Immune System Flashcards
What percentage of blood volume to white blood cells occupy?
1%
What is leukocytosis?
Leukocytosis refers to an increase in the total number of white blood cells (WBCs) due to any cause. More than 11, 000 per microliter of blood.
What are the two major groups of leukocytes?
Granulocytes and agranulocytes
What is the process of leukocytes leaving capillaries called?
Diapedesis
True or false: Leukocytes move through tissue spaced by amoeboid motion and positive chemotaxis
True
Which leukocytes are considered granular?
Neutrophils, eosinophils, basophils
Which leukocytes are considered a granular?
Lymphocytes, monocytes
True or false: Neutrophils contain many differently shaped nuclear lobes
True
What is the name of the process that neutrophils use to kill microbes using oxidizing substances such as bleach or hydrogen peroxide?
Respiratory burst
What is the most numerous leukocyte?
Neutrophils (50-70% of WBCs)
What is the rarest leukocyte?
Basophils (0.5-1%)
Which leukocyte releases enzymes on large parasitic worms, digesting their surface?
Eosinophils
True or false: Eosinophils play a role in allergies and asthma
True
Which leukocyte contains histamine?
Basophils
What is the difference between granulocytes and agranulocytes?
Granulocytes contain visible granules
True or false: Monocytes are the second most abundant WBC
False: Lymphocytes are (25%)
Which leukocyte is mostly found in lymphoid tissue?
Lymphocytes
What is the function of T lymphocytes?
Act against virus-infected cells and tumor cells
What is the function of B lymphocytes?
Give rise to plasma cells, which produce antiobdies
What is the largest of all leukocytes?
Monocytes
Which leukocyte has a kidney-shaped nuclei?
Monocyte
Which leukocyte differentiates into macrophages that can activate lymphocytes to mount an immune response?
Monocyte
What two hormones regulate the production of leukocytes?
Interleukins (ILs) and Colony-stimulating factors (CSFs)
True or false: All leukocytes originate from hemocytoblast stem cell
True
Where are mature granulocytes stored?
Bone marrow
What is the life span of granulocytes?
0.5-9 days
What is leukemia?
Cancerous condition involving overproduction of abnormal WBCs, usually involving the clones of a single abnormal cell
What is acute leukemia derived from?
Stem cells
What is the name of the disease that is caused by the Epstein-Barr virus and results in lymphocytes that become enlarged?
Infectious mononucleosis (kissing disease)
What is leukopenia?
Abnormally low WBC count, usually due to drugs
What do the surface barriers of the innate defenses consist of?
Skin and mucous membranes
What do the internal defenses of the innate defenses consist of?
Phagocytes, natural killer cells, inflammation, antimicrobial proteins, fever
Which cells are present for humoral immunity in the adaptive defenses?
B cells
Which cells are present for cellular immunity in the adaptive defenses?
T cells
Which system, innate or adaptive, protects against foreign substances without having to specifically identify them?
Innate
True or false: Keratin is present in the second line of defense
False, first line of defense
What are the protective chemicals that skin and mucous membranes produce that inhibit or destroy microorganisms?
Acid, enzymes, mucin, defensins, and other chemicals
True or false: Many second-line cells have pattern recognition receptors that disarm microbes before they do harm
True
What are phagocytes?
WBCs that eat foreign invaders yummy yummy in my motherfucking tummy bitch fuck you
True or false: Neutrophils are the most abundant phagocytes, but die fighting
True
Describe the two types of macrophages
Free macrophages: wander through tissue spaces
Fixed macrophages: Permanent residents of some organs
What is opsonization?
When the immune system uses antibodies or complement proteins that coat pathogens to make it easier for phagocytes to grab on to the pathogen, thus enhancing phagocytosis
Which cells trigger macrophages to produce a respiratory burst that kills pathogens resistant to lysosomal enzymes during phagocytosis?
Helper T cells
True or false: Neutrophils have defensin granules that merge with the phagosome to form spears that pierce holes in membrane of ingested microbe
True
True or false: Natural killer cells are phagocytic
False
Do natural killer cells identify invaders?
No. They recognize abnormalities on surface of body cells such as loss of self-antigens
True or false: People with AIDS have greatly reduced phagocytes
False, they have greatly reduced natural killer cells
What are the benefits of inflammation?
Prevents spread of damaging agents to nearby tissues, disposes of cell debris and pathogens, sets the stage for repair processes, alerts the adaptive immune system
What are the 4 key signs of inflammation?
Redness, heat, swelling, pain. Sometimes there is a fifth sign: impairment of function.
What are the three stages of inflammation?
Inflammatory chemical release, vasodilation and increased vascular permeability, and phagocyte mobilization
What chemical compound do mast cells release that acts as a key inflammatory chemical?
Histamine
What causes redness and heat in inflammation?
Vasodilation which causes hyperemia (increased blood flow)
Why do we feel pain when there’s inflammation?
Swelling pushes on nerve endings
Why is edema (swelling) important in inflammation?
Surge of fluid sweeps foreign material into lymphatic vessels for filtration
Delivers clotting proteins and complement to area
Clotting factors form fibrin mesh that acts as scaffold for repair and so that invaders cannot spread
What causes swelling in inflammation?
Increased capillary permeability causes exudate to leak into tissue
What are the first and second responders in the phagocyte mobilization stage of inflammation?
Neutrophils first, then macrophages
What are the four steps of phagocyte mobilization?
Leukocytosis, margination, diapedesis, chemotaxis
Describe the four steps of phagocyte mobilization
Leukocytosis: neutrophils enter blood from bone marrow
Margination: neutrophils cling to capillary wall (cell-adhesion molecules)
Diapedesis: Neutrophils flatten and squeeze out of capillaries
Chemotaxis: Neutrophils follow chemical trail
How do antimicrobial proteins enhance innate defense?
Attack microorganisms directly or hinder their ability to reproduce
What are the two most important types of antimicrobial proteins?
Interferons and complement proteins
What is the role of interferon?
Secreted by virus-infected cells to warn healthy neighbouring cells, activate macrophages and mobilize natural killer cells
What is the role of complement proteins?
Provide major mechanism for destroying foreign substances, activation enhances inflammation and directly destroys bacteria (enhances both innate and adaptive defenses)
What are the three pathways of complement system activation?
Classical pathway, lectin pathway, alternative pathway
Proteins C1-C9 are what kind of proteins?
Complement proteins
Describe the classical pathway of complement system activation
Antibodies bind to invading organisms, then bind to complement components, activating them. The double binding is called complement fixation. Once initial complement proteins are activated, an activation cascade is triggered.
True or false: Complement proteins circulate in the blood in active forms
False, inactive forms
Describe the lectin pathway of complement system activation
Lectins are produced by innate system to recognize foreign invaders. When lectin is bound to specific sugars on foreign invaders, it can also bind and activate complement
Describe the Alternative pathway of complement system activation
Complement cascade is activated spontaneously when certain complement factors bind directly to foreign invader (due to lack of inhibitors on microorganism’s surface)
Why is high fever dangerous?
Can denature proteins and enzymes
How is the body’s thermostat reset?
Pyrogens released by leukocytes and macrophages
True or false: the adaptive immune system is systemic
True
Which type of immunity, humoral or cellular, has extracellular targets?
Humoral immunity
What are antigens?
A molecule that the immune system recognizes as foreign (non-self) and treats as a foe. Substances that can mobilize adaptive defenses and provoke an immune response. They are the targets of all adaptive immune responses and most are large, complex molecules that are not normally found in the body
What is an incomplete antigen called?
Hapten
What are antigenic determinants?
Parts of the antigen that antibodies or lymphocyte receptors bind to
What two important functional properties are associated with complete antigens?
Immunogenicity and reactivity
What is immunogenicity?
Property of complete antigens, it is their ability to stimulate proliferation (immune response) of specific lymphocytes (B and T cells)
The ability to react with activated lymphocytes and antibodies released by immunogenic is known as antigen ________.
Reactivity
True or false: Incomplete antigens (haptens) involve molecules too small to be seen so are not immunogenic by themselves
True
Which type of antigen, complete or incomplete, causes the immune system to mount an attack that is harmful to a person?
Incomplete proteins: attacks self-proteins as well as hapten
What is the name of the self-glycoprotein that is unique to each individual?
Major histocompatibility complex (MHC)
True or false: T lymphocytes can only recognize antigens that are presented on MHC proteins
True
What three types of cells does the adaptive immune system involve?
B lymphocytes, T lymphocytes, and antigen-presenting cells (APCs)
True or false: T and B lymphocytes share common development and steps in their life cycles
True
Where do T and B lymphocytes originate in their development?
Bone marrow
At which stage of the developmental process do lymphocytes develop immunocompetence and self-tolerance?
Maturation stage
What is immunocompetence?
Education process where lymphocytes only recognize 1 specific antigen.
What is self-tolerance?
Education process where lymphocytes must be unresponsive to the body’s self-antigens
What happens during the seeding stage of lymphocyte development?
Naive immunocompetent B and T cells are exported from primary lymphoid organs (bone marrow and thymus) to secondary lymphoid organs (lymph nodes and spleen) to increase their chance of encounter with antigen
What occurs when a lymphocyte first encounters its unique antigen?
They become activated in a process called clonal selection
What happens in the final stage of lymphocyte development, proliferation and differentiation?
The activated lymphocyte forms an army of exact copies of itself referred to as clones. These clones can become effector cells that fight infections and a few remain as memory cells to respond to the same antigen more quickly the next time it is encountered.
Where do T cells mature?
In the thymus
What is the difference between positive and negative selection processes?
Positive selection: Occurs first. T cell must recognize self MHC
Negative selection: Occurs second. T cell must not recognize self-antigens
Hypothetically, what would happen if a T cell recognized a self-antigen and wasn’t removed in the negative selection stage?
It could result in autoimmune diseases
What is the function of antigen-presenting cells?
To engulf antigens and present fragments of antigens to T cells for recognition
What are the 3 types of antigen-presenting cells?
Dendritic cells, macrophages, and B cells
What is the most effective antigen presenter to known?
Dendritic cells
Which type of cell do macrophages present antigens to that not only activates that cell, but further activates the macrophage?
T cells
What role do B cells play as an antigen-presenting cell?
Present antigens to helper T cell to assist their own activation
When a B cell becomes activated by a specific antigen, it proliferates to form a clone of itself, and then creates ______ cells that secrete antibody molecules.
Plasma
What happens to clone cells that do not become plasma cells in the humoral immunity response?
They become memory cells
In the primary immune response, upon exposure to antigen for the first time, how many days does it take for peak levels of plasma antibody to circulate in the body?
10 days
In the primary immune response, there is a lag period of 3 to 6 days. How quickly do memory cells respond to a secondary immune repsonse?
Within hours
What are the 4 main types of vaccines?
- Live-attenuated vaccines
- inactivated vaccines
- Subunit, recombinant, polysaccharide, and conjugate vaccines
- Toxoid vaccines
What are the three main types of COVID-19 Vaccines?
- mRNA vaccines
- Protein subunit vaccines
- Vector vaccines
What happens with active humoral immunity?
B cells encounter antigens and produce specific antibodies against them
What happens with passive humoral immunity?
Ready-made antibodies are introduced to our body
What is another name for antibodies?
Immunoglobulins
True or false: antibodies are capable of binding specifically with antigen detected by B cells
True
What are the five immunoglobulin classes?
IgM- Pentamer: first antibody released
IgA- Monomer or dimer: found in mucuous and other secretions
IgD- Monomer: attached to surface of B cells
IgG- Monomer: 75-80% of antibodies in plasma
IgE- Monomer: Active in some allergy reactions and parasitic infections
Which immunoblobulin is released during primary response?
IgM
Which immunoglobulin is primarily used in secondary responses?
IgG
True or false: antibodies destroy antigens
False, they inactivate and tag them
What happens when antibodies undergo neutralization?
Antibodies block specific sites on viruses or bacterial exotoxins and prevents antigens from binding to receptors on tissue cells
What is agglutination?
Cell-bound antigens to form a clump
What happens when antibodies undergo precipitation?
Similar to agglutination, soluble molecules are cross-linked into complexes
What is the result of complement fixation of antibodies?
Enhances phagocytosis, inflammation, and leads to cell lysis
What are the four mechanisms of antibody action?
Neutralization, agglutination, precipitation, complement activation
True or false: antibodies can only handle antigens that are outside of cells
True
What do CD4 cells usually become?
Helper T cells
What is the function of helper T cells?
Activate B cells, other T cells, and macrophages
What do regulatory T cells do?
Moderate immune response
What do CD8 cells usually become?
Cytotoxic T cells
True or false: Helper, cytotoxic, and regulatory T cells are activated T cells
True
True or false: Class 1 MHC proteins are displayed by all cells except WBCs
False: All except RBCs
What class of MHC proteins activate CD8 cells?
Class 1 MHC
True or false: Class 2 MHC proteins are displayed by all cells, except RBCs
False: Class 2 MHC proteins are only displayed by Antigen-presenting cells (dendritic cells, macrophages, B cells)
What type of T cell recognize class 2 MHC proteins?
Helper T cells: they then signal CD4 cells that help is required
True or false: T cells can be activated only when antigen is presented to them
True
Briefly describe how T cells become activated
Antigen presents itself on APC
CD4 T cell uses double recognition by recognizing both MHC and foreign antigen it displays
Co-stimulation occurs: T cell binds with co-stimulatory signals on surface of APC (without it, it will undergo anergy)
Clone formation
What happens when T cells undergo anergy due to lack of co-stimulation?
They become tolerant to that antigen, are unable to divide, and do not secrete cytokines
What are cytokines?
Chemical messenger of immune system, include interferons and interleukins
