Microbiology Final Exam Review: Innate Immunity and Host Defenses

Q1. What is the definition of "microbial antagonism"?

Background

Topic: Innate Immunity & Normal Microbiota

This question tests your understanding of how the normal microbiota protect the host by competing with potential pathogens.

Key Terms:

• Microbial antagonism: The competition between normal microbiota and potential pathogens.

• Normal microbiota: Microorganisms that colonize the body without causing disease under normal conditions.

Step-by-Step Guidance

1. Recall that the human body is colonized by many harmless or beneficial microbes (normal microbiota).

2. Think about how these microbes can prevent the growth of harmful pathogens (e.g., by competing for nutrients or producing inhibitory substances).

3. Consider the term "antagonism" and how it relates to the interactions between different microbial species.

Try explaining the concept in your own words before checking the answer!

Final Answer:

Microbial antagonism is the competition between normal microbiota and potential pathogens for nutrients and space, which helps protect the host from infections.

This process is also known as competitive exclusion.

Q2. What antibacterial chemical is present in tear fluid?

Background

Topic: First Line of Defense – Chemical Barriers

This question focuses on the chemical defenses found in body fluids that help prevent microbial invasion.

Key Terms:

• Tear fluid (lacrimal secretions): Fluid produced by the lacrimal glands to protect the eyes.

• Antibacterial chemical: A substance that inhibits or destroys bacteria.

Step-by-Step Guidance

1. Recall which enzyme is commonly found in tears and other secretions (like saliva and mucus).

2. Think about how this enzyme acts on bacterial cell walls, specifically targeting peptidoglycan.

3. Remember the name of this enzyme and its role in innate immunity.

Try to recall the enzyme before revealing the answer!

Final Answer:

Lysozyme is the antibacterial enzyme present in tear fluid. It breaks down the peptidoglycan in bacterial cell walls, leading to cell lysis.

Q3. What are the functions of eosinophils?

Background

Topic: White Blood Cells – Granulocytes

This question tests your knowledge of the roles of different white blood cells in the immune response, specifically eosinophils.

Key Terms:

• Eosinophils: A type of granulocytic white blood cell involved in immune responses, especially against parasites and in allergic reactions.

Step-by-Step Guidance

1. Recall that eosinophils are especially important in defending against multicellular parasites (like helminths).

2. Think about their role in modulating allergic inflammatory responses.

3. Consider how eosinophils can release toxic granules and enzymes to attack pathogens.

List at least two functions before checking the answer!

Final Answer:

Eosinophils function to combat parasitic worm infections and modulate allergic inflammatory responses by releasing enzymes and toxic proteins.

Q4. What are the stages of phagocytosis?

Background

Topic: Innate Immunity – Phagocytic Process

This question examines your understanding of the steps involved when phagocytic cells ingest and destroy pathogens.

Key Terms:

• Phagocytosis: The process by which certain cells engulf and digest microorganisms and cellular debris.

Step-by-Step Guidance

1. Recall the sequence of events from the initial attraction of the phagocyte to the pathogen, to the destruction of the pathogen.

2. List the main stages, such as chemotaxis, adherence, ingestion, and digestion.

3. Think about what happens to the pathogen inside the phagocyte.

Try to list the stages in order before revealing the answer!

Final Answer:

The stages of phagocytosis are: chemotaxis, adherence, ingestion, formation of the phagosome, fusion with lysosome (phagolysosome), digestion, and exocytosis of debris.

Q5. Give examples of agranulocytes.

Background

Topic: White Blood Cells – Classification

This question tests your ability to distinguish between granulocytic and agranulocytic white blood cells.

Key Terms:

• Agranulocytes: White blood cells that lack visible cytoplasmic granules.

Step-by-Step Guidance

1. Recall the two main types of agranulocytes in the blood.

2. Think about their roles in the immune system (e.g., antibody production, phagocytosis).

3. List their names.

Try to name both types before checking the answer!

Final Answer:

Examples of agranulocytes are lymphocytes and monocytes.

Q6. Name the white blood cells.

Background

Topic: Hematology – Leukocytes

This question asks you to recall the five main types of white blood cells found in human blood.

Key Terms:

• White blood cells (leukocytes): Cells of the immune system involved in protecting the body against infectious disease.

Step-by-Step Guidance

1. Recall the two main categories: granulocytes and agranulocytes.

2. List the three types of granulocytes and two types of agranulocytes.

3. Make sure you can spell each one correctly.

Try to list all five before revealing the answer!

Final Answer:

The five types of white blood cells are neutrophils, eosinophils, basophils, lymphocytes, and monocytes.

Q7. Which white blood cell becomes a macrophage when leaving the bloodstream?

Background

Topic: White Blood Cells – Mononuclear Phagocyte System

This question tests your knowledge of the differentiation of white blood cells and their roles in the immune system.

Key Terms:

• Monocytes: A type of agranulocyte that circulates in the blood.

• Macrophages: Large phagocytic cells derived from monocytes that reside in tissues.

Step-by-Step Guidance

1. Recall which white blood cell circulates in the blood and differentiates upon entering tissues.

2. Think about the function of macrophages in phagocytosis and antigen presentation.

Try to recall the cell type before checking the answer!

Final Answer:

Monocytes become macrophages when they leave the bloodstream and enter tissues.

Q8. The components of the second line of defense against microbes may be characterized as:

Background

Topic: Innate Immunity – Second Line of Defense

This question asks you to identify the general characteristics of the second line of defense in the immune system.

Key Terms:

• Second line of defense: Non-specific immune responses that act after pathogens bypass the first line of defense.

Step-by-Step Guidance

1. Recall that the first line includes physical and chemical barriers (e.g., skin, mucous membranes).

2. Think about what happens if pathogens get past these barriers—what defenses are activated?

3. Consider the types of cells and processes involved (e.g., phagocytes, inflammation, fever, antimicrobial proteins).

Try to describe the second line of defense before checking the answer!

Final Answer:

The second line of defense includes non-specific cellular and chemical responses such as phagocytosis, inflammation, fever, and antimicrobial proteins (e.g., complement).

Q9. Fever is beneficial during viral infection because:

Background

Topic: Innate Immunity – Fever

This question tests your understanding of the physiological role of fever in fighting infections, especially viral ones.

Key Terms:

• Fever (pyrexia): An elevated body temperature that is part of the body's defense mechanism.

Step-by-Step Guidance

1. Recall how fever can affect the growth and replication of pathogens.

2. Think about how fever influences the immune response (e.g., speeding up reactions, enhancing interferon activity).

3. Consider the overall impact on the body's ability to fight infection.

Try to list at least two benefits before checking the answer!

Final Answer:

Fever inhibits the growth of some pathogens and enhances the activity of immune cells and interferons, helping the body fight viral infections more effectively.

Q10. What substance contributes to the edema associated with inflammation?

Background

Topic: Inflammation – Chemical Mediators

This question focuses on the substances released during inflammation that cause fluid accumulation (edema).

Key Terms:

• Edema: Swelling caused by excess fluid in tissues.

• Inflammation: The body's response to injury or infection, involving increased blood flow and permeability.

Step-by-Step Guidance

1. Recall which chemical mediators increase the permeability of blood vessels during inflammation.

2. Think about substances like histamine, kinins, and prostaglandins.

3. Identify the main mediator responsible for increased vascular permeability and fluid leakage.

Try to name the substance before checking the answer!

Final Answer:

Histamine is a key substance that increases vascular permeability, leading to edema during inflammation.

Q11. Give examples of a walled-off site of infection that contains a fluid made of dead and dying tissue cells, leukocytes, and pathogens.

Background

Topic: Inflammation – Pus Formation

This question tests your understanding of localized infections and the formation of pus-filled lesions.

Key Terms:

• Pus: A thick fluid composed of dead cells, leukocytes, and pathogens.

• Abscess: A localized collection of pus in tissues.

Step-by-Step Guidance

1. Recall the term for a localized, walled-off collection of pus.

2. Think of common examples, such as those found in the skin or internal organs.

Try to name at least one example before checking the answer!

Final Answer:

Examples include abscesses, boils (furuncles), and pustules.

Q12. How does aspirin act to decrease the symptoms of inflammation?

Background

Topic: Inflammation – Pharmacology

This question examines your understanding of how anti-inflammatory drugs like aspirin work at the molecular level.

Key Terms:

• Aspirin: A nonsteroidal anti-inflammatory drug (NSAID).

• Prostaglandins: Lipid compounds that mediate inflammation and pain.

Step-by-Step Guidance

1. Recall the enzyme that aspirin inhibits (cyclooxygenase, or COX).

2. Think about how this inhibition reduces the production of prostaglandins.

3. Consider how decreased prostaglandin levels reduce inflammation, pain, and fever.

Try to explain the mechanism before checking the answer!

Final Answer:

Aspirin inhibits the enzyme cyclooxygenase, reducing prostaglandin synthesis and thereby decreasing inflammation, pain, and fever.

Q13. Chemotaxis is defined as:

Background

Topic: Innate Immunity – Phagocyte Movement

This question tests your understanding of how immune cells are directed to sites of infection.

Key Terms:

• Chemotaxis: Movement of cells toward or away from chemical stimuli.

Step-by-Step Guidance

1. Recall that chemotaxis is a process by which cells move in response to chemical signals.

2. Think about how this process helps immune cells find and migrate to sites of infection or injury.

Try to define chemotaxis before checking the answer!

Final Answer:

Chemotaxis is the movement of cells (such as phagocytes) toward chemical signals released at sites of infection or tissue damage.

Q14. Opsonization is:

Background

Topic: Innate Immunity – Phagocytosis Enhancement

This question tests your understanding of how the immune system marks pathogens for destruction.

Key Terms:

• Opsonization: The process of coating pathogens with molecules that enhance phagocytosis.

• Opsonins: Molecules such as antibodies or complement proteins that bind to pathogens.

Step-by-Step Guidance

1. Recall how opsonins (like antibodies or complement) bind to pathogens.

2. Think about how this binding makes it easier for phagocytes to recognize and ingest the pathogen.

Try to define opsonization before checking the answer!

Final Answer:

Opsonization is the process by which pathogens are coated with opsonins, enhancing their recognition and ingestion by phagocytes.

Q15. Give examples of the first line of defense.

Background

Topic: Innate Immunity – Physical and Chemical Barriers

This question tests your knowledge of the body's initial barriers to infection.

Key Terms:

• First line of defense: Physical and chemical barriers that prevent pathogen entry.

Step-by-Step Guidance

1. Recall examples of physical barriers (e.g., skin, mucous membranes).

2. Think about chemical barriers (e.g., lysozyme in tears, acidic pH of the stomach).

3. List at least two examples from each category.

Try to list at least three examples before checking the answer!

Final Answer:

Examples include the skin, mucous membranes, tears (with lysozyme), saliva, and stomach acid.

Q16. The first and second lines of defense against microbial invasion are part of:

Background

Topic: Innate Immunity

This question tests your understanding of the distinction between innate and adaptive immunity.

Key Terms:

• Innate immunity: Non-specific defense mechanisms present from birth.

• Adaptive immunity: Specific defenses that develop after exposure to pathogens.

Step-by-Step Guidance

1. Recall the definitions of innate and adaptive immunity.

2. Think about which lines of defense are present at birth and act non-specifically.

Try to identify the correct category before checking the answer!

Final Answer:

The first and second lines of defense are part of innate immunity.

Q17. The second line of defense against invading microbes includes:

Background

Topic: Innate Immunity – Second Line Components

This question asks you to list the main components of the second line of defense.

Key Terms:

• Second line of defense: Non-specific immune responses after pathogen entry.

Step-by-Step Guidance

1. Recall the main processes and cells involved (e.g., phagocytes, inflammation, fever, antimicrobial proteins).

2. List at least three components.

Try to list the components before checking the answer!

Final Answer:

The second line of defense includes phagocytic cells, inflammation, fever, and antimicrobial proteins such as complement.

Q18. The immune response to specific pathogens that can improve with subsequent exposure is:

Background

Topic: Adaptive Immunity

This question tests your understanding of the difference between innate and adaptive immunity, focusing on memory and specificity.

Key Terms:

• Adaptive immunity: Immune responses that are specific to particular pathogens and improve with repeated exposure.

• Immunological memory: The ability of the immune system to respond more rapidly and effectively to pathogens it has encountered before.

Step-by-Step Guidance

1. Recall which branch of the immune system is specific and has memory.

2. Think about how vaccines work by stimulating this type of immunity.

Try to name this type of immunity before checking the answer!

Final Answer:

Adaptive (or acquired) immunity is the immune response that is specific to pathogens and improves with subsequent exposures.

Q19. Which white blood cells increase in number during an infection with parasitic worms?

Background

Topic: White Blood Cells – Eosinophils

This question tests your knowledge of the immune response to parasitic infections.

Key Terms:

• Eosinophils: White blood cells that play a key role in defense against parasitic worms (helminths).

Step-by-Step Guidance

1. Recall which type of granulocyte is especially active against multicellular parasites.

2. Think about the role of eosinophils in releasing toxic granules to attack parasites.

Try to recall the cell type before checking the answer!

Final Answer:

Eosinophils increase in number during infections with parasitic worms.