Immune System and Pathogens: Key Concepts and Structures

What is the primary role of the immune system?

To protect the body from infection and invaders.

Name the major organs of the immune system.

Tonsils, adenoids, lymph nodes, thymus, appendix, spleen, bone marrow, Peyer's patches.

What do tonsils do?

Trap germs and produce antibodies to prevent throat and lung infections.

What is the function of the thymus gland?

Generates mature T lymphocytes for adaptive immunity.

What do lymph nodes do?

Filter lymph fluid, trap bacteria/viruses, and destroy them with lymphocytes.

What does bone marrow produce?

Red marrow → RBCs, WBCs, platelets. Yellow marrow → fat, connective tissue, some WBCs.

What is the role of the spleen?

Filters blood, removes old/damaged cells, destroys bacteria.

What are white blood cells also called?

Leukocytes.

What is the difference between innate and acquired immunity?

Innate = nonspecific, immediate defense. Acquired = specific, develops after exposure.

What are the three phases of immune response?

Innate (0-4 hrs), Early induced innate (4-96 hrs), Adaptive (>96 hrs).

What is an antigen?

A foreign substance that provokes antibody production.

What is an antibody?

A protein produced to neutralize antigens.

What is active immunity?

Body produces antibodies (infection or vaccination).

What is passive immunity?

Antibodies received from outside (maternal transfer or injection). Short-lived.

What are the links in the chain of infection?

Agent, reservoir, mode of transmission, portal of entry, portal of exit, susceptible host.

Name the five types of pathogens.

Bacteria, viruses, fungi, prions, parasites.

What are the shapes of bacteria?

Cocci (round), bacilli (rod), spirilla (spiral), diplococci (pairs), streptococci (chains), staphylococci (clusters).

What are the six stages of the virus lifecycle?

Attachment, penetration, uncoating, replication, assembly, release.

What are prions?

Misfolded proteins causing brain diseases (e.g., mad cow). No cure.

What is a parasite?

Organism living on/in host, feeding at host's expense (e.g., giardia, tapeworms, lice).

Innate immune system

Naturally occurring immune mechanisms

Acquired immune system

Immune mechanisms that occur as the result of the antigen-antibody response

Nonspecific immune responses

The innate immune system's immune mechanisms

Specific immune responses

The acquired immune system's immune mechanisms

Germs

Microorganisms that cause infections

Pathogens

Microorganisms that cause infections

Chain of infection

The manner with which infections are transmitted and carried

The reservoir

The part of the chain of infection that is the environment or habitat, within which the pathogen lives, grows and reproduces.

Mode of transmission

The part of the chain of infection that allows a pathogen, or disease causing germ, to move from its reservoir to its susceptible host.

Direct contact transmission

The mode of transmission that occurs with direct contact with the pathogen

Droplet transmission

The mode of transmission that consists of direct contact with a spray of infectious material with can occur as the result of coughing and even speaking.

Indirect contact transmission

The mode of transmission that involves the movement of an infectious agent from the reservoir to the host with inanimate, or nonliving, objects

Airborne transmission

The mode of transmission that occurs when the pathogen is carried in dust or droplets in the air that remain in place for a sufficiently enough time to infect a person exposed to this air

Vehicle transmission

The mode of transmission that occurs when a person comes into contact with an infectious agent that is in water, blood, and even inanimate objects like a toy or a door knob

Vector transmission

The mode of transmission that entails a mode of transportation with a vector which, unlike vehicles, are live beings like ticks and mosquitoes that spread infections with relatively direct mechanical means like an insect bite

Bloodborne pathogens

Diseases causing pathogens that are spread and transmitted to others via contact with blood and other bodily fluids

Antibody

A protein in the blood that is produced as the result of an exposure to an antigen or pathogen.

Antigen

A foreign and unnatural substance that provokes the body to produce antibodies to fight if off.

Immunization

The process with which a person becomes immune with an injection

Natural immunity

Immunity that is acquired in a natural way

Artificial immunity

Immunity that is NOT acquired in a natural way

Active immunity

Immunity that occurs as the result of getting a particular infection and also by being given an immunization against the particular infection

Passive immunity

Immunity that occurs without the antigen-antibody response, but instead, with the direct receiving of antibodies

Bacteria

Singular cell beings that appear as spirals, rods, spheres and other shapes and can be pathogenic, leading to infection and also releasing tissue damaging toxins

Viruses

Pathogens are much smaller than bacteria; viruses have RNA, DNA and long molecules which comprise its genetic composition, a protein coat and an outer coating that contains lipids

Attachment

The first stage of viral growth

Penetration

The second stage of viral growth

Uncoating

The third stage of viral growth

Replication

The fourth stage of viral growth

Release

The fifth stage of viral growth

Fungi

Plant source microorganisms that affect human beings and typically classified as superficial, cutaneous, subcutaneous and systemic.

Superficial fungal infections

Fungal infections that affect and infect the skin's epidermis and the hair.

Cutaneous fungal infections

Fungal infections that include invasive hair and nail infections that goes beyond the epidermis

Subcutaneous fungal infections

Fungal infections that infect all layers of the skin to the muscles and the fascia

Systemic fungi infections

Fungal infections that can affect the entire body; these infections are typically highly virulent and they can spread to virtually all organs of the body

A prion

A nonliving pathogen that consists of an abnormal folding of normal cellular, or prion, proteins

A parasite

A living organism that lives on or in a host and gets its food from or at the expense of its host

Asepsis

Methods used to prevent the spread of infection.

Contaminated

Having been in contact with a microorganism.

Sterile/sterility

Free from all living microorganisms

Sterilization

The destruction of all microorganisms and large numbers of bacterial spores with the use of a chemical or physical sterilizer

Antiseptic

A germicidal solution that can be used on the skin to inhibit the growth of microorganisms, including pathogens

Cleaning

The physical, manual removal of visible material from a device or surface using scrubbing, water and a detergent or surfactant

Disinfection

The destruction of microorganisms including pathogens using a chemical or physical means of disinfection.

Opportunistic infection

An infection caused by a microorganism that does not ordinarily cause disease but is capable of doing so under certain host conditions

Personal protective equipment (PPE)

Specialized equipment and attire that is used by employees in healthcare to protect against infections.

Immunosuppression

Any disorder or treatment, like chemotherapy for cancer, that causes the immune system to be dysfunctional and not functioning correctly to protect the body

HIV/AIDS

Human immunodeficiency virus and autoimmune deficiency syndrome are viral infections that lead the immune system to be dysfunctional and not functioning correctly to protect the body

Hashimoto's thyroiditis

The autoimmune disorder that leads to thyroid gland damage and dysfunction

Rheumatoid arthritis

A type of arthritis that is caused by an autoimmune disorder

Systemic lupus erythematosus

Also referred to as lupus, this is a chronic autoimmune disorder that causes one's own immune system to destroy its own organs

Grave's disease

The disorder that affects the thyroid gland and increases its activity

Addison's disease

An autoimmune disorder that leads to the lack of adrenal gland functioning

Multiple sclerosis

A systemic autoimmune disorder that adversely affects the central nervous system