Serology and Blood Flashcards

Questions and Answers

What is serology?

The study of bodily fluids left at a crime scene.

What's the difference between a presumptive and confirmatory test?

Presumptive tests establish if a substance is present; confirmatory tests identify the substance.

Name the components of blood.

Plasma, erythrocytes, leukocytes, hemoglobin.

What are leukocytes and what do they do?

They are white blood cells that fight infection. Signup and view all the answers

What is a blood group?

A class of antigens that determine compatibility in transfusion. Signup and view all the answers

List three presumptive tests for blood.

Leuchomalachite green, Bendizine, Phenolphthalein. Signup and view all the answers

What's luminol?

Luminol is used for seeing blood under black light. Signup and view all the answers

What does the precipitin test determine?

It determines if something is human blood or animal blood. Signup and view all the answers

What is the most common presumptive test for semen?

Brentamine fast Blue B. Signup and view all the answers

How long can motile sperm survive in the vagina?

About 3 hours, possibly ranging from 1 to 8 hours. Signup and view all the answers

Name the presumptive test for saliva.

Phadebas to detect amylase. Signup and view all the answers

What's the difference between a wipe and a swipe?

A wipe is when an object moves through a pre-existing stain; a swipe is the transfer of blood onto a target. Signup and view all the answers

What is a cast-off stain?

Cast-off stains are the result of blood being flung or projected from a bloody object in motion. Signup and view all the answers

How is point-of-origin determined?

By seeing how many paths converge at one point. Signup and view all the answers

Is there a presumptive test for urine?

True Signup and view all the answers

What is the angle of impact?

The acute angle created by the intercept of the target with the droplet's vector. Signup and view all the answers

What is the difference between forward and backward splatter?

Forward splatter is when blood droplets are projected away from the impact item; backward splatter is when droplets are projected toward it. Signup and view all the answers

What is acid phosphatase?

A common enzyme that occurs at a high level in semen. Signup and view all the answers

What are lymphocytes?

They are white blood cells produced in the bone marrow and thymus gland. Signup and view all the answers

What is blood?

Blood is a tissue composed of several types of cells in a matrix called plasma. Signup and view all the answers

What is genome?

The genetic makeup of an individual. Signup and view all the answers

What are platelets?

Fragments of cells involved in the clotting process. Signup and view all the answers

Who discovered human blood groups?

Karl Landsteiner. Signup and view all the answers

What is semen?

A complex gelatinous mixture produced by post-pubescent males. Signup and view all the answers

What is saliva?

Saliva can be evidence in a number of crimes. Signup and view all the answers

What is urine?

The excreted fluid and waste products filtered by the kidneys. Signup and view all the answers

What is bloodstain pattern analysis?

BPA is the analysis of bloodstains at a crime scene to reconstruct events. Signup and view all the answers

What are passive bloodstains?

Clots, drops, flows, pooling. Signup and view all the answers

What are transfer bloodstains?

Wipes, swipes, pattern transfers, and general contact bloodstains. Signup and view all the answers

What are projected/impact bloodstains?

Splatters, splashes, cast-off stains, and arterial spurts. Signup and view all the answers

What is splatter?

A stain that results from blood hitting a target. Signup and view all the answers

What are fly spots?

When a fly lands in blood and lands elsewhere. Signup and view all the answers

What are skeletonized stains?

Stains that retain the size and shape of the original stain. Signup and view all the answers

What is point of origin?

Where the blood splatters originate from. Signup and view all the answers

Study Notes

Serology and Blood Overview

Serology studies bodily fluids collected at crime scenes, providing crucial evidence for investigations.
Blood is a tissue comprising various cells suspended in plasma, about 90% water and 10% other substances.

Blood Testing Techniques

Presumptive tests indicate the presence of a substance but lack specificity; examples include Leuchomalachite green, Bendizine, and Phenolphthalein.
Confirmatory tests definitively identify substances, distinguishing them with accuracy.
Common tests for blood include Luminol, which reacts with blood under black light to make it visible.
The precipitin test differentiates between human and animal blood.

Components of Blood

Erythrocytes (red blood cells) transport oxygen throughout the body.
Leukocytes (white blood cells) are vital for immune defense against infections.
Hemoglobin is the protein responsible for oxygen transport within erythrocytes.
Platelets are cell fragments essential for blood clotting.

Blood Types and Groups

Blood is classified into groups based on the presence of specific antigens; types include A, B, AB, and O, with O being the universal donor.
Karl Landsteiner discovered human blood groups, enhancing transfusion safety.

Semen and Saliva Analysis

Brentamine Fast Blue B is the most common presumptive test for semen presence.
Saliva can serve as evidence in various crimes, although detection can be challenging; Phadebas tests for amylase in saliva.

Evoking Blood Patterns

Bloodstain pattern analysis (BPA) reconstructs events at a crime scene through the study of bloodstain dispersion, shape, and number.
Passive bloodstains are caused by gravity, including drops and pools.
Transfer bloodstains result from contact between a blood-stained object and another surface, including wipes and swipes.
Projected bloodstains occur due to force, producing splatters or spurts.

Bloodstain Characteristics

Cast-off stains result from blood flinging off a moving object.
The angle of impact refers to the angle at which blood strikes a surface, influencing stain shape.
Forward splatter occurs when blood is projected away from the impact site, while backward splatter returns toward it, often being smaller in size.
Skeletonized stains indicate the aging of a stain, preserving its original shape and size.

Unique Biological Entities

Lymphocytes are white blood cells generated in the bone marrow and thymus, playing a significant role in immune response.
Acid phosphatase is an enzyme present in semen, helpful in forensic analysis.
The genome consists of the complete genetic material of an individual.

Urine Testing

Urine can be presumptively tested for urea or creatine, indicative of its presence as waste filtered by the kidneys.

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Description

Test your knowledge on serology and blood components with these flashcards. Learn the definitions, differences between test types, and key components of blood. Perfect for students or anyone interested in forensic science.