Podcast
Questions and Answers
Which characteristic distinguishes innate immunity from acquired immunity?
Which characteristic distinguishes innate immunity from acquired immunity?
What is a primary function of physiological barriers in innate immunity?
What is a primary function of physiological barriers in innate immunity?
Which of the following factors does NOT influence innate immunity?
Which of the following factors does NOT influence innate immunity?
What is the role of skin in innate immunity?
What is the role of skin in innate immunity?
Signup and view all the answers
Which division of antigens is categorized as self-antigens?
Which division of antigens is categorized as self-antigens?
Signup and view all the answers
Which of the following statements about innate immunity is false?
Which of the following statements about innate immunity is false?
Signup and view all the answers
What type of barrier does mucus membrane represent in innate immunity?
What type of barrier does mucus membrane represent in innate immunity?
Signup and view all the answers
Which cells are primarily responsible for the immune response in the acquired immune system?
Which cells are primarily responsible for the immune response in the acquired immune system?
Signup and view all the answers
What distinguishes mononuclear phagocytes from polymorphonuclear granulocytes (PMNs)?
What distinguishes mononuclear phagocytes from polymorphonuclear granulocytes (PMNs)?
Signup and view all the answers
Which killing pathway of phagocytes relies on altering pH within the environment?
Which killing pathway of phagocytes relies on altering pH within the environment?
Signup and view all the answers
What role do NK cells play in the immune response?
What role do NK cells play in the immune response?
Signup and view all the answers
What characteristic is unique to Ab-dependent cytotoxic cells when targeting cells?
What characteristic is unique to Ab-dependent cytotoxic cells when targeting cells?
Signup and view all the answers
Which type of cells can contribute to resistance against fungal infections?
Which type of cells can contribute to resistance against fungal infections?
Signup and view all the answers
What is a primary role of lysozyme in innate immunity?
What is a primary role of lysozyme in innate immunity?
Signup and view all the answers
Which of the following accurately describes Pathogen Associated Molecular Patterns (PAMPs)?
Which of the following accurately describes Pathogen Associated Molecular Patterns (PAMPs)?
Signup and view all the answers
What initiates the process of phagocytosis in phagocytic cells?
What initiates the process of phagocytosis in phagocytic cells?
Signup and view all the answers
Which of the following statements is true regarding complement system in innate immunity?
Which of the following statements is true regarding complement system in innate immunity?
Signup and view all the answers
What is the role of interferons (INF) in the immune response?
What is the role of interferons (INF) in the immune response?
Signup and view all the answers
During phagocytosis, what occurs after formation of pseudopodia?
During phagocytosis, what occurs after formation of pseudopodia?
Signup and view all the answers
Which component is involved in attracting phagocytic cells to sites of infection?
Which component is involved in attracting phagocytic cells to sites of infection?
Signup and view all the answers
What defines the non-specific immune response primarily mediated by humoral factors?
What defines the non-specific immune response primarily mediated by humoral factors?
Signup and view all the answers
Natural Killer Cells (NKCs) arise from the same lineage as T-cells and B-cells.
Natural Killer Cells (NKCs) arise from the same lineage as T-cells and B-cells.
Signup and view all the answers
Polymorphonuclear granulocytes (PMNs) include both neutrophils and macrophages in their classification.
Polymorphonuclear granulocytes (PMNs) include both neutrophils and macrophages in their classification.
Signup and view all the answers
The killing mode of lymphokine-activated killer cells (LAK cells) is primarily extracellular.
The killing mode of lymphokine-activated killer cells (LAK cells) is primarily extracellular.
Signup and view all the answers
The oxygen dependent microbicidal system of phagocytes is less toxic than the oxygen independent system.
The oxygen dependent microbicidal system of phagocytes is less toxic than the oxygen independent system.
Signup and view all the answers
Antibody-dependent cellular cytotoxicity (ADCC) requires the participation of complement to kill target cells.
Antibody-dependent cellular cytotoxicity (ADCC) requires the participation of complement to kill target cells.
Signup and view all the answers
Innate immunity is also referred to as specific immunity.
Innate immunity is also referred to as specific immunity.
Signup and view all the answers
Autoantigens are substances that originate from external sources.
Autoantigens are substances that originate from external sources.
Signup and view all the answers
Barriers in innate immunity include factors such as skin and mucus membranes.
Barriers in innate immunity include factors such as skin and mucus membranes.
Signup and view all the answers
Non-specific immune responses improve with repeated exposure to the same antigen.
Non-specific immune responses improve with repeated exposure to the same antigen.
Signup and view all the answers
Lactic acid in fatty secretions plays a role in the mechanical barriers of innate immunity.
Lactic acid in fatty secretions plays a role in the mechanical barriers of innate immunity.
Signup and view all the answers
Corticosteroids can influence the hormonal status affecting innate immunity.
Corticosteroids can influence the hormonal status affecting innate immunity.
Signup and view all the answers
Innate immunity does not require previous exposure to an antigen.
Innate immunity does not require previous exposure to an antigen.
Signup and view all the answers
Sweat glands produce substances that encourage the growth of pathogenic organisms.
Sweat glands produce substances that encourage the growth of pathogenic organisms.
Signup and view all the answers
Lysozyme has the capability to hydrolyze the protein layer of the cells of many fungi.
Lysozyme has the capability to hydrolyze the protein layer of the cells of many fungi.
Signup and view all the answers
Phagocytosis is a passive process that does not require enzymes.
Phagocytosis is a passive process that does not require enzymes.
Signup and view all the answers
Complement activation leads to the generation of chemotactic factors such as C5a and C3a.
Complement activation leads to the generation of chemotactic factors such as C5a and C3a.
Signup and view all the answers
Interferon gamma is secreted by macrophages after infection stimulation.
Interferon gamma is secreted by macrophages after infection stimulation.
Signup and view all the answers
Pathogen Associated Molecular Patterns (PAMPs) are structures unique to human cells.
Pathogen Associated Molecular Patterns (PAMPs) are structures unique to human cells.
Signup and view all the answers
Cytokines play a crucial role in calling phagocytes to specific locations during an immune response.
Cytokines play a crucial role in calling phagocytes to specific locations during an immune response.
Signup and view all the answers
Lactoferrin and transferrin compete with bacteria for iron, thereby playing a role in innate immunity.
Lactoferrin and transferrin compete with bacteria for iron, thereby playing a role in innate immunity.
Signup and view all the answers
The formation of phagolysosome occurs after the fusion of phagosome with mitochondria.
The formation of phagolysosome occurs after the fusion of phagosome with mitochondria.
Signup and view all the answers
Describe the primary distinction between the oxygen-dependent and oxygen-independent microbicidal systems of phagocytes.
Describe the primary distinction between the oxygen-dependent and oxygen-independent microbicidal systems of phagocytes.
Signup and view all the answers
Explain the role of natural killer cells (NKCs) in the immune response.
Explain the role of natural killer cells (NKCs) in the immune response.
Signup and view all the answers
What is the function of antibodies in antibody-dependent cellular cytotoxicity (ADCC)?
What is the function of antibodies in antibody-dependent cellular cytotoxicity (ADCC)?
Signup and view all the answers
Identify the cells involved in the antibody-dependent cellular cytotoxicity (ADCC) mechanism.
Identify the cells involved in the antibody-dependent cellular cytotoxicity (ADCC) mechanism.
Signup and view all the answers
How do protective barriers contribute to the innate immune response?
How do protective barriers contribute to the innate immune response?
Signup and view all the answers
How do phagocytes recognize Pathogen Associated Molecular Patterns (PAMPs)?
How do phagocytes recognize Pathogen Associated Molecular Patterns (PAMPs)?
Signup and view all the answers
Describe the role of cytokines in phagocytosis.
Describe the role of cytokines in phagocytosis.
Signup and view all the answers
What is the significance of nitrogen species in the phagolysosome during the process of phagocytosis?
What is the significance of nitrogen species in the phagolysosome during the process of phagocytosis?
Signup and view all the answers
Explain the importance of chemotactic factors like C5a and IL-8 in innate immunity.
Explain the importance of chemotactic factors like C5a and IL-8 in innate immunity.
Signup and view all the answers
What is the function of the complement system in relation to non-specific immunity?
What is the function of the complement system in relation to non-specific immunity?
Signup and view all the answers
How do lactoferrin and transferrin assist in the body's defense against bacterial infections?
How do lactoferrin and transferrin assist in the body's defense against bacterial infections?
Signup and view all the answers
Detail the steps involved in the phagocytosis process.
Detail the steps involved in the phagocytosis process.
Signup and view all the answers
Identify the role of interferons in the immune response.
Identify the role of interferons in the immune response.
Signup and view all the answers
What are the two main divisions of antigens recognized in innate immunity?
What are the two main divisions of antigens recognized in innate immunity?
Signup and view all the answers
Identify one genetic factor that influences innate immunity.
Identify one genetic factor that influences innate immunity.
Signup and view all the answers
Explain how physiological barriers contribute to innate immunity.
Explain how physiological barriers contribute to innate immunity.
Signup and view all the answers
What characteristic of innate immunity indicates it is non-specific?
What characteristic of innate immunity indicates it is non-specific?
Signup and view all the answers
Describe the role of mechanical barriers in innate immunity.
Describe the role of mechanical barriers in innate immunity.
Signup and view all the answers
What impact does hormonal status have on innate immunity?
What impact does hormonal status have on innate immunity?
Signup and view all the answers
How does the age of an individual influence innate immunity?
How does the age of an individual influence innate immunity?
Signup and view all the answers
What is a fundamental property that distinguishes innate immunity from acquired immunity regarding memory?
What is a fundamental property that distinguishes innate immunity from acquired immunity regarding memory?
Signup and view all the answers
Lysozyme destroys the cell wall of bacteria by targeting ______.
Lysozyme destroys the cell wall of bacteria by targeting ______.
Signup and view all the answers
Phagocytic cells utilize ______ to engulf and destroy pathogens.
Phagocytic cells utilize ______ to engulf and destroy pathogens.
Signup and view all the answers
The fusion of the phagosome with lysosomes forms the ______.
The fusion of the phagosome with lysosomes forms the ______.
Signup and view all the answers
Cytokines are critical in attracting ______ to the site of infection.
Cytokines are critical in attracting ______ to the site of infection.
Signup and view all the answers
Interferon-alpha is secreted by ______ during viral infections.
Interferon-alpha is secreted by ______ during viral infections.
Signup and view all the answers
The directed movement of a cell towards an attracting molecule is known as ______.
The directed movement of a cell towards an attracting molecule is known as ______.
Signup and view all the answers
Lactoferrin and transferrin compete with bacteria for ______.
Lactoferrin and transferrin compete with bacteria for ______.
Signup and view all the answers
Pathogen Associated Molecular Patterns (PAMPs) are recognized by ______ on phagocytic cells.
Pathogen Associated Molecular Patterns (PAMPs) are recognized by ______ on phagocytic cells.
Signup and view all the answers
The two types of immunity are non-specific (innate) and ______ immunity.
The two types of immunity are non-specific (innate) and ______ immunity.
Signup and view all the answers
Innate immunity provides the body's first line of defense against ______ and non-microbial agents.
Innate immunity provides the body's first line of defense against ______ and non-microbial agents.
Signup and view all the answers
The absence of ______ immunity means that there is no improvement with repeated exposure to the same antigen.
The absence of ______ immunity means that there is no improvement with repeated exposure to the same antigen.
Signup and view all the answers
Physical barriers, such as skin and mucous membranes, are part of the innate immune ______.
Physical barriers, such as skin and mucous membranes, are part of the innate immune ______.
Signup and view all the answers
Monocytes are found in the ______.
Monocytes are found in the ______.
Signup and view all the answers
Neutrophils release granules and cytotoxic substances through an ______ killing pathway.
Neutrophils release granules and cytotoxic substances through an ______ killing pathway.
Signup and view all the answers
Autoantigens are categorized as ______-antigens.
Autoantigens are categorized as ______-antigens.
Signup and view all the answers
One example of a physiological barrier present in innate immunity is ______ substances like HCL in the stomach.
One example of a physiological barrier present in innate immunity is ______ substances like HCL in the stomach.
Signup and view all the answers
Natural killer cells contribute 10-15% of lymphocytes in ______ blood.
Natural killer cells contribute 10-15% of lymphocytes in ______ blood.
Signup and view all the answers
The oxygen independent microbicidal system lowers ______ to kill pathogens.
The oxygen independent microbicidal system lowers ______ to kill pathogens.
Signup and view all the answers
Ciliary movement and sneezing are examples of ______ barriers that contribute to innate immunity.
Ciliary movement and sneezing are examples of ______ barriers that contribute to innate immunity.
Signup and view all the answers
Lymphokine-activated killer cells (LAK cells) are a type of ______ cell.
Lymphokine-activated killer cells (LAK cells) are a type of ______ cell.
Signup and view all the answers
Genetic factors can influence innate immunity at the species, race, and ______ level.
Genetic factors can influence innate immunity at the species, race, and ______ level.
Signup and view all the answers
Match the following types of phagocytic cells with their descriptions:
Match the following types of phagocytic cells with their descriptions:
Signup and view all the answers
Match the following killing pathways of phagocytes with their characteristics:
Match the following killing pathways of phagocytes with their characteristics:
Signup and view all the answers
Match the following types of lymphocytic cells with their primary roles:
Match the following types of lymphocytic cells with their primary roles:
Signup and view all the answers
Match the following components of the immune response with their actions:
Match the following components of the immune response with their actions:
Signup and view all the answers
Match the following types of immune barriers with their functions:
Match the following types of immune barriers with their functions:
Signup and view all the answers
Match the following components with their respective functions in innate immunity:
Match the following components with their respective functions in innate immunity:
Signup and view all the answers
Match the following immune cells with their primary roles:
Match the following immune cells with their primary roles:
Signup and view all the answers
Match the following types of immune responses with their characteristics:
Match the following types of immune responses with their characteristics:
Signup and view all the answers
Match the following chemotactic factors with their sources:
Match the following chemotactic factors with their sources:
Signup and view all the answers
Match the following types of interferons with their origin:
Match the following types of interferons with their origin:
Signup and view all the answers
Match the following steps of phagocytosis with their sequences:
Match the following steps of phagocytosis with their sequences:
Signup and view all the answers
Match the following proteins with their roles in iron sequestration:
Match the following proteins with their roles in iron sequestration:
Signup and view all the answers
Match the following pathogen recognition structures with their types:
Match the following pathogen recognition structures with their types:
Signup and view all the answers
Match the following types of antigens with their descriptions:
Match the following types of antigens with their descriptions:
Signup and view all the answers
Match the following innate immunity components with their functions:
Match the following innate immunity components with their functions:
Signup and view all the answers
Match the following mechanisms of innate immunity with their types:
Match the following mechanisms of innate immunity with their types:
Signup and view all the answers
Match the following characteristics of innate immunity with their descriptions:
Match the following characteristics of innate immunity with their descriptions:
Signup and view all the answers
Match the following determining factors of innate immunity with their types:
Match the following determining factors of innate immunity with their types:
Signup and view all the answers
Match the following types of innate immune responses with their definitions:
Match the following types of innate immune responses with their definitions:
Signup and view all the answers
Match the following physiological barriers with their examples:
Match the following physiological barriers with their examples:
Signup and view all the answers
Match the following responses with their types in innate immunity:
Match the following responses with their types in innate immunity:
Signup and view all the answers
Study Notes
Immunity
- Immunity (resistance): The body’s defense mechanisms against infectious diseases.
- Two types of immunity:
- Innate immunity: Natural, non-specific, present at birth.
- Adaptive immunity: Specific, acquired, develops after exposure to a pathogen.
Innate Immunity
- Provides the body's first line of defense against infectious agents (microbial and non-microbial).
- Does not require prior exposure and does not have memory.
- Components react immediately to an invading organism or antigen.
- Antigen: A substance that stimulates the immune response, specifically activating lymphocytes (white blood cells).
- Two types of antigens are recognized:
- Foreign antigens (heteroantigens): Non-self antigens.
- Autoantigens (self-antigens) : Antigens present on the body's own cells.
Characteristics of Innate Immunity
- Non-specific: Effective against a wide range of antigens.
- Natural: Present at birth.
- No memory: Does not improve with repeated exposure to the same antigen.
Determining Factors of Innate Immunity
- Genetic factors:
- Species level
- Race level
- Individual level
- Age: Elderly individuals have weaker immune systems.
- Hormonal status: Corticosteroids suppress immune function.
- Nutritional status: Malnutrition weakens immune function.
Mechanism of Innate Immunity
- Barriers
- Physical barriers:
- Skin: The most important physical barrier.
- Mucous membranes: Line the internal surfaces of the body.
- Mechanical barriers:
- Ciliary movement: Removal of mucus and debris (e.g. trachea).
- Sneezing and coughing: Expel pathogens.
- Washing action of bodily fluids: Tears, saliva and urine remove pathogens.
- Physiological barriers:
- Bactericidal substances: HCL in the stomach, lysozyme in tears.
- Normal bacterial flora (commensal): Suppress growth of pathogenic organisms (e.g. Lactobacilli in the vagina).
- Sweat glands: Salt inhibits growth of pathogens by drawing water from their cells.
- Antimicrobial peptides
- Lysozyme: Destroys bacteria by breaking down peptidoglycans in bacterial cell walls.
- Physical barriers:
- Cellular Factors:
- Phagocytic cells: Engulf and destroy pathogens.
- Natural Killer (NK) cells: Destroy abnormal or infected cells.
- Dendritic cells: Present antigens to adaptive immune cells.
- Humoral Factors:
- Complement system: Proteins that help to destroy pathogens.
- Cytokines: Signaling molecules produced by cells that modify the immune response.
- Acute phase proteins: Produced by the liver in response to inflammation (e.g. C-reactive protein (CRP) & fibrinogen).
Phagocytosis
- An important feature of cellular innate immunity.
- Phagocytic cells: Ingest and destroy pathogens or particles.
- Phagocytes patrol the body for pathogens and are attracted to specific locations by cytokines.
- Phagocytes perform the following steps in destroying pathogens:
- Chemotaxis: Directed movement towards an attractant (e.g. C5a, IL-8).
- Attachment to the organism
- Formation of pseudopodia (arms) around the pathogen.
- Fusion of pseudopodia and phagosome formation.
- Fusion of phagosome with lysosomes, forming a phagolysosome that digests the pathogen.
Phagocytic Cells
- Two types of phagocytes:
- Mononuclear phagocytes:
- Monocytes: Found in the blood.
- Macrophages: Found in the tissues (e.g. Kupffer cells in the liver, histiocytes in connective tissue).
- Polymorphonuclear granulocytes (PMNs):
- Neutrophils: Primary phagocytes and can also release granules and cytotoxic substances extracellularly.
- Mononuclear phagocytes:
Killing Pathways of Phagocytes
- Oxygen dependent microbicidal system
- Oxygen independent microbicidal system.
Lymphocytic cells
- Certain lymphocytes contribute to nonspecific immune responses.
- Examples:
- Natural killer cells (NKCs): Granular lymphocytes that circulate in the body and recognize and destroy abnormal or infected cells (e.g. cancer cells, virally-infected cells).
- Activated by IL-2.
- Not T-cells or B-cells
- Play a role in resistance to some bacterial, fungal, and parasitic infections.
- Killing method: Extracellular killing.
- Antibody-dependent cytotoxic cells (ADCC): Kill target cells coated with specific antibody.
- Utilize the Fc portion of IgG to recognize the antibody.
- Cells include: NKCs, macrophages, and neutrophils.
- Lymphokine-activated killer cells (LAK cells): Can also be used in cancer immunotherapy.
- Natural killer cells (NKCs): Granular lymphocytes that circulate in the body and recognize and destroy abnormal or infected cells (e.g. cancer cells, virally-infected cells).
Protective Barriers of the body
- The first line of defense against invading pathogens.
- Prevent or retard the entry of cells and molecules into the body.
Immunity
- Immunity is the body's ability to resist infection and disease.
- It is a complex system of defenses that protects against a wide range of harmful invaders, including bacteria, viruses, fungi, and parasites.
Types Of Immunity
- Innate Immunity: This is the body's first line of defense and is present from birth.
- Acquired Immunity: This type of immunity develops after exposure to a specific pathogen, and is characterized by the ability to remember and mount a more rapid and effective response upon re-exposure.
Innate Immunity
- The innate immune system provides immediate protection against infection.
- This system includes physical barriers, chemical defenses, and cellular components.
-
Characteristics:
- Non-specific: It acts against a wide range of pathogens.
- Natural: It is present from birth, without previous exposure.
- No Memory: With repeated exposure, it does not improve its response.
Factors Determining Innate Immunity
- Genetics: Species, race, and individual genetic variations influence innate immunity.
- Age: Eldery individuals may have a weakened immune system.
- Hormonal Status: Corticosteroids can suppress the immune system.
- Nutritional Status: Malnutrition can impair immune function.
Mechanisms of Innate Immunity
-
Barriers: These prevent pathogens from entering the body:
- Physical Barriers: Skin and mucous membranes are the first lines of defense.
- Mechanical Barriers: Cilia, sneezing, coughing, tears, saliva, and urine help to remove pathogens.
-
Physiological Barriers:
- Bactericidal Substances: Stomach acid and lysozyme in tears kill bacteria.
- Normal Bacterial Flora: Commensal bacteria compete with pathogens for resources.
- Sweat Glands: The salt in sweat inhibits pathogen growth.
- Antimicrobial Peptides: These molecules directly kill pathogens.
- Lysozyme: This enzyme destroys the cell walls of bacteria.
-
Cellular Factors: These recognize and destroy pathogens:
- Phagocytic Cells: Monocytes (in blood), macrophages (in tissues), and neutrophils engulf and destroy pathogens.
- Natural Killer (NK) Cells: These cells recognize and kill tumor cells and virus-infected cells.
- Dendritic Cells: These cells capture and present antigens to adaptive immune cells.
-
Humoral Factors: These contribute to the immune response:
- Complement System: This group of proteins works with antibodies to lyse pathogens.
- Cytokines: These signaling molecules regulate immune responses.
- Acute Phase Proteins: C-Reactive Protein (CRP) and fibrinogen are produced in response to inflammation.
- Interferons (IFNs): These proteins are produced during viral infections to inhibit viral replication.
- Lactoferrin & Transferrin: These proteins bind iron, preventing it from being used by bacteria.
- Lysozyme: This enzyme hydrolyzes the cell walls of bacteria.
Phagocytosis
-
Steps in Phagocytosis:
- Chemotaxis: Phagocytes are attracted to the site of infection by chemical signals.
- Attachment: Phagocytes attach to the pathogen.
- Pseudopodia Formation: The phagocyte extends protrusions to engulf the pathogen.
- Phagosome Formation: The pathogen is enclosed within a membrane-bound vesicle called a phagosome.
- Phagolysosome Formation: The phagosome fuses with a lysosome, releasing enzymes that destroy the pathogen.
Lymphocytic Cells
- Natural Killer (NK) Cells: These cells are cytotoxic lymphocytes that kill virally infected cells and tumor cells.
- Antibody-Dependent Cytotoxic Cells: These cells kill target cells coated with antibodies.
- Lymphokine-Activated Killer (LAK) Cells: These cells are activated by cytokines and kill target cells.
Protective Barriers
- Physical Barriers: Skin, mucous membranes, and cilia are essential for preventing pathogen entry.
Immunity
- The body's natural defense mechanisms against infections
- Two types: innate and adaptive immunity
Innate Immunity
- The body's first line of defense
- Does not require prior exposure to pathogens
- It recognizes and responds to a broad range of pathogens
- No memory, meaning repeated exposure does not lead to improved response
Characteristics of Innate Immunity
- Non-specific: Works against a wide range of antigens
- Natural: Present at birth
- No Memory: Does not improve with repeated exposure to the same antigen.
Factors Affecting Innate Immunity
- Genetic: Species, race, and individual level variation
- Age: Elderly individuals are more susceptible to infections
- Hormonal status: Corticosteroids can suppress immunity
- Nutritional status: Malnutrition weakens the immune system
Mechanisms of Innate Immunity
-
Barriers: Prevent pathogens from entering the body
- Physical barriers: Skin, mucus membranes
- Mechanical barriers: Ciliary movement, sneezing, coughing, washing action of body fluids (tears, saliva, urine)
- Physiological barriers: Bactericidal substances (HCl in stomach, lysozyme in tears), normal gut bacteria, sweat glands, antimicrobial peptides, lysozyme
-
Cellular Factors: Phagocytic cells (monocytes, macrophages, neutrophils), NK cells, dendritic cells
- Recognize Pathogen Associated Molecular Patterns (PAMPs)
- Structures common to pathogens, essential for their survival, replication, infectivity
- Not present on human cells (ex: bacterial cell wall, viral nucleic acids)
- Recognize Pathogen Associated Molecular Patterns (PAMPs)
-
Humoral Factors: Contribute to the non-specific immune response
- Complement system: A group of proteins that can lyse bacteria and activate other immune cells.
- Cytokines: Signaling molecules that coordinate immune responses
- Acute phase proteins: Proteins produced in response to inflammation (ex: C-Reactive Protein (CRP) and fibrinogen)
Phagocytosis
- Process by which phagocytic cells engulf and destroy pathogens
- Steps:
- Chemotaxis: Movement of phagocytes towards chemoattractant molecules (C5a, IL-8)
- Attachment: Binding of the phagocyte to the pathogen
- Formation of Pseudopodia: Extensions of the phagocyte's cytoplasm that engulf the pathogen
- Phagosome Formation: Formation of a vesicle containing the pathogen
- Phagolysosome Formation: Fusion of the phagosome with a lysosome, releasing digestive enzymes that destroy the pathogen
-
Phagocytic Cells:
- Mononuclear Phagocytes: Monocytes in blood, macrophages in tissues (Kupffer cells in liver, Histiocytes in connective tissue)
- Polymorphonuclear Granulocytes (PMNs): Neutrophils
Killing Pathways of Phagocytes
- Oxygen-dependent Microbicidal System: Metabolism of oxygen into toxic metabolites that kill pathogens
- Oxygen-Independent Microbicidal System: Lowering pH, releasing proteolytic and hydrolytic enzymes
Lymphocytic Cells in Innate Immunity
-
Natural Killer Cells (NKC): Granular lymphocytes that perform immune surveillance and kill tumor cells and virally infected cells
- Activated by IL-2
- Lineage distinct from T and B cells
- Kill target cells extracellularly
- Antibody-dependent Cytotoxic Cells (ADCC): Kill target cells coated with specific antibody using FC receptors on their surface
- Lymphokine-activated Killer Cells (LAK cells): Activated by cytokines (lymphokines)
Protective Barriers
- The body's first line of defense
- Prevent or delay the entry of pathogens into the body
Immunity
- Immunity is the body's defense against pathogens.
- There are two types of immunity: Innate and Adaptive.
Innate Immunity
- Innate immunity is the body's first line of defense.
- Present at birth and doesn't require prior exposure to pathogens.
- Doesn't improve with repeated exposure to the same pathogen.
-
Components:
- Barriers: Physical (skin, mucous membranes), mechanical (cilia, coughing, sneezing), physiological (bactericidal substances like stomach acid, normal flora, sweat).
- Cellular factors: Phagocytic cells, NK cells, dendritic cells.
- Humoral factors: Complement system, cytokines, acute phase proteins like C-reactive protein (CRP) and fibrinogen.
Determining Factors of Innate Immunity
- Genetic factors: Species, race, individual variation
- Age: Elderly individuals have weaker immunity
- Hormonal status: Corticosteroids can suppress immune responses
- Nutritional status: Malnutrition weakens the immune system
Mechanism of Innate Immunity
- Barriers: prevent pathogens from entering the body.
-
Cellular factors:
-
Phagocytic cells: engulf and destroy pathogens.
- Monocytes: in the blood
- Macrophages: in tissues (e.g. Kupffer cells in the liver, histiocytes in connective tissue).
- Polymorphonuclear granulocytes (PMNs): Neutrophils can release cytotoxic substances extracellularly
- NK cells: cytotoxic lymphocytes that attack tumor cells and virally infected cells.
-
Phagocytic cells: engulf and destroy pathogens.
-
Humoral factors:
- Complement system: proteins that lyse bacteria.
- Cytokines: signaling molecules that regulate immune responses.
- Acute phase proteins: like CRP, produced in response to inflammation.
Phagocytosis
- Phagocytosis: process of engulfing and ingesting pathogens or particles.
-
Steps:
- Chemotaxis: Movement of phagocytes towards the pathogen.
- Attachment: Phagocyte binds to the pathogen.
- Formation of pseudopodia: Phagocyte creates projections that surround the pathogen.
- Fusion of pseudopodia and phagosome formation.
- Fusion of phagosome with lysosomes: forms phagolysosome, where digestive enzymes destroy the pathogen.
-
Killing pathways:
- Oxygen-dependent: uses toxic metabolites to kill bacteria.
- Oxygen-independent: uses enzymes (proteolytic and hydrolytic), changes in pH, and other mechanisms to destroy pathogens.
Lymphocytic Cells
-
Lymphocytes: contribute to non-specific immunity.
- Natural Killer Cells (NK cells): granular lymphocyte that kill cells without prior exposure.
- Antibody-dependent cytotoxic cells (ADCC): kill cells coated with antibodies.
- Lymphokine-activated killer cells (LAK cells): activated by cytokines to eliminate infected cells.
Protective Barriers of the Body
- Barriers are the first line of defense.
- They prevent or delay the entry of pathogens into the body.
Immunity
- Immunity refers to the protective mechanisms preventing infections
- Two types of immunity: innate and acquired
Innate Immunity
- Non-specific, first line of defense against microbes and non-microbial agents
- Present at birth, no memory
- Doesn't improve with repeated exposure to the same antigen
Determining Factors of Innate Immunity
- Genetic factors: species, race, and individual level
- Age: elderly individuals may have weakened immunity
- Hormonal status: corticosteroids can suppress the immune system
- Nutritional status: malnutrition weakens immunity
Mechanisms of Innate Immunity:
- Barriers: prevent entry of microorganisms into the body
- Physical:
- Skin: the most important barrier, contains lactic acid
- Mucous membranes: covering internal surfaces, prevents attachment of organisms
- Mechanical:
- Ciliary movement, sneezing, coughing
- Washing action: tears, saliva, urine
- Physiological:
- Bactericidal substances: HCl in the stomach, lysozyme in tears.
- Normal bacterial flora (commensal): Lactobacilli in the vagina suppress the growth of pathogens
- Sweat glands: salt inhibits pathogen growth
- Antimicrobial peptides
- Lysozyme: destroys bacterial cell walls
- Physical:
- Cellular Factors:
- Recognize Pathogen Associated Molecular Patterns (PAMPs)
- PAMPs are structures common to certain pathogens
- Not present on human cells
- Examples: bacterial cell wall structures (LPS, peptidoglycans)
- Recognize Pathogen Associated Molecular Patterns (PAMPs)
- Humoral Factors:
- Complement system
- Cytokines
- Acute phase protein = C-Reactive Protein (CRP), fibrinogen
Phagocytosis
- Important part of cellular innate immunity
- Performed by phagocytic cells: engulf and kill pathogens
- Phagocytes patrol the body and are called to specific locations by cytokines
- Pathogens are killed by digestive enzymes or a respiratory burst
- Steps:
- Chemotaxis: movement towards attracting molecules
- Attachment to the organism
- Formation of pseudopodia
- Fusion of pseudopodia to form a phagosome
- Fusion of phagosome with lysosomes to form a phagolysosome
Phagocytic Cells:
- Mononuclear phagocytes
- Monocytes in blood
- Macrophages in tissues (e.g., Kupffer cells in the liver)
- Polymorphonuclear granulocytes (PMNs)
- Neutrophils release granules and cytotoxic substances extracellularly
Killing Pathway of Phagocytes:
- Oxygen-dependent microbicidal system: metabolize oxygen into toxic metabolites
- Oxygen-independent microbicidal system: lowers pH, uses proteolytic and hydrolytic enzymes
Lymphocytic Cells:
- Certain lymphocytes are cytotoxic in the absence of prior exposure to the target
- Natural Killer cells (NKCs):
- Granular lymphocytes that function in immune surveillance
- Naturally occurring cytotoxic lymphocytes activated by IL-2
- Arise from bone marrow
- Toxic to tumor and virally infected cells
- Mode of killing is extracellular
- Antibody-dependent cytotoxic cells:
- Kill target cells coated with antibodies
- Cells involved in antibody-dependent cellular cytotoxicity (ADCC) have an FC receptor
- Types: NKCs, macrophages, neutrophils
- Lymphokine-activated killer cells (LAK cells):
- Activated by cytokines
- Natural Killer cells (NKCs):
Protective Barriers of the Body
- Represent the first line of defense
- Prevent or retard entry of cells and molecules into the body
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on the immune system, focusing on innate and adaptive immunity. Explore key concepts such as types of immunity, the role of antigens, and characteristics of the body's defense mechanisms. This quiz will help reinforce your understanding of how the body fights infections.