Blood Basics Forensic Science

Are we sure it’s blood? If so, is it human? ... tests What is it? ... components Are we sure it’s blood? If so, is it human? ... tests What does it do when it “travels”? … spatter

What makes up our blood? RBCs (Red Blood Cells) Why is your blood red? How does its redness relate to its function? Hemaglobin – a protein Each RBC has ~ 280 million Hemaglobin proteins in it. Each Hemaglobin protein has 4 iron (Fe) atoms in it. Each iron atom binds to an O2 molecule… their purpose!

RED BLOOD CELLS RBCs

Why is your blood red? How does its redness relate to its function? Cells Proteins Atoms bind to ___ …which is what these cells are for! Important: RBCs have no nucleus, so they contain no ______.

WHITE BLOOD CELLS (Leukocytes) – WBCs IMMUNE CELLS What makes up our blood? WHITE BLOOD CELLS (Leukocytes) – WBCs IMMUNE CELLS

RED BLOOD CELLS (RBCs), with a lone WHITE BLOOD CELL (center)… in the early stages of blood clotting.

What makes up our blood? PLASMA – YELLOWISH LIQUID - nutrients and vitamins, hormones, clotting factors, and antibodies. PLATELETS (Thrombocytes) – coagulate (clot) your blood, when you have a wound

Platelets

UNIVERSAL DONORS: O type Rh – UNIVERSAL RECIPIENTS: AB type Rh + What are blood types? UNIVERSAL DONORS: O type Rh – UNIVERSAL RECIPIENTS: AB type Rh +

How common is your blood type? 46.1% 38.8% 11.1% 3.9%

Are we sure it’s blood? If so, is it human? ... tests Is it blood? Kastle-Meyer test Uses Phenolthalein Detects Hemoglobin Pink if +

KASTLE-MEYER video clip

Luminol Is it blood? in a B I G area Drawbacks !! Some metals, paints, cleaning products, and plant materials also react. Can destroy DNA in blood.

Luminol can destroy evidence (DNA) http://www.youtube.com/watch?v=iNl-I4DUSyI

Crime Scene Analysis: Luminol in action

If it’s blood, is it HUMAN? Is it HUMAN blood? HemaTrace test

Is it HUMAN?? Microscope Views Bird Blood Cat Blood Dog Blood Fish Blood Frog Blood Snake Blood Human Blood Horse Blood

Blood loss A Class I Hemorrhage is usually considered 15%, or less, of an adult’s blood volume. In an 80 kg person this would be about 0.84 liters. At this level there are almost no signs or symptoms. A Class II Hemorrhage is 15 to 30% loss of an adult’s blood volume. In an 80 kg person this would be about 1.68 liters. At this level the heart will start to beat faster, and the person will start to look pale, and feel cool. This is the beginning stages of shock. A Class III Hemorrhage is 30 to 40% loss of blood. In an 80 kg person this would be about 2.24 liters. At this level the heart will be beating very fast, trying to keep up with the bodies needs. The person will look very pale, and start to be confused. This person is in shock, and in trouble. Fluids are needed very quickly in order to raise blood volume. A Class IV Hemorrhage is greater than 40% and in an 80 kg adult this would be more than 2.24 liters. The body can no longer keep up with the blood loss and the person is in serious trouble.

http://www.pbs.org/wgbh/nova/tech/forensics-on-trial.html  http://video.pbs.org/video/2223977258/

What are the 4 components of blood What are the 4 components of blood? Alternate with your partner to explain each one, starting with RBCs.

Blood reagent tests (screening tests) rely on the presence of what protein in the blood sample? What does the name of this protein say about it? Why might rust stains and blood stains appear similar? What does this protein do?

What is the quickest and most widely used screening test for blood What is the quickest and most widely used screening test for blood? Explain how it works, and what reagents are used? What does a positive test look like?

How does luminol work? Are there any drawbacks to using luminol at a crime scene?

If the screening test on a piece of evidence is positive, which test is used to confirm that the blood is actually human?