The Immune System Flashcards
pathogens
agents that cause disease, such as bacteria, viruses, fungi, or others
Function of Immune System
recognizes foreign bodies and responds with the production of immune cells and proteins
innate immunity
a defense active immediately upon infection, consists of external barriers, and internal cellular and chemical defenses
adaptive immunity
a defense developed after exposure to toxic agents. Specific response to pathogens.
innate immunity is found in
all animals and plants
adaptive immunity is found in
all vertebrates
phagocytosis
the ingestion and breakdown of foreign substances including bacteria
lysozyme
an enzyme, in the digestive system, that breaks down bacterial cell walls, protecting against pathogens ingested with food
innate immunity in insects
exoskeleton
innate defenses in humans
phagocytosis, barrier defenses, and antimicrobial peptides, inflammatory response,
barrier defenses
the skin and mucous membranes of the respiratory, urinary, and reproductive tracts. Many body fluids including saliva, mucus, and tears are hostile to many microbes
Toll-like receptors (TLRs)
phagocytic cells recognize groups of pathogens by TLRs
cellular innate defense
Pathogens entering the mammalian body are subject to phagocytosis.
phagocytic cells(2)
neutrophils and macrophages.
neutrophils
circulate in the blood and are attracted by signals from infected tissue.
macrophages
a type of phagocytic cell found throughout the body
T cells
an adaptive immunity
B cells
lymphoid cells that turn into the adaptive immunity of antibodies
2 other phagocytic cells
dendritic cells, within cells that contact the environment, and eosinophils, discharge destructive enzymes beneath mucosal surfaces
cellular innate defense of natural killer cells
These cells circulate the body and detect abnormal cells, release chemicals leading to cell death, ending viral infections.
interferons
provides innate defense, interfering with viruses and activating macrophages.
inflammatory response
The inflammatory response, such as pain and swelling, is brought about by molecules released upon injury of infection. Such as mast cells, cytokines
fever
the systemic(throughout the body) inflammatory response triggered by substances released by macrophages
septic shock
a life-threatening condition caused by an overwhelming inflammatory response
mast cells
releases histamine, which triggers blood vessels to dilate and become more permeable
cytokines
released by monocytes and neutrophils, they are signaling molecules that modulate the immune response and promote blood flow to the site of injury or infection
The adaptive response relies on:
lymphocytes: that are mature in the thymus above the heart(T cells), and those that are mature in bone marrow(B cells)
antigens
substances that can elicit a response from a B or T cell
epitope
The small accessible part of an antigen that binds to an antigen receptor
B-cell antigen receptor
Y- shaped, 2 heavy chains and 2 light chains
the V region of the heavy and light chains forms:
the antigen-binding site
antibody or immunoglobulin(Ig)
The binding of a B cell antigen receptor to an antigen gives rise to cells that secrete a soluble form of the protein(Ig)
antigen recognition by T cells
Each T cell receptor consists of two different polypeptide chains (called α and β). The tips of the chain form a variable (V) region; the rest is a constant (C) region. The V regions of the α and β chains together form an antigen-binding site. T cells bind only to antigen fragments displayed or presented on a host cell
MHC (major histocompatibility complex)
molecules are host proteins that display the antigen fragments on the cell surface
antigen presentation
MHC molecules bind and transport the antigen fragments to the cell surface, a process called antigen presentation
T cells bind to:
both the antigen fragment and the MHC molecule. This interaction is necessary for the T cell to participate in the adaptive immune response
The adaptive immune system has four major characteristics
Diversity of lymphocytes and receptors
Self-tolerance; lack of reactivity against an animal’s own molecules
Proliferation of B and T cells after activation
Immunological memory
B and T cell diversity: ex. light chain gene
The gene contains one C segment, 40 different V segments, and 5 different J segments
immunology memory
is responsible for long-term protection against diseases
primary immune response
first exposure to a specific antigen. During this time, selected B and T cells give rise to their effector forms
secondary immune response
In which memory cells facilitate a faster, stronger, and longer response
allergies
exaggerated (hypersensitive) responses to antigens called allergens
Antihistamine function
Antihistamines block receptors for histamine and diminish allergy symptoms
autoimmune diseases
In individuals with autoimmune diseases, the immune system targets certain molecules of the body. ex arthritis
