Microbio Module 11 Notes

What is the primary role of the immune system? 

To recognize and destroy foreign molecules, invading microbes and their products, and mutant or damaged cells

Innate immune system

the body’s immediate, non-specific first line of defense against pathogens, active from birth

• present before infection

Adaptive immune system

a highly specific, second line of defense in vertebrates that identifies and remembers specific pathogens, providing long-lasting protection

• develops over time as a response to infections

What does it mean that the immune system relies on the ability to recognize self from non-self? Why is this important? 

• it distinguishes the body’s own healthy cells (self-antigens) from foreign invaders like bacteria, viruses, or cancer cells (non-self antigens)

• crucial because it allows the immune system to destroy pathogens and dangerous cells while leaving healthy tissues unharmed

Name seven factors that can influence the function of the immune system. 

1. Age

2. Sex

3. Race

4. Nutrition

5. Health status

6. Genetics

7. Physical/mental stress

Name four detrimental roles of the immune system and explain how they are a malfunction of the immune response. 

1. Hypersensitivity reaction- allergic reaction when immune system goes into overdrive

2. Allergies- adverse immune response to protein molecules associated with allergens

3. Autoimmune diseases- failure of immune system to distinguish self from nonself

4. Reaction to organ transplantation

How does the innate immune system recognize self from non-self? 

• pathogen-associated molecular patterns (PAMPs)- innate immune cells rely on PAMPs to identify and respond to an infection

• Pattern recognition receptors (PRRs)- innate immune cells (most notably white blood cells/leukocytes) have PRRs that recognize PAMPs

How does the adaptive immune system recognize self from non-self? 

training lymphocytes (T cells and B cells) to recognize foreign antigens while eliminating or silencing those that react to the body's own tissues

Lymphocytes

defend the body against infections, viruses, and diseases as part of the immune system

B cells

a type of white blood cell called lymphocytes that produce antibodies

T cells

a type of white blood cell that help your immune system fight germs and protect you from disease

• necessary for adaptive immunity

Natural killer cells

white blood cells that destroy infected and diseased cells, like cancer cells

Neutrophils

destroy pathogens through phagocytosis

Eosinophils

fight parasitic infections and drive allergic responses by causing inflammation

Basophils

a type of white blood cell that defends your body from allergens

Explain the role of cytokines in immune cell communication?

act as the chemical "language" of the immune system, orchestrating immune responses, inflammation, and cellular communication

What type of cytokine is primarily responsible for the antiviral immune response? 

Interferons

What is a differential count and what is the purpose of performing one?

Reflects the ratio of the white blood cells and is an important tool in the diagnosis of infection

What are the three components of blood plasma?

1. Globulin fraction

2. Complement proteins

3. Interferon

Globulin fraction

• contains antibodies

• Recognize and bind to specific foreign antigens (adaptive response)

Complement proteins

series of proteins that act as significant defense mechanism

Interferon

group of proteins that act to interfere with viral replication

What is the purpose of the lymphatic system in immune function? 

produces and releases lymphocytes (a type of white blood cell) and other immune cells

How do lymph nodes contribute to innate and adaptive immunity? 

• Swollen lymph nodes in armpits, groin, neck, etc. indicate an active immune response to an infection

• Contain both B and T cells and are the site of antibody production

• Also contain phagocytic cells which destroy microbes and stimulate adaptive immune response

What are the two primary immune structures?

1. Bone marrow

2. Thymus

Bone marrow contribution to the immune system

Two pathways of blood cell maturation

• myeloid path

  • Platelets and red blood cells

  • Leukocytes: monocytes, neutrophils, eosinophils, basophils

• Lymphoid path

  • B lymphocytes mature in bone marrow

  • T lymphocytes created in bone marrow but mature in thymus

Thymus contribution to the immune system

• in thymus T cells build their genes that encode for their antigen-specific receptors and learn what is self

• Once mature they leave the thymus and migrate to secondary lymphoid tissues and are ready to respond to infections

Myeloid path

• Platelets and red blood cells

• Leukocytes: monocytes, neutrophils, eosinophils, basophils

Lymphoid path

• B lymphocytes mature in bone marrow

• T lymphocytes created in bone marrow but mature in thymus

What is the role of the secondary immune structures in immune function?

primary sites for initiating adaptive immune responses

Name the four structures/organs of the secondary immune structures

1. Lymph nodes

2. Spleen

3. Tonsils and adenoids

4. Peyer’s patches

lymph nodes function in the immune system

• contain phagocytic cells and mature T and B cells

• Almost all antigens end up in lymph or blood → then carried to lymph nodes, site of antibody production

spleen function in the immune system

contains phagocytic cells and mature T and B cells

Tonsils and adenoids

protect against microbes entering the nose and throat

Peyer’s patches

protect against microbes entering through mucosal surfaces

What are the two main goals of the physical/chemical barriers of the innate immune system? 

1. Prevent microbes from gaining access into the body

2. Quickly eliminate any microbes that do gain access

How does skin act to prevent or eliminate microbial infections?

• first line of defense against microbial infection

• Physical barrier that block entry of microorganisms into the body

How does mucous membranes act to prevent or eliminate microbial infections?

• constantly bathed in secretions (ex. Mucous)

• Peristalsis of intestines, mucociliary escalator of respiratory tract removes microbes

• Acidity of stomach acid

How does antimicrobial substance act to prevent or eliminate microbial infections?

Protects skin and mucous membranes

How does normal microbiota act to prevent or eliminate microbial infections?

• compete with pathogens for space and nutrients

• Immune stimulation

• Potential secretion of toxins to ward off pathogens

• Nutritional support

What is the role of the complement system?

destroys pathogens, triggers inflammation, and clears immune complexes/damaged cells

What are the three potential outcomes of complement activation? 

1. Leads to chemotaxis of phagocytes and initiates inflammation

2. Enhances phagocytosis

3. Can bring about lysis of the target cell via building a pore through the cell

What is the role of phagocytosis in the immune response? 

removes infectious agents, clears dead cells to maintain homeostasis, and initiates the adaptive immune response by presenting antigens

What cells are able to perform phagocytosis?

• monocytes

• Macrophages

• Neutrophils

Explain the process of phagocytosis. 

1. Phagocytes recruited by chemoattractants to invader

2. Phagocytes recognize and bind to invader

3. Pseudopods surround invader and form phagosome

4. Lysosomes fuse with phagosome forming phagolysosome

5. Within phagolysosome invader is killed and digested via enzymes and production of toxic products

6. Release of degraded products

What is the purpose of inflammation? 

• contain site of damage

• Localize response

• Eliminate invader

• Restore tissue function

What are the four cardinal signs of inflammation? 

1. Redness

2. Heat

3. Swelling

4. Pain

Explain the cascade of events that occurs during the process of inflammation.

• dilation of small blood vessels

• Migration of leukocytes from bloodstream to tissues

• Clotting factors to wall off site of infection

• Dead neutrophils, tissue debris accumulate as pus

What is the role of fever in the immune response?

• an important host defense mechanism

• Strong indicator of infectious disease, especially bacterial

What does a fever help to enhance in the immune response?

• inflammatory response

• Phagocytosis

• Multiplication of lymphocytes

• Production of interferons and antibodies

• Release of leukocytes from bone marrow

The spleen is a __________ immune structure that contains ____________________.

Secondary, mature T and B cells

What component of the blood contains the most antibodies?

gamma globulin

PAMPs are associated with ___________ and are recognized by ____________.

An infection/pathogen, immune cells

____________ act(s) as the "eyes" and "ears" of the cell during communication involved with the immune response?

Cytokines

The myeloid lineage does NOT lead to

lymphocytes

Complement activation can lead to ____________________________. 

Chemotaxis of phagocytes to the site of infection

How does the normal microbiota contribute to innate immunity?

It competes with pathogens for space and nutrients

The purpose of complement is to _____ , choose all that apply.

• lyse invader cells

• Enhance phagocytosis

The engulfment stage of phagocytosis involves _____________  of a phagocyte surrounding the invader and forming a phagosome. 

Pseudopods

Which of the following is the FIRST step in the inflammatory response?

Dilation of small blood vessels

Which of the following statements best describes the innate branch of the immune system?

You are born with the components of the innate immune system, and it is responsible for an immediate and general response to invaders

What does it mean that the immune system needs to recognize "self" from "non-self"?

Immune cells should only recognize and attack invaders/infected cells