Chapter 6—Body Systems
Introduction—Objectives
1. Discuss the structure and function of the circulatory system.
2. Evaluate the forensic implications of the circulatory system.
3. Discuss the structure and function of the respiratory system.
4. Evaluate the forensic implications of the respiratory system.
5. Discuss the structure and function of the muscular system.
6. Evaluate the forensic implications of the muscular system.
7. Identify body systems and discuss their forensic implications.
Introduction—Vocabulary

asphyxiation - a condition in which the amount of oxygen available
to the lungs decreases sharply while the level of other gases,
especially carbon monoxide, increases

erythrocyte - red blood cell

homeostasis - an organism’s relatively stable internal conditions

leukocyte - white blood cell

lividity - pooling of blood in the lowest portion of the body

platelets - cell fragments that help form blood clots at wound sites;
also called thrombocytes

rigor mortis - the stiffening of the skeletal muscles after death

suffocation - condition in which the amount of oxygen available to
the lungs is quickly diminished
Leann Fletcher

Michael Fletcher heard a gun shot and found his wife on the floor
in a pool of blood

Lividity showed time of death to be just over an hour

Gun shot wound indicated that gun was about 18 inches from
body
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publicly accessible website, in whole or in part.
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
Michael was arrested, charged, and convicted of second-degree
murder
Introduction

Anatomy—the study of the structure of the human body

Physiology—the study of the function of the body systems

Homeostasis—a stable internal environment
The Circulatory System (Obj 6.1, 6.2)

Systemic—the heart pumps oxygenated blood through arteries to
body cells

Pulmonary—the heart pumps the deoxygenated blood, carbon
dioxide and other wastes to the lungs
Properties of Blood

Red Blood Cells

White Blood Cells

Platelets

Plasma
Red Blood Cells

Also called erythrocytes

Carries oxygen throughout the body

Concave shape creates a large, efficient surface area

Hemoglobin—a protein that binds oxygen for transport
White Blood Cells

Also called leukocytes

Protects the body against infection and fight viruses and bacteria.
Platelets

Also called thrombocytes

Helps form blood clots that act as a plug at open wounds
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publicly accessible website, in whole or in part.
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
These clots become scabs when hardened
Plasma

The liquid potion of blood—92% water

Blood cells and platelets are suspended in plasma

Transports important nutrients, vitamins and gases
Human Heart

Atria—upper chamber

Ventricles—lower chamber
Forensic Implications of the Circulatory System

Blood type—class characteristic

DNA—individual characteristic

Blood—biological evidence

Hemastix®—a presumptive test for blood

Luminol—another presumptive test

Collect samples of blood evidence
Lividity

Lividity—the pooling of blood in the direction of gravity

Livor mortis—
•
•
the change in color caused by lividity
Bluish purple or reddish purple
Petechiae

Often occurs when a limb is in a hanging position

Small red dots underneath the surface of the skin
Blood Splatters
The Respiratory System (Obj 6.3, 6.4)
The Respiratory System—Structures
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publicly accessible website, in whole or in part.
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Forensic Implications of the Respiratory System

Cellular respiration
6O2 + C6H12O6  6CO2 + 6H2O + Energy

C6H12O6 is glucose which comes from food

Oxygen from the air combines with glucose to create energy for
the cells in your body

Asphyxiation—when the available oxygen decreases sharply while
the level of toxic gases increases
The Muscular System (Obj 6.5, 6.6)
Forensic Importance of the Muscular System

Actin and myosin—two proteins that form fibers within muscles

Muscles contract when myosin attaches to the actin, forming a
bridge

Lack of oxygen after death prevent muscles from relaxing

Rigor mortis—the process in which the muscles of a body begin
to stiffen
The Forensic Implications of Other Body Systems
(Obj 6.7)
Chapter Summary

Each body system can offer clues regarding the events that led up
to or occurred during the crime.

The circulatory system
•
•

systemic circulation
pulmonary circulation
The primary role of blood is to transport oxygen to the cells and
wastes from them. Components are:
•
•
•
•
red blood cells,
white blood cells,
platelets, and
plasma.

Gas exchange occurs in the alveoli of the lungs.

Capillaries, very small blood vessels surrounding the alveoli,
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publicly accessible website, in whole or in part.
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transport oxygen into the body and carbon dioxide out of the body.

Lividity occurs when blood pools in the lowest part of the body
after a person dies. Lividity provides clues about the time and the
position of the body at death.

The primary function of the respiratory system is to remove
gaseous wastes from the blood and to transport oxygen.

The respiratory tract is divided into upper and lower.

Asphyxia occurs when the amount of available oxygen decreases
while toxic gases increase.

Suffocation is a form of asphyxia that occurs when the amount of
available oxygen decreases.

Rigor mortis is the process where the muscles of the body begin to
stiffen after death. Rigor begins within two hours after death and
can last from 24 to 48 hours.
© 2012 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a
publicly accessible website, in whole or in part.
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