MICB W12 Human Defence and Sharp Injuries

Define Innate Defenses and Acquired defences. Give 1 example of each.

Innate = always active; first and second line of defense

• Physical Barriers

• Mechanical Barriers

• Antimicrobial Chemicals

• Cellular Barriers 

Acquired = must be stimulated to be come active; third line of defense 

• Immune system learning to attack antigens 

List examples of Physical/Mechanical barriers

1. skin, hair

2. Mucous membranes, eyes, nose, mouth, vagina

3. Defecation urination, vomiting 

4. Washing action of secretions and excretions

5. Sticky nature of mucous 

6. Coughing, sneezing, 

List examples of Chemical barriers

1. Lysosome

2. Gastric juice

3. Saliva - dilutes MO’s and washes oral cavity

List examples of second line of defense - non-specific resistance

1. Phagocytosis

2. Inflammation

3. Fever

List examples of Third line of defense - specific resistance

Relites on antigens found in foreign microbes to initiate response

1. T-Lymphocytes

• Cell-mediated response

• helper T-cells and killer T-cells

1. B-Lymphocutes

• Antibody mediated response

• memory cells

• plasma produces antibodies

What are the 5 main types of Leukocutes (WBC)? 

1. Lymphocyte

2. Monocytes

3. Neutrophils

4. Eosinophils

5. Basophils 

Describe Lymphocytes

• more common in lymph than in blood

• longest life span (memory cells)

• include: be cells (plasma and memory) and T cells (helper and killer)

What kind of leukocyte is often referred to as “antibody mediated response”

B-lymphocytes (B-cells)

What is the function of Plasma B-cells?

Produces antibodies which bind to antigens of foreign particles so they can be eliminated

How Plasma B Cells Work

1. Antigen Encounter: When a B cell encounters a specific antigen (a foreign substance), it differentiates into a plasma cell.

2. Antibody Production: The plasma cell then produces antibodies that are highly specific to that antigen.

3. Antibody Release: These antibodies are released into the blood and lymphatic systems.

4. Target Neutralization/Destruction: Once in the bloodstream, the antibodies find and bind to their target antigen, leading to its neutralization or destruction by the immune system.

What is the function of Memory B-cells?

Is activated in response to a second encounter with a pathogen.

• memory cells can live for years unlike most WBC which may only live a few days

Compare and contrast Helper T-cells and Killer/cytotoxic T-Cells.

Helper T-cells (CD4⁺):

• Function: “Managers” of the immune response.

• Release cytokines to activate B-cells, macrophages, and cytotoxic T-cells.

• Do not directly kill infected cells.

Cytotoxic/Killer T-cells (CD8⁺):

• Function: Direct “attackers.”

• Bind to and destroy virus-infected, tumor, or transplanted cells by releasing perforins and granzymes.

• Work after activation, often signaled by Helper T-cells.

Describe Monocytes and its function.

Monocytes are large, circulating white blood cells with a kidney-shaped nucleus.

• Largest WBC 

• Phagocytic 

• Turn into macrophages when they leave the blood stream

Describe Neutrophils and its function.

Neutrophils are the most abundant granulocytes; first responders to infection

• makes pus

• phagocytic

• often referred to as PMNs=Polymorphonuclear Leukocytes

Describe Eosinophils

• Found mostly in mucous membranes

• deals with parasitic infections and allergic reactions

Describe Basophils

• rarest of the WBC

• responsible for allergic and antigen response by releasing histamines

Inflammation is ___ line of defense. Describe the process.

Second line of defense - innate immunity

1. Blood supply to site increased

2. Capillary permeability increased to allow immune cells to reach the site

3. Neutrophils and macrophages are already present at the site

4. WBC migrate from capillaries into affected tissue

What is the sequence of WBC arrival the site of affected tissue?

*Neutrophils are the earliest cell to arrived, then monocytes/macrophages, then lymphocytes

Neutrophils → monocyte/macrophage → lymphocytes

Phagocytic cells are part of the __ line of defense. How do they work?

2nd line of defense of innate immunity

• Phagocytic cells are constantly patrolling to destroy any foreign particles/pathogens

• Cell membrane of a phagocyte will surround bacterial/pathogen to create a pocket that will enclose the bacteria. = phagosome

• Lysosome merge with phagosome = phagolysosome

• Lysosomal enzymes released into the phagosome to kill the bacteria

Most of the time ___ and ____ function as low-level garbage collectors.

Macrophages and Neutrophils

Which conditions is not protected against by our Long-term immunity?

Dental caries, periodontal disease, gonorrhoea, common cold

What is Artificial Immunity?

The immunity we get by being immunized or vaccinated against a specific disease 

What are examples of damages by our own immune system to our body?

1. antibody-mediated allergic reaction in nose/eyes = hay fever or respiratory = asthma

2. anaphylactic shock → allergy to a substance causing widespread reaction affecting blood stream, lungs and heart

3. contact dermatitis → cell-mediated allergic reaction to something

Percutaneous injury

through the skin injury

What are the main diseases that are primarily associated with sharp injuries ?

Hep B, HepC and HIV.

What is the CDHO IPAC definition of Handling Sharps and Exposure prevention?

Sharps are devices that are capable of causing a cut or puncture wound. Sharps should be kept out of the reach of clients and safely collected in a clearly labelled puncture-resistant container at point of use and/or must be transported to the reprocessing area in a leak-proof covered container

(i.e. plastic tray with a secured hard plastic cover) or cassette.

Blood-borne pathoigens exposure can occur via…

1. percutaneous injuries

2. non-intact skin

3. through the eyes, mouth, nose

What must be included in the exposure management protocol in the IPAC manual?

1. First aid procedures

2. Treatment procedure

What must be documented in the Exposure Management Report?

1. Documentation of the incident

2. Name and vaccine status of persons exposed

3. Record date and time of the incident and what was the Occupational Health Care Worker doing, including DH procedure being performed

4. Identify what preventative measures were being implemented at the time (ex. utility gloves while handling sharps)

5. Document name and health status of source person if known; include any blood-borne diseases (ex. Hep B, HepC, HIV)