Chapter 17: Innate Non-Specific Host Defenses

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Questions and Answers

What initiates the inflammation process?

Recruitment of neutrophils to tissues

Formation of a fibrin clot

Activation of the complement system

Release of cytokines by macrophages (correct)

Which mechanism directly leads to fluid accumulation during inflammation?

Formation of complement proteins

Vasodilation of capillary walls (correct)

Activation of cytokines

Recruitment of phagocytes

What is the primary function of a fibrin clot in the inflammatory response?

To enhance phagocytosis

To prevent the spread of infection (correct)

To promote cytokine release

To inhibit vasodilation

Pyrogens are substances classified as what?

Substances that induce fever by acting on the hypothalamus Signup and view all the answers

Which mechanism describes the process of marking pathogens for phagocytosis?

The marking of pathogens for phagocytosis Signup and view all the answers

In terms of inflammation, what does edema refer to?

The accumulation of fluid in tissues Signup and view all the answers

Which signaling type is associated with cytokines that affect nearby cells?

Paracrine Signup and view all the answers

Which acute-phase protein is responsible for binding and sequestering iron?

Ferritin Signup and view all the answers

Which antimicrobial peptide secreted by salivary glands disrupts intracellular function?

Histatins Signup and view all the answers

What role do chemokines serve in innate immunity?

To attract neutrophils and macrophages to infected tissue Signup and view all the answers

What distinguishes the paracrine signaling mechanism from other signaling types?

Signals are secreted and act on adjacent cells. Signup and view all the answers

Which type of immune cell is primarily responsible for the rapid response in the initial stage of infection?

Neutrophils Signup and view all the answers

What role do chemokines play during the inflammatory response?

They attract phagocytes to the site of infection. Signup and view all the answers

What is the primary function of interleukins in the immune system?

To facilitate communication between different immune cells. Signup and view all the answers

Which of the following best describes the role of microbiota in innate immunity?

They compete with pathogens for nutrients and space. Signup and view all the answers

Which of the following statements about natural killer (NK) cells is accurate?

They destroy infected cells without prior sensitization. Signup and view all the answers

What is the primary function of lysozyme found in tears and saliva?

To target and break down Gram-positive peptidoglycan. Signup and view all the answers

In the context of phagocytosis, what does opsonization refer to?

The marking of pathogens to enhance ingestion. Signup and view all the answers

What is a primary characteristic of macrophages in the immune system?

Phagocytic activity and long-term presence. Signup and view all the answers

Which component is NOT considered a physical barrier in the innate immune system?

Antimicrobial peptides Signup and view all the answers

Which type of cytokine is primarily involved in the antiviral response?

Interferons Signup and view all the answers

What function do acute phase proteins serve in the innate immune response?

Coat bacteria to prepare them for ingestion. Signup and view all the answers

Which component of blood is crucial in forming a fibrin clot to prevent the spread of infection?

Platelets Signup and view all the answers

What is the primary role of the complement system in innate immunity?

To enhance phagocytosis, inflammation, and pathogen lysis. Signup and view all the answers

Which type of immunity is characterized by specific resistance to pathogens?

Acquired Immunity Signup and view all the answers

What is the primary role of pyrogens in the body?

To induce fever by acting on the hypothalamus. Signup and view all the answers

What is the primary role of defensins in innate immunity?

To disrupt the membranes of various pathogens. Signup and view all the answers

Which of the following best describes the function of cytokines in the immune response?

They act as signaling proteins to recruit immune cells. Signup and view all the answers

Which of the following is NOT a function of plasma protein mediators in innate immunity?

Disrupting intracellular functions of viruses. Signup and view all the answers

What is a primary characteristic of the 1st line of defense in innate immunity?

It consists of physical and chemical barriers. Signup and view all the answers

Study Notes

Innate Non-Specific Host Defenses Study Notes

Immunity: The body's ability to resist disease.
Immune System: Collection of cells, tissues, and molecules protecting the body from pathogens.
Immunology: Scientific study of the immune system's function.
Innate Immunity: Nonspecific, inborn defense mechanisms.
1st Line of Defense: Physical barriers (skin, mucous membranes/secretions).
2nd Line of Defense: White blood cells, inflammation, antimicrobial substances.
Acquired Immunity: Specific resistance, with memory and targeted response.
3rd Line of Defense: Antigen-specific defenses targeting particular pathogens.

Physical Barriers

Skin: Keratinized barrier, sheds microbes, compromised skin allows entry.
Mucous Membranes: Line internal tracts (respiratory, digestive, urogenital).
Mechanical Defenses: Flushing (tears, urine), mucus trapping/expelling pathogens.
Microbiota: Competes with pathogens for resources (nutrients, space).

Chemical Barriers

Enzymatic Mediators:
- Lysozyme: Tears, saliva; targets Gram-positive peptidoglycan.
- Digestive Enzymes: (amylase, bile, lipase) in saliva, stomach acid.
Lactoferrin: Sequesters iron, inhibits pathogen growth.
Antimicrobial Peptides:
- Bacteriocins: Secreted by microbiota, disrupt membranes.
- Cathelicidin, Defensins, Dermicidin: Secreted by skin cells; disrupt microbial membranes.
- Histatins: Secreted by salivary glands; disrupt intracellular function.
Plasma Protein Mediators (produced in liver):
- Acute Phase Proteins:
  - C-reactive protein/Serum amyloid A: Coats bacteria for ingestion.
  - Ferritin/transferrin: Bind & sequester iron, inhibiting growth.
  - Fibrinogen: Forms blood clots.
  - Mannose-binding lectin: Activates complement cascade.
Complement System: Enhances phagocytosis, inflammation, and pathogen lysis (effective against Gram-negative bacteria).
Opsonins: Enhance phagocytosis by marking pathogens for recognition.
Cytokines: Signaling proteins, recruiting immune cells, antiviral actions. (Autocrine, paracrine, endocrine signaling mechanisms).
- Interleukins: Stimulate most immune functions.
- Chemokines: Stimulate migration of neutrophils/macrophages to infected tissues.
- Interferons: Trigger macrophage activation, interfere with RNA viral reproduction.

Cellular Barriers

Blood: Fluid, clotting agents.
Serum: Fluid portion of blood.
Blood Platelets: Small, disk-shaped cells from bone marrow.
Granulocytes: Initial infection stage, concentrated in skin, lungs, and GI tracts.
- Neutrophils: First responders, short lifespan.
Agranulocytes:
- Monocytes: Single nucleus, phagocytic after leaving bloodstream.
- Macrophages: Mature monocytes, effective long-term phagocytosis.
- Dendritic Cells: Link innate and acquired immunity.
- Natural Killer (NK) Cells: Attack and destroy cancer/infected cells without prior sensitization. (release perforins & granzymes)

Phagocytosis and Inflammation

Phagocytosis: Immune cells capturing & digesting foreign particles.
Inflammation: Response to infection, tissue damage.
Steps of Inflammation:
- Initiation: Macrophages release cytokines.
- Vasodilation: Capillaries dilate, fluid accumulation (edema).
- Phagocyte Recruitment: Chemokines attract phagocytes.
- Formation of Fibrin Clot: Prevents infection spread.

Other Key Concepts

Pyrogens: Substances that induce fever.
Edema: Fluid accumulation due to vasodilation.

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Explore the fundamental concepts of the immune system and innate non-specific host defenses. This quiz covers the lines of defense, physical barriers, and the role of white blood cells in immunity. Perfect for students studying immunology or related fields.