your veins are blue. When hemoglobin is carrying a lot of oxygen (like when just leaving the lungs), blood is bright red.