BloodCHS Forensics

Blood History

Different blood types were recognized in 1875, but it wasn't until 1901 that Karl Landsteiner named and standardized the groups.

In 1940, Landsteiner also discovered the rhesus factor in blood, labeling it Rh+ if the antigen was present in the red blood cells and Rh- if not. 

What is in Blood?

The three types of cellular elements in the blood are: erythrocytes (red blood cells), leukocytes (white blood cells), and platelets.

Plasma is the other portion that is in blood.

What is in Blood

The plasma is the liquid part of the blood, which is 90% water. The other 10% contains proteins, waste products, gases, and nutrients.

Plasma makes up 55% of blood.

Red Blood Cells

Red Blood Cells transport oxygen on molecules called Hemoglobin.

Erythropoiesis is the production of new red cells.

They are made at 2-3 million a second.

Average lifespan is 120 days.

White Blood Cells

Leukocytes are the mobile units of the body’s immune system. They are also called white blood cells.

They defend against the invasion of pathogens. They identify cancer cells. They remove the body’s litter by phagocytosis. They can leave the circulation and go to the

sites of invasion and tissue damage. There are five kinds of leukocytes. 5-10 million/ml of blood normal.

Platelets

They remain functional for about 10 days.

1/3 stored in spleen

250 million/ml of blood

They begin the clotting to a wound.

Blood Typing

RH factor is an antigen on blood that may or may not be on the red blood cell. It is labeled as + or -.

Rare blood types exist in addition to the basic ABO system.

ABO vs DNA

ID stain to one individual Prior to DNA typing

ABO typingPolymorphic blood enzymes and

proteins Supplanted by the newer DNA

technology DNA analysis

Associate blood and semen stains to a single individual

ABO Reactions

Heredity and Paternity

Transmission of hereditary materialGenesLocated on chromosomes

Alleles Alternative forms of genesInfluence a given characteristic (such as eye color or blood type)

Heredity and Paternity

HistoricallyABO blood typing systemPlus blood factors other than ABO

CurrentlyDNA test proceduresOdds of establishing paternity beyond 99 percent