1 Red blood cells (RBCs) are also called erythrocytes. They make up almost half of blood. Red blood cells are filled with hemoglobin. That's a protein that picks up oxygen in the lungs and brings it to cells all around the body.  White blood cells (WBCs) are also called leukocytes.
Pain originating in the stomach or esophagus is often felt in the upper abdomen and can be due to heartburn, gastroesophageal reflux disease (GERD), or hiatal hernia (weakening in the diaphragm that allows the stomach to protrude into the chest). You may also have gastritis (inflammation of the stomach lining) or ulcers.
11. Bulging or herniated disc, spondylitis (spinal arthritis), broken vertebra or other disorder in the chest or lumbar part of the spine may cause upper middle abdominal pain and middle or lower back pain.Pain usually changes with moving or body position, aggravates with sitting and is relieved by walking.eart attack may appear with upper middle or left upper abdominal pain and is rare before 40 years of age. Smoking and high blood cholesterol are two important risk factors. Diagnosis is made on the basis of symptoms, ECG and elevation of certain enzymes in the blood.