Body Fluids: Types and Examples

Study Notes

Definition: Body fluids are liquids originating from inside the bodies of living humans, including fluids secreted or excreted from the body.
Examples: Bile, blood serum, breast milk, gastric juice, mucus, saliva, sebum, semen, sweat, tears, vomit, and urine.

Secreted fluids: Produced by cells, glands, or organs, including hormones, stomach acid, and bile.
Excreted fluids: Produced to remove waste from the body, including fecal matter, urine, tears, and sweat.

Body fluids can be found at crime scenes, including blood, semen, and saliva.
These fluids are considered biological evidence and can be used for identification and characterization through DNA analysis.

Definition: Blood is a red fluid that circulates in blood vessels, including veins and arteries.
Function: Blood acts as the body's transport system and plays a major role in defense against infection.
Composition: Blood consists of cells (red blood cells, white blood cells, and platelets) and plasma (liquid part of blood).

ABO Blood Types:
- A (A antigen, anti-B antibody)
- B (B antigen, anti-A antibody)
- AB (A and B antigens, no antibody)
- O (no antigen, anti-A and anti-B antibodies)
Rh Factor:
- Rh positive (has D antigen on red blood cells)
- Rh negative (does not have D antigen on red blood cells)

Definition: Saliva is a clear liquid produced in the mouth for lubrication and digestion.
Composition: Water, enzymes, electrolytes, mucus, and epithelial cells.
Significance: Saliva can be used for DNA profiling and detecting drugs and toxins.

Definition: Semen is the fluid expelled during male ejaculation, carrying sperm cells.
Significance: Semen is important for DNA profiling and linking suspects to crime scenes.
Detection: Acid phosphatase test is used to detect semen, and ultraviolet light can visualize latent evidence.### Biological Evidence
Acid phosphatase is present in semen, but also in other bodily fluids, making it a presumptive test for semen.
Prostate-Specific Antigen (PSA or P30) is a glycoprotein produced in the prostate gland, useful in detecting semen, but also found in urine, making it a presumptive test.

Microscopic detection of sperm is a more confirmatory method, allowing for the viewing of sperm cells and proving their presence.
Fresh and well-preserved samples are preferred, as older samples may have undergone decomposition.

Blood evidence is valuable in crimes such as murder, rape, and assault.
Blood evidence can aid in investigations by locating the crime scene, identifying the weapon used, and eliminating suspects.
DNA profiling can be performed on any biological substance.

Analysis is necessary to determine if a stain is blood, as its appearance varies greatly depending on age, weather, and other factors.
Species origin must be determined, usually to distinguish between human and non-human blood.
Further classification involves isoenzyme and DNA analysis.
DNA typing can determine the sex of the person from whom the sample originated.

Private laboratories are used for DNA analysis in cases requiring paternity determination.
DNA analysis is limited to three or four samples per case: victim's blood, suspect's blood, and one or two questioned samples.

Seminal stains can be identified by testing for prostatic acid phosphatase, spermatozoa, or P-30 protein, and further identified by DNA typing.
Saliva stains can be identified by the presence of amylase and further identified by DNA typing.
Urine can be identified by the presence of creatinine and urea, but cannot be typed.
Skin tissue can be DNA typed.

Forensic biologists, biochemists, and technicians work in laboratories and police forces to analyze biological evidence.
Some institutions have forensic serologists who specialize in the study of body fluids.