Forensics Chapter 8 Test - Blood Spatter

agglutination

clumping of cells caused by an antigen-antibody response

angle of impact

angle at which blood strikes a target surface relative to the horizontal plane of the target surface

antibodies

proteins secreted by white blood cells that attach to specific antigens

antigen

substance that provokes an immune response in the body

antigen-antibody response

white blood cells recognize a substance as foreign and try to destroy it

area of convergence

two-dimensional view of the intersection of lines formed by drawing a line through the main axis of at least two drops of blood that indicates the general area of the source of the blood spatter

area of origin

the location of a blood source viewed in three dimensions as determined by projecting angles of impact of individual bloodstains

cast-off pattern

blood projected onto a surface as a result of being flung from an object in motion

passive drop

blood drop created solely as a result of gravity

satellite

smaller droplets of blood projected from larger drops of blood upon impact with a surface

spine

elongated blood streaks radiating away from the center of a bloodstain

blood stain pattern: swipe

lateral transfer of wet blood from a moving source onto a surface; feathered edge indicates direction from source

Blood stain pattern: wipe

object moves through partly dried blood with lateral motion, altering appearance

How long has blood been studied?

Since around 2500 BC by the Egyptians in an effort to cure disease

Blood is composed of what three components?

red blood cells, white blood cells, platelets

What is plasma?

Plasma is what the three components of blood are carried in.

What does plasma carry?

antibodies, hormones, clotting factors, nutrients such as glucose, amino acids, salts, and minerals throughout the body.

What do red blood cells carry?

They carry respiratory gases. The hemoglobin binds to the oxygen and transports it.

What do white blood cells do?

They fight disease and foreign elements.

What are the main divisions of blood types?

A, B, AB, O

Cohesion and blood

causes most of the blood to remain in a single drop

How to determine the directionality of blood

When blood comes into contact with another surface, blood adheres to is. As a result, less blood moves forward. IN OTHER WORDS: The blood starts out wide and as it moves in a direction it gets skinnier

Blood stain patterns: Passive Drops

linear pattern of round droplets of blood

Blood stain patterns: Cast-off pattern

seen on walls or ceilings; pattern of lines with blood direction changing as arm moves up and back; blood flung off weapon; change in direction of blood drops

Blood stain patterns: Transfer pattern

wet, bloody surface contacts a second surface, minimal lateral motion

Blood stain patterns: arterial gush

blood exiting under pressure from an artery and striking a surface; peaks indicate heart contraction

Blood stain patterns: Expired blood

blood blown out of nose or mouth as a result of air pressure, similar to high-velocity blood spatter, often with bubbles

Blood stain patterns: Shadowing or Void

area devoid of blood spatter

How to collect blood in liquid pools

should be picked up in gloved hands with gauze pads or sterile cotton cloths, allow cloths to dry thoroughly before packing

What is blood considered evidence wise?

Class

What do blood types result from?

the presence of antigens on the surface of red blood cells and vary among individuals

How do you reveal hidden blood?

Luminol

How can you determine if blood is human?

chemical tests