What type of immunity are B cells responsible for?
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Antibody-mediated immunity.
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What type of immunity are B cells responsible for?
Antibody-mediated immunity.
What do plasma cells synthesize and secrete?
Antibodies into interstitial fluid.
What is active immunity?
Immunity developed through exposure to pathogens.
What is the role of perforin molecules?
To form pores in abnormal cells.
How do B cells attack antigens?
By producing specific antibodies.
What is the process by which macrophages move through capillary walls?
Emigration.
What is the role of memory B cells?
They remain in reserve to respond to the next infection.
What do macrophages secrete after binding and digestion?
Pro-inflammatory cytokines.
What is C5 convertase?
An enzyme complex involved in the complement system that cleaves C5 into C5a and C5b.
What is passive immunity?
Immunity acquired without the immune system's direct involvement.
What is the process called when B cells prepare for activation?
Sensitization.
What is the role of Helper T cells in B cell activation?
They activate sensitized B cells by binding to the same antigen.
How is naturally acquired active immunity obtained?
Through environmental exposure to pathogens.
What type of cell secretes perforin?
Natural Killer (NK) cells.
What do NK cells use to identify cancer cells?
Tumor-specific antigens.
What term describes the movement of phagocytes in response to chemicals in surrounding fluids?
Chemotaxis.
What is the primary focus of the Khan Academy website?
Providing free educational resources and courses.
How many populations of B cells exist?
Millions, each with different antibody molecules.
What are interferons?
Proteins (cytokines) released by activated lymphocytes and macrophages.
What are the two classes of phagocytes?
Microphages and macrophages.
What is the purpose of the pro-inflammatory cytokines secreted by macrophages?
To recruit more immune cells or activate specific immune cells.
What does hydrolysis refer to?
The chemical breakdown of a compound due to reaction with water.
How are memory B cells similar to memory T cells?
Both remain in reserve to respond to future infections.
How does a Helper T cell activate a B cell?
By binding to the MHC complex.
How is naturally acquired passive immunity obtained?
Through antibodies acquired from the mother.
What binds to B cell receptors during sensitization?
Corresponding antigens in interstitial fluids.
What are fixed macrophages also known as?
Histiocytes.
What are phagocytic antigen-presenting cells (APCs)?
Cells that engulf and present antigens to T cells.
What is immunological surveillance?
A process carried out by natural killer (NK) cells to identify and attack abnormal cells.
What is artificially induced active immunity?
Immunity developed through vaccines containing pathogens.
What happens to an abnormal cell when perforin is secreted?
It undergoes lysis.
What is the primary function of T cells in cell-mediated immunity?
To recognize and respond to infected or abnormal cells.
What is a mechanism by which some cancer cells avoid detection by NK cells?
Immunological escape.
What initiates the process of phagocytosis?
When a phagocyte attaches to a target (adhesion).
What types of subjects can you find on Khan Academy?
A wide range of subjects including math, science, economics, and humanities.
What is one effect of inflammation?
Temporary repair and barrier against pathogens.
What do Helper T cells secrete to promote B cell activation?
Cytokines.
What pathway do Cl and C4 bind to?
Classical pathway.
What role do cytokines play in the immune system?
They act as chemical messengers to coordinate local activities and can affect the whole body as hormones.
What do activated NK cells do first in immunological surveillance?
Identify and attach to abnormal cells (non-selective).
Which types of cells are classified as microphages?
Neutrophils and eosinophils.
What is the role of C5 convertase in the immune system?
It activates the complement component C5, leading to inflammation and opsonization.
What process do macrophages undergo after binding?
Phagocytosis.
What role do dead viruses play in immunity?
They are used in vaccines to induce active immunity.
What do Class II MHC proteins bind to?
Antigenic fragments from antigen processing of pathogens.
What happens to antigens during the sensitization of B cells?
They are taken into the B cell, processed, and reappear on the surface bound to Class II MHC protein.
What is artificially induced passive immunity?
Immunity gained by an injection of antibodies.
What are free and fixed macrophages?
Types of macrophages found in connective tissues.
Where are microglia found?
In the central nervous system.
What is inflammation also known as?
Inflammatory response.
How can the action of perforin be metaphorically described?
Like poking a hole in a balloon, leading to deflation.
What do T cell receptors (TCR) recognize?
Specific antigens presented by other cells.
What happens after a phagocyte attaches to its target?
It surrounds the target with a vesicle.
What is the result of activating either the classical or alternative pathways in the complement system?
It activates the common pathway, leading to the generation of the membrane attack complex (MAC).
What do cells infected with viruses present on their plasma membranes?
Abnormal proteins.
What is the role of physical barriers in the immune system?
They keep hazardous materials, such as biological pathogens, outside the body.
What is the inflammatory response?
A localized, tissue-level response that limits the spread of injury or infection.
How does Khan Academy support learning?
Through instructional videos, practice exercises, and a personalized learning dashboard.
What are pathogens?
Microorganisms that can cause disease.
What are the two types of cells that an activated B cell divides into?
Plasma cells and Memory B cells.
How does inflammation prevent the spread of pathogens?
By creating a barrier in the affected area.
What structure in NK cells forms perforin vesicles?
The Golgi apparatus.
What is formed when C3b attaches to an antigen-antibody complex?
Membrane Attack Complex (MAC).
Who releases interferons?
Activated lymphocytes and macrophages.
What is a key characteristic of microphages?
They leave the bloodstream and enter peripheral tissues to fight infections.
What do macrophages increase the production of after binding?
Some genes that form proteins encouraging inflammation.
What is the role of Class II MHC proteins in the immune response?
They are inserted in the plasma membrane to stimulate T cells.
What are plasma cells responsible for?
Antibody production.
What type of immunity is associated with B cell sensitization?
Antibody-mediated immunity.
What are the two forms of passive immunity?
Naturally acquired and artificially induced.
What type of macrophages are found in liver sinusoids?
Kupffer cells.
What are Kupffer cells?
Macrophages located in the liver.
What type of response is inflammation?
A localized response.
What type of immunity is associated with B cell activation?
Antibody-mediated immunity.
What are perforins?
Proteins released by NK cells that lyse abnormal plasma membranes.
What role do T cells play in the immune response?
They help in the activation of other immune cells and directly kill infected cells.
What does the membrane attack complex (MAC) do?
It causes cell lysis on the surface of bacteria.
What role do NK cells play in viral infections?
They identify and destroy virus-infected cells.
What role do mast cells play in the inflammatory response?
They are resident cells in connective tissues that contribute to the inflammatory response.
What do phagocytes do?
They attack and remove dangerous microorganisms and ingest foreign pathogens.
What are the two classes of MHC proteins?
Class I and Class II.
Is Khan Academy a paid service?
No, it is completely free to use.
What is a common example of food poisoning?
Caused by bacterial pathogens.
What role does inflammation play in the body's defenses?
Mobilization of local and systemic defenses.
What are complement proteins?
30 special proteins found in plasma that form the complement system.
What is the function of interferons in the body?
To coordinate local activities and act as hormones affecting the whole body.
What activates the formation of the complex involving Cl?
Antigen-antibody reaction.
What are physical barriers in the immune system?
They include the outer layer of skin, hair, and epithelial layers of internal passageways.
How do microphages compare in size and lifespan to other phagocytes?
They are smaller and short-lived.
What are antigen-presenting cells (APCs) responsible for?
Activating T cells against foreign cells and proteins.
What type of cells are formed from activated B cells?
Plasma cells and memory B cells.
What are interferons?
Chemical messengers that trigger the production of anti-viral proteins in normal cells.
What are alveolar macrophages also referred to as?
Phagocytic dust cells.
What are microglia?
Macrophages found in the central nervous system (CNS).
How do NK cells release perforins?
Through exocytosis of perforin vesicles.
What is the role of the alternative pathway in the immune system?
It is important in the defense against bacteria, some parasites, and virus-infected cells.
What type of immunity is present at birth?
Innate immunity.
What triggers inflammation?
Any stimulus that kills cells or injures tissue.
What type of immunity is characterized by specific resistance to antigens?
Adaptive (specific) immunity.
What is THC in the context of T cells?
It refers to T cell receptor (TCR) proteins involved in antigen recognition.
What is the end-point of the complement activation pathways?
The generation of the membrane attack complex (MAC).
What is the limitation of immunological surveillance?
It doesn't work all the time, leading to cancer growth.
What is fever?
A high body temperature.
Where are Class I MHC proteins found?
In the membranes of all nucleated cells.
What is immune surveillance?
It constantly monitors normal tissues for potential threats.
What type of bacteria is commonly associated with the gut?
E. coli.
What is facilitated by inflammation in terms of tissue?
Repairs and regeneration.
What is the function of the complement system?
To enhance the ability of antibodies to clear pathogens from an organism.
What components are broken down in the complement activation process?
C4a, C4b, C2a, C2b.
What is a distinguishing feature of microphages compared to neutrophils?
Microphages are more reddish than neutrophils.
What role do secretions play in physical barriers?
They flush away materials and can kill or inhibit microorganisms.
What type of immunity is associated with the activation of T cells by APCs?
Cell-mediated immunity.
What is the role of memory B cells?
They remain inactive until re-exposure to the same antigen.
What types of cells do NK cells attack?
Cancer cells and cells infected with viruses.
What is the function of Class I MHC proteins?
They pick up small peptides in the cell and carry them to the surface as a label indicating the cell is infected.
What is the function of anti-viral proteins produced by interferons?
They block replication of viruses in neighboring cells.
What type of immunity is associated with phagocytic APCs?
Cell-mediated immunity.
What initiates the alternative pathway?
Interaction of several complement proteins, notably properdin, in the plasma triggered by exposure to foreign materials.
When does adaptive immunity develop?
After birth.
What is the role of activated T cells in adaptive immunity?
They find pathogens and attack them through phagocytosis or the release of chemical toxins.
What distinguishes free macrophages from fixed macrophages?
Free macrophages can move throughout the body, while fixed macrophages are stationary.
What is the role of phagocytes in the immune system?
They engulf pathogens and cell debris.
What are inactive CD4 T cells also known as?
Memory T H cells.
Which cells are primarily involved in the coordinated action of adaptive immunity?
T cells and B cells.
What is secreted by T cells to help in the immune response?
Cytokines, which are signaling proteins.
How does fever affect the body?
It increases body metabolism, accelerates defenses, and inhibits some viruses and bacteria.
What is the role of C3 convertase in the complement system?
It is a cylindrical structure that plays a key role in the activation of the complement pathways.
What does an antigen bound to Class I MHC protein indicate?
That the cell is infected or otherwise abnormal.
Where are Class II MHC proteins found?
In the membranes of antigen-presenting cells (APCs) and lymphocytes.
What type of cells are involved in immune surveillance?
Natural killer (NK) cells.
What type of immunity is always non-specific and works the same way against any invading agent?
Innate (non-specific) immunity.
What are the two types of E. coli?
Good and bad types.
How does inflammation get help from other parts of the body?
Through the bloodstream.
How do complements work?
They work together in cascades.
What activates macrophages?
The presence of pathogens.
What is the role of convertases in the complement system?
They help in the activation of C3 convertase.
What is sensitization in the context of the immune system?
The process by which B cells become activated upon exposure to antigens.
What are examples of secretions that help in flushing away materials?
Sweat, mucus, and urine.
What do cells use to distinguish 'self' from 'non-self'?
Pathogen-associated molecular patterns (PAMPs) unique to pathogens.
What is the role of Interferon alpha (α)?
It attracts and stimulates NK cells and enhances resistance to viral infection.
What happens to B cells upon activation?
They differentiate into plasma cells and memory B cells.
What do T cells do with normal peptides?
T cells ignore normal peptides.
Do anti-viral proteins kill viruses directly?
No, they do not kill viruses per se.
What is the end result of the alternative pathway?
The attachment of an activated C3b protein to the bacterial cell wall.
What characterizes active immunity?
Antibodies develop after exposure to an antigen.
What triggers specific defenses in the immune response?
Antigen presentation.
What are interferons?
Chemical messengers that coordinate defenses against viral infections.
What is the role of active T H cells in the immune response?
They secrete cytokines that stimulate both cell-mediated and antibody-mediated immunity.
What does adaptive immunity respond to?
Specific antigens.
What do phagocytic antigen-presenting cells (APCs) do?
They engulf extracellular pathogens.
Which type of T cells are activated by Class I MHC proteins?
CD8 T Cells (Cytotoxic T Cells).
What is the optimal body temperature range for bacterial growth?
36-37°C.
What type of immunity protects against specific pathogens?
Adaptive (specific) immunity.
What type of immunity is associated with MHC proteins?
Cell-mediated immunity.
What type of immunity is described by physical barriers and phagocytes?
Innate (non-specific) immunity.
What are the two usual activation pathways of the complement system?
Classical pathway and Alternative pathway.
What is the role of good bacteria in the gut?
They help with digestion and overall health.
How do macrophages respond to pathogens?
In several ways, including engulfing and destroying them.
What are antigens?
Substances that can provoke an immune response.
What are non-phagocytic antigen-presenting cells (APCs)?
Cells that present antigens without engulfing them.
What substances in secretions can kill or inhibit microorganisms?
Enzymes, antibodies, and stomach acid.
Which cells produce Interferon alpha (α)?
Cells infected with viruses.
What do immune cells have on their surface to recognize pathogens?
Receptors for PAMPs.
What activates T cells to destroy a cell?
Abnormal peptides or viral proteins.
What do the classical and alternative pathways activate?
The common pathway (C5 to C9).
What is the complement system?
A system of circulating proteins that amplify in a cascade manner to damage pathogens.
What type of immunity do T cells provide?
Cell-mediated immunity.
What is passive immunity?
Antibodies are transferred from another source.
Which proteins combine to form C3 convertase?
C3b, Properdin, Factor B, and Factor D.
What do activated B cells produce?
Cells that produce antibodies.
What is the primary function of the innate immune system?
To prevent the entry of pathogens by an effective barrier.
What is the most rapid and effective activation pathway of the complement system?
The classical pathway.
What is immune surveillance?
The destruction of abnormal cells by natural killer (NK) cells in peripheral tissues.
What do active helper T cells secrete?
Cytokines.
What triggers antigen presentation by Class I MHC proteins?
Viral or bacterial infection of a body cell.
What is produced by lysosomal action in phagocytic APCs?
Antigenic fragments.
What are Memory T Cells?
T cells that remain in circulation and can quickly form cytotoxic T cells upon re-exposure to the same antigen.
What is the main feature of adaptive (specific) defenses?
They provide specific resistance (immunity).
What does the classical pathway of complement activation involve?
Antibodies.
What is the primary function of the immune system?
To protect the body against pathogens and foreign substances.
What do macrophages use to destroy engulfed pathogens?
Lysosomal enzymes.
What can cause food poisoning?
Bacterial unicellular pathogens.
What role do Class II MHC molecules play?
They present antigens to helper T cells, facilitating B cell activation.
What is the role of complement in the immune system?
It is a system of circulating proteins that assist antibodies in the destruction of pathogens.
What is the role of an Antigen-Presenting Cell (APC)?
To present foreign antigens to T cells.
Why is a body temperature above 37°C not conducive to bacterial growth?
Because it can inhibit bacterial growth and enhance immune responses.
What type of cells are Langerhans cells?
A type of dendritic cell found in the skin.
What is the function of Cytotoxic T Cells?
To attack and destroy infected and abnormal cells displaying antigen.
What is adaptive immunity?
Immunity that is not present at birth and develops in response to exposure to specific antigens.
What does adaptive immunity depend on?
The activities of lymphocytes.
What is an abnormal immune system characterized by?
Attacking normal cells.
What is the function of Interferon beta (β)?
It slows inflammation in a damaged area.
What complex is generated by the activation of the common pathway?
The membrane attack complex (MAC).
What type of immunity is associated with the activation of T cells?
Cell-mediated immunity.
What are the seven major categories of innate immunity?
What do T cells defend against?
Abnormal cells and pathogens inside cells.
What are the two classes of phagocytes?
Macrophages and microphages.
How does the complement system assist in immunity?
It assists antibodies in the destruction of pathogens.
What does C3 convertase bind with to form C5 convertase?
C3b.
What determines different forms of immunity?
Genetic factors and exposure.
