Blood and Blood Spatter

Blood 3 Types of Cells – Red Blood Cells – White Blood Cells – Platelets All contained in plasma that contains proteins: – Antibodies – Hormones – Clotting factors – Nutrients (amino acids, minerals, etc.)

Blood Cells Red Blood Cells – Hemoglobin in the cell is iron-containing protein that transport oxygen to the tissues of the body White Blood Cells – Fights diseases and foreign invaders Platelets – Aid in blood clotting and are involved in repairing damaged blood vessels

Antibodies B-lymphocytes (special white blood cells) secrete antibodies – Helps white blood cells identify foreign proteins Y-shaped proten molecule that binds to the shape of an antigen. – The binding site of the antibody is located on the tip of the Y and the antibody recognizes a foreign substance as an invader and attaches to it.

DNA PROFILING Dr. Alec Jeffreys used white blood cells as a source of DNA to produce the first DNA Profile DNA profiling or DNA fingerprinting is widely accepted in programs such as The Innocence Project to help free inmates who have been falsely convicted of crimes.

Blood Splatters Passive Fall – Blood falls directly to floor at 90-degree angle produces circular drops Arterial spurts – Typically found on walls or ceilings causes by the pumping action of the heart Splashes – Shaped like exclamation points – Can help locate the position of the victim at time of attack

Blood Splatters Smears – Left by bleeding victims depositing blood as they touch something Trails – Left my bleeding victims trying to move – Droplets can appear as round, smeared, or spurts Pools – Form around victim who is bleeding heavily

Directionality of Blood The shape of an individual blood drop provides clues to the direction of where the blood originated. – Circular drop: blood fell straight down – Elongated: possible to determine direction the blood was traveling as it struck the surface – Blood strikes the surface Cohesion: force between 2 similar substances Adhesion: force between 2 unlike surfaces (ex- blood and wall) Surface tension: elastic characteristic along the outer edge of liquid caused by attraction of like molecules