PLTW Principles of Biomedical Sciences Unit 1: Blood Evidence

Vocabulary flashcards covering blood components, presumptive and confirmatory testing, ABO blood typing, and blood spatter analysis.

Blood

A body fluid and connective tissue with different types of cells suspended in plasma that carries nutrients and oxygen to cells and removes waste products such as $CO_2$.

Erythrocytes

Also known as red blood cells; components of blood responsible for carrying oxygen.

Leukocytes

Also known as white blood cells; components of blood that play an important part in defense and immunity.

Thrombocytes

Also known as platelets; blood components that play an important role in blood clotting.

Plasma

The liquid component of blood that is mostly water and carries proteins, lipids, hormones, wastes, and salts.

Presumptive Testing

Initial testing, such as LCV, Luminol, or the Kastle-Meyer test, that suggests a sample may be blood.

Confirmatory Testing

Testing, such as RSID or ABO blood type testing, that confirms the presence of blood at a scene by relying on unique properties like antigens on red blood cell surfaces.

Kastle-Meyer Test

A presumptive blood test that uses the chemical phenolphthalein, which reacts with the iron found in hemoglobin to produce a pink color indicating a sample may be blood.

Antigens

Structures present on the surface of red blood cells or anything that stimulates an immune response when reacting as non-self.

Agglutination

The clumping of blood that occurs when antibodies react with non-self antigens.

ABO System

A classification system consisting of 8 blood types based on specific antigens present on the surface of red blood cells.

Transfers

Blood evidence patterns that occur when a blood source comes into contact with a surface.

Spatters

Blood evidence patterns produced when a source of liquid blood travels through the air before landing on a surface.

Falling Droplets

Blood spatters formed when a droplet is dropped directly from above and strikes a horizontal surface at $40^\times$ forming a circular stain.

Force & Direction Spatters

Spatters with an elliptical or elongated shape that struck a surface at an angle due to an external force providing horizontal velocity, where greater elongation indicates faster speed.

Radial Spatter

A blood spatter pattern created when a high-impact force strikes a pool of blood, sending droplets traveling away from the impact site at high speed.