Immune System

What does the immune system provide?

Resistance to disease.

What are the two main divisions of the immune system?

Innate and adaptive.

What is the first line of defense in the innate immune system?

External membranes such as mucosae and skin.

What is the second line of defense in the innate immune system?

Includes antimicrobial proteins, phagocytes, and other components.

What is the purpose of skin and mucous membranes in the immune system?

They serve as physical barriers to most microorganisms.

What is Keratin's role in the immune system?

It is resistant to weak acids, bases, bacterial enzymes, and toxins.

What does the acid mantle do?

Inhibits the growth of pathogens through acidity of skin and some secretions.

What enzymes found in saliva and other secretions kill microorganisms?

Lysozyme.

What is the role of defensins in the immune system?

They are antimicrobial peptides that inhibit microbial growth.

How does the respiratory system help prevent pathogen entry?

With mucous-lined hairs and cilia that trap and sweep particles out.

What triggers the second line of defense in the innate immune system?

Breaching of surface barriers by cuts or pathogens.

What is involved in the second line of defense?

Phagocytes, natural killer (NK) cells, Inflammation, antimicrobial proteins.

What does inflammation indicate in the body?

That tissues are injured.

What are the benefits of inflammation?

Quarantines the area so it doesn’t travel, disposes of cell debris and pathogens, alerts adaptive immune system, and starts the repair process.

What happens during the chemical release stage of inflammation?

Chemicals like histamine are released to make capillaries leaky and attract phagocytes.

What does vasodilation and increased permeability do to the injured tissue?

Vasodilation causes hyperemia, which causes redness and heat. Permeability causes exudate and edema.

What is margination in the context of inflammation?

Endothelial cells project cell adhesion molecules to grab passing neutrophils.

What activates the complement system?

Antibodies binding to invading organisms.

What are cytokines?

Chemical messengers that mediate immune system responses.

What do helper T cells do?

Activate B cells and orchestrate the immune response.

What is the primary function of B cells?

Produce antibodies for humoral immunity.

What is the difference between humoral and cellular immunity?

Humoral immunity involves antibodies, while cellular immunity involves T cells attacking infected cells.

What triggers the activation of T cells?

The binding of antigens and co-stimulation on antigen presenting cells.

What is the role of antigen presenting cells in the immune response?

They engulf antigens and present fragments to T cells.

What is the primary function of cytotoxic T cells?

To directly kill virus-infected or cancerous cells.

What are the two types of active humoral immunity?

Naturally acquired and artificially acquired.

What is the role of antibodies?

To neutralize pathogens and mark them for destruction.

What type of hypersensitivity is also known as allergies?

Immediate hypersensitivity.

What is anaphylaxis?

A severe and life-threatening allergic reaction.

What are the major classes of antibodies?

IgM, IgA, IgD, IgG, and IgE.

What are characteristics of IgM?

Pentamer, potent agglutinating agent, ready fixes and activates complement.

What are characteristics of IgA?

Monomer or dimer, found in mucus and other secretions, and help prevent pathogen entry.

What are characteristics of IgD?

Monomer attached to surface of B cells.

What are characteristics of IgG?

Monomer, 75%-85% of antibodies in plasma from secondary and late primary responses, and crosses placental barrier

What are characteristics of IgE?

Monomer active in some allergies and parasitic infections and causes mast cells and basophils to release histamine.

What is the importance of memory cells?

They provide immunological memory for faster and stronger responses upon re-exposure.

What are examples of autoimmune diseases?

Myasthenia gravis, Graves’ disease, and Rheumatoid arthritis.

What triggers the adaptive immune response?

Re-exposure to the same virus or antigen.

What is the role of natural killer cells?

To kill cells that do not have 'name tags' indicating they belong to the body.

What is the primary source of immune stem cells after the fetal stage?

Bone marrow.

How does the immune system change with age?

It becomes less effective, increasing the likelihood of autoimmune diseases.

What type of cells can directly kill infected cells in cellular immunity?

Cytotoxic T cells.

What substance is responsible for raising body temperature during a fever?

Pyrogens.

What kind of immunity is gained from vaccines?

Artificially acquired active immunity.

How do T cells recognize their target antigens?

Through specific antigen receptors.

What proteins are found on the surface of all cells that can indicate self versus non-self?

MHC antigens.

What occurs during the process of leukocytosis in inflammation?

Release of neutrophils from the bone marrow.

What happens during the priming of the adaptive immune system?

It prepares specific lymphocytes to respond to an antigen.

What do regulatory T cells do?

They control the immune response to prevent excessive tissue damage.

What is SCID?

Severe combined immunodeficiency syndrome, a genetic defect in immune function.

What is autoimmunity?

Loss of the immune system's ability to distinguish self from foreign.

What differentiates an antigen from a hapten?

Antigens are complete and can provoke an immune response, while haptens are incomplete.

How does an individual develop sensitization to an allergen?

Through the initial asymptomatic contact that leads to memory cell formation.

What is the significance of the CD4 receptor?

It is found on helper T cells which activate B cells.

What is significant about CD8?

CD8 becomes cytotoxic T cells that aids in recognizing and responding to infected cells.

What molecule mediates the activation of T cells?

Cytokines.

What does complement fixation refer to?

Antibodies binding to antigens which triggers a series of reactions to destroy the pathogen.

What is delayed hypersensitivity?

A reaction that occurs slower and is mediated by T cells.

What is an example of a type III hypersensitivity reaction?

Systemic lupus erythematosus.

What do mast cells release in allergic reactions?

Histamine.

What is the role of interleukin-2?

It promotes T cell proliferation.

What is meant by 'stress' influencing the immune response?

Emotional stress can impair immune function.

Why do older adults have an increased risk of cancer?

Due to a decline in immune system efficiency.

What is the significance of the 'lethal hit' mechanism in cytotoxic T cells?

It allows them to directly kill infected cells by creating pores and releasing enzymes.

What is the process called when phagocytes recognize pathogens?

Adherence.

What do humoral immune responses target, extracellularly or intracellularly?

Extracellular targets.

What do cellular immune responses target, extracellularly or intracellularly?

Intracellularly.

What defines a complete antigen?

It has both immunogenicity and reactivity.

What happens to the immune system's ability as one ages?

It tends to decline, leading to increased susceptibility to infections.

How does the body respond to a second exposure to the same pathogen?

With a faster and more effective immune response.

What can trigger autoimmune diseases?

Foreign antigens resembling self-antigens.

How are cells affected during chronic inflammation?

They can experience ongoing damage and dysfunction.

What can happen if the immune system fails to maintain self-tolerance?

It may result in autoimmune diseases.

What is the primary antibody produced in response to a secondary immune response?

IgG.

What type of immune cells originate from lymphoid stem cells?

T cells and B cells.

What molecules are used as 'name tags' for self-identification on cell surfaces?

MHC molecules.