Immunology 1

Questions and Answers

What role do defensins play in the respiratory epithelium?

They enhance bacterial adhesion to cell surfaces.

They secrete mucus to trap dust and microorganisms.

They create holes in bacterial cell walls, limiting bacterial survival. (correct)

They neutralize gastric acids in the respiratory tract.

How does the mucous membrane contribute to the respiratory system's function?

By promoting the growth of normal flora in the lungs.

By filtering air and trapping dust and microorganisms. (correct)

By facilitating gas exchange between air and blood.

By producing hydrochloric acid to kill microorganisms.

What is the pH range of gastric juices, which aids in digestive processes?

7.0 to 7.5

4.5 to 5.5

1.2 to 3.5 (correct)

6.0 to 6.5

What is the function of ciliated cells in the respiratory tract?

They drive mucus upward toward the orifices. Signup and view all the answers

What role does Lactobacillus acidophilus play in the genitourinary tract?

It breaks down glycogen into lactic acid, lowering pH. Signup and view all the answers

What is a primary benefit of mucus in the respiratory tract?

It prevents the respiratory tract from drying out. Signup and view all the answers

In which environments are slightly acidic conditions commonly found?

Vaginal secretions and urine. Signup and view all the answers

What is the primary function of mucus-coated nasal hair?

To filter air and trap particles. Signup and view all the answers

What occurs when bacterial surface proteins adhere to cells in the respiratory tract?

Enhanced bacterial colonization. Signup and view all the answers

What is the role of NK cells in the immune response?

They are responsible for killing intracellular viruses. Signup and view all the answers

Which component is important for stimulating neutrophils and monocytes during inflammation?

C5a Signup and view all the answers

What is NOT a function of the complement system?

Producing lytic granules Signup and view all the answers

How do NK cells interact with healthy host cells?

They bind to MHC 1 complex using their inhibitory receptor. Signup and view all the answers

What process allows more immune cells to enter the site of infection?

Chemotaxis Signup and view all the answers

What is an anaphylatoxin?

A complement component that triggers inflammation Signup and view all the answers

Which of the following statements about complement system is true?

It plays a role in both inflammation and opsonization. Signup and view all the answers

Which receptor is involved in inhibiting NK cell activity against healthy cells?

Inhibitory receptor Signup and view all the answers

Which cells are directly involved in the activation of natural killer cells?

T cells Signup and view all the answers

Which pathway of the complement system is triggered by antibodies?

Classical Pathway Signup and view all the answers

What is the role of Interferon Lambda in immune response?

Stimulates B lymphocytes Signup and view all the answers

What does the complement system primarily act in conjunction with?

Antibodies Signup and view all the answers

Where are most complement factors produced in the body?

Hepatocytes Signup and view all the answers

What indicates that a tissue is inflamed?

Increased blood flow Signup and view all the answers

Which of the following is NOT part of the cardinal signs of inflammation?

Numbness Signup and view all the answers

What is primarily involved in the second line of defense against pathogens?

Inflammatory responses Signup and view all the answers

Which of the following responses is characteristic of fever?

Increased core body temperature Signup and view all the answers

What happens when neutrophils and macrophages fail to destroy pathogens?

Chronic inflammation may develop Signup and view all the answers

Which of the following is a non-specific defense mechanism?

Interferon Signup and view all the answers

Which process is directly involved in the destruction of pathogens in the second line of defense?

Phagocytosis Signup and view all the answers

What is a major role of the second line of defense?

Surveying and destroying pathogens Signup and view all the answers

Which of the following statements about the first line of defense is true?

It provides a physical and chemical barrier. Signup and view all the answers

What occurs during the inflammatory response?

Increased blood flow and fluid accumulation happen. Signup and view all the answers

What type of white blood cells are primarily increased during an immune response?

Neutrophils Signup and view all the answers

What are Pattern Recognition Receptors (PRRs) responsible for?

Surveying the environment for foreign material Signup and view all the answers

Where do Toll-Like Receptors (TLRs) primarily reside?

On the surface membrane of macrophages Signup and view all the answers

Which of the following is true about Pathogen Associated Molecular Patterns (PAMPs)?

They have structural features that can trigger an immune response. Signup and view all the answers

Which immune cells are specifically mentioned as possessing PRRs?

Macrophages and Dendritic cells Signup and view all the answers

What is one of the main roles of phagocytes in the immune response?

To digest and eliminate microbes Signup and view all the answers

Which statement best describes the sequence of activities performed by phagocytes?

Survey tissue, digest material, and extract immunogenic information. Signup and view all the answers

How do macrophages recognize foreign pathogens?

By utilizing Pattern Recognition Receptors to detect PAMPs Signup and view all the answers

What is the significance of immunogenic information extracted by phagocytes?

It can be used to trigger a stronger adaptive immune response. Signup and view all the answers

What distinguishes PAMPs from PRRs?

PAMPs are pathogen markers, whereas PRRs are receptors on immune cells. Signup and view all the answers

What is a characteristic feature of the second line of defense in the immune system?

Non-specific responses that act rapidly Signup and view all the answers

Which of the following elements is NOT typically involved in the first line of defense?

Inflammation Signup and view all the answers

What role do interferons play in the immune response?

Inhibit viral replication Signup and view all the answers

Which statement accurately describes the third line of defense?

It is characterized by highly-specific defenses Signup and view all the answers

What is one of the main purposes of phagocytosis in the immune response?

To remove microbes and dead cells from tissues Signup and view all the answers

Which of the following factors can inhibit the colonization of pathogens on the skin?

Epithelial cell shedding Signup and view all the answers

What is a typical response of the body when the first line of defense is breached?

Rapid inflammation and phagocytosis Signup and view all the answers

Which environmental condition poses a higher risk for fungal infections?

High humidity or moisture levels Signup and view all the answers

What is the primary role of pyrogens in the body?

To initiate fever and reset the thermostat Signup and view all the answers

What is the function of Toll-Like Receptors (TLRs) in the immune response?

To recognize specific components of microbes Signup and view all the answers

Which substances are classified as exogenous pyrogens?

Endotoxins from bacteria Signup and view all the answers

What physiological response is associated with an abnormal elevation of body temperature?

Fever Signup and view all the answers

What primarily triggers the systemic response seen during fever?

Infections and their toxins Signup and view all the answers

Which component of the immune system is involved in producing endogenous pyrogens?

Macrophages Signup and view all the answers

How does the hypothalamus respond to pyrogens?

By resetting the body's temperature set point Signup and view all the answers

What primarily distinguishes exogenous from endogenous pyrogens?

Their source Signup and view all the answers

Which Toll-Like Receptor (TLR) specifically binds to lipopolysaccharides?

TLR-4 Signup and view all the answers

What role do endogenous pyrogens like Interleukin 1 play in fever?

They stimulate the hypothalamus to increase temperature Signup and view all the answers

What is the primary function of anaphylatoxins in the immune response?

To enhance vasodilation and increase vascular permeability Signup and view all the answers

Which component does C5 convertase cleave to form C5a?

C5 Signup and view all the answers

What is the first step in the classical pathway of the complement system after antibody-antigen complex formation?

Binding of C1 to the complex Signup and view all the answers

What triggers NK cells to recognize and kill tumor or virus-infected cells?

Recognition of MHC I molecules Signup and view all the answers

Which receptor on NK cells is responsible for recognizing abnormalities in target cells?

Killer-activating receptor Signup and view all the answers

What role does fever play in inhibiting bacterial growth?

It impedes nutrition by reducing iron availability. Signup and view all the answers

What is a potential danger associated with extremely high fever?

It can cause convulsions and death if it exceeds 42°C. Signup and view all the answers

What is a key action of alpha and beta interferons during a viral infection?

They inhibit viral replication. Signup and view all the answers

How does fever affect the immune system aside from inhibiting microorganisms?

It accelerates hematopoiesis and immune reaction. Signup and view all the answers

Which microorganisms' multiplication is inhibited by higher temperatures during fever?

Polioviruses and Herpes virus. Signup and view all the answers

What triggers the synthesis of alpha and beta interferons in response to viral infection?

Viral particles binding to host cell receptors. Signup and view all the answers

Why is fever considered a beneficial immune response only up to a certain degree?

It can lead to direct tissue damage at extreme temperatures. Signup and view all the answers

What happens to the iron stores in the body during a fever?

They become unavailable to bacteria. Signup and view all the answers

Which of the following best describes the role of macrophages during fever?

They stop releasing iron stores necessary for bacteria. Signup and view all the answers

Which of the following statements is true regarding interferons?

They act as regulatory cytokines in viral defense. Signup and view all the answers

What is one way that normal flora can help prevent pathogens from colonizing the host?

Competing for nutrients Signup and view all the answers

Which of the following correctly describes a function of perspiration as a chemical barrier?

Flushes microorganisms from the skin Signup and view all the answers

What role does the long urethra in males play in the genitourinary tract?

It acts as a distance barrier to pathogens. Signup and view all the answers

How do some bacteria inhibit the growth of harmful microorganisms?

By producing antibiotics. Signup and view all the answers

What is the significance of a slightly acidic pH in the skin's chemical barriers?

It inhibits the growth of harmful microorganisms. Signup and view all the answers

What is a potential consequence of impaired peristalsis in the gastrointestinal tract?

Reduced elimination of pathogens. Signup and view all the answers

Which of the following statements about chemical barriers is true?

They include secretions that can flush harmful microorganisms. Signup and view all the answers

What is the role of bacteriocin in the body?

To inhibit the growth of harmful microorganisms. Signup and view all the answers

Which of the following is NOT a function of normal flora?

Producing substances that promote inflammation. Signup and view all the answers

What aspect of the urination process aids in preventing infection in the urinary tract?

The flushing action of urine. Signup and view all the answers

Study Notes

Immune Response and Mechanisms

Histamines are released to increase blood flow to the site of injury, facilitating the arrival of immune cells.
Viruses must enter host cells to replicate and initiate infection.
Natural Killer (NK) cells target and destroy cells infected by intracellular viruses.

Importance of Complement System

Complement system contributes to immune defense through:
- Production of anaphylatoxins, small proteins that can trigger inflammation.
- Chemotaxis, where C5a attracts neutrophils and monocytes to inflammation sites.
- Opsonization, enhancing pathogen recognition and elimination by phagocytes.

Functions of NK Cells

NK cells possess receptors:
- Activating receptors for recognizing abnormal cells.
- Inhibitory receptors for identifying healthy cells via MHC 1 complex.
Lytic granules within NK cells contain cytotoxic substances used to kill infected cells.

First and Second Line of Defense

First line of defense includes physical barriers like mucous membranes which secrete antimicrobial peptides (defensins) that prevent bacterial adhesion.
The second line of defense involves non-specific immune responses, including:
- Inflammation characterized by redness, heat, swelling, tenderness, and pain.
- Phagocytosis by immune cells such as neutrophils and macrophages to engulf pathogens.
- Fever, which inhibits pathogen growth and enhances immune response.

Molecular Defenses in the Immune System

Pattern Recognition Receptors (PRRs) identify pathogens via Pathogen Associated Molecular Patterns (PAMPs).
Toll-Like Receptors (TLRs), a type of PRR, detect external and internal signals of infection.

Role of Cytokines and Interferons

Interferons, produced during viral infections, can activate NK cells and enhance immune responses.
Various cytokines, like IL-2 and IL-12, facilitate maturation and activation of B and T lymphocytes.

Complement Activation

The complement system comprises about 30 serum proteins that work in conjunction with antibodies.
The classical pathway is initiated when antibodies bind to pathogens, triggering a cascade of reactions that help clear infections.

Immune System Overview

The immune response involves inflammation, phagocytosis, and fever as initial reactions.
Defenses occur on both local and systemic levels, activated once the first line of defense is breached.
Protection mechanisms are generally non-specific.

First Line of Defense

Involves cellular and chemical systems that respond to breaches in skin and epithelial barriers.
Physical barriers also include periodic shedding of skin to remove pathogens.

Second Line of Defense: Innate Immunity

Combats infections with rapid, non-specific responses through components such as interferons and complement systems.
Body's temperature regulation is influenced by pyrogens, overwhelming responses can lead to high fever or convulsions.

Adaptive Immunity: Third Line of Defense

Provides highly specific protection developed through exposure to infectious agents.
Involves specialized defenses like antibodies and lymphocytes.

Microbial Defense Mechanisms

Normal flora protect the body by competing for nutrients and preventing colonization by pathogens.
Chemical barriers such as perspiration help flush out microorganisms and maintain an acidic environment to inhibit pathogen growth.

Fever and Its Benefits

Fever inhibits multiplication of specific microorganisms and reduces the availability of iron for bacterial growth.
Physiological heat enhances hematopoiesis, phagocytosis, and overall metabolic function of immune responses.

Interferons and Immune Response

Interferons (alpha and beta) disrupt viral replication and enhance overall antiviral defenses.
They are produced in response to viral infections and intracellular pathogens.

Toll-Like Receptors (TLRs)

TLRs recognize specific microbial components, aiding in the immune response.
Approximately 10 types of TLRs identify shared pathogen structures, enhancing the ability to combat various microbes.

Natural Killer (NK) Cells

NK cells recognize infected or abnormal cells using killer-activating and killer-inhibitory receptors.
They play a role in targeting virus-infected and tumor cells to eliminate threats.

Anaphylatoxins and Inflammation

Anaphylatoxins promote vasodilation and increase vascular permeability, essential during immune responses.
They bind to receptors on mast cells and basophils, activating further immune activities.

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Description

This quiz explores the mechanisms of the immune response, focusing on the release of histamines and the role of various immune cells during an infection. You'll learn how complement systems and NK cells contribute to fighting viruses and enhancing blood flow to sites of injury.