Blood

Question 1

What are the components of blood? What is their purpose?

Answer 1

Serum (liquid) + Solid
Red blood cells: no DNA (has no nucleus)
White blood cells: , fight infections
Platelets: coagulation, stopping bleeding

Question 2

If a pool of red liquid is found on site, what is the procedure?

Answer 2

1. Test for blood
   Preliminary tests:
   * Luminol
   * hydrogen peroxide
   * Benzidine (Alder Test)
   * Kastle Meyer Test
   * Malachite Green Test
2. Precipitin Test

Question 3

What is a Precipitin Test?

Answer 3

Sample of blood is mixed with rabbit serum. Serum has sntibodies against huamn blood.
If blood reacts and antibodies are present, the blood is human (cloud layer on top of solution)

Question 4

What are Antigens? Define

Answer 4

Antigens - react with antibodies (secreated by WBC), molecules/cells attached to RBC
Blood type is determined by what antigen is on the RBC (ex. Ant. B = Type B | O has no antigens, AB has both)

Question 5

What are antibodies? define

Answer 5

Antibodies - proteins secreated by WBC, attach to antigens to detroy them
Antibodies are opposite of Blood type (ex. Antg. A –> Type B | O has both and AB has none)

Question 6

What determines pos. or neg. types?

Answer 6

Antigen D - if present, type is positive |if absent, type is negative

Question 7

What happens if the wrong blood is given?

Answer 7

Agglutination - clumping of RBC, leads to thick/unmoving blood (can lead to blocked arteries)

Question 8

What is BPA?

Answer 8

Blood Spatter Analysis - Looks at velocity, height, and angle of impact of blood

Question 9

What are the different kinds of Impact?

Answer 9

• Low velocity - 9.8 m/s2, perpendicular drops of blood, circular pattern (higher the height, larger the circle)
• Medium Velocity - gravity plus a force (ex. A punch to the nose), elliptical shape w/ or w/out a tail pointing away from the source of the bleeding
• High Velocity - Gunshot, sneezing, explosions | look like mist or fog, takes on a shape that comes outward from point of origin

Question 10

Point of Origin & Area of Convergence

Answer 10

Need width & length of at least 2 splatter stains (without tail) → divide length by width, will give you the angle of impact of splatter

AOC - gives insight on size of the body/person

Question 11

What is WIpe and Swipe

Answer 11

Wipe - surface already has blood
Swipe - surface is clean and blood is transferred to it

Question 12

What is Cast-off?

Answer 12

Dont come from bleeding source, comed from object in contact with something that’s bleeding (secondary)
*Ex. a bat hitting blood, being swung and spreading it onto the ceiling

Question 13

What is Back Spatter

Answer 13

Exit hole, blood shoots out in cone from the body (where the bullet entered is smaller)
Sheperd Case - Kert (biochemist)