FSCI 371 Serology

Composition of Blood

• An adult typically has 5 to 6 liters of blood, which is 7-8% of their total body weight.
• Blood transports oxygen from the lungs to tissues and carries waste products, such as CO2.
• Waste products like urea and uric acid, which are produced during metabolism, are transported by blood to the kidneys.
• Hormones, which regulate body functions, are special chemicals transported in blood.
• Blood, with a specific gravity of 1.06, is slightly heavier than water.

Blood Makeup

• Plasma accounts for 55% of blood's composition.
• Suspended solids account for 45% of blood’s composition.
• Red blood cells (erythrocytes) are a suspended solid in the blood
• White blood cells (leukocytes) are a suspended solid in the blood
• Platelets re a suspended solid in the blood

Hematopoiesis

• Hematopoiesis is blood development and production.

Blood Creation

• Ten stem cells can develop into blood cells.
• 30 trillion red blood cells are synthesized.
• 30 billion white blood cells are created.
• 1.2 trillion platelets are created.
• Blood is made in 4 weeks.
• There is enough blood made to replace every blood cell in the body.

Plasma

• Plasma is a clear, yellowish fluid.
• 95% of plasma is water.
• Plasma also contains nutrients such as glucose, fats, proteins, and amino acids needed for protein synthesis, vitamins, and minerals.
• The salt level of plasma is about equal to that of seawater.
• The kidneys maintain the salt concentration in plasma.
• Extreme conditions, such as imbalances in salt concentration, can cause seizures, coma, or death.
• Plasma can temporarily develop a milky color when a person eats a fatty meal.

Hemoglobin

• Hemoglobin is about 35% of the red blood cell weight.
• Red blood cells must contain adequate hemoglobin to combine properly with oxygen.
• Iron is needed for hemoglobin formation.
• Hemoglobin is an iron-protein compound in red blood cells which, gives blood its red color.
• Hemoglobin is present in almost all animals.
• Venous blood has low oxygen and a dark red color.
• About 2.5 million red blood cells are produced every second.
• About 2.5 million red blood cells are destroyed per second.
• A RBC will travel about 250 miles within blood vessels during its 120-day lifespan.
• Tissues have a lower pH compared to lungs, hence CO2 + H2O > HCO3 + H.
• The Bohr effect is the effect of pH on oxygen dissociation in hemoglobin.
• Low pH causes the heme to release O2 and pick up HCO3.
• Carbon Monoxide (CO) is 100 times more attracted to hemoglobin than O2 or CO2.

Red Blood Cells

• Red blood cells make up 45% of blood volume.
• The biconcave shape of the erythrocyte is an adaptation for maximizing the surface area and penetrating the smallest of capillaries.
• Spleen and sometimes the liver provide removal of red blood cells.
• Red blood cells recycle proteins and iron.
• There is poor gastrointestinal uptake of iron.
• A red blood cell has a normal lifespan 100-120 days.

Cardiac Information

• The coronary arteries encircle the heart muscle to provide a constant supply of oxygen and nutrients to the heart.
• On average, the heart beats 2.5 billion times in a lifetime.
• Atherosclerosis is when plaques consist principally of fat and cholesterol deposits containing blood platelets, decomposing muscle cells, and other tissues.
• The Jarvik-7 artificial heart was used in the 1980s, it lasted for up to 620 days, but caused many serious medical complications.

White Blood Cells

• White blood cells are leukocytes.
• Leukocytes have a nucleus that are the source of DNA testing.
• Most leukocytes have a lifespan of 18-36 hours.
• A drop of blood can contain 7,000 -25,000 white blood cells.
• Some white blood cells sustain immunological memory.
• Memory cells last years to decades.
• Lymphocytes produce and secrete antibodies.
• Neutrophils may develop into macrophages and eat foreign items such as bacteria through- phagocytosis.
• Immature white blood cells are called bands or stab cells.
• Some T lymphocytes directly destroy invading organisms.
• Other T lymphocytes regulate the immune system by directing immune responses.
• Monocytes travel about the body eating stuff that has been identified as being foreign are phagocytes
• Eosinophils and basophils increase in response to allergic reactions and parasitic infection.
• Eosinophiles are involved in killing parasites, such tape worms.

HIV

• HIV stands for Human Immunodeficiency Virus.
• Being HIV-positive is not the same as having AIDS.
• Many people can be HIV-positive but don't get sick for many years.
• HIV slowly wears down the immune system, viruses, parasites, fungi and bacteria can make individuals very sick when the immune system is damaged.
• When the immune system is damaged it causes "opportunistic infections."

Blood Clotting

• Fibrin, a protein, traps and enmeshes the red blood cells to cause clotting.
• The liver produces fibrinogen.
• Serum is a pale yellowish liquid left behind when clotted substances are removed.
• Serum = Plasma - Clotting Factors

Thrombocytes, or Platelets

• Thrombocytes, or Platelets, are the smallest cellular component of blood.
• Thrombocytes circulate inactivated, about 250,000 per cubic mm of blood.
• Platelets come into contact with a damaged blood vessel.
• Platelets form a clump, adhering to each other and to the blood vessel wall.
• Constant minor bleeding occurs daily.
• Calcium, Vitamin K and Fibrinogen help blood clot.
• Blood clotting begins within seconds of injury when blood is exposed to air.
• An internal clot is a bruise - ecchymosis.
• Aspirin causes effects that influence clotting.

Sickle-Cell Anemia

• The curved, crescent-shaped blood cells indicates the presence of sickle-cell anemia.
• 72,000 people in the United States, primarily African Americans are affected by the disease.
• Sickle-cell anemia is caused by a defective gene.
• Sickle-cell is in many nationalities, including African Americans, Arabs, Greeks, Italians, Latin Americans, and those from India.
• Sickle cell trait is a person who carries one sickle hemoglobin-producing gene inherited from their parents and one normal hemoglobin gene.
• The hemoglobin is called S and found on the hemoglobin electrophoresis as hemoglobin AS.
• The condition will not cause sickle cell disease and occurs when the misshapen, or sickled, cells cannot pass smoothly through tiny blood vessels, it results in blockages which, cause intense pain and serious deficiencies of oxygen and nutrients.

Malaria

• Malaria spreads to humans when bitten by a malaria-infected mosquito.
• Tthe malaria parasite must grow in the mosquito for about a week before a host is infected.
• Parasites then travel to the person's liver, enter the liver's cells, grow and multiply.
• The distribution of malaria and sickle cell anemia overlap in areas of Africa, southern Asia, and the Mediterranean.
• HbS allele persists because heterozygous individuals are resistant to malaria.
• Leukemia (or cancer of the blood) occurs when blood cell precursors become abnormal and divide in an uncontrolled manner.

Blood Typing

• Karl Landsteiner discovered blood typing in 1901.
• In 1930, Landsteiner won a Nobel Prize for his work in blood types.
• Landsteiner developed the A-B-O system.
• Landsteiner, Levine, and others also discovered the Rh factor in blood in 1937.
• Karl Landsteiner discovery saved lives by insuring safe blood transfusions

Forensic Blood Identification

• Red blood cells have millions of characteristic chemical structures on their surface called antigens.
• Blood serum contains proteins called antibodies.

Serology

• Serology is a range of laboratory tests using antigens and antibodies.

Red Blood Cells

• The antigen systems on Red Blood Cells are A-B-O and Rh factor.

Antibodies

• Bodies make antibodies to protect from "foreign" molecular species.

Blood Types

• If blood type A is transfused into a person with B type blood, anti-A antibodies in the recipient will destroy the transfused A red cells.
• Blood types O and AB are called universal donors and universal recipients, respectively.

Rh Factor

• Also called the “Rhesus System”
• The Rh blood group system is one of the most polymorphic and immunogenic systems known in humans
• Has over 45 antigens
• Discovered in 1940 after work on Rhesus monkeys.
• RH gene located on short arm of chromosome 1.
• The Rh system is based on the Rh factor or D antigen.
• A person whose RBCs have the D antigen is said to be Rh positive.
• A person whose RBCs do not have the D antigen is said to be Rh negative.
• Rh factor becomes important only during pregnancy If a is carrying an Rh positive fetus when the mother is Rh negative.
• The mother will then become exposed to the Rh positive blood of her first baby prompting the mother's immune system to build up antibodies to fight the foreign blood protein.

How Accurate Is A Paternity Test

• Paternity testing will definitively exclude a non father.

Forensic Analysis of Bloodstains

• Steps include determining whether or not it is blood, species identification, and association with an individual
• Kastle-Meyer color test for identifying a stain as blood, hemoglobin acts like a peroxidase
• Hemastix® is another test for the presence of blood
• Luminol test can identify blood.

Blood Spattering

• Blood spattering can be found at most violent crime scenes.
• Its interpretation is a multi-disciplined process involving biology, physics and mathematics. Blood Spatter analysis can assist in determining the origin of the blood stains/spatter.
• Determine position of victim at time of blows.
• Infer the number of blows struck.
• Determine direction of deposit.
• Determine manner of deposition (drip, blunt force trauma and gun shot wounds).
• Establish direction of travel after injury.
• To analyze blood spattering, you ask the question "Is it blood?", "From what species did the blood come from?", and "If the blood is of human origin, how closely can it be associated to a particular individual?"

Blood Drop Properties

• Before a drop of blood can fall, it needs to be absent from any other form of applied energy.
• Gravitational attraction acting on blood must exceed its surface tension.
• Blood drops adopt an essentially spherical shape in flight.
• Standard drop size is 50ul (0.05ml).
• Rapid bleeding gives slightly larger drop.
• Shaking or movement casts off smaller drops.
• A single drop of blood formed by the force of gravity alone has a volume of 0.05 mL (cc).
• Drops formed by forces greater than gravity will have a volume that is inversely proportional to the force by which they are formed; the greater the force, the smaller the drops.
• Drops in flight pulled by the force of gravity accelerate the drops 32 feet/second/second.
• Drops accelerated by gravity will reach their terminal velocity when wind resistance prevents further acceleration.
• The terminal velocity of a 0.05 mL drop of blood is 25 feet/second plus or minus 0.5 foot/second
• Single drops of blood falling from fingertip onto smooth cardboard from various heights will not change in diameter beyond drops falling from 7 ft.
• Wave Cast-off is used during blood pattern analysis. The tail of elongated stain.
• A drip pattern has free-falling drops dripping into wet blood, a large irregular central stain, and small round & oval satellite stains.
• Different results occur on smooth and rough surfaces including Spreads out smoothly on the former and ST (Surface Tension) of spreading edge is broken by irregular surface on the latter.

Blood Spatter: Angle of Impact

• Measure height above point of convergence.
• Determine length and width.
• Determine Angle of impact = arc sin W/L

Blood and Injury Speeds

• Low velocity has speeds up to 5 f/s
• Includes free-falling drops and when blood is cast off from a weapon
• Medium velocity has speeds of 25-100 f/s and spot diameter: mostly 1 - 4 mm
• This is from blows inflicted with a weapon
• High velocity has speeds greater than100 f/s
• Fine mist with spot size is < 0.1 mm from gunshot and high-speed machinery

Blood in flight:

• When a bloody object is swung, centrifugal force throws blood.
• Cast-off blood will make a track of blood drops and this defines the arc of the swing.
• Back spatter of atomized blood can be observed, which will carry the droplets up range in the direction of the direction of the shooter.
• When blood is projected upward with sufficient force to strike a ceiling, this is mostly caused from a gunshot that had an upward trajectory.
• Direction indicates suicide rather than homicide.
• Flow Patterns are the result of horizontally or vertically moving liquid in a manner that is often alters with the contours of the impacted surface and mostly ends up becoming a pool of blood