Immunology Lecture 5: Immune System Overview

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Questions and Answers

What is the immune system?

Complex organization of cells, tissues, chemicals; regulated by checks, balances, back-ups, and fail safes.

What are the jobs of the immune system?

Prevent pathology caused by microbes.

What must a pathogen do to cause disease?

Gain access to the body, attach to host cells, and evade host defense systems.

What is the first line of defense for the immune system?

Serves as barriers to invasion. Signup and view all the answers

What mechanical defenses are present in the skin?

Epithelial cells joined by tight junctions and longitudinal flow of air or fluid. Signup and view all the answers

What are the chemical defenses in the skin?

Fatty acids and antibacterial peptides. Signup and view all the answers

What mechanical defenses are present in the gut?

Epithelial cells joined by tight junctions and longitudinal flow of air or fluid. Signup and view all the answers

What are the chemical defenses in the gut?

Low pH, enzymes (like pepsin), and antibacterial peptides. Signup and view all the answers

What mechanical defenses are present in the lungs?

Epithelial cells joined by tight junctions and movement of mucus by cilia. Signup and view all the answers

What are the first line defenses in the eyes/nose?

Epithelial cells joined by tight junctions, tears, and nasal cilia. Signup and view all the answers

What are the two forms of immunity?

Innate and Adaptive. Signup and view all the answers

What is innate immunity?

Non-adaptive, immediate response with broad specificity. Signup and view all the answers

What is adaptive immunity?

Highly specific response that takes time to develop. Signup and view all the answers

What are the innate host defense mechanisms?

Mechanical and physical barriers, chemical factors, microbial antagonism, fever, inflammatory response, and phagocytic white blood cells. Signup and view all the answers

What are the goals of inflammation in innate immunity?

Prevent entry/proliferation of pathogens, kill invading pathogens, localize damage, recruit other cells, and activate immune response. Signup and view all the answers

What physical barriers to infection does the skin provide?

Protective shield made by keratinocytes with slightly acidic pH. Signup and view all the answers

What is skin-associated lymphoid tissue (SALT)?

Recognizes microbes that may slip past the physical barrier. Signup and view all the answers

What role do mucous membranes play in immunity?

Barrier against invading pathogens and secretes mucus to trap microbes. Signup and view all the answers

What are microbe-associated molecular patterns (MAMPs)?

Patterns recognized by cell surface receptors such as Toll-like receptors. Signup and view all the answers

What are mucosa-associated lymphoid tissue (MALT) and gut-associated lymphoid tissue (GALT)?

They are lymphoid tissues associated with the mucosa and gut areas. Signup and view all the answers

Study Notes

Immune System Overview

Complex organization of cells, tissues, and chemicals; governed by checks, balances, and fail safes.
Organized into tissue-specific systems to prevent pathogen invasion.
Functions are diverse and specialized for targeted pathogen response.

Jobs of the Immune System

Prevents pathology caused by microbes with specific functions to block pathogen-induced harm.

Pathogen Requirements for Disease

Gain entry through skin penetration or designated portals.
Attach to host cells to establish infection.
Evade host defense systems to persist.

First Line of Defense

Acts as barriers against invasions: skin, gut, lungs, and eyes/nose.

Skin as a Defense

Mechanical: Epithelial cells with tight junctions and fluid flow.
Chemical: Fatty acids and antibacterial peptides provide a hostile environment for pathogens.
Microbiological: Normal flora competes with potential invaders.

Gut as a Defense

Mechanical: Similar epithelial structure and fluid dynamics.
Chemical: Low pH, pepsin, and antibacterial peptides protect against pathogens.
Microbiological: Hosts normal flora that further inhibit harmful microbes.

Lungs as a Defense

Mechanical: Epithelial cells and cilia-driven mucus movement trap and expel particles.
Chemical: Secretion of antibacterial peptides.

Eyes/Nose as a Defense

Mechanical: Epithelial cells and protective secretions like tears and nasal cilia.
Chemical: Enzymes (e.g., lysosome) in tears target microbes.

Types of Immunity

Two forms: Innate and Adaptive.

Innate Immunity

Non-adaptive, immediate response within minutes to hours; broad specificity.
Recognizes microbial patterns, operates continuously during infections.
Lacks memory but includes antimicrobial peptides and phagocytic cells.

Adaptive Immunity

Develops over days, highly specific for individual pathogens.
Provides long-lasting protection and establishes memory through genetic changes, antibodies, and lymphocytes.

Innate Host Defense Mechanisms

Defend against harmful substances through:
- Mechanical and physical barriers.
- Chemical factors and microbial antagonism.
- Fever, inflammatory response, and phagocytic activity.

Goals of Inflammation in Innate Immunity

Direct Actions: Prevents pathogen entry, kills invaders, and localizes damage.
Indirect Actions: Recruits cells, regulates immune response, facilitates healing, and induces inflammation.

Skin as a Physical Barrier

Keratinized shield protects underlying tissues; slightly acidic pH inhibits bacteria.
Sebum covers skin, competing with pathogens and aiding in removal of outer layers.
Skin-associated lymphoid tissue (SALT) plays a role in immune recognition.

Skin-Associated Lymphoid Tissue (SALT)

Recognizes microbes that breach skin barriers; Langerhans cells act as specialized dendritic cells.

Mucous Membranes as Barriers

Selectively permeable, secreting mucus that traps microbes and coalitions antibacterial compounds.
Structures include MAMPs, MALT, GALT, Peyer's patches, and M cells enhance mucosal immunity.

Microbe-Associated Molecular Patterns (MAMPs)

Recognized by surface receptors such as Toll-like receptors and CD14, facilitating immune responses.

Mucosa-Associated and Gut-Associated Lymphoid Tissue (MALT/GALT)

Integral to immune monitoring and responses within mucosal surfaces.
Support immune function against pathogens entering through mucosal surfaces.

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Explore the fundamentals of the immune system in this flashcard quiz from Lecture 5. Learn about its organization, specialized functions, and how it serves as the first line of defense against pathogens. Perfect for those studying immunology.