After the hem-occult card is prepared, and the reagent is dropped on to the specimen, if blood is present there will be a color change resembling that of the positive control. The color change isn't necessarily limited to the perimeter of the drop.
Blood is scarlet red in color when it is loaded with oxygen. Oxygenated blood appears bright red, while deoxygenated blood appears darker.
When blood lacks oxygen, it appears dark red or maroon in color.
Presence of occult fecal blood in stool is often used as an indicator of peptic ulcers or colorectal cancer, depending on what other signs/symptoms are present. It's important to note that a POSITIVE test for occult blood does NOT automatically mean cancer. It is simply a sign that needs further investigation, usually by an colonoscopy, sigmoidoscopy or endoscopy to establish the root cause.
The commonly used tests to detect occult blood in feces require a small sample of stool that is collected in a special container provided by the laboratory. The sample is usually collected at home by the individual and returned to the laboratory for analysis. The tube color for this test may vary depending on the specific laboratory protocol, but a common color for the container is brown or green.
Blood appears red due to the presence of red blood cells, which contain a protein called hemoglobin that binds to oxygen and gives blood its red color. The yellow color of plasma is due to the presence of proteins and fats in the liquid component of blood. When combined with the red blood cells, the overall color of blood appears red.
Pulmonary artery carries deoxygenated blood and appears blue, while pulmonary vein carries oxygenated blood and appears red.
Blood is actually red due to the presence of hemoglobin, a protein that contains iron and binds with oxygen. When blood is oxygen-rich, it appears bright red, while oxygen-poor blood appears darker red. The misconception that blood is blue comes from the color of veins, which can appear blue under the skin due to how light interacts with it.
A positive test for protein typically appears as a violet or purple color when using chemical indicators such as Biuret reagent. This color change indicates the presence of proteins in the test sample.
Blood appears red because that's the colour that they do not absorb, same with all other objects. This depends on the ions and electrons in blood.
Insects and invertebrates like them do not have any red blood cells in their blood. That is why it does not have a red color.
Blood containing red blood cells filled with oxyhemoglobin appears bright red.