chapter 14

What is the first line of defense in innate immunity?

Physical and chemical barriers that prevent pathogen entry.

What type of response does innate immunity provide?

An immediate and non-specific response to pathogens.

What are the three lines of defense in innate immunity?

Physical/Mechanical, Chemical, and Cellular Defenses.

What are tight junctions?

Cell junctions that keep pathogens from entering tissues.

What role does keratin play in skin defense?

Keratin forms a tough layer on the epidermis that resists breakdown by bacterial enzymes.

How do mucous membranes protect against infection?

They secrete mucus that traps debris and microbes.

What mechanical defense does the body use to expel mucus?

The mucociliary escalator.

What is the role of sebum in skin defense?

Sebum creates an acidic environment that inhibits the growth of many pathogens.

What is opsonization in the context of the complement system?

The process of coating a pathogen to enhance its uptake by immune cells.

What are antimicrobial peptides (AMPs)?

Proteins secreted by cells that damage microorganism membranes or interfere with cell-wall synthesis.

What are cytokines?

Proteins that act as communication signals between cells and stimulate various cell functions.

What are the two main types of white blood cells involved in innate immunity?

Agranulocytes and Granulocytes.

What role do neutrophils play in innate immunity?

They destroy bacteria and migrate to areas of infection.

What do eosinophils protect against?

Protozoa and helminths, and they play a role in allergic reactions.

How do Natural Killer (NK) cells identify and kill abnormal cells?

They recognize and kill cells lacking MHCI on their surface.

What are pattern recognition receptors (PRRs) in phagocytes?

Receptors that recognize pathogen-associated molecular patterns (PAMPs).

Name one bacterial PAMP that phagocytes recognize.

Peptidoglycan.

What is the function of the skin in innate immunity?

The skin acts as a physical barrier that prevents pathogen entry and protects underlying tissues.

What role do lysozymes play in innate immunity?

Lysozymes are enzymes found in bodily fluids that break down bacterial cell walls.

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

The complement system enhances the ability of antibodies and phagocytic cells to clear pathogens.

How do macrophages contribute to innate immunity?

Macrophages engulf and digest pathogens and debris and also present antigens to activate adaptive immunity.

What is the inflammatory response?

A protective response that involves the recruitment of immune cells to the site of injury or infection.

How do dendritic cells function in innate immunity?

Dendritic cells capture antigens and present them to T cells, linking innate immunity with adaptive immunity.

What triggers the release of histamines during an immune response?

Histamines are released from mast cells in response to injury or allergens, promoting vasodilation and increased permeability.

What is the role of phagocytosis in innate immunity?

Phagocytosis is the process by which certain immune cells engulf and digest pathogens.

What is an antigen?

An antigen is a substance that induces an immune response, often found on the surface of pathogens.

How do cytokines influence the immune response?

Cytokines regulate the intensity and duration of immune responses by mediating communication between cells.

What is the role of inflammatory mediators in innate immunity?

Inflammatory mediators, like bradykinin and prostaglandins, promote local inflammation and recruit immune cells to sites of infection.

What is the function of natural barriers in innate immunity?

Natural barriers, such as skin and mucous membranes, act as the first line of defense to prevent pathogen entry.

How do neutrophils respond to an infection?

Neutrophils rapidly migrate to sites of infection where they perform phagocytosis and release enzymes to kill pathogens.

What is the function of dendritic cells in linking innate and adaptive immunity?

Dendritic cells capture pathogens and present their antigens to T cells, activating the adaptive immune response.

What is the purpose of fever in innate immunity?

Fever raises body temperature, which can inhibit pathogen growth and enhance the immune response.

How does the skin microbiome contribute to innate immunity?

The skin microbiome competes with pathogens and produces substances that inhibit their growth.

What are defensins?

Defensins are small cationic peptides that disrupt microbial membranes and have antimicrobial activity.

What is the significance of the blood-brain barrier in immunity?

The blood-brain barrier protects the central nervous system by restricting the entry of pathogens and inflammatory cells.

What role does the gastrointestinal tract play in innate immunity?

The gastrointestinal tract has mechanisms like acid secretion and beneficial microbiota that provide protection against pathogens.

What is the significance of the acute phase response?

The acute phase response involves immediate changes in the concentration of plasma proteins that enhance immune response during inflammation.

What initiates the complement system?

The complement system can be initiated by pathogen surfaces, antibodies bound to pathogens, or certain pathogens directly.

What are the three main pathways of the complement system?

The classical pathway, alternative pathway, and lectin pathway.

What is the end result of the complement system activation?

Activation leads to the formation of the membrane attack complex (MAC), which can lyse pathogens.

How does the complement system enhance opsonization?

The complement system coats pathogens with proteins that facilitate their recognition and phagocytosis by immune cells.

What is the role of C3 in the complement system?

C3 is a key protein that, when cleaved, initiates both the classical and alternative pathways of the complement system.

What are anaphylatoxins and their role in innate immunity?

Anaphylatoxins, like C3a and C5a, promote inflammation by activating mast cells and recruiting more immune cells to the site of infection.

How do complement proteins facilitate inflammation?

Complement proteins promote vasodilation, increase vascular permeability, and attract immune cells to sites of infection.

What is the role of the membrane attack complex (MAC)?

The MAC forms pores in the pathogen membrane, leading to cell lysis and death of the pathogen.

What is the relationship between the complement system and antibodies?

Antibodies can activate the classical pathway of the complement system, enhancing the immune response against pathogens.

What is the importance of regulatory proteins in the complement system?

Regulatory proteins prevent excessive complement activation and damage to host cells.