“Out damned spot! Out, I say
Here’s the smell of the blood still,
All the perfumes of Arabia will not
Sweeten this little hand. Oh, Oh, Oh!”
—William Shakespeare’s Lady Macbeth, in Macbeth

Questions to be answered:
•Is it blood?
•Is it human blood?
•Whose is it?
•Determine blood type.
•What caused the blood spatter?
•Determine the method(s) in which blood may have been deposited.

• Whole blood carries cells and plasma —the fluid with hormones, clotting factors, and nutrients.
Shown below:
• Red (Erythrocyte) blood cells carry oxygen to the body’s cells and carbon dioxide away.
• Platelets aid in blood clotting and the repair of damaged blood vessels.
• White (Leukocyte) blood cells fight disease and foreign invaders and, alone, contain cell nuclei.
Erythrocyte Platelet Leukocyte

What are the four types of blood?
• A, B, AB, and O
What do we use to identify the blood types?
• ABO Blood Typing
What is the population distribution in the
US?
Type Percent
O 45
A
B
AB
40
11
4

What is the difference between the types?
• Antigen – cells are located on the red blood cell.
• Antibody —are proteins secreted by white blood cells that attach to antigens to destroy them, located outside the red blood cell.
• Agglutination —clumping of red blood cells; will result if blood types with different antigens are mixed

•Has A antigens on the surface of red blood cells and B antibodies in blood serum.
• The B antibodies will attack and destroy
Type B blood cells when they are introduced into the body.
•Can give blood to A and AB, can received blood from O and A

•Has B antigens on the surface of red blood cells and A antibodies in blood serum.
• The A antibodies will attack and destroy Type
A blood cells when they are introduced into the body.
• Can give blood to B and AB; can receive blood from O and B

• Has both A + B antigens on the surface of red blood cells + NO A or B antibodies in blood serum.
• Will not reject or attack any blood types =
Universal Recipient
• Can give blood to AB, can receive blood from A, B,
O, and AB

•Has NO A or B antigens on the surface of red blood cells but has BOTH A + B antibodies in blood serum.
•Will not “provoke” and attack by any antibodies
= Universal Donor
• Can give blood to A, B, O, and AB; can receive blood from O

Type
A
B
AB
Universal Acceptor
O
Universal Donor
Antigen Antibody
A B
Can Give
Blood To
A, AB
Can Get
Blood From
O, A
B
A and B
Neither
A nor B
A
Neither
A nor B
A and B
B, AB
AB
A, B, O, AB
O , B
A, B, O, AB
O
11

• A certain blood protein was discovered while studying Rhesus Monkeys called: Rh
• If this protein is present in your blood, you are: Rh + (positive).
• If your blood lacks this protein, you are:
Rh (negative).
* This is why we have positive (O + ) and negative (B ) blood types!

• Kastle-Meyer color test —a mixture of phenolphthalein and hydrogen peroxide; the hemoglobin will cause the formation of a deep pink color if blood is present
• Hematest® tablet —reacts with the heme group in blood causing a blue-green color
• Luminol test —reaction with blood to produce light

• Microscopic observation
• RBC in animal has a nucleus
• RBC in human no nucleus
Frog Blood
Human Blood

• Precipitin test
• Blood is injected into a rabbit; antibodies are formed; the rabbit’s blood is extracted as an antiserum; the antiserum is placed on sample blood. The sample will react with human proteins if human blood is present. This test is very sensitive and requires only a small amount of blood.