Unit 5: Blood Splatter Flashcards
What are the 4 main components of blood?
- Plasma
- Red blood cells
- White blood cells
- Platelets
Made of cells and plasma
Name 2 functions of blood…
- Transporting oxygen and nutrients to the lungs and tissues
- Forming blood clots to prevent excess blood loss
What does it mean by whole blood?
The blood that runs through the veins, arteries and capillaries (55% plasma, 45% blood)
How many pints of blood does an average person have?
Man: 12
Woman: 9
What are the 4 major blood types?
A, AB, B, O
What antigen does group A have?
Antigen A
What antigen does group B have?
Antigen B
What antigen does group AB have?
A and B antigens
What antigen does group O have?
Neither
How are the blood groups broken down to create 8 different blood types?
Rh factor; if the antigen Rh is present the blood is Rh+ and if not the blood is Rh -
What is the role of the white blood cells in terms of antibodies in Blood Type A blood?
The persons white blood cells will make antibodies against the B antigen (anti-B)
What causes the clumping of the blood when testing for blood type?
With anti-A, anti-B, or anti-Rh antibodies and seeing which antibodies make it clump together
What does it mean if an unknown blood sample “clumps” when exposed to anti-A?
That the blood has A (but not B) antigens mainly that person type A
What are antigens?
Are carbohydrates that are attached to RBC’s
What does it mean when you are Blood Type B?
Your cells have B antigens attached, so your body makes antibodies against only type A
Who can Blood Type B donate to?
AB, B
Why is AB blood unique
You can receive blood from a donor with any blood type (cells don’t make antibodies towards anything)
How is O blood unique?
- Can donate blood to anybody (universal donor)
- But can only receive from type O because cells make antibodies against both type A and B antigens
How do crime scene investigators use blood typing?
- To eliminate someone from a crime scene
- To narrow down the suspect pool
What is forensic serology?
Is the study of blood applied to crime
What can blood splatter patterns be used for?
- To reconstruct a crime scene
- Show how the attack was made
- Blood can connect an object with a crime (ex. discarded weapon)
- Blood can connect a suspect with a crime (ex. blood on clothing) or place a suspect at a crime scene
What type of evidence is blood typing?
Class evidence and is useful to rule out suspects
What type of evidence is DNA profiling?
Is considered to be individual evidence and can help pinpoint a suspect
What is blood?
Blood is a tissue that circulates around through the body
Is blood made mostly of plasma?
True (55%)
Where are blood cells made?
In the bone marrow
What is red bone marrow?
Red bone marrow produces red and white blood cells and platelets, is found in humerus, femur, sternum, ribs, vertebrae, and pelvis
Where is yellow bone marrow?
Yellow bone marrow in other bones contains stored fat
What are RBC’s?
-RBCs are erythrocytes
- They contain hemoglobin and carry oxygen and carbon dioxide
- Hemoglobin is an iron-containing protein that binds to oxygen and gives blood its red colour
- They have no nucleus and no nuclear DNA
What are WBC’s?
- Called leukocytes
- They are immune system cells that fight diseases and produce antibodies
- They are the only blood cells that contain DNA; therefore are the only blood cell useful in DNA profiling
What are the 2 most common types of WBC’s?
Lymphocytes: are made in lymphoid tissue in the spleen, lymph nodes, and thymus gland. Lymphocytes identify foreign substances from germs (bacteria or viruses) in the body and produce antibodies and cells that specifically target them
Neutrophils: kill and digest bacteria and fungi. They are the most numerous type of white blood cells and your first line of defense when infection strikes. They move out of blood vessels into infected tissue to attack the bacteria. Pus is made up largely of neutrophils. Normally a serious bacterial infection causes the body to produce an increased number of neutrophils, resulting in a higher-than-normal white blood cell count
What are platelets?
- Called thrombocytes
- They are small cell fragments that assist in blood clotting and repair damaged blood vessels
What is blood plasma?
The yellowish portion of blood
- Plasma is made up of 90% water. The other 10% are…
- Dissolved proteins (antibodies, hormones, clotting factors)
- Nutrients (O2, glucose, amino acids, salts, minerals)
- Wastes (urea, CO2)
What do arteries do?
Carry blood away from the heart
What do capillaries do?
Very small vessels, capillaries supply cells with nutrients then remove wastes
What do veins do?
They are large vessels called veins, veins carry blood towards the heart
What does blood typing do?
Blood typing identifies the presence or absence of particular proteins embedded in the cell
Why does the forensics team go to blood typing before DNA testing?
- It is quicker and less expensive than DNA profiling
- The presence or absence of cell-surface proteins determines a person’s blood type
What are antigens?
A and B proteins are found on the surface of some RBCs
If a person’s blood cells have A antigen proteins they have…
Type A blood
If a person’s blood cells have B antigen proteins they have…
Type B blood
If a person’s blood cells have both A and B antigen proteins they have…
Type AB blood
If a person’s blood cells have neither A nor B antigen proteins they have…
Type O blood
How do you determine blood type…
One would preform an antigen test and look for agglutination (clumping)
What does it mean when you have the Rh protein…
Means you have Rh+ positive blood
What does it mean when you don’t have the Rh protein?
This means you have Rh- blood
Why is Rh called that?
Because it was first discovered in 1940 in Rhesus monkeys
Where are antigens found?
Antigens are found in red blood cells and (foreign cell) membranes
Where are antibodies found?
Antibodies are found in blood plasma
What is the Antigen-Antibody Response?
When a foreign material enters your body, your immune system launches an attack called an antigen-antibody response in which WBCs called B-lymphocytes release antibodies to attack the foreign substance
What is considered to be the universal receiver?
AB+
What is considered to be the universal donor?
O-
What causes an antigen-antibody response?
Viruses, bacteria, and the RBCs of someone with a different blood type all have antigen proteins
Antibodies are shaped like what?
Y-shaped proteins secreted by white blood cells that attach to antigens to destroy them
What antigen and antibody does blood type A have?
Antigen: A in RBC’s
Antibody: B in plasma
What antigen and antibody does blood type B have?
Antigen: B in RBC’s
Antibody: A in plasma
What antigen and antibody does blood type AB have?
Antigen: A and B
Antibody: none
What antigen and antibody does blood type O have?
Antigen: none
Antibody: both A and B
What happens when a person receives a blood type that isn’t theirs?
Antibodies can cause the blood to clump which can possibly lead to death
What is the clumping of RBCs called?
Agglutination
Can the same ethnicities reduce the chance of a reaction?
Yes
What are some other blood proteins?
Glycophorin Antigen- M
Glycophorin Antigen- N
Phosphoglucomutase- PGM
Adenylate Kinase- AK
Adenosine Deaminase- ADA
Esterase D- EsD
Glucose- 6 Phosphate dehydrogenase (G-6-PD)
What are polymorphic proteins?
They are group-specific components (Gc) and haptoglobins (Hp)
What does testing for more blood proteins increase?
The probability of uniqueness increases, making the blood evidence more individualized
What is the blood type that can only accept one blood type?
O- is the universal donor
What is the most common blood type?
O+
What is the least common blood type?
AB-
What is blood spatter?
it is a grouping of blood stains
What can blood splatter patterns help with?
- Helps to reconstruct the events surrounding shootings, stabbings, beatings, etc.
- Direction of blood traveled
- Angle of impact
- Point of origin of the blood
- Velocity of the blood
- Manner of death
- They are also useful to evaluate the credibility of statements provided by a witness, a victim, or a suspect
Who was the first person to research and analyze blood spatter patterns?
In 1939, Dr. Victor Balthazard
What does it mean when blood splatters with cohesion?
- Blood sticks together as it falls maintaining a round shape
- Blood also resists flattening out when it falls on a flat surface. Cohesion and surface tension helps to maintain a curved shape
What does it mean when blood falls from a height or at a high velocity?
It forms satellite droplets, small secondary droplets around the main drops
What does it mean when blood falls onto a less-than-smooth surface?
The edges may have spikes or extensions
What does it mean when a blood drop has a 90-degree impact angle?
Will have a circular shape
What does it mean when blood strikes a surface at angles less than 90 degrees
Will have a teardrop shape
What does a circular drop of blood indicate?
That a drop fell straight down without force; typical of a dripping wound
What does an elongated blood drop indicate?
Blood was traveling from a different direction when it landed
What will the point of impact appear as?
May appear darker and wider than the rest of the drop with a tail pointing in the direction of the movement of the blood
Smaller, secondary droplets may break off and will land…
In front of the moving droplets of blood, allowing those to determine the direction of the splatter
What can scientists do when there are two or more blood splatters?
Draw lines of convergence that can pinpoint the location of the blood source
How do you measure the point of origin?
Measuring the length and width of these blood drops and using trigonometry allows us to determine an approximate point of origin. Strings can be placed over blood drops along the axes of the stains at the calculated impact angles, and a resulting point of origin can be visualized in three dimensions
How do you calculate the angle of impact?
width of the bloodstain in mm/the length of the bloodstain in mm then take the inverse sin of that
What is a circular blood splatter called?
Passive drops (circular) means its passive results from one standing acting passive, means falling 90 degrees angle to the floor drops with secondary satellites
What does a lot of blood look like a sprinkler called?
Arterial gushes (a lot of blood, looks like a sprinkler follows heart beat rhythm)
What does a blood splatter with a tail called?
Splashes (anything with a tail and it can be from someone walking with a bloody nose)
What do blood splashes show?
Help to show the position of the victim (tails show the direction of motion)
What do smears show?
Bleeding victim touching walls or furniture (ex. bloody handprint smeared)
What do blood trails show?
Victim was moving from one place to another (see blood in a linear motion)
What do blood pools show?
The victim bleeds heavily (looks like a pool)
What are transfer patterns?
Part of smears; occur when a wet bloody surface contacts a second unstained surface creating a recognizable mirror image or at least a recognizable portion of the original surface
What is a swipe pattern?
The transfer of blood onto a surface not already contaminated with blood. One side is usually feathered which indicates the direction of travel eg. hair swipe
What is a wipe pattern?
Created when an object moves through the blood that has not completely dried or moves, removes, or otherwise alters it
What is arterial spurting?
- Occurs when an artery is damaged and the blood spurts or gushes from the wound in large-volume pulses. It continues spurting as long as the heart continues beating
- Large drops striking a vertical surface decelerate from air resistance and produce a pattern without spines. The drops strike the surface and then characteristically drip or run down due to their large volume
What does a cutting in the artery represent?
- Spurting blood
- Pulsating blood
- Bright red colour
What does a cutting in the veins represent?
- Steady, slow flow
- Dark red colour
What does a cutting in the capillaries show?
- Slow, even flow
The higher the energy, the greater the division and how does the splatter look?
Finer the splatter
The lower the energy, the less the division and how does the splatter look?
Larger the splatter
What does cast-off blood splatter look like?
Blood is cast off the weapon… the movement and the number of swings can often be documented by examining the cast-off pattern eg of weapons: hammers, bats, tools
- Will strike ceilings and walls at a 90-degree impact angle
- These drops will make a linear pattern
- The small drops will strike at increasing acute angles and become elongated
What is it called when cast-off blood splatter is interrupted?
Cessation cast off
Can you remove all traces of blood?
Even with the most thorough cleaning, blood leaves residue that is difficult to remove
What does luminol reveal?
Luminol powder mixed with hydrogen peroxide is able to detect hemoglobin left behind by blood spraying the area and if blood is present it will luminesce for about 30 seconds
Why can luminol be bad?
Because it destroys the blood so it cannot be tested later
What test turns pink when blood is detected?
Kastle-meyer test
For a blood sample to be presented in court it must…
- When possible deliver blood or stained object to the lab immediately
- If unable to deliver to a lab or if the object must be mailed, allow the stain to air-dry completely before packaging
- Blood that is in pools should be absorbed by a gauze pad as it dries it should be refrigerated or frozen ASAP
- Blood should be taken to the lab immediately, because delays past 48 hours may make the sample useless
- If not completely dry, label and roll in paper or place in a paper bag or box and seal and label it
- Place only one item in each container
- DO NOT use plastic containers
All mammals except lamas and camels have what kind of RBCs?
Circular un-nucleated
Animals that are not mammals (birds, fish, etc) have what kind of RBC?
Oval with a nucleus
What kind of test uses antibodies to react to human blood to tell if mammal blood is from human blood?
ELISA test (enzyme-linked immunosorbent assay); it is a test that detects and measures antibodies in your blood
CSI of blood steps…
- Conform the stain is blood
- Visualization with luminol and Kastle-Meyer test - Confirm the strain is human
- ELISA test is human, try to determine whose blood it is
- First determine the blood type
- Antibody test - If an individual info is needed, then do DNA analysis
What are presumptive tests (presume it is blood check to see if it is blood)?
Can establish the possibility that a specific bodily tissue or fluid is present
Ex. Luminol or Kastle Meyer
What are confirmatory tests (confirm to see if it is human blood)?
Can identify a specific biological material
Ex. ELISA test, RDIS Test for Human Blood, or ABA Card Hematrace, or the seeing if the RBCs are circular and unnucleated
What blood types can O+ donate to?
O+, A+, B+, AB+
What blood types can O+ receive from?
O+, O-
What blood types can O- donate to?
All types (universal donor)
What blood types can O- receive from?
O-
What blood types can A+ donate to?
A+, AB+
What blood types can A+ receive from?
A-, A+, O+, O-
What blood types can A- donate to?
A+, A-, AB+, AB-
What blood types can A- receive from?
A-, O-
What blood types can B+ donate to?
B+, AB+
What can B+ receive from?
O+, O-, B+, B-
Who can B- donate to?
B-, B+, AB-, AB+
Who can B- receive from?
B-, O-
Who can AB+ donate to?
AB+
Who can AB+ receive from?
All types
Who can AB- donate to?
AB-, AB+
Who can AB- receive from?
AB-, O-, A-, B-
