Podcast
Questions and Answers
Which of the following is NOT a characteristic of the innate immune system?
Which of the following is NOT a characteristic of the innate immune system?
- Involvement of physical barriers like skin
- Rapid response
- Specificity for particular pathogens (correct)
- Lack of immunological memory
The primary role of the skin and mucous membranes is to actively destroy pathogens that have already entered the body.
The primary role of the skin and mucous membranes is to actively destroy pathogens that have already entered the body.
False (B)
Following adherence and engulfment during phagocytosis, what cellular organelle fuses with the phagosome to degrade the ingested material?
Following adherence and engulfment during phagocytosis, what cellular organelle fuses with the phagosome to degrade the ingested material?
lysosome
Natural killer (NK) cells recognize infected or cancerous cells by detecting the absence of "self" cell-surface proteins referred to as __________.
Natural killer (NK) cells recognize infected or cancerous cells by detecting the absence of "self" cell-surface proteins referred to as __________.
Match each inflammatory process to its respective physiological effect:
Match each inflammatory process to its respective physiological effect:
What is the primary function of antimicrobial proteins like interferons?
What is the primary function of antimicrobial proteins like interferons?
Fever primarily inhibits the activity and migration of immune cells, thus slowing down the immune response.
Fever primarily inhibits the activity and migration of immune cells, thus slowing down the immune response.
What is the term for the process by which neutrophils squeeze through capillary walls to exit blood vessels and enter the interstitial fluid during inflammation?
What is the term for the process by which neutrophils squeeze through capillary walls to exit blood vessels and enter the interstitial fluid during inflammation?
The coating of pathogens with sugar molecules that phagocytes recognize and bind to is called __________.
The coating of pathogens with sugar molecules that phagocytes recognize and bind to is called __________.
Which of the following statements best describes the role of the acid mantle in innate defense?
Which of the following statements best describes the role of the acid mantle in innate defense?
Unlike adaptive immunity, the innate immune system improves in speed and effectiveness upon repeated exposure to the same pathogen.
Unlike adaptive immunity, the innate immune system improves in speed and effectiveness upon repeated exposure to the same pathogen.
Besides initiating inflammation, what other crucial function does the delivery of clotting proteins to the interstitial fluid serve during an immune response?
Besides initiating inflammation, what other crucial function does the delivery of clotting proteins to the interstitial fluid serve during an immune response?
__________ are substances released by injured cells that induce the formation of white blood cells during the inflammatory response.
__________ are substances released by injured cells that induce the formation of white blood cells during the inflammatory response.
What cellular process is directly inhibited by antiviral proteins produced in response to interferon secretion?
What cellular process is directly inhibited by antiviral proteins produced in response to interferon secretion?
The primary benefit of fever is that it directly kills pathogens by raising the body temperature above their survival threshold.
The primary benefit of fever is that it directly kills pathogens by raising the body temperature above their survival threshold.
What is the initial trigger that activates the inflammatory process?
What is the initial trigger that activates the inflammatory process?
The process by which neutrophils cling to the capillary wall during inflammation is known as __________.
The process by which neutrophils cling to the capillary wall during inflammation is known as __________.
Which of the following is an example of a fixed macrophage?
Which of the following is an example of a fixed macrophage?
Mucin primarily acts as an enzyme that dissolves bacterial cell walls.
Mucin primarily acts as an enzyme that dissolves bacterial cell walls.
Match the following immune processes to their associated cells:
Match the following immune processes to their associated cells:
Flashcards
Immune System
Immune System
Provides resistance to disease-causing microorganisms; not an organ system.
Surface Barriers
Surface Barriers
First line of defense; includes skin, mucous membranes, and secretions.
Innate Internal Defenses
Innate Internal Defenses
Attacks anything not recognized as "friend"; include phagocytes and inflammation.
Phagocytes
Phagocytes
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Phagocytosis Steps
Phagocytosis Steps
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Natural Killer (NK) Cells
Natural Killer (NK) Cells
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Inflammation
Inflammation
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Inflammation Process
Inflammation Process
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Benefits of Inflammation
Benefits of Inflammation
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Neutrophil Mobilization
Neutrophil Mobilization
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Interferons
Interferons
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Steps of Interferon Action
Steps of Interferon Action
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Fever
Fever
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Fever Mechanism
Fever Mechanism
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Lysozyme
Lysozyme
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Mucin
Mucin
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Adherence (Phagocytosis)
Adherence (Phagocytosis)
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Antiviral Proteins
Antiviral Proteins
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Leukocytosis
Leukocytosis
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Margination
Margination
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Study Notes
Immune System Overview
- The immune system offers resistance to disease-causing microorganisms
- It is a functional system rather than an organ system
- It comprises all the molecules and immune cells that inhabit lymphoid tissue and circulate in the body
- There are two types of immunity: innate and adaptive
Lines of Defense
- The immune system has three main lines of defense which act as successive layers of protection
First Line of Defense: Surface Barriers
- Skin and epithelial membranes/mucous membranes act as physical barriers, preventing pathogen entry
- Skin possesses multiple layers
- Keratin stops bacterial enzymes and toxins
- Acidity of skin and stomach secretions inhibits bacterial growth (acid mantle)
- Lysozyme enzymes found in saliva, respiratory mucus, and lacrimal eye fluid destroy bacteria
- Mucin, found in respiratory and digestive tract mucus, traps microorganisms
Second Line of Defense: Internal Defenses (Phagocytes)
- Neutrophils and macrophages are phagocytes
- Macrophages are "big-eaters"
- Free macrophages (wanderers) are derived from WBC monocytes
- Fixed macrophages (resident) arise early in embryonic development
- Pathogen receptors on phagocytes recognize and bind to sugar molecules on pathogen surfaces
Phagocytosis Steps
- Adherence: Phagocyte adheres to pathogens or debris
- Engulf: Phagocyte forms pseudopods that eventually engulf the particles, forming a phagosome
- Lysosome Fusion: Lysosome fuses with the phagocytic vesicle, forming a phagolysosome
- Digestion: Toxic compounds and lysosomal enzymes destroy pathogens
- Exocytosis: Exocytosis of the vesicle removes indigestible and residual material
Second Line of Defense: Internal Defenses (Natural Killer Cells)
- Natural killer (NK) cells are non-specific killers that target virus-infected cells and cancer cells
- NK cells identify infected or cancerous cells by detecting the lack of "self" cell-surface proteins called MHC class I, which is the major histocompatibility complex
- NK cells attack the target cell's membrane by releasing perforins and granzymes, leading to nuclear disintegration and inflammation
Second Line of Defense: Internal Defenses (Inflammation)
- Inflammation is a nonspecific response to localized tissue injury
- The signs of inflammation are redness, heat, swelling, and pain
Inflammatory Process
- Injured or stressed tissue cells and immune cells release a chemical 'alarm' (histamine, kinins, prostaglandins, etc.)
- Small blood vessels dilate, causing redness and heat
- Chemicals increase capillary permeability, causing fluid to leak out. This results in edema/swelling, and pain due to the swelling
How Inflammation Aids Healing
- Limits movement
- Increases metabolic rate of cells
- Delivers oxygen and nutrients
- Delivers clotting proteins to interstitial fluid which helps prevent the spread of damaging agents to nearby tissue
Neutrophil Mobilization
- Neutrophil mobilization starts soon after inflammation begins
- Leukocytosis: Injured cells release leukocytosis-inducing factors (increasing WBC formation)
- Margination: Neutrophils cling to the capillary wall
- Diapedesis: Neutrophils exit blood vessels
- Chemotaxis: Neutrophils follow chemical trails to the site of infection
Second Line of Defense: Internal Defenses (Antimicrobial Proteins - Interferons)
- Viruses cannot replicate themselves because they lack the cellular machinery to generate ATP or synthesize proteins
- Virus-infected cells can secrete antimicrobial proteins called interferons
Steps of Interferon Action
- Virus enters and replicates within a host cell
- Interferon genes are switched on in infected cells
- Infected cells secrete interferons
- Interferons stimulate the production of antiviral proteins in uninfected cells
- Antiviral proteins prevent virus replication
Second Line of Defense: Internal Defenses (Fever)
- Fever is an abnormally high body temperature, which is a systemic response to invading microorganisms
- Bacteria leads to leukocytes, which stimulate the hypothalamus via pyrogens, leading to the elevation of body temperature
Benefits of Fever
- Increases the ability of immune cells to migrate to lymph nodes
- Liver and spleen sequester iron and zinc, which bacteria need to grow
- Increases the metabolic rate of tissue cells, speeding up repair
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