Blood Background for Forensic Science

Plasma

Plasma is yellow or straw-colored and is 90 percent water, with red and white blood cells suspended in it. Plasma accounts for about 55 percent of a person's blood volume, making it the largest component of blood. It is the only liquid component of blood, and because it is liquid, plasma is what allows blood to circulate throughout the body, making it essential to human life.

Platelets

Red Blood Cells

Platelets (thrombocytes) are actually not true cells but merely circulating fragments of cells. But even though platelets are merely cell fragments, they contain many structures that are critical to stop bleeding. Platelets are produced in the bone marrow, the same as the red cells and most of the white blood cells. Platelets are produced from very large bone marrow cells called megakaryocytes.

Red blood cells (erythrocytes): Red blood cells compose 45% of the blood. Their main function is to transport oxygen from the heart and lungs to the rest of the body tissue, where it is needed. Simultaneously, red blood cells take away carbon dioxide from the body tissue and transport it to the lungs, where it will be oxygenated. Their special feature, which enables red blood cells (erythrocytes) to bind oxygen and carbon dioxide, is a molecule called hemoglobin that contains iron. In a cubic millimeter there are 4-5 million red blood cells in women and 5-6 million in men. So, the total amount of red blood cells is about 2-3 trillion (10 to the 13th power). They are produced in the bone marrow and one single circulation through the whole body takes them about 20 seconds. Furthermore, their life expectancy varies from 100 to 120 days.

White Blood Cells

Check out this white blood cell chasing bacteria!

Whenever a germ or infection enters the body, the white blood cells (leukocytes) snap to attention and race toward the scene of the crime. The white blood cells are continually on the lookout for signs of disease. When a germ does appear, the white blood cells have a variety of ways by which they can attack. Some will produce protective antibodies that will overpower the germ. Others will surround and devour the bacteria.

Type O blood can be received by any type. Type AB can receive any type.

"Universal Donor" "Universal Recipient"

Blood as Evidence

BloodBasics

We'll Cover:

• Two Basic Components
• Blood Types
• Blood Facts

But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus, his Son, purifies us from all sin. If we claim to be without sin, we deceive ourselves and the truth is not in us. If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness. - 1 John 1:7-9