Podcast Beta
Questions and Answers
What percentage of blood volume is composed of plasma?
What is the primary function of red blood cells (RBC)?
At what percentage of blood loss is irreversible shock (death) likely to occur?
What is the role of platelets in the blood?
Signup and view all the answers
What percentage of total body weight does blood constitute?
Signup and view all the answers
What component of blood is primarily responsible for transporting oxygen?
Signup and view all the answers
Which condition leads to blood clotting?
Signup and view all the answers
What is the primary component of the blood's liquid portion?
Signup and view all the answers
What blood type is characterized by mixed ancestry and a combination of type A and type B?
Signup and view all the answers
What does a blue coloration in the Benzidine test indicate?
Signup and view all the answers
Which test is sensitive to very old blood stains and yields a blue coloration?
Signup and view all the answers
In the Kastle-Meyer test, which substance is initially added to the blood stain?
Signup and view all the answers
What is the role of hydrogen peroxide in the Kastle-Meyer test?
Signup and view all the answers
Which of the following statements about the Van Deen’s test is true?
Signup and view all the answers
What does a violet color in the Kastle-Meyer test imply?
Signup and view all the answers
What is the main disadvantage of the Guaiacum test?
Signup and view all the answers
What is the main purpose of a Hemastix test strip?
Signup and view all the answers
What color results from the luminol test when blood is present?
Signup and view all the answers
Which test is characterized by the formation of malachite green?
Signup and view all the answers
What type of crystals are produced in the Takayama test?
Signup and view all the answers
Which test is considered not very sensitive for blood detection?
Signup and view all the answers
What reagent is used in the Hemin crystal test?
Signup and view all the answers
What is a common characteristic of the acetone-Haemin or Wagenhaar test?
Signup and view all the answers
Which test includes the use of a spray reagent for blood detection?
Signup and view all the answers
What is the quantity of semen typically present in a single ejaculation?
Signup and view all the answers
Which method of examination can detect the presence of seminal stains under ultraviolet light?
Signup and view all the answers
What is a limitation of the Florence test for examining semen?
Signup and view all the answers
What characterizes semen when it is first collected?
Signup and view all the answers
What effect does enzyme action have on semen after exposure?
Signup and view all the answers
What crystal shape is associated with the Barberios test?
Signup and view all the answers
To maintain the integrity of evidence, how should clothing with stains be stored?
Signup and view all the answers
In assessing sperm diseases, which terms refer to a lack of sperm production?
Signup and view all the answers
What are the three subfields of forensic entomology?
Signup and view all the answers
Which type of forensic entomology deals with pest infestations that may lead to litigation between landlords and tenants?
Signup and view all the answers
How can stored-product forensic entomology be defined?
Signup and view all the answers
What is the role of medico-legal forensic entomology?
Signup and view all the answers
What significant contribution to forensic entomology is attributed to Sung Tz’u?
Signup and view all the answers
In forensic investigations, which insects are specifically mentioned as being necrophagous?
Signup and view all the answers
What information can forensic entomology provide in murder investigations?
Signup and view all the answers
What method did Sung Tz’u use to solve the murder case he documented?
Signup and view all the answers
Study Notes
Nature of Blood
- Blood is a specialized circulating tissue made of cells, enzymes, proteins, and inorganic substances in a fluid medium.
- Blood volume constitutes about 8% of body weight: approximately 5-6 liters in males and 4-5 liters in females.
- Blood components include:
- Plasma (55%): the fluid portion mainly composed of water, enzymes, and glucose.
- Cells (45%): consist of red blood cells (RBC), white blood cells (WBC), and platelets.
- RBCs: transport respiratory gases; contain hemoglobin, giving blood its red color.
- WBCs: responsible for immune defense against diseases.
- Platelets: cell fragments crucial for blood clotting.
- Loss of 40% blood volume can lead to irreversible shock; 1.5 liters loss causes incapacitation.
- Clotting occurs when fibrin in plasma traps red blood cells, forming a solid clot separating serum.
- Blood type AB indicates mixed ancestry, consisting of A and B types.
Presumptive Tests for Blood
- Benzidine Test: Blue coloration indicates the presence of peroxidase enzyme in blood.
- Kastle-Meyer Test: Involves ethanol and phenolphthalein; violet color results from alcohol solvent reacting with hemoglobin.
- Guaiacum Test: Detects blood through blue coloration; less effective on older stains.
- Hemastix: Test strips become color bands when in contact with blood.
- Luminol Test: Produces bright blue color under UV light, indicating blood presence.
- Leucomalachite Green Test: Oxidation gives peacock blue color; less sensitive than benzidine test.
Microcrystalline Tests
- Teichmann Test: Evaporation of salt and acetic acid yields reddish-brown hemin crystals.
- Takayama Test: Addition of Takayama reagent results in large rhombic crystals with salmon color.
- Acetone-Haemin Test: Formation of small dark dichroic crystals.
Confirmatory Tests for Blood
- Stains on clothing should be air-dried, avoiding sunlight, and wrapped in paper for preservation.
- Soil exhibits the same care as other samples; store in glass containers or new paint cans, maintaining chain of custody.
Forensic Characterization of Semen
- Semen is viscous and gelatinous, becoming more liquid over time due to enzymes.
- Normal ejaculation volume ranges 1.5 to 3.5 ml, containing spermatozoa, epithelial cells, choline, and lecithin; slightly alkaline.
- The healthy male produces approximately 400 to 500 million sperm per ejaculation.
- Sperm conditions include aspermia (absence of sperm) and oligospermia (low sperm count).
Examination of Semen and Seminal Stains
-
Physical Examination:
- Microscopic examination stains sperm cells for observation under high power.
- Ultraviolet examination reveals bright bluish fluorescence in seminal stains.
-
Chemical Examination:
- Florence Test: Tests for choline by forming dark brown rhombic crystals; limited by specimen handling and blood contamination.
- Barberios Test: Identifies spermine picrate via slender yellow rhombic needles.
Forensic Entomology
- Medico-legal forensic entomology involves insects in crime investigations, including murder, suicide, and physical abuse.
- It assesses insect activity on bodies to estimate time of death (postmortem interval) and location.
History of Forensic Entomology
- Sung Tz’u (1235 AD): Early death investigator noted for using insect behavior to solve a murder case.
- The case described involved flies being attracted to sickles, leading to a confession.
- Importance of necrophagous insects in determining crime scene details was highlighted.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Explore the essential components of blood, including its volume, composition, and the critical role of blood cells in the body. This quiz also covers key presumptive tests used to detect blood, highlighting their importance in forensic science. Test your knowledge on these crucial topics in biology and medicine!
