Blood

"Blood is a constantly circulating fluid providing the body with nutrition, oxygen, and waste removal. Blood is mostly liquid, with numerous cells and proteins suspended in it, making blood ""thicker"" than pure water. The average person has about 5 liters (more than a gallon) of blood.
A liquid called plasma makes up about half of the content of blood. Plasma contains proteins that help blood to clot, transport substances through the blood, and perform other functions. Blood plasma also contains glucose and other dissolved nutrients.
About half of blood volume is composed of blood cells:
• Red blood cells, which carry oxygen to the tissues.
• White blood cells, which fight infections.
• Platelets, smaller cells that help blood to clot.
Blood is conducted through blood vessels (arteries and veins). Blood is prevented from clotting in the blood vessels by their smoothness, and the finely tuned balance of clotting factors."

Hematemesis

A regurgitation of blood via the upper gastrointestinal tract is called Hematemesis. The upper part of the gastrointestinal tract includes mouth, stomach, throat, the first part of the small intestine and the esophagus. The cause of this includes ulcer, inflammation, varices caused by cirrhosis in the upper gastrointestinal tract and cancer. Other symptoms include weakness, nausea, sweat, fatigue and abdominal pain and shock. The source of bleeding can be identified through endoscopy, ultrasonography, and biopsy. The treatment that should be done to the person who suffers from hematemesis is dependent on the underlying cause.
The purpose of surgical and medical therapy is to correct the coagulation abnormalities and shock and to stabilize the patient so that further treatment and evaluation can proceed. The prognosis of this condition depends on the extent and range of the hemorrhage and its underlying cause. What are the symptoms of hematemesis? This includes nausea, vomiting blood, weakness, fatigue, abdominal pain, dark colored, tar like stool, sweat, shock and hypotension.