Chapter 8 Blood “Out damned spot! Out, I say Here’s the smell of the blood still, All the perfumed of Arabia will not Sweeten this little hand. Oh, Oh, Oh!” —William Shakespeare’s Lady Macbeth, in Macbeth
Dec 23, 2015
Chapter 8
Blood
“Out damned spot! Out, I say Here’s the smell of the blood still,All the perfumed of Arabia will not
Sweeten this little hand. Oh, Oh, Oh!”
—William Shakespeare’s Lady Macbeth, in Macbeth
Blood That an antibody and
an antigen of different types will agglutinate, or clump, when mixed together.
That the significance of the evidence depends on a characteristic’s relative occurrence in the population.
You will learn:
Blood You will be able to:
Determine whether a stain is blood.
Determine whether a bloodstain is human or animal blood.
Determine the blood type of a simulated bloodstain using the ABO/Rh system.
SerologyThe examination and analysis of body fluids
From 1950’s to 1980’s -- high importance
With DNA -- now a matter of economics
Blood Characteristics Plasma is the fluid portion of the
blood (55%) Cells (45%)
Erythrocytes are red blood cells. They are responsible for oxygen distribution.
Leukocytes are the white blood cells; they are responsible for “cleaning” the system of foreign invaders.
Platelets (proteins) are responsible for blood clotting
Serum is the liquid that separates from the blood when a clot is formed.
Parts of Blood
Unknown Stain at a SceneQuestions to be answered: Is it blood? Is it human blood? Whose is it?
Determine blood type, alcohol content, drugs present
Determine the method(s) in which blood may have been deposited
Presumptive Tests forBlood Determination
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
Testing for Blood
Both the Kastle Meyer and Luminol test for presence of blood are examples of chemical reactions.
Human vs Animal Blood
Microscopic observation
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.
Animal Blood
Larger nucleic red blood cells
Frog Blood
Human Blood Red blood cells are most
numerous; 5 to 6 million per mm3
White blood cells are larger and less numerous; 5 to 10,000 per mm3
Platelets are tiny, cellular fragments; 350 to 500,00 per mm3
Secretors
80% of the population are secretors. Their blood-type antigens are found in high concentration in their body fluids such as saliva, semen, vaginal secretions and gastric juice.
Historical Perspective
of Blood TypingKarl Landsteiner
1900
4 types
In 1940 Rh factor
85% of Caucasions
94% Black Americans
99% Asians
How is our blood type determined?
Your blood type is established before you are BORN, by specific GENES inherited from your parents.
You receive one gene from your MOTHER and one from your FATHER.
These two genes determine your blood type by causing proteins called AGGLUTINOGENS to exist on the surface of all of your red blood cells.
Blood Typing A-B-O and Rh systems are the most important in identifying blood
An individual that is type A has A antigens on his/her red blood cells
Type B has B antigens Type AB has both A and B antigens Type O has neither A nor B antigens
Agglutination For every antigen there is a specific antibody that will react with it to form clumps (agglutination)
For example, Red blood cells containing B antigens will react in the presence of B antibodies
What are blood types?
http://learn.genetics.utah.edu/units/basics/blood/types.cfm
There are 3 alleles or genes for blood type: A, B, & O. Since we have 2 genes, there are 6 possible combinations.
Blood Types
AA or AO = Type ABB or BO = Type B
OO = Type OAB = Type AB
http://www.lanecountyblood.org/images/other/bloodfacts.jpg
45%
40%
11%
4%
How common are the 4 blood types?
Blood Groups
Type Antigen Antibody Can GiveBlood To
Can GetBlood From
A
B
AB
O
A
B
A and B
NeitherA nor B
B
A
NeitherA nor B
A and B
A, AB O, A
B, AB O , B
AB
A, B, O, AB
A, B, O, AB
O
Rh Factors Scientists sometimes study Rhesus monkeys to learn
more about the human anatomy because there are certain similarities between the two species. While studying Rhesus monkeys, a certain blood protein was discovered. This protein is also present in the blood of some people. Other people, however, do not have the protein.
The presence of the protein, or lack of it, is referred to as the Rh (for Rhesus) factor.
If your blood does contain the protein, your blood is said to be Rh positive (Rh+). If your blood does not contain the protein, your blood is said to be Rh negative (Rh-).
A+ A-B+ B-
AB+ AB-O+ O-
http://www.fi.edu/biosci/blood/rh.html
Rh factor Determined by presence of another antigen
People having antigen are Rh +
People not having are Rh-
Blood Typing Use the results shown to determine the blood type
for each sample.
- = No Clumps
+ = Clump
A
B
Rh
Blood Type: ___
To determine a person’s blood type, we add three different serums to blood samples and see if clumps form.
Clumps = Positive (+)No Clumps = Negative (-)
What would the blood type be for this sample?
A
B
Rh
Blood Type: ___
A
B
Rh
Blood Type: ___
A
B
Rh
Blood Type: ___
A
B
Rh
Blood Type: ___
A
B
Rh
Blood Type: ___
Blood Typing Use the results shown to determine the blood type for each sample.
- = absent
+ = present