How Does Infection Occur?
CA Standards• Know and understand medical terminology to interpret, transcribe, and communicate
information and observations necessary for workers in the health care industry. (Health Sciences and Medical Technology Standard 2.5)
• Understand the importance and requirements of using sterile techniques in a laboratory. (Health Sciences and Medical Technology Standard A4.4)
• Students know the role of the skin in providing nonspecific defenses against infection. (Science Grades 9-12, Biology/Life Sciences Standard 10a)
• Students know the role of antibodies in the body’s response to infection. (Science Grades 9-12, Biology/Life Sciences Standard 10b)
• Students know how vaccination protects an individual from infectious diseases. (Science Grades 9-12, Biology/Life Sciences Standard 10c)
• Students know there are important differences between bacteria and viruses with respect to their requirements for growth and replication, the body’s primary defenses against bacterial and viral infections, and effective treatments of these infections. (Science Grades 9-12, Biology/Life Sciences Standard 10d)
• Students determine the domain of independent variables and the range of dependent variables defined by a graph, a set of ordered pairs, or a symbolic expression. (Algebra I Standard 17.0)
Learning Objectives
• Students will:• Observe and compare microorganisms
found on fomites• Identify different types of pathogens, types
of diseases, and types of body defenses• Simulate the spread of an infection
throughout a population• Determine factors that affect the rate of
spread of a disease
How Does Infection Occur?
• Microorganisms are small, living organisms not visible to the naked eye.
• Pathogens are microorganisms that cause disease.
A DISEASE results if the invading
pathogen causes the host to get sick.
Types of Pathogens
There are differenttypes of pathogens –they include:• FUNGI• BACTERIA• VIRUSES• PROTOZOANS• PRIONS
Bacteria
Bacteria
• Single-celled organisms
• Live in a variety of environments
• Only 1% cause disease
• Usually killed by antibiotics
• Examples of diseases caused by bacteria include pneumonias, strep throat, tuberculosis
Viruses
Viruses
• Smallest of pathogens• Nonliving• Can only reproduce by
invading a host cell• NOT cured by
antibiotics• Examples of diseases
caused by viruses include chicken pox, colds, influenza, small pox, HIV
Types of Disease
Endogenous = the
disease begins WITHIN
the body
Examples:– Metabolic disorders– Birth defects– Tumors
Types of DiseaseExogenous = the diseasebegins OUTSIDE the body
Examples:– Pathogenic organisms– Radiation– Chemicals– Trauma – Electric shock– Temperature extremes
Types of Disease
Nosocomial = diseases
acquired by an
individual in a health
care facility– Usually present in the
facility and transmitted by health care workers to the patient
Types of Disease
Opportunistic = disease
that occurs when the
body’s defenses are
weak
Common Body Defenses
Mucous membrane:
lines the respiratory,
digestive, and
reproductive tracts; traps microorganisms to prevent them from invading
Common Body Defenses
Cilia: tiny hairlike
structures that line the
respiratory tract to move
pathogens out of the
body
Common Body Defenses
Coughing and sneezing removes microorganisms from the respiratory tract.
Common Body Defenses
Hydrochloric acid:
destroys pathogens in
the stomach
Common Body Defenses
Tears in the eye:
contain chemicals that
kill bacteria
Common Body Defenses
Fever: kills pathogens
by heat
Common Body Defenses
Immune response: body
produces white blood
cells and antibodies to fight pathogens