BIOS242 Exam 3 Review Flashcards

Host Defenses

Innate and acquired immunological defenses.

Innate Immune Response

The body's immediate, non-specific defenses against pathogens, including physical barriers, phagocytic cells, and inflammatory responses.

Acquired Immune response

A specific immune response developed over time, characterized by the production of antibodies and memory cells following exposure to pathogens.

Physical barriers

The first line of defense in the immune system that includes skin, mucous membranes, and secretions that prevent pathogen entry.

Microbiota barrier

A defensive mechanism provided by the diverse community of microorganisms living in and on the body, which helps to prevent pathogen colonization and infection.

Chemical barriers

Substances produced by the body, such as enzymes and antimicrobial peptides, that help inhibit pathogen growth and promote a healthy environment.

First line of defense

A surface protection composed of anatomical and physiological barriers that keep microbes from penetrating sterile body compartments.

• Barriers that block invasion at the portal of entry

• Does not involve recognition of foreign substances

• General in action

Second line of defense

A cellular and chemical system that comes immediately into play if infectious agents make it past the surface defenses.

• Nonspecific

• Internalized system of protective cells and fluids

• Inflammation and phagocytosis

• Acts rapidly at the local and systemic levels

Phagocytosis

The process by which certain cells, such as macrophages and neutrophils, engulf and digest pathogens or debris to protect the body from infection.

Inflammation

A biological response to harmful stimuli such as pathogens or injury, characterized by redness, heat, swelling, and pain, aimed at removing the injurious stimuli and initiating the healing process.

Fever

An elevated body temperature that occurs as part of the immune response to infection, helping to enhance the activity of immune cells and inhibit the growth of pathogens.

Antimicrobial products

Substances that kill or inhibit the growth of microbes, including bacteria, viruses, and fungi, and are often used in medical and personal care applications to prevent infections. Examples such as antibiotics, antiseptics, and disinfectants.

Third line of defense

Includes specific host defenses that must be developed uniquely for each microbe through the action of specialized white blood cells.

• Acquired on an individual basis as each foreign substance is encountered by lymphocytes

• Produces unique protective substances and cells that can come into play if the microbe is encountered again

• Provides long-term immunity

B cells

A type of white blood cell that plays a crucial role in the adaptive immune response by producing antibodies specific to antigens, aiding in the neutralization and elimination of pathogens.

T cells

A type of lymphocyte that plays a central role in cell-mediated immunity, these cells recognize and attack infected or cancerous cells, and help coordinate the immune response.

Neutrophils

• Phagocytic

• Found in blood

• First to respond

• Increase during bacterial infections

Basophils

• Function in inflammatory events

• Usually found in low numbers

Eosinophils

• Active in protozoal and helminth reactions

• Usually found in low numbers

• Elevated in allergic reactions

Mast cells

• Found in the tissues

• Similar to basophils

• Contain histamine

Monocytes

Blood phagocytes that rapidly leave the circulation; mature into macrophages and dendritic cells

Macrophages

Large phagocytic cells; high capacity for killing microbes and cleaning up dead cells; antigen-presenting cells

Dendritic cells

Reside in tissues and MPS; process foreign matter and present it to lymphocytes; antigen-presenting cells

Natural killer (NK) cells

A type of lymphocyte that plays a crucial role in the immune response by detecting and destroying abnormal cells, such as virus-infected or cancer cells, without requiring prior sensitization.

Phase 1 of phagocytosis

Chemotaxis by phagocyte

• Phagocytes must move to the site of injury

• They follow the trails of chemicals released by damaged tissues

Phase 2 of phagocytosis

Adhesion of bacteria

• Phagocytic cell PPRs (Pattern recognition receptors) recognize and bind microbial PAMPs (Pathogen-associated molecular patterns)

Phase 3 of Phagocytosis

Engulfment into phagocytic vacuole

Phase 4 of phagocytosis

Phagosome

Phase 5 of phagocytosis

Phagolysosome formation

Phase 6 of phagocytosis

Killing and destruction of bacterial cells

Phase 7 of phagocytosis

Release of residual debris

• Not all the debris is released

• Some debris is shown to T cells

Classical Pathway

A complement activation pathway triggered by antigen-antibody complexes, leading to opsonization and lysis of pathogens.

Lectin Pathway

A complement activation pathway initiated by the binding of lectins to specific carbohydrates on pathogen surfaces, which activates complement proteins.

Alternative Pathway

A complement activation pathway that is triggered by the spontaneous activation of complement proteins on pathogen surfaces, leading to opsonization and inflammation.

Adaptive Immunity: Specificity

Response can be focused on a single antigen

Adaptive Immunity: Diversity

Always at least one cell that can react against any antigen

Adaptive Immunity: Inducibility

Only turned on when triggered

Adaptive Immunity: Clonality

Generates millions of cells with the same specificity.

Adaptive Immunity: Tolerance

Does not react with self antigens

Adaptive Immunity: Memory

Rapid mobilization of lymphocytes preprogrammed to recall their first engagement with the antigen

Antigen

Molecules that can be seen and identified by the immune system

Epitope

Specific region of an antigen that is recognized by the immune system.

Hapten

Small molecule that must bind to a carrier molecule; enhances immunogenicity.

B cell maturation

Bone marrow

B cells binding and location

Bind to antigens and are found in the blood with their cell receptor

B cell activation requirement

Help from helper T cells

Maturation of B cells

Mature into plasma cells once activated, they then start to secrete antibodies.