Second Line of Defense

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Questions and Answers

What is the primary role of the membrane attack complex formed by complement proteins?

To puncture the pathogen's cell wall (correct)

To enhance antibody production

To promote inflammation

To regulate immune cell activity

Which pathway is triggered by antibodies binding to a pathogen?

Adaptive Pathway

Alternative Pathway

Lectin Pathway

Classical Pathway (correct)

What triggers the alternative pathway for complement activation?

Components on pathogens themselves (correct)

Binding of lectin to pathogens

Antibody and pathogen interaction

Cytokine release from immune cells

Which of the following is a result of complement activation?

Opsonization of pathogens Signup and view all the answers

How is the lectin pathway for complement activation initiated?

By lectin binding to pathogen components Signup and view all the answers

What common outcome results from all pathways that activate the complement system?

Elimination of pathogen cells Signup and view all the answers

Why is the alternative pathway considered beneficial to the immune system?

It directly recognizes and destroys pathogens Signup and view all the answers

What role does opsonization play in the immune response?

It enhances the recognition and ingestion of pathogens by phagocytes Signup and view all the answers

Which statement accurately describes the outcomes of complement activation?

It results in opsonization, inflammation, and the membrane attack complex Signup and view all the answers

What is the relationship between the classical, alternative, and lectin pathways?

They are variations of the same activation process Signup and view all the answers

What role does complement play in the immune system?

It is a part of the second line of immune defenses. Signup and view all the answers

Why are patients with complement deficiencies at higher risk for infections?

They are unable to activate opsonization effectively. Signup and view all the answers

How does the complement cascade amplify the immune response?

Each activated protein activates multiple copies of the next protein. Signup and view all the answers

What is one function of complement during the immune response?

Binding to pathogens to promote phagocytosis. Signup and view all the answers

What initiates the inflammation response in response to complement activation?

Binding of complement proteins to mast cells. Signup and view all the answers

In what form do complement proteins exist in the blood before activation?

As inactive precursors waiting for stimulation. Signup and view all the answers

What does the term 'cascade' refer to in the context of complement activation?

Sequential activation of proteins where one activates another. Signup and view all the answers

Which of the following statements about N. meningitidis is true?

It has a large capsule that helps protect it from host defenses. Signup and view all the answers

What is the significance of the active forms of complement proteins?

They are the cleaved versions of inactive proteins that can combat pathogens. Signup and view all the answers

What happens to complement proteins during activation?

They get cleaved to create their active forms. Signup and view all the answers

Match the complement pathways with their initiating factors:

Classical Pathway = Antibody binding to a pathogen Alternative Pathway = Pathogen components Lectin Pathway = Lectin protein binding All pathways = Result in pathogen death Signup and view all the answers

Match the outcomes of complement activation with their descriptions:

Opsonization = Enhances phagocytosis of pathogens Inflammation = Recruitment of immune cells to the site Membrane Attack Complex = Formation of pores in pathogen cell walls Cascade amplification = Sequential activation of complement proteins Signup and view all the answers

Match the complement pathways with their characteristics:

Classical Pathway = Antibody-dependent activation Alternative Pathway = Can occur independently of antibodies Lectin Pathway = Requires the presence of lectin Common Result = All lead to pathogen destruction Signup and view all the answers

Match the complement proteins with their roles in activation:

C3 = Central to opsonization and membrane attack C5 = Involved in formation of the membrane attack complex C1 = Initiates the classical pathway upon antibody binding Factors B and D = Key players in the alternative pathway Signup and view all the answers

Match the type of immune response with the corresponding complement trigger:

Antibody response = Classical Pathway Natural pathogen recognition = Alternative Pathway Liver-derived protein interaction = Lectin Pathway Resulting immune effect = Enhanced inflammation and opsonization Signup and view all the answers

Match the complement activation pathways with their source:

Classical Pathway = Triggered by antibodies Alternative Pathway = Activated by pathogen surfaces Lectin Pathway = Dependent on liver-synthesized lectin All pathways = Lead to enhanced immune function Signup and view all the answers

Match the term with its correct description:

C3 convertase = Enzyme critical for complement activation Phagocytosis = Process of engulfing pathogens by immune cells Complement fixation = Binding of complement proteins to pathogens Inflammatory response = Local immune activation resulting in redness and heat Signup and view all the answers

Match the complement pathways with their unique features:

Classical Pathway = Relies on antibodies Alternative Pathway = Does not require antibodies Lectin Pathway = Utilizes soluble lectin proteins General outcome = Killing of pathogens via membrane attack Signup and view all the answers

Match the immune outcomes with their corresponding complement functions:

Opsonization = Facilitates pathogen recognition and binding Cytolysis = Destroys pathogens via membrane attack complex Chemotaxis = Attracts immune cells to the infection site Inflammation = Increases permeability of blood vessels Signup and view all the answers

Match the following functions of the complement system with their descriptions:

Opsonization = Binding to pathogen surfaces to enhance phagocytosis Inflammation = Activation of mast cells to recruit immune cells Cascade Activation = Sequential activation of proteins leading to large immune response Complement Proteins = About 30 proteins involved in immune defense Signup and view all the answers

Match the following statements about complement activation with their correct implications:

Inactive Proteins = Proteins in the blood must be cleaved to become active Amplification = One activated protein can activate several others Classical Pathway = Triggered by antibodies binding to pathogens Capsule Defense = Bacterial capsules can hinder immune responses like phagocytosis Signup and view all the answers

Match the following components of the immune system with their roles:

Neutrophils = White blood cells that phagocytize pathogens Macrophages = Present in inflammation to clear pathogens Mast Cells = Involved in initiating inflammation responses Pathogens = Microbial invaders targeted by the immune system Signup and view all the answers

Match the following aspects of complement with their benefits:

Immune Defense = Provides defense against encapsulated bacteria Phagocytosis Stimulation = Enhances destruction of pathogens by immune cells Rapid Response = Allows quick immunological reaction to threats Immune Control = Multiple activation points for regulatory responses Signup and view all the answers

Match the following types of immune responses to their characteristics:

Second Line Defenses = Includes mechanisms like complement and inflammation Adaptive Immunity = Relies on antibodies for specific pathogen targeting Innate Immunity = General defenses such as skin and complement systems Complement Cascade = A series of protein activations leading to pathogen elimination Signup and view all the answers

Match the following terms related to Neisseria meningitidis and complement with their descriptions:

N. meningitidis Capsule = Protective structure against immune defenses Complement Deficiency = Increased susceptibility to encapsulated pathogens Classical Pathway = Part of the complement system activated by antibodies Phagocytosis = Process enhanced by opsonization of pathogens Signup and view all the answers

Match the following phases of immune response with their functions:

Initial Activation = First complement protein is cleaved to start cascade Cascading Effect = Activation of numerous proteins from one stimulus Inflammatory Response = Recruitment of more immune cells to the site of infection Final Outcome = Destruction of the microbial invader through immune actions Signup and view all the answers

Match the following immune system terms with their functionalities:

Complement Proteins = Act in a sequence to amplify the immune response Mast Cell Activation = Initiates inflammatory responses to threats Phagocytosis = Engulfing and destruction of pathogens by immune cells Cascades in Biology = Provide multiple control points for biological processes Signup and view all the answers

Match the following descriptions of complement-related processes with their names:

Cleave = Cutting of inactive complement proteins to activate them Opsonization = Enhanced phagocytosis via binding proteins to pathogens Inflammation Initiation = Binding of complement proteins to mast cells Cascade Mechanism = Sequential activation process of immune proteins Signup and view all the answers

What part of the brain is responsible for regulating body temperature?

Hypothalamus Signup and view all the answers

Which of the following substances are considered common pyrogens?

LPS from gram-negative bacteria Signup and view all the answers

How can fever be beneficial to the body?

Inhibits the growth of some bacteria by limiting iron availability Signup and view all the answers

What are possible dangers of fever, especially in certain populations?

Nerve damage from prolonged high temperatures Signup and view all the answers

Fever triggers are primarily released by which type of agents?

Pathogens Signup and view all the answers

What mechanism does the body NOT use to maintain its temperature?

Neurotransmitter release Signup and view all the answers

What is a consequence of the hypothalamus resetting the body's thermostat?

Increase in body temperature Signup and view all the answers

What might happen if the body's temperature regulation fails?

Decreased efficiency of muscle contractions Signup and view all the answers

What condition could indicate that a fever is potentially dangerous?

Fever in a young child with a temperature over 104°F Signup and view all the answers

Which physiological response helps raise the body's temperature during a fever?

Muscle shivering Signup and view all the answers

What triggers the process of diapedesis in white blood cells?

Chemokines released by mast cells Signup and view all the answers

Which of the following statements accurately describes the process of phagocytosis?

It includes the formation of a phagosome that fuses with a lysosome. Signup and view all the answers

What is the main function of mast cells in the immune response?

To increase blood vessel permeability and attract white blood cells. Signup and view all the answers

Which symptom is primarily caused by the increase of blood flow and fluid accumulation during inflammation?

Redness Signup and view all the answers

What effect does fever have on the body during an infection?

Raises body temperature to enhance immune response. Signup and view all the answers

What are the four classic signs of inflammation?

Pain, swelling, warmth, redness Signup and view all the answers

What is pus primarily a result of?

The accumulation of cellular debris and dead cells during phagocytosis. Signup and view all the answers

What role does chemotaxis play in the immune response?

It refers to the movement of cells toward chemical signals. Signup and view all the answers

Which of the following correctly distinguishes the purpose of inflammation?

To stimulate tissue repair and destroy or contain pathogens. Signup and view all the answers

What immediate response occurs right after tissue injury?

Vasoconstriction to control bleeding Signup and view all the answers

Match the following immune system processes with their descriptions:

Phagocytosis = Ingesting foreign microbes by white blood cells Diapedesis = Exit of white blood cells from the circulatory system Inflammation = Defensive response to infection or injury Fever = Abnormally high body temperature caused by pyrogens Signup and view all the answers

Match the steps of inflammation with their correct sequence:

Step 1 = Vasoconstriction to limit blood loss Step 2 = Mast cells release histamine Step 3 = Neutrophils engage in phagocytosis Step 4 = Macrophages clean up debris Signup and view all the answers

Match the following signs of inflammation with their descriptions:

Redness = Increased blood flow to the area Pain = Sensitivity caused by tissue damage Heat = Elevated temperature in the affected area Swelling = Accumulation of fluid in tissues Signup and view all the answers

Match the following components of pus with their characteristics:

Digested bacteria = Broken down by digestive enzymes Dead white blood cells = Result of phagocytosis Fluid = Leaked from blood vessels during inflammation Chemokines = Attract white blood cells to the site of infection Signup and view all the answers

Match the types of white blood cells with their functions:

Neutrophils = Engage in phagocytosis at infection sites Macrophages = Clean up remaining debris Mast cells = Release chemicals to initiate inflammation Lymphocytes = Involved in adaptive immune response Signup and view all the answers

Match the following pyrogens with their roles:

Exogenous pyrogens = Produced by pathogens Endogenous pyrogens = Released by the immune system Cytokines = Signal the hypothalamus to raise temperature Prostaglandins = Modulate fever response and inflammation Signup and view all the answers

Match the following stages of fever with their events:

Onset = Hypothalamus resets body temperature Plateau = Sustained elevated temperature Resolution = Return to normal body temperature Crisis = Rapid drop in temperature Signup and view all the answers

Match the following terms related to inflammation with their descriptions:

Vasoconstriction = Narrowing of blood vessels to limit blood loss Vasodilation = Widening of blood vessels to increase blood flow Histamine = Chemical that causes blood vessel leakage Chemokines = Attracts white blood cells to the injury site Signup and view all the answers

Match the following white blood cell types with their specific actions:

Neutrophils = First responders to infection sites Macrophages = Engulf and digest foreign substances B cells = Produce antibodies T cells = Destroy infected host cells Signup and view all the answers

Match the following processes with their descriptions concerning immune response:

Phagocytosis = Formation of a phagosome around microbes Diapedesis = Movement of white blood cells through tissues Fever = Increase in basal metabolic rate Inflammation = Recruitment of immune cells to an area Signup and view all the answers

Study Notes

Complement

Part of the second line of immune defense along with inflammation and fever.
Consists of around 30 blood proteins working together to destroy microorganisms.
Functions as a cascade where each protein activates the next in a chain reaction.
Amplifies the immune response through multiple activations.
Proteins are activated when cleaved (cut in half).
Provides three primary immune benefits: opsonization, inflammation, and the membrane attack complex (MAC).
Opsonization enhances pathogen phagocytosis by white blood cells.
Inflammation attracts more neutrophils and macrophages to engulf pathogens.
MAC forms a hole in the pathogen's cell wall causing cell death.
Activated through three pathways: classical, alternative, and lectin.
Classical pathway: Antibodies bound to pathogens trigger activation.
Alternative pathway: Pathogen components directly trigger activation.
Lectin pathway: Lectin protein binds to pathogens and activates complement.
Although the activation pathways differ, the end result is always the same: opsonization, inflammation, and MAC formation leading to pathogen destruction.

Complement

Second-line immune defense mechanism consisting of about 30 blood proteins.
Works as a cascade, where each protein activates the next, leading to amplification of the response.
Activated by cleaving inactive proteins in the blood, resulting in active, cut-up forms.
Provides immune benefits through:
- Opsonization: Certain complement proteins bind to pathogens, enhancing phagocytosis by white blood cells.
- Inflammation: Complement proteins activate mast cells, triggering the inflammatory response, which recruits more neutrophils and macrophages for phagocytosis.
- Membrane Attack Complex (MAC): Other complement proteins form MACs, which punch holes in the pathogen's cell wall, leading to cell death.
Complement activation pathways:
- Classical pathway: Triggered when an antibody binds to a pathogen.
- Alternative pathway: Pathogen components directly trigger complement activation.
- Lectin pathway: Liver-produced lectin protein binds to pathogens, activating complement.
Regardless of the activation pathway, complement activation always leads to opsonization, inflammation, and MAC formation, ultimately resulting in pathogen destruction.