How Does Infection Occur?

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