Podcast
Questions and Answers
Which of the following are considered part of the first line of defense?
Which of the following are considered part of the first line of defense?
What does lysozyme do?
What does lysozyme do?
Lysozyme is an antimicrobial enzyme that destroys the cell wall of bacteria. It is found in tears, saliva, mucus secretions, and perspiration.
What type of white blood cell differentiates into macrophages?
What type of white blood cell differentiates into macrophages?
Monocytes
What process do macrophages use to engulf and destroy microbes?
What process do macrophages use to engulf and destroy microbes?
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Which of the following is NOT a symptom of the inflammatory response?
Which of the following is NOT a symptom of the inflammatory response?
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The second line of defense is responsible for the body's specific immune response.
The second line of defense is responsible for the body's specific immune response.
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What is the main function of complementary proteins in the immune system?
What is the main function of complementary proteins in the immune system?
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Macrophages are only active during an initial infection and are not found in healthy tissue.
Macrophages are only active during an initial infection and are not found in healthy tissue.
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Which type of lymphocyte is responsible for producing antibodies?
Which type of lymphocyte is responsible for producing antibodies?
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Which of the following is NOT involved in the immune response?
Which of the following is NOT involved in the immune response?
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What is the role of helper T-cells in the immune response?
What is the role of helper T-cells in the immune response?
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What is the function of killer T-cells in the immune response?
What is the function of killer T-cells in the immune response?
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What is the role of suppressor T-cells in the immune response?
What is the role of suppressor T-cells in the immune response?
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Memory B-cells are responsible for the body's ability to mount a faster and more effective response to a re-infection by the same pathogen.
Memory B-cells are responsible for the body's ability to mount a faster and more effective response to a re-infection by the same pathogen.
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HIV/AIDS targets and destroys B-cells, weakening the immune system.
HIV/AIDS targets and destroys B-cells, weakening the immune system.
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What is the main reason why people with HIV/AIDS are more susceptible to infections?
What is the main reason why people with HIV/AIDS are more susceptible to infections?
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What role do interferons play in the immune response?
What role do interferons play in the immune response?
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The innate immune system provides a specific response to each pathogen.
The innate immune system provides a specific response to each pathogen.
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What is the main function of phagocytic cells in innate immunity?
What is the main function of phagocytic cells in innate immunity?
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Natural killer cells are a type of __________ that destroy infected or cancerous cells.
Natural killer cells are a type of __________ that destroy infected or cancerous cells.
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Match the following components of adaptive immunity with their functions:
Match the following components of adaptive immunity with their functions:
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What is the role of memory in the adaptive immune response?
What is the role of memory in the adaptive immune response?
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Complement proteins only function in the adaptive immune response.
Complement proteins only function in the adaptive immune response.
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What are the two main components of adaptive immunity?
What are the two main components of adaptive immunity?
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Study Notes
First Line of Defense
- Physical barriers: skin, mucous membranes, secretions (e.g., earwax, mucus) prevent entry of pathogens.
- Chemical barriers: enzymes in secretions (e.g., lysozyme in tears, saliva, mucus) and stomach acid destroy microbes.
- Cellular defenses: phagocytic cells (macrophages, neutrophils) and natural killer cells are part of the first line of defense.
Second Line of Defense: Macrophage Method
- Macrophages (a type of white blood cell) engulf and destroy microbes (phagocytosis) when they breach physical barriers.
- Macrophages use enzymes to destroy ingested microbes.
Second Line of Defense: Chemotaxis
- Neutrophils (another type of white blood cell) are recruited to infection sites by chemical signals (chemotaxis).
- They migrate to infected tissues and engulf microbes via phagocytosis.
- Neutrophils release enzymes, leading to the formation of pus. This is a crucial part of the inflammatory response.
Second Line of Defense: Inflammatory Response
- Damaged tissue triggers an inflammatory response, characterized by swelling, redness, heat, and pain due to increased blood flow.
- It's also marked by recruitment and activation of immune cells including phagocytic cells like macrophages and neutrophils.
- Pus and inflammation indicate the second line of defense is actively combating infection.
Second Line of Defense: Fever
- Macrophages release chemicals that raise body temperature to make it harder for pathogens (bacteria) to survive.
- Increased temperature helps fight infection, but high fevers can cause convulsions or cell death.
Complement Proteins
- Complement proteins enhance immune response by forming barriers around invaders, puncturing their membranes, or attracting phagocytic cells for destruction.
- Their activation is triggered by the presence of foreign organisms.
Macrophages - Further Role
- Patrol the body, and remain in tissues filtering pathogens and debris.
Lymphocytes: T-Cells and B-Cells
- Lymphocytes (T-cells and B-cells) are crucial for antibody production and are a type of white blood cell.
- T-cells mature in the thymus and identify antigens, while B-cells mature in the bone marrow and produce antibodies.
- B-cells clone themselves and circulate to find and neutralize invaders.
Immune Response Steps 1-3
- A bacterium enters the body.
- Macrophages engulf the bacterium, displaying its antigen on their surface.
- Helper T-cells recognize the displayed antigen as foreign and release lymphokines.
Immune Response Steps 4-6
- Lymphokines stimulate B-cell division.
- Helper T-cells signal B-cells to produce antibodies; Killer T-cells become active.
- Killer T-cells destroy infected cells and invaders.
Immune Response Steps 7-10
- Suppressor T-cells signal immune system shutdown.
- Memory B-cells store information about the antigens for later faster responses to same pathogens.
- Phagocytes clean up debris and damaged cells.
- Tissues repair and replace damaged areas.
Memory B Cells
- Enable a rapid response if the same pathogen re-enters the body due to previously generated memory cells.
Viruses and HIV/AIDS
- Viruses, particularly HIV, can attack T-cells, weakening the immune response to infections.
- Weakened immunity can make the body more susceptible to secondary bacterial infections.
- HIV is incurable, and may not show symptoms immediately upon infection.
Innate Immunity (First Line of Defense)
- Comprises physical barriers (skin, mucous membranes), chemical barriers (enzymes, stomach acid), and cellular defenses (phagocytes, NK cells).
Innate Immunity (Second Line of Defense)
- Includes phagocytosis, interferons (interfere with viral replication), natural killer cells (destroy infected cells), and complement proteins (enhancing inflammation, phagocytosis, and pathogen destruction).
Adaptive Immunity (Third Line of Defense)
- Involves specific recognition, wide variety of lymphocytes capable of recognizing various antigens, tailored and enhanced response to particular pathogens upon subsequent exposure, distinction between self and non-self, humoral immunity (using antibodies), cellular immunity (using T cells), and antigen-presenting cells (initiating adaptive immunity by presenting antigens to T cells).
- B cells produce antibodies, neutralizing pathogens;
- Helper T cells activate B cells and cytotoxic T cells;
- Cytotoxic T cells directly kill infected cells.
- Different responses in the primary and secondary immune responses to pathogen exposure are observed.
- Antibodies' generation in response to specific antigens is also described.
Interactions Between the Lines of Defense
- Innate immunity initiates the immune process.
- Adaptive immunity is boosted by innate immune signals.
- The innate and adaptive immune systems work together to produce effective immunity.
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Description
Test your knowledge on the body's first and second lines of defense against pathogens. This quiz covers the role of physical barriers, macrophages, neutrophils, and the inflammatory response. Understand how your immune system protects you from infections.
