Physiology (Forensic Science)
The study of physiology begins with the cell, the fundamental unit that makes up living things. Groups of similar cells form tissues, and groups of tissues form organs. The organs combine into systems that make up higher-level living organisms. Some of the systems in the human body of particular interest to forensic scientists are the cardiovascular, nervous, digestive, and respiratory systems.
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Human Physiology (Forensic Science)
The functions of the human body can contribute invaluable information that investigators can use in solving crimes. Human physiology plays a major role, for example, in determination of cause of death, DNA (deoxyribonucleic acid) analysis, blood spatter analysis, polygraph testing, and the effects of drug and alcohol consumption.
When a person dies, the physiological processes cease, and the cessation of these processes can provide valuable information about the time and cause of death. In an autopsy, a forensic pathologist completes a thorough investigation of the external and internal parts of the body. This investigation includes the evaluation of any wounds, the contents of the digestive system, and any residues on the body, such as gunpowder. Hair and nail samples are also analyzed, and toxicology tests are performed on the blood.
DNA stores a cell’s information and directs its activities. A portion of the DNA molecule contains a code that directs its activities, and a portion of the molecule contains a unique code for each person. The primary use for DNA in forensics is thus the identification of persons. DNA can be used to identify crime victims or the perpetrators of crimes. By analyzing skin, blood, semen, or other body tissues collected from a victim’s body, investigators may be able to make connections to suspects. DNA analysis has proven to be a valuable technique in solving crimes.
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Physiology of Other Organisms (Forensic Science)
Forensic evidence is sometimes provided by nonhuman organisms such as plants, insects, and microbes. Because plants produce pollen and seeds and are fixed in their particular geographic locations, evidence of plant life can be used to connect possible suspects to crime scenes. For example, at a crime scene where specific plants are present, the perpetrator may unknowingly carry away seeds or pollen from those plants on body, shoes, or clothing; by analyzing such evidence, investigators can connect the person to the crime scene.
Insects can provide forensic evidence through experts’ analysis of insect bite marks and waste products found on the bodies of crime victims or suspects. In addition, the types of insects found on human remains, as well as the activity patterns of those insects, can help determine the time and location of death. Some kinds of insect activity are also used in the determination of neglect and abuse in children and the elderly. The types of insects found splattered on vehicle windshields and radiator grills can provide information about where the vehicles have traveled.
Microbes—that is, microscopic organisms—can provide information about the origins of infections. Forensic scientists may also examine microbes and their DNA in cases of biological crimes, such as mailings of the spores that cause anthrax. By comparing the DNA of microbes used in a crime with the DNA of any such...
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Further Reading (Forensic Science)
Breeze, Roger G., Bruce Budowle, and Steven E. Schutzer, eds. Microbial Forensics. Burlington, Mass.: Elsevier Academic Press, 2005. Reviews the relationships between microbe physiology and forensics.
Coyle, Heather Miller, ed. Forensic Botany: Principles and Applications to Criminal Casework. Boca Raton, Fla.: CRC Press, 2005. Contains information on plant physiology and its relationship to forensic science.
James, Stuart H., and Jon J. Nordby, eds. Forensic Science: An Introduction to Scientific and Investigative Techniques. 2d ed. Boca Raton, Fla.: CRC Press, 2005. Provides an overview of forensic science procedures, many of which are based on physiology.
Mozayani, Ashraf, and Carla Noziglia, eds. The Forensic Laboratory Handbook: Procedures and Practice. Totowa, N.J.: Humana Press, 2006. Covers most of the procedures based on physiology that are used in forensic laboratories.
Mozayani, Ashraf, and Lionel P. Raymon, eds. Handbook of Drug Interactions: A Clinical and Forensic Guide. Totowa, N.J.: Humana Press, 2004. Evaluates various drugs and describes their physiological effects on the body.
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The Fundamentals of Physiology (Magill’s Medical Guide, Sixth Edition)
Physiology is a branch of science that applies to all living things. The goal of the physiologist is to understand the mechanisms leading to the proper functioning of organisms such as bacteria, plants, animals, and humans. Physiology is an important aspect of many of the medical sciences. In immunology, researchers seek to understand the functioning of the immune system. Cardiovascular scientists study the workings of the heart. Knowledge of the normal physiologic functioning of an organism is important in identifying the diseases that cause a deviation from the normal state.
Essential to the discovery of new data is the application of the scientific method of research. The first step in this method is observation. This involves examining a particular system or organism of interest, such as the transport of nutrients in a plant stem or the flow of air into the lungs of an animal, and initially observing a specific event or phenomenon. Asking why and how the event occurs leads to the next step—forming a hypothesis, or scientific question. A hypothesis is a possible explanation of the observation, which can be tested further to see if it is true. Testing, or experimentation, is the third step in the scientific method. The experiment involves setting up a controlled situation that directly tests the hypothesis in order to determine the cause-and-effect relationship between the hypothesis and the initial...
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Homeostasis and Feedback Systems (Magill’s Medical Guide, Sixth Edition)
Each of the aforementioned variables has an optimum physiologic range over which the body can function normally. The systems of the body work together in an attempt to keep the body’s internal environment within these normal ranges. This process is called homeostasis. Stress placed on the body—whether from the outside environment (heat, cold) or from within (disease, emotional reactions)—can lead to fluctuations in the internal environment. Significant deviations from the normal can lead to a state of disease in the body. To prevent these types of changes, the body has incorporated a number of control devices that are governed by the nervous and endocrine systems. The nervous system is constantly evaluating the state of the body and is able to detect when something is awry. When the body strays too far from its balanced condition, it responds in one of two ways. First, it may send nervous impulses to the proper organs that counteract the stress and return it toward its original state. Second, it may activate the endocrine system to release its chemical messengers or hormones that will bring the body back into balance.
The nervous and endocrine systems are also important components in the feedback systems that regulate the body’s internal environment. The two basic types of feedback systems are called negative feedback and positive feedback. Negative feedback is a homeostatic control mechanism that...
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Perspective and Prospects (Magill’s Medical Guide, Sixth Edition)
Physiology began more than two thousand years ago during the time of the ancient Greeks. The well-known philosopher Aristotle (384-322 b.c.e.) was also a physiologist who made biological observations and described the blood vessels as part of a system with the heart at its center. He also believed that the heart was a furnace that heated the blood and that it was the body’s seat of intellect. In the city of Alexandria, Herophilus (335-280 b.c.e.) believed that the seat of intellect was the brain, not the heart. He studied arteries and veins and determined that arteries have thicker walls. Erasistratus (310-240 b.c.e.) began his training under Herophilus. He believed that arteries served as air vessels and that the veins carried the blood, which was made in the liver from food. Several hundred years later, Galen (129-c. 199 c.e.) conducted an experiment that showed that blood, not air, flowed through arteries. Though some of his other ideas were later disproved, he left behind a considerable number of writings on physiology, medicine, and philosophy.
Galen’s ideas were taught for many hundreds of years until the Renaissance. During this time, physiologists made important discoveries and observations that challenged the findings of Galen. Andreas Vesalius (1514-1564) was trained as a doctor and became a professor of surgery and anatomy at a medical school in what is now Italy. Vesalius’s style of teaching was to...
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For Further Information: (Magill’s Medical Guide, Sixth Edition)
Fox, Stuart Ira. Human Physiology. 11th ed. Boston: McGraw-Hill, 2010. The author presents a simplified, yet highly accurate, account of human medical physiology that is profusely illustrated with color photographs, line drawings, and abundant tables. Applications of physiological principles are frequently highlighted. Appropriate for high school students and for the general public.
Ganong, William F. Review of Medical Physiology. 23d ed. New York: Lange Medical Books/McGraw-Hill Medical, 2009. The author attempts to detail the concepts of medical physiology in a succinct but coherent fashion. This book is designed to refresh the memory of the reader regarding specific details of physiology.
Guyton, Arthur C., and John E. Hall. Guyton and Hall Textbook of Medical Physiology. 12th ed. Philadelphia: Saunders/Elsevier, 2011. Guyton’s textbook has been the recognized authoritative work on medical physiology for several decades. Specific details of physiological systems are clearly described in understandable terms.
Prosser, C. Ladd, ed. Environmental and Metabolic Animal Physiology. 4th ed. New York: Wiley-Liss, 1991. The author approaches physiology by comparing how specific systems differ among various animal organisms such as humans, rodents, and fish. Much of the experimentation in physiology is initially done with animals and then applied to humans.
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Physiology (Encyclopedia of Science)
Physiology is the branch of biology that deals with the functions of living organisms and the parts of which they are made. This scientific discipline covers a wide variety of functions, ranging from the cellular and below to the interaction of organ systems that keep the most complex biological machines running.
Some of the questions that physiologists investigate include how plants grow, how bacteria divide, how food is processed in various organisms, and how thought processes occur in the brain. Investigations in physiology often lead to a better understanding of the origins of diseases.
History of physiology
Human (or mammalian) physiology is the oldest branch of this science. It dates back to at least 420 B.C. and the time of Hippocrates, the father of medicine. Modern physiology first appeared in the seventeenth century when scientific methods of observation and experimentation were used to study the movement of blood in the body. In 1929, American physiologist W. B. Cannon coined the term homeostasis to describe one of the most basic concerns of physiology: how the varied components of living things adjust to maintain a constant internal environment that makes possible optimal functioning.
A number of technological advances, ranging from the simple microscope to ultra-high-technology computerized scanning devices,...
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Physiology (World of Forensic Science)
Physiology is the study of how various biological components work independently and together to enable organisms, from animals to microbes, to function. This scientific discipline covers a wide variety of functions from the cellular and sub-cellular level to the interaction of organ systems that keep the complex biological machines of humans running.
Because a forensic examination involving an injury or death is often concerned with establishing cause, a forensic investigator will of necessity be concerned with physiology. By understanding the proper functioning of organs and organ systems, a forensic investigator is able to recognize abnormalities. Moreover, the nature of an abnormality can provide clues as to the nature of its cause.
For example, if a person experienced a rapid onset of paralysis prior to their death, the investigator might suspect the involvement of the toxin produced by the bacterium Clostridium botulinum. Appropriately, nervous tissue and blood would be examined for the presence of the toxin.
More generally, physiological studies are aimed at answering many other questions in addition to forensic questions. Physiologists investigate topics ranging from precise molecular studies of how food is digested to more general studies of how thought processes relate to electrical and biochemical patterns found in the brain (a branch of this discipline known as neurophysiology). It is often physiology-related investigations that uncover the origins of diseases.
While physiological studies are one of the cutting-edge tools in a forensic examination, the roots of the discipline date back to at least 420 B.C. and the time of Hippocrates. More refined physiological approaches first appeared in the seventeenth century when scientific methods of observation and experimentation were used to study blood movement, or circulation, in the body. In 1929, American physiologist W. B. Cannon coined the term homeostasis to describe how the varied components of living things adjust to maintain a constant internal environment conducive to optimal functioning. Proper physiology relies on homeostasis.
Homoestasis is an important aspect of forensic science. A specific disturbance to the body caused by, for example, a poison such as a toxin can have other effects (e.g., loss of muscle control, difficulty breathing, mental confusion) as the body is more generally affected.
Physiological studies have evolved from the first visual-based methods to now encompass a variety of analytical procedures. The use of analytical instruments such as the gas chromatograph, electrophoretic techniques that can detect and identify components such as toxins, the elemental analytical power of mass spectroscopy, and various other techniques have made forensic physiological determinations highly sensitive and specific.
SEE ALSO Analytical instrumentation; Blood; Death, mechanism of; Epilepsy; Hemorrhagic fevers and diseases; Immune system; Nervous system overview; Organs and organ systems.