Chapters 14, respiratory and skin, 15

Surface receptors

"eyes" and "ears" of the cell. Protein where the cell signals bind- they allow the cell to sense and respond to a signal, receptors are specific with what specific compounds will bind- binding is ligands

Secondary response

"memory response" second immune response that occurs upon secondary exposure to an antigen caused by rapid avtivation of long term memory cells

locations of PRR

(1) on the cell surface, (2) in endosomes and phagosomes, and (3) free in the cytoplasm. these locations, PRRs provide cells with information about not only which microbes are present, but also whether the microbes are inside or outside a host cell. The signals from PRRs in different locations can complement each other, provoking a stronger response when an invader is detected.

Cell-mediated immunity (CMI)

(cellular immunity) involves T cell response deals with invaders inside of the host cell, also attacks cancerous cells

IgD

IgD accounts for less than 1% of all serum immunoglobulins. It is involved with the development and maturation of the antibody response, but its functions in serum have not been clearly defined.

heavy chain

two higher molecular weight polypeptide chains that makeup the antibody molecule, heavy chain type determines the class of antibody

light chain

two lighter molecular weigth polypeptide chains of the antibody

B cells (lymphocytes)

type of lymphocite programmed to make antibodies- developes in the bone marow of mammals

regulatory T cells (T repressor cell)

type of lymphocyte that helps control immune response. Regulatory T cells are similar to the other T cells in that they have TCRs, but their role is entirely different. Instead of fostering an immune response, they help prevent one. This is important because it stops the immune system from overreacting and responding to harmless substances. Regulatory T cells (Treg), often referred to as "T regs,"

Natural Killer (NK) cell

type of lymphocyte that induces apoptosis to cells which antibody has been bound or that lack MHCclass 1 molecules on the surface and are stressed

T cells

type of lymphocyte that matures in the Thymus

Macrophages

type of phagocytoic cell that resides in the tissue, has multiple roles- including scavenging debris and producing pro inflammatory cytokines. Important type of sentinel cell, present in nearly all tissues, and are particularly abundant in the liver, spleen, lymph nodes, lungs, and peritoneal (abdominal) cavity. When residing in tissues, they are sometimes given different names based on their location

humoral immunity

Immunity involving B cells which eliminated invading microbes and their toxins in the blood stream and tissue fluids (invaders are considered extracellular antigens because they are outside of the host cell)

Primary response characteristics with B cells

In the first (primary) exposure to an antigen, it takes about 10 to 14 days for a significant concentration of antibodies to accumulate. During this delay, the person might experience signs and symptoms of an infection, which could be life-threatening. The immune system, however, is actively responding. Naive B cells that bind the antigen present the peptide fragments to TH cells. Once those B cells get the signal from TH cells, they multiply, generating a population of cells that recognize the antigen. As some of the activated B cells continue dividing, others differentiate to form antibody-secreting plasma cells (generally undergoes apoptosis)

rimantadine

used in chickens, huge resistance to it now

Phagosome Maturation and Phagolysosome Formation

Initially, a phagosome has no antimicrobial capabilities, but it matures to develop these. The maturation stages are highly regulated, and depend on the type of material ingested. If a phagocyte's toll-like receptors (TLRs) indicate that a phagosome contains microbial components, for instance, then that phagosome will have a different fate than if the contents are only host cell material. Eventually, the phagosome fuses with enzyme-filled lysosomes, forming a phagolysosome (membrane bound vaceole that forms when a phagosome fuses with a lysosome)

Memory lymphocytes

Long-lived descendants of activated lymphocytes that can quickly respond when a specific antigen is encountered again (secondary response)

Peroxidases

using hydrogen peroxide (H2O2) in the process. Microorganisms that produce the enzyme catalase are less susceptible to the lethal effects of peroxidase systems because they can potentially convert hydrogen peroxide to water and O2 before peroxidases have a chance to use it. Peroxidase systems are found in saliva, milk, body tissues, and phagocytes

Lymphatic/ lymphatic vessels

Lymphatic capillaries arise in the tissues and carry an almost colorless fluid called lymph, which comes from plasma (the fluid portion of the blood). Fluid seeps through the walls of the blood capillaries and joins interstitial fluid that bathes and feeds the tissue cells. A portion of this fluid enters the lymphatic capillaries, becoming lymph. Lymphatic capillaries are permeable to large molecules and take up foreign material such as invading microbes and their products, including toxins and other antigens. The lymphatic capillaries converge to form lymphatic vessels (lymphatics) that carry lymph to blood veins entering the heart. As with the veins, lymph is propelled by skeletal muscle contractions.As lymph is carried through the lymphatics, it passes through lymph nodes where it is exposed to phagocytes and lymphocytes that trap and destroy foreign materials such as microbial cells.

T cells (lymphocytes)

Lymphocyte that matures in the thymus

Macrophage characteristics

Macrophages routinely phagocytize dead cells and debris, but are ready to destroy invaders and call in reinforcements when needed. They are always present in tissues, where they either slowly wander or remain stationary.Macrophages live for weeks to months, or even longer. They maintain their killing power by continually regenerating their lysosomes. As macrophages die, circulating monocytes—which can differentiate into macrophages—leave the blood and migrate to the tissues to replace them. Monocyte migration increases in response to invasion and tissue damage. very important sentinel cells. They are well-equipped with pattern recognition receptors (PRRs), allowing them to "see" microbes in the surrounding environment, in material they have ingested, and in their cytoplasm.

Neutrophil (PMN-polymorphic netrophil)

Major type of phagocytic cell in the blood, quickly move to infected tissue where they destroy invading microbes. Increase in PMN=bacterial infection

Lectin pathway

Mannose-binding lectin (MBL) on the surface of invaders,These bind to certain arrangements of multiple mannose molecules; mannose is a type of carbohydrate commonly found on the surface of some microbial cells, particularly bacteria and fungi. Once an MBL attaches to a surface, Page 375it can interact with other complement system components to form a C3 convertase

B-cell receptor (BCR)

Membrane-bound derivative of the antibody that a B cell is programmed to make; it alolows the B cell to recognize a specific epitope.When a naive B cell encounters an antigen that its BCR binds, the interaction signals the cell that it should respond. Before the B cell can begin multiplying, however, it requires a second signal, usually from a specific type of T cell (confirmation of antigen)

T-cell receptor (TCR)

Molecule on the surface of a T cell that can bind to a specific antigen fragment, must be presented by one of the body's own cells. dendritic cell presents the antigen to the cell along with stimulatory signal

Mononuclear phagocytes

Monocytes and macrophages, makeup the mononuclear phagocyte system (MPS)

IgA

Most IgA is the secreted form, a dimer called secretory IgA (sIgA)-important in mucosal immunity and is found on the mucous membranes that line the gastrointestinal, genitourinary, and respiratory tracts. It is also in secretions such as saliva, tears, and breast milk. Secretory IgA in breast milk protects breast-fed infants against intestinal pathogens. Binding cites include neutralizing toxins and viruses and interfering with the attachment of microbes to host cells.produced mainly by the plasma cells that reside in the mucosa-associated lymphoid tissues (MALT). Recall that plasma cells are the antibody-secreting form of B cells. As IgA is transported across the mucosa (mucous membranes), a polypeptide called the secretory component is added. This attaches the antibody to the layer of mucus that coats the mucosal surface and protects it from destruction by enzymes there. Although IgA is the most abundant immunoglobulin class produced, relatively little is in the serum; only about 10% to 13% of antibodies in the serum are IgA, and these are the monomeric form

Lymphatic vessels

vessels that carry the lymph which is collected from the fluid that bathes the body's tissue (lymphatic)

RLR vs NLR detect trouble INSIDE the cell

NLR= detects types of bacterial secreation system/peptidocglycan (bacteria) and inflamation RLR=detects uncapped single stranded RNA and double stranded RNA which then rund off to give the signal for anothe cytokine

B-cell activation

Naive B cells gather in the secondary lymphoid organs, where they encounter antigens. When a B cell's antigen receptor (B-cell receptor) binds to a T-dependent antigen, the B cell takes the antigen in by endocytosis, enclosing it within an endosome. There, the antigen is degraded into peptide fragments that are then delivered to protein structures called MHC class II molecules. These move to the B-cell surface, where they "present" pieces of the antigen for inspection by TH cells—a process called antigen presentation. TH cells, which also gather in the secondary lymphoid organs, scan the naive B cells that are presenting antigens. If a TH cell's antigen receptor (T-cell receptor) binds one of the peptide fragments being presented by a B cell, then that T cell activates the B cell. It does this by delivering cytokines to the B cell, initiating the process of clonal expansion of that particular B cell. If no TH cells recognize the peptides presented by a B cell, that B cell may become anergic (unresponsive to future exposure to the antigen). This results in tolerance to that antigen, a mechanism the adaptive immune system uses to avoid responses against "self" and other harmless antigens

Negative selection of self-reactive B cells

Once a maturing B cell has developed its antigen receptor (B-cell receptor), it undergoes a process called negative selection, which eliminates any B cell that binds "self." Most developing B cells fail negative selection and, as a consequence, are induced to undergo apoptosis. If these cells are not eliminated, then the immune system may attack "self" substances by mistake, resulting in autoimmunity

Engulfment

Once the phagocyte has attached to a particle, it sends out pseudopods that surround and engulf the material. This action brings the material into the cell, enclosed in a phagosome (membran bound vacuole that contins material engulfed by a pahgocyte) If a phagocyte encounters something too large to engulf, it releases its toxic contents as a means of destroying it.

Primary Lymphoid organs

Organs in which lymphocytes mature, the thymus and bone marrow. . The bone marrow is where hematopoietic stem cells reside; recall that these give rise to all blood cells, including lymphocytes. B cells and T cells all originate in the bone marrow but only B cells mature there; immature T cells migrate to the thymus and mature there. Once mature, the lymphocytes gather in the secondary lymphoid organs just described, waiting to encounter antigen

C-type lectin receptors (CLRs)

Other PRRs that monitor the cell's surroundings have also been discovered, such as membrane-anchored versions.These receptors bind to certain carbohydrate molecules often found on the surface of microorganisms. Dendritic cells have TLRs as well as CLRs, so they are able to gather a great deal of information about invaders they encounter. They then pass that information on to lymphocytes, thereby helping to shape that response.

Chemotaxis

Phagocytic cells are recruited to the site of infection or tissue damage by chemicals that act as chemoattractants. These include products of microorganisms, phospholipids released by injured host cells, chemokines, and the complement system component C5a.

Opsonization

Phagocytic cells have receptors for the Fc region of IgG molecules, making it easier for the phagocyte to engulf antibody-coated antigens. Recall that the complement protein C3b opsonizes antigens; IgG molecules have a similar effect.

Recognition and Attachment

Phagocytic cells use various receptors to bind invading microbes either directly or indirectly. For example, direct binding occurs when a phagocyte's receptors bind mannose. Indirect binding happens when a particle has first been opsonized. Opsonins are extracellular proteins that tag particles for phagocytosis and include the complement component C3b and certain classes of antibody molecules. Phagocytes have specific receptors for opsonins, so opsonized material is easier for the phagocyte to attach to and engulf.

Pattern Recognition Receptors (PCR)

Proteins on or in the cell that recognize specific compounds unique to microbes or tissue damage

Cytokines

Proteins that function as a chemical messenger (allowing cells involved in host defense to communicate)

Pattern Recognition Receptors (PRRs) That Monitor a Cell's Cytoplasm

RIG-like receptors (RLRs) and NOD-like receptors (NLRs)

Epitopes (antigenic determinants)

Region of an antigen recognized by antibodies and antigen receptors on lymphocytes, also refered to as antigenic determinants.Some epitopes are stretches of 10 or so amino acids, whereas others are three-dimensional shapes such as a region that sticks out in a molecule. A bacterial cell usually has a diverse assortment of macromolecules on its surface, each with a number of distinct epitopes, so the entire cell has an enormous number of different epitopes.

Complement System

Series of proteins in blood and tissue fluids that can be activated to help destroy and remove invading microbes.

Inflamatory response to a cut process

Some of the pro-inflammatory cytokines cause endothelial cells of the local blood vessels to produce adhesion molecules that loosely "grab" phagocytes. The phagocytes normally flow rapidly through the vessels but slowly tumble to a halt as the adhesion molecules attach to them. The phagocytic cells themselves begin producing a different type of adhesion molecule that strengthens the attachment. Then, in response to various chemoattractants, the phagocytes leave the blood vessels and move into the surrounding tissues. They do this by squeezing between the cells of the dilated vessel, a process called diapedesis. Neutrophils are the first to arrive at the site of infection, and they actively phagocytize foreign material. Monocytes (which mature into macrophages at the site of infection) and lymphocytes arrive later. Clotting factors in the fluid that leaks into the tissues initiate clotting reactions in the surrounding area, walling off the site of infection. This helps prevent bleeding and stops the spread of invading microbes. As the inflammatory process continues, large quantities of dead neutrophils accumulate. Those dead cells, along with tissue debris, make up pus. A large amount of pus in a confined region constitutes an abscess

Antimicrobial substances

Substances that kill or inhibit microorganisms- lysozyme, peroxidase, lactoferrin, transferrin, Antimicrobial peptides (AMP), defensins

T cell receptor

TCR, has two polypeptide chains (a set of either alpha and beta or gamma and delta), each with a variable and constant region

Pro-inflammatory cytokines

TNF, IL-1, IL-6 cytokines work in groups this is specific to inflammatory response

Immuniglobin domains

The amino acids in the chains fold into characteristic domains- light chains have 2, heavy have 4. Light chain linked to heavy chain by disulfide bond. The fork of the Y is a flexible stretch called the hinge region, and one or more disulfide bonds link the two heavy chains there

inflamatory response

The complement component C5a is a potent chemoattractant, drawing phagocytes to the area where the complement system has been activated. In addition, C3a and C5a induce changes in the endothelial cells that line the blood vessels, contributing to the vascular permeability associated with inflammation. They also cause mast cells to release various pro-inflammatory cytokines

Ears

The ear has three parts: external, middle, and inner ear. The external ear includes the outer portion of the ear and the auditory canal, which is protected from microbes by cerumen (ear wax). The middle ear, which is separated from the auditory canal by the eardrum, is sterile. It is connected by the Eustachian tubes to the upper portion of the pharynx. These tubes equalize the pressure in the middle ear and drain normal mucous secretions. They are also a route through which microbes can enter the middle ear. Enlargement of the adenoids can contribute to middle ear infections by interfering with normal drainage from the Eustachian tubes. The fluid-filled inner ear is also microbe-free. Occasionally, however, viruses or bacteria enter the inner ear, often following an upper respiratory tract infection. Ear infections may extend to nearby structures such as the mastoid air cells in the skull, causing mastoiditis

Cross-linking

The ends of the two arms of an antibody can bind separate but identical antigen molecules, linking them. The overall effect is that large antigen-antibody complexes form, creating big "mouthfuls" of antigens for phagocytic cells to engulf.

The lower respritoy tract

The lower respiratory tract includes the larynx (voice box), trachea (windpipe), bronchi, and lungs. nflammation of the larynx is called laryngitis and results in hoarseness. The trachea is a continuation of the larynx and branches into two bronchi. Inflammation of the bronchi is called bronchitis, commonly the result of viral infection or chronic coughing due to smoking. The bronchi branch repeatedly, becoming bronchioles, the site of an important viral infection called bronchiolitis. The smallest bronchioles end in the alveoli, which are tiny, thin-walled air sacs where gas exchange occurs. Inflammation of the lungs is called pneumonitis. Pneumonitis that causes the alveoli to fill with pus and fluid is called pneumonia. Lung tissues have many macrophages that readily move into the alveoli and airways to engulf infectious agents, helping to prevent pneumonia. The lungs are surrounded by two membranes called pleura; one adheres to the lung and the other to the chest wall and diaphragm. The pleura normally slide over each other as the lung expands and contracts. Inflammation of the pleura is called pleurisy (pleuritis), characterized by severe chest pain. The action of the mucociliary escalator and the antimicrobial action of alveolar secretions help to keep microorganisms out of the lungs.

Respritory Tract

The major function of the respiratory system is gas exchange. Each breath brings in O2, which replenishes the supply in the blood, and then releases CO2, the waste product of cellular metabolism. In addition, movement of air over the vocal cords makes sound, which allows us to speak, and sensors in the nose detect odors. Although the mouth can also be used for breathing, it is considered part of the digestive tract. consists of the upper respiratory tract and the lower respiratory tract. We also include the eyes and the ears in our discussion. Even though these are not part of the respiratory tract, they are associated with ducts that open onto mucous membranes lining the nasal cavity and throat

Variable region

The portion of an antibody molecule that contains the antigen-binding sites. Tremendous variation exhists between amino acid sequence region and antibody molecules. the antigen-antibody interaction is reversible, and the molecules can separate, leaving both antigen and antibody unchanged.

Secondary response B cells characteristics

The secondary response is much faster and more effective than the primary response. there are more cells—memory B cells as well as memory helper T cells—that can respond to a specific antigen. In addition, the memory B cells are able to scavenge even low concentrations of antigen because their receptors have been fine-tuned through affinity maturation. Likewise, the antibodies coded for by these cells bind antigen more effectively.memory B cells become activated, some quickly differentiate to form plasma cells, resulting in the rapid production of antibodies. Because of class switching, these antibodies are often IgG or IgA. Other activated memory B cells begin proliferating, once again undergoing affinity maturation to generate even more effective antibodies. Additional exposures to the same antigen lead to an even stronger response.

Spleen

The spleen is a fist-sized organ found on the left side of the abdominal cavity, behind the stomach. It contains two kinds of tissue: red pulp (multiple blood-filled passageways) and white pulp (lymphoid tissue). The spleen has several functions. The red pulp cleans the blood by filtration, in the same way that the lymph nodes clean the lymph. Large numbers of phagocytes in red pulp remove aging or damaged red blood cells, bacteria, and other foreign materials from the blood. The red pulp also has a reserve of monocytes and produces new blood cells in rare situations where the bone marrow is unable to make enough. The white pulp, which contains both B and T lymphocytes, provides an active immune response to microbial invaders.

Eyes

The surface of the eyes and the lining of the eyelids are covered by mucous membranes called conjunctiva. the conjunctiva of healthy people usually have very few bacteria. This is because the eye is bathed with tears rich in lysozyme and secretory IgA, and is cleaned by the blinking reflex, which wipes the eye surface like a car windshield wiper cleans a windshield. From the conjunctiva, microbes may be swept into the tear duct and then into the nasal cavity.

Cytokine types and definition

The voices of the cell, they are produced by one cell diffuses to another and binds to the appropriate cytokine receptor of that cell. Binding of a cytokine to its receptor induces a change in the cell such as growth, differentiation, movement, or cell death. Cytokines act at extremely low concentrations, having local, regional, or systemic effects. Cytokines include: chemokines, colony-stimulation factors (CSF), Interferons (IFN), Interleukins (IL), and tumor necrosis factor (TNF)

activated lymphocytes

These are able to proliferate; they recognize that a specific antigen is present because their antigen receptor has attached to it, and they have received the second signal confirming that the antigen requires a response

Effector Lymphocytes

These are descendants of activated lymphocytes, armed with the ability to produce specific cytokines or other protective substances. Plasma cells are effector B cells, TC cells are effector cytotoxic T cells, and TH cells are effector helper T cells

Chemokines

These are important in chemotaxis of immune cells. Certain types of cells have receptors for chemokines, allowing the cells to sense the location where they are needed, such as an area of inflammation.

Colony-Stimulation factors (CSF)

These are important in the multiplication and differentiation of leukocytes. When more leukocytes are needed during an immune response, a variety of different colony-stimulating factors direct immature cells into the appropriate maturation pathways.

Memory Lymphocytes

These are long-lived descendants of activated lymphocytes; they can quickly become activated when an antigen is encountered again. Memory lymphocytes are responsible for the speed and effectiveness of the secondary response.

Interleukins (IL)

These are produced by leukocytes and have diverse, often overlapping, functions. As a group, they are important in both innate and adaptive immunity.

immature lymphocytes

These have not fully developed their antigen-specific receptors.

Interferons (IFN)

These were discovered because of their antiviral effects, but they have several roles in the host defenses. They are important in a number of regulatory mechanisms, stimulating the responses of some cells and inhibiting others

Cell Death and the Inflammatory Response

This capability allows the host to eliminate any cells no longer needed, and it also serves as a mechanism for sacrificing "self" cells that might otherwise spread an infection.- apoptosis and pyroptosis

Epidermis

This is the surface layer, made up of multiple layers of flat epithelial cells. The outermost cells are dead and filled with keratin, a tough, water-resistant protein also found in hair and nails. These skin cells regularly flake off, exposing their replacements immediately below. Microbes living on the outermost cells are shed with the flaking skin cells. Cells at the boundary between the dermis and the epidermis are actively dividing. These newly formed cells migrate to the skin's surface, become flattened, and die as keratin fills their cytoplasm.

Tumor necrosis factor (TNF)

This was discovered because of its role in killing tumor cells, a characteristic reflected by the name, but it has multiple roles. It helps initiate the inflammatory response and triggers one process of "cell suicide," a programmed cell death called apoptosis.

Neutralization

Toxins and viruses must bind specific molecules on a cell surface before they can damage that cell. A toxin or virus coated with antibodies cannot attach to cells and is said to be neutralized.

B cells

Type of lymphocyte that produces antibodies (lymph nodes/lymphatic tissues)

Macrophage

Type of phagocytic cell that resides in the tissue and has multiple roles, including scavenging debris and producing pro-inflammatory cytokines

Nose and Nasal Cavaties

When cold air enters the nose, the blood flow immediately increases due to nervous reflexes. This warms the air in the nose to near body temperature while passage over mucous membranes saturates it with water vapor.The nasal entrance usually contains diphtheroids and staphylococci. Up to 30% of healthy people consistently carry Staphylococcus aureus in their noses; an even higher percentage of hospital personnel are likely to carry this important hospital- or community-acquired pathogen. Farther inside the nasal passages, the normal microbiota is similar to that of the throat. Infection of the nasal passages, usually by viruses, causes inflammation or rhinitis, resulting in the familiar "runny nose."skull contains air-filled cavities called sinuses that are lined with ciliated epithelium continuous with that of the nasal cavity. Infection of the sinuses is called rhinosinusitis, or sinusitis, and may cause a "sinus headache" or postnasal "drip."

Antibody-dependent cell-mediated cytotoxicity (ADCC)

When multiple IgG molecules bind to a virally infected cell or a tumor cell, that cell becomes a target for destruction by natural killer (NK) cells. The NK cell attaches to the Fc regions of IgG and, once attached, kills the target cell by delivering destructive compounds directly to it.

antibodies

Y shaped protein that binds to antigen

Defensins

a group of AMPs that are important to protecting the epithelial borders. positively charged AMPs that insert into microbial membranes, forming pores that damage cells. Certain epithelial cells produce and release defensins, preventing invasion of those body surfaces. Expression of defensins increases when microbial invasion is detected, helping the body to eliminate the infection. Defensins are also produced by phagocytes, which use them to destroy the microorganisms they have ingested. In addition to directly killing invading microorganisms, defensins and other AMPs also promote and direct various immune responses

Toll-like receptors (TLRs)

a group of pattern recognition receptors on the surface of the cell in the endosomes (most well characterized aspect of PRRs). Each TLR recognizes a distinct compound or group of compounds associated with microbes. at least 10 in humans. TLRs anchored in the cytoplasmic membrane generally detect components of the outermost layers of microbial cells, including lipopolysaccharide (LPS), lipoproteins, and flagellin (bacteria). Detects double stranded RNA, uncapped RNA, and bacteria methylate A not cPG(like humans)

Lymphocytes

a group of white blood cells involved in adaptive immunity- B and T cells

Naive lymphocyte

a lymphocyte that has an antigen receptor but has not encountered an antigen yet, can't react until it has a specific signal to confirm the antigen is harmful to avoid attacking the body

the heart

a muscular pump enclosed in a fibrous sac called the pericardium—pumps the blood around the body. A wall of tissue (septum) separates the right and left sides of the heart, each of which is divided into two chambers—the atrium that receives blood, and the ventricle that discharges it.Blood from the right ventricle flows through the lungs and then back to the heart and into the left atrium. From there, the blood passes into the left ventricle and is then pumped through the aorta to the arteries and capillaries that supply the tissues of the body. The blood is then returned to the heart and into the right atrium by the veins. Valves at the entrance and exit of each ventricle prevent the blood flow from reversing. Although not common, infections of the heart valves, heart muscle, and pericardium can be serious because they affect blood circulation.

Complement Sysrem C

a series of proteins that circulate in the blood and the fluid that bathes the tissues, routinely circulate in an inactive form, but certain signals that indicate the presence of microbial invaders start a reaction cascade that rapidly activates the system. The activated complement proteins have specialized functions that help remove and destroy the invader.Each of the major complement system proteins has been given a number along with the letter C (for complement). The nine major proteins, C1 through C9, were numbered in the order of their discovery and not the order in which they react. When a complement protein is split into two fragments, those fragments are distinguished by adding a lowercase letter to each name.complement system can be activated by three different pathways that converge when a complex called C3 convertase is formed (alternative, lectin, and classical)

T-independent antigens

activate B cells without TH cell help; include lipopolysaccharide (LPS) and molecules with repeating subunits such as some carbohydrates

Interferon alpha and beta

all cells with nucleus can make this because they have RLR and NLR, only red nlood cells can't. These cells recieve the distress signal from the RLR, dendritic cells in this case can make TONS. A lot of interferon made- actually causes the feelings of fatigue and soreness becaus the body is so focused on infection. Interferon is released to tell the news by attaching to the interferon binding receptor which then transmist the the signal to the nucleus of another cell. This warning is used to protect the cell The cell protects itelf with an inactive antiviral protein. This activates antiviral protein if it is connected to double stranded RNA causes apoptosis.

ADCC (antibody-dependent cell-mediated cytotoxicity)

allows NK cells to destroy host cells that have viral or other foreign proteins inserted into their membrane. they have Fc receptors for IgG molecules on their surface; recall that Fc receptors bind the "red flag" portion of antibody molecules. The NK cell attaches to the antibodies and then delivers perforin- and protease-containing granules directly to the antibody-bound cell, initiating apoptosis.

Lactoferrin

an iron-binding protein in saliva, mucus, milk, and some types of phagocytes. similar to transferrin

Natural Killer cells (NK cells)

are innate lymphoid cells (ILC), meaning they are lacking the antigen-specific receptors that characterize B cells and T cells. The activities of NK cells assist the adaptive immune responses. Induce apoptosis in antibody bound "self cells" (ADCC). recognize and destroy stressed host cells that do not have MHC class I molecules on their surface

IgE

barely detectable in serum, because most is tightly bound via the Fc region to basophils and mast cells, rather than being free in the circulation. The bound IgE molecules allow these cells to detect and respond to antigens. IgE-mediated responses seem to be important in eliminating parasites, particularly parasitic worms (helminths). when antigen binds to two adjacent IgE molecules carried by a mast cell, the cell releases histamine and other inflammatory mediators

some antivirals against viral uncoating

but only against infuenza A

Activated lymphocyte

can proliferate, so that for every single naive lymphocyte that becomes activated, millions of progeny are formed.

Inflamatroy mediators

chemicals such as histamine that trigger inflamatory response when released

Opsonization

coating an object with molecule for which phagocytes have a receptor-making it easier for phagocytosis to occur

Peyer's patches

collection lymphoids in the gastrointestinal tract- part of the mucousal- associated lymphoid tissue(MALT) in the intestinal wall. They inspect sampled of tissue in the wall. dendritic cells in and near the Peyer's patches can also reach through the epithelial layer and grab material in the intestine to present it to lymphocytes.

granulomas

collection of lymphocytes and macrophages that accumulate in certain chonic infections in effort to barrier off consistent antigens. Macrophages, giant cells, and T cells form these

lymphatic system

collection of tissues and organs that bring populations of B and T cells into contact with antigens. each lymphocyte recognizes only one or a few different antigens. Before the immune system can develop an effective response, the appropriate lymphocyte must encounter the given antigen

Lymph

colorless contains leukocytes and flows within lymphatic cells. As blood enters capillaries, some of the liquid is forced out to join the tissue fluid (the extracellular fluid that bathes the tissues). Most of the liquid will re-enter the capillaries, but some is left in the tissues. Excess tissue fluid enters lymphatic vessels, carrying various antigens and other material along with it, to become lymph. As the lymph is pushed through the lymphatic vessels, it passes through lymph nodes, a type of secondary lymphoid organ

Membrane attack complexes (MACs)

complement system components assembled to form pores in the membranes of invading cells

Granulocytes

contain cytoplasmic granules filled with various compounds important for the cells' protective functions. The three types of granulocytes—neutrophils, basophils, and eosinophils—are named based on the staining properties of their granules

Outcome of Cytoplasmic Pattern Recognition: The Interferon Response

cytoplasmic pattern recognition receptors (PRRs) detect viral RNA, the cell responds by synthesizing and secreting a type of interferon (IFN) that induces nearby cells to develop an antiviral state. Interferon molecules attach to specific receptors on neighboring cells, causing the cells to express what can be viewed as inactive "suicide enzymes." For convenience, we will refer to these collectively as inactive antiviral proteins (iAVPs). These iAVPs can be activated by viral dsRNA. Once activated, the antiviral proteins (AVPs) degrade mRNA and stop protein synthesis, leading to apoptosis of that cell. A key feature of this response is that the iAVPs are activated by long dsRNA, which is typically found only in virally infected cells.

NOD-like receptors (NLRs)

cytoplasmic proteins that detect either microbial components or signs of cell damage. within the cell

Tc Cell

cytotoxic T lymphocyte (CTL), effector form of cytotoxic t cell, induces apoptosis

Important cell in epidermis

dendritic cells, hod on to one another and if broken by MAMPS can communicate this their are dermal diendric cells under these

Plasma Cells

descendants of activated B cells differentiate to these. They then make Y-shaped proteins called antibodies which then bind to the surfaces of cells, toxins, viruses, and other antigens, and in doing so, protect the body against the effects of that antigen.

Effector lymphocytes

descendants of activated lymphocytes, short lived that express specific response to eliminate invaders

Inflammatory process results in

diameter of local blood vessels increases due to the action of inflammatory mediators. This results in greater blood flow to the area, causing the heat and redness associated with inflammation. It also slows the blood flow in the capillaries. Because of the dilation, normally tight junctions between endothelial cells are disrupted, allowing more fluid to leak from the vessels and into the tissue. This fluid contains various substances, such as transferrin, complement system proteins, and antibodies, that help counteract invading microbes. The increase of fluids in the tissues causes the swelling and pain associated with inflammation. Pain also results from the direct effect of certain chemicals on sensory nerve endings. Some of the pro-inflammatory cytokines cause endothelial cells of the local blood vessels to produce adhesion molecules that loosely "grab" phagocytes. The phagocytes normally flow rapidly through the vessels but slowly tumble to a halt as the adhesion molecules attach to them. The phagocytic cells themselves begin producing a different type of adhesion molecule that strengthens the attachment. Then, in response to various chemoattractants, the phagocytes leave the blood vessels and move into the surrounding tissues. They do this by squeezing between the cells of the dilated vessel, a process called diapedesis.As the inflammatory process continues, large quantities of dead neutrophils accumulate. Those dead cells, along with tissue debris, make up pus. A large 1amount of pus in a confined region constitutes an abscess

Dermis

directly below the epidermis. This layer is composed of connective tissue and contains many tiny nerves, glands, blood vessels, and lymphatic vessels. The dermis provides the epidermis with nutrients and removes wastes from it.

Class switching

during the primary response, this allows B cells to change the antibody class it is programmed to make. After class switching, some B cells become memory B cells. These persist in the body for years and accumulate in high enough numbers to give a fast secondary response if the same antigen is encountered again later.

Neutrophils (polymorphonuclear neutrophilic leukocytes, polys, or PMNs, names that reflect the appearance of multiple lobes of their single nucleus)

efficiently engulf and destroy bacteria and other material. Their granules, which stain poorly, contain many enzymes and antimicrobial substances that help destroy the engulfed materials.Most numerous/important granulocyte. . They normally account for over half of the circulating white blood cells, and their numbers increase during most bacterial infections. Few neutrophils are generally found in tissues, except during inflammation.

Constant region

entire Fc region and part of two Fab region does not vary in amino acid sequences among molecules of the same Ig class. five general types of constant regions, and these correspond to the major classes (also called isotypes) of immunoglobulin (Ig) molecules: IgM, IgG, IgA, IgD, and IgE. Each class has distinct functions and properties (Antibody molecules in all five major immunoglobulin classes have the same basic monomeric structure, but each class has a different constant portion of the heavy chain. Some of the immunoglobulins are made up of multiple copies of the basic monomeric structure)

Lysozyme

enzyme that degrades peptidoglycan, is in tears, saliva, and mucus. It is also found within the body, in phagocytic cells, blood, and the fluid that bathes tissues

Skin layers

epidermis, dermis, subcutaneous tissue

Positive and Negative Selection of Self-Reactive T Cells

fate of developing T cells rests on two phases of trials: positive and negative selection. Positive selection permits only those T cells that recognize MHC to develop further. Recall that the T-cell receptor, unlike the B-cell receptor, recognizes a peptide:MHC complex. The T-cell receptor, therefore, must show at least some recognition of an MHC molecule regardless of the peptide it is carrying. T cells that show insufficient recognition fail positive selection and, as a consequence, are eliminated. Each T cell that passes positive selection is also subjected to negative selection. T cells that recognize "self" peptides presented on MHC molecules are eliminated. Positive and negative selection processes are so strict that over 95% of developing T cells undergo apoptosis in the thymus.

Pyrogens

fever-inducing substances, Pyrogenic cytokines are endogenous pyrogens, meaning the body makes them, whereas microbial products such as lipopolysaccharide (LPS) are exogenous pyrogens, meaning they are introduced from external sources.

hematopesis

formation and development of blood cells

hematopoeitic STEM cell

found in the bone marrow, this is a cell that gives rise to red blood cells

Unlike the B-cell receptor, the T-cell receptor does not interact with...

free antigen, it must be presented

Giant cells

fusion of many macrophages, large cell many nuclei, furing chronic inflamatory respons

naive lymphocytes

have antigen receptors, but have not yet encountered the antigen to which they are programmed to respond

Cardiovascular system

heart, blood vessels, and blood

Innate immunity

host defense involving anatomical barriers, sensor systems that recognize patterns associated with microbes or tissue damage, phagocytic cells, the inflammatory response, and fever

Fab region

identical arms of antibody that bind antigen

Mucousal immunity

immune response that protects the mucous membrane, specifically seperatory IgA. Prevents from spread of disease via mucous membranes

Antibodies are also called

immunoglobulins with two general parts-the arms and stems. (Fab and Fe regions)

Host or Self Cells

in immunology, one of the body's own cells

Fever

increase in internal body temperature 37.8 celsius or higher, an important host defense mechanism and a strong indication of infectious disease, particularly a bacterial one. Higher temperature results when macrophages release pro-inflammatory cytokines in response to microbial products. The cytokines act as messages carried in the bloodstream to the brain, where the temperature-regulating center raises the body temperature in response. The rise in temperature prevents microbes with lower optimum temperatures from growing, giving the immune system time to eliminate the microbes before they cause too much harm.

Blood and lymph both carry....

infection-fighting leukocytes and antimicrobial proteins, including antibodies, complement, lysozyme, and interferon. An inflammatory response may cause lymph and blood to clot in vessels close to areas of infection, preventing microbes from spreading.

Oitis media

inflamation of the middle ear

Conjuctivitis

inflamation of the outer surface of the eye causes by the infection of the conjuctivia

Pharyngitis

inflamation of the throat, commonly the result of a ciral infection

Lymphangitis

inflammation of lymph vessel, when limb is infected a red line may connect it to the neares lymoh node

lymphocytes

innate or adaptive Il-1 (m1 macrophages spill these out-pyogen(induce fever)), IL-6, and TNF2. IL2 and IL4 are in adaptive imune response

Basophils

involved in allergic reactions and inflammation. Their granules, which stain dark purplish-blue with the basic dye methylene blue, contain histamine and other chemicals that increase capillary permeability during inflammation

Mucociliary escalator

layer of mucous moved by cilia (tiny hair like projections along the border of epithelial cells) lining the respritoy tracts that traps bacteria and other particles and moves them up/out to avoid infection of the lungs

White blood cells

leukocytes can divide into three broad groups (granulocytes, mononuclear phagocytes, lymphocytes

Mucous membrane

line the digestive tract, respiratory tract, and genitourinary tract. The respiratory tract is lined with ciliated cells; the hair-like cilia constantly beat in an upward motion, moving materials away from the lungs to the throat, where they can then be swallowed. This movement out of the respiratory tract is referred to as the mucociliary escalator. As with skin cells, there is a constant turnover of mucosal epithelial cells. Movement towards elimination

Chronic inflmation

long term inflamaory response marked by macrophages, giant cells, and granulomas

Helper T cells CD marker to distinguish fom Cytotoxic T cells (B/c similar proteins)

lymphocyte programmed to activate B cells and macrophages and assist other parts of the adaptive immune reponse

Tonsils

lymphoid organs, located so that they come into contact with microbes entering the upper respiratory tract. They are important in the immune response but can also be the sites of infection, resulting in tonsillitis.Tonsils in the upper throat are called adenoids

Mucousal associated lymphoid tissue (MALT)

lymphoid tissue present in the mucosa of the respritory, gastrointestinal, and genitourinary tracts. Playa a crucial role in mucousal immunity

Skin-associated lymphoid tissue (SALT)

lymphoid tissues under the skin (seondary lymphoid tissue)

Activated macrophages

macrophages stimulated by cytokines to enlarge and enance abillity to kill molecules. "killer macrophages" are sometimes referred to as M1 macrophages. Other chemicals cause macrophages to produce cytokines that lessen the inflammatory response, as well as promote wound healing and tissue repair; these "healer macrophages" are sometimes referred to as M2 macrophages. Note, however, that the differentiation of M1 versus M2 macrophages is not fixed; a macrophage can change its role in response to environmental cues, so presenting the types as two polarized alternatives is not entirely accurate. (M1) macrophages in the adipose tissue decreases the sensitivity of various tissues to insulin. In contrast, anti-inflammatory macrophages (M2) promote an environment where tissue cells respond to insulin.

Skin

made of dermis (tightly woven fibrous connective tissue-super tough) and epidermis (composed of many layers of epithelial cells that become progressively flattened toward the surface) fibrous connective tissues. The outermost sheets are made up of dead cells filled with a water-repelling protein called keratin; the result is that the skin is a dry environment. The cells continually flake off, taking with them any microbes that might be adhering

Inaflamazone is the created complex that

makes IL1 (pro-inflamatory cytokine)

primary response

marks the adaptive immune response's first encounter with a specific antigen

Inducers of the inflamatroy process

microbes (microbial surfaces trigger complement activation, also leading to an inflammatory response) and tissue damage (NOD-like receptors (NLRs). When cells detect DAMPs, they respond by releasing inflammatory mediators. If blood vessels are injured, two enzymatic cascades are activated. One is the coagulation cascade, which results in blood clotting, and the other produces several molecules that increase blood vessel permeability.)

When inflamation occurs

microbes are introduced into normally sterile body sites, or when tissues are damaged. The purpose of this is to contain a site of damage, localize the response, eliminate the invader, and restore tissue function.

Benefits of fever

moderate fever has also been shown to enhance several protective processes, including the inflammatory response, phagocytic activity, multiplication of lymphocytes, release of substances that attract neutrophils, and production of interferons and antibodies. Release of leukocytes into the blood from the bone marrow also increases. These effects are likely due to increased rates of enzymatic reactions.

Adhesion Molecules

molecule on the surface of cells allow cells to adhere or "grab" each other

Ligands

molecule that binds specifically to a receptor

Antigen

molecule that reacts specifically with either an antibody or an antigen receptor on a lymphocyte

Damage-associated molecular patterns (DAMPs)

molecules that characterize damaged tissue

microbe-associated molecular patterns (MAMPs)

molecules that characterizes invading microbes

Monocytes

mononuclear phagocytes of the blood, part of the mononuclear phagocytes system, travel through the blood

Protective Outcomes of Antibody-Antigen Binding

neutralization, opsonization, complement system activation, immobilization and prevention of adherence, Cross-linking, antibody-dependent cellular cytotoxicity (ADCC)

Upper respritory tract

nose and nasal cavity, pharynx (throat), and epiglottis. Goblet cells synthesize mucous

affinity maturation

occurs during primary response, due to mutations that occur when activated B cells multiply. This results in fine tuning of an antibody for an antigen. changes in the antigen-binding site of the antibody (and therefore the B-cell receptor). B cells that bind antigen for the longest duration are most likely to proliferate, and these give rise to plasma cells that secrete antibodies that bind antigen more effectively.

some antivirals against entry but...

only against hiv

Interferon Gamma

only produced in white blood cells of the immune system- NK cells, Macrophages in the presence of this ifn become more toxic via more lysosymes and more ROS production

complement system eventually leads to three major protective outcomes:

opsonization, an inflammatory response, and lysis of foreign cells

Secondary lymphoid organs

organs where lymphocytes function in the immune response. lymph nodes, spleen, and tonsils, appendix-The anatomy of these organs provides a structured center for various cells of the immune system to interact and transfer cytokines. No other places in the body do this, so these organs are the only sites where adaptive immune responses can be initiated

T cells are always found where with lymph

paracortex

antibiotics

people getting this for viruses, will harm-dysbiosis

lysozymes in tears attack

peptidoglycan sideosphores (gram positives)

exocytosis

phagolysosome releases undigested debris to the outside of the cell by fusing with the phagocyte's cytoplasmic membran. a special process in macrophages puts some of the ingested material on the cell's surface as a way of displaying bits of invaders to certain cells of the adaptive immune system

Normal Microbiota (flora)

population of microorganisms that routinely grow on the body surfaces of healthy humans. Not technically part of the immune system, but they do play a part in homeostasis. They cover potential binding cites for pathogens, produce compounds that are toxic to certain bacteria, antibiotics can cause disruption in the normal microbiota= C.diff or other symptoms

Clonal Selection

process by which a lymphocyte's antigen receptor binds to a an antigen allowing the lymphocyte to multiply. Critical to adaptive immune response. explains how immune system can make a seemingly unlimited range of antibody specificities

Goblet cells

produce mucous in the upper respritory tract, look narow at the base and wide at the surface. Mucous secreting epithelial cells

Apoptosis

programmed cell death

Pyroptosis

programmed cell death that=inflamatory response, this programmed self-destruction triggers an inflammatory response. Thus, pyroptosis sacrifices infected macrophages so that they cannot play host to an invader, and it also recruits various components of the immune system to the region

Apoptosis

programmed cell death, the shape of the cell changes, enzymes cut the DNA, and pieces of the cell bud off, effectively shrinking the cell. Some changes appear to serve as a signal to macrophages that the remains of the cell are to be engulfed without the events associated with inflammation.

adaptive immunity

protection provided by immune system that develops over time (uses B and T cells)

Inflammasome

protein complex in macrophages that activates potent proinflammatory cytokine thereby initialing inflamatory response

Characteristics of Neutrophils

quick to move into an area of trouble and ready to eliminate the invaders. These phagocytic cells play a crucial role during the early stages of inflammation, being the first cell type recruited to the site of damage from the bloodstream. They have more killing power than macrophages. The cost for their effectiveness, however, is a relatively short life span of only a few days in the tissues; once they have used their granules, they die. not only kill microbes through phagocytosis, they can also release the contents of their granules. In essence, they can behave as mobile grenades, exploding in an area of infection to release destructive enzymes and antimicrobial peptides. They also release their DNA to form neutrophil extracellular traps (NETs). The DNA strands in the NET ensnare microbes, allowing the granule contents that accumulate within the NET to destroy them.

RIG-like receptors (RLRs)

recognize molecules associated with infecting viruses. within the cell

Erythrocytes

red blood cells, carry O2

If the skin barrier breaks...

resident macrophages and dendritic cells produce cytokines that trigger an immune response. Collections of lymphocytes found in skin-associated lymphoid tissues (SALT) are ready to proliferate when needed

The inflammatory process

sequence of events that result in dilation of small blood vessels, leakage of fluids from those vessels, and the migration of leukocytes out of the bloodstream and into the tissues

Phagocytosis process

1. chemotaxis 2. ecognition and attachment 3. engulfment 4. Phagosome maturation and phagolysosome formation 5. Distruction and Digestion 6. Exocytosis

Antimicrobial peptides (AMPS)

short chains of amino acids (usually 15-20 amino acids long) that have antimicrobial activity and are produced by a wide range of organisms. The role of these peptides in host defenses is not completely understood

Acute inflamation

short term inflamatroy response characterized by an abundance of neutrophils

Mast Cells

similar in appearance and function as Basophils. Doesn't come from the same precursor and is an important inflammatory response/ allergic reaction responses

Innate Lymphoid cells (ILC)

A group of lymphocytes that lack specificity in their mechanisms of antigen recognition- includes natural killer (NK cells). Differ from B to T cells, and common near mucous membrane and appear to have multiple roles that can promote balanced inflammatory response

VDJ segments

A human hematopoietic stem cell has about 40 different V segments, 25 different D segments, and 6 different J segments in the DNA that encodes the variable region of the heavy chain. As a B cell develops, however, two large regions of DNA are permanently removed, thereby joining distinct V, D, and J regions. The joined segments encode the heavy chain of the antibody that the mature B cell is programmed to make. Thus, one B cell could express the combination V3, D1, and J2 to produce its heavy chain, whereas another B cell might use V19, D25, and J6; each combination would result in a unique antibody specificity.

Transferrin

similar to lactoferrin. It s in blood and tissue fluids. By binding to iron, these proteins make it unavailable to microorganisms. Recall that iron is one of the major elements required by organisms, so withholding it prevents microbial growth. Some microorganisms can capture iron from the host, however, counteracting this defense

Destruction and Digestion

A number of factors within the phagolysosome work together to destroy an engulfed invader. O2 consumption increases dramatically—a phenomenon called respiratory burst—allowing an enzyme to produce reactive oxygen species (ROS), which are toxic. Another enzyme makes nitric oxide, which reacts with ROS to produce additional toxic compounds. Special pumps move protons into the phagolysosome, further lowering the pH. The various enzymes contributed by the lysosomes degrade peptidoglycan and other components. Antimicrobial peptides damage membranes of the invader, and lactoferrin binds iron

Gene rearrangement

A primary mechanism for generating a wide variety of different antibodies using a limited-size region of DNA,, a B cell expresses three gene segments, one each from DNA regions called V (variable), D (diversity), and J (joining), to form a nearly unique variable region of the heavy chain of an antibody

Cytotoxic T cells CD marker to distinguish from helper (B/c similar proteins)

A type of lymphocyte that kills infected body cells and cancer cells

Eosinophils

A type of white blood cell important in expellingparasitic worms from the body. . The granules of eosinophils, which stain red with the acidic dye eosin, contain antimicrobial substances and also histaminase, an enzyme that breaks down histamin

Physical barriers of the body

skin, mucous membrane

afferent, efferent

Afferant incoming fluid, and efferent is leaving

Phagocytic cells have pattern recognition receptors (PRRs) that allow them to inspect material ingested by the cell. Specific toll-like receptors (TLRs) are in phagosomal and endosomal membranes, facing the lumen of the organelle (the inside of the organelle, which is exposed to the organelle's contents). These TLRs typically recognize characteristics of nucleic acids that indicate a microbial origin

Although it might seem surprising that a cell can recognize microbial nucleic acid, several features distinguish it from normal host nucleic acid. For one thing, certain nucleotide sequences are much more common in bacterial DNA than in normal host cell DNA, and these can be recognized by a TLR. In addition, the genome of RNA viruses is often double-stranded during the viral replication cycle. Even DNA viruses may generate long dsRNA because both strands of DNA are sometimes used as templates for transcription, leading to production of complementary RNA molecules. Long pieces of cellular RNA are typically not double-stranded because only one DNA strand in a gene is used as a template for mRNA synthesis

Damaging Effects of Inflammation

Although the process usually limits damage and restores function, the response itself can cause significant harm. One undesirable consequence is that some enzymes and toxic products contained within phagocytic cells are inevitably released, damaging tissues.If inflammation is limited, such as in a response to a cut finger, the damage caused by the process is normally minimal, however infection can occur

Classical pathway

Antibodies binding to microbial inavders, When antibodies bind to an antigen (forming an antigen-antibody complex, also called an immune complex), they interact with the same complement system component involved with the lectin pathway to form a C3 convertase.

Complement system activation

Antigen-antibody complexes (commonly called immune complexes) can trigger the classical pathway of complement system activation. When multiple molecules of certain antibody classes are bound to a cell surface, a specific complement system protein attaches to side-by-side Fc regions. This activates the cascade of reactions that lead to production of the opsonin C3b, initiation of an inflammatory response, and formation of membrane attack complexes

Dendritic Cells

Antigen-presenting cells that play an essential role in the activation of naive T cells. Also are a sentinel cells that function as "scouts." They engulf material in the tissues and then bring it to the cells of the adaptive immune system for "inspection." Most dendritic cells develop from monocytes, but some develop from other cell types.

strataphied vs mucousal epithelium

stratafied has more layers of cells, moves up to the surface and dies/ becomes water resistant 99.9 percent of stuff can't get through thickness. mucousal is thinner that allows nutrients in

Antigen

substance that causes an immune response (reacts with antibody or lymphocyte)

T-dependent antigens

Antigens that can stimulate antibody production only with participation from T helper cells (B cell requires signal from helper). Typically these are proteins

T-dependent antigens

Antigens that evoke an antibody response only with the participation of Th cells, have a protein component. Proteins generally induce a strong response, whereas lipids and nucleic acids often do not

T-independent antigens

Antigens that evoke and antibody response without the Th cells.include lipopolysaccharide (LPS) and molecules with identical repeating subunits, such as some carbohydrates.

How immune cells communicate about invasion

surface receptors, cytokines, and adhesion molecules

Imprecise joining

As the DNA segments are joined during gene rearrangement, nucleotides are often deleted or added between the sections. This imprecise joining changes the reading frame of the encoded polypeptide so that two B cells that have the same V, D, and J segments for their heavy chain could potentially give rise to antibodies with very different specificities. Likewise, the segments that encode the light chain often join imprecisely.

First line of defense

Barriers that shield the inside of the body from the surrounding environment- skin, mucous membrane and antimicrobial substances

Suncutaneous tissue

Below the dermis is supportive tissue containing blood vessels, fat, and other types of cells.

Immobilization and prevention of adherence

Binding of antibodies to flagella interferes with a microbe's ability to move; binding to pili prevents a bacterium from attaching to surfaces. Movement and attachment are often necessary for a pathogen to infect a host, so antibodies that bind to flagella or pili can prevent infection.

Blood Vessels

Blood vessels include arteries, veins, and capillaries. Arteries carry blood away from the heart and have thick muscular walls to withstand the high pressure of blood pumped by the ventricles. Exchange of materials between the blood and the tissues occurs across the very thin walls of microscopic capillaries. Veins carry blood back to the heart. Valves in veins play an important role in keeping the blood flowing in one direction, because the venous pressure is very low. Veins are easily compressed, so the action of skeletal muscles also aids the flow of venous blood.

M2 vs M1

Both come from monocytes M1=killer M2=healer secretes cytokines to bandage up and repair generation depends on signal

IgM

the first class produced during the primary response to an antigen. It is the principal class produced in response to some T-independent antigens. IgM accounts for 5% to 13% of the circulating antibodies. It is a pentamer. main role is to control bloodstream infections. The five monomeric subunits give IgM a total of 10 antigen-binding sites, so it cross-links antigens very effectively. It is the most efficient class in triggering the classical pathway of complement system activation.

alternative pathway

C3 binding to microbial invaders quickly and easily triggered, providing vital early warning that an invader is present. The alternative pathway is triggered when C3b binds to foreign cell surfaces. The binding of C3b allows other complement proteins to then attach, eventually forming the C3 convertase. What might seem confusing is the fact that C3b is a product of complement activation, yet it also triggers the alternative pathway. How can it be both a product and a trigger? This can occur because C3 is somewhat unstable, and spontaneously splits to C3a and C3b at a low rate even when the complement system has not been activated. The C3a and C3b formed this way are rapidly inactivated by regulatory proteins, but some C3b is always present to trigger the alternative pathway when needed.

Opsonization process

C3b concentration increases substantially when the complement system is activated, and these molecules bind to bacterial cells or other foreign particles. This has two effects: (1) continued complement activation via the alternative pathway, and (2) opsonization (coating of a particle with oposin for eating) Material that has been opsonized (meaning "prepared for eating") is easier for phagocytes to bind to and engulf. This is because phagocytes have receptors that attach specifically to molecules referred to as opsonins (in this case, C3b)

Cytotoxic and helper T cells are identical microscopically, so scientists distinguish them based on the presence of surface proteins called

CD, cluster of differentiation markers. Most cytotoxic T cells have the CD8 marker and are frequently referred to as CD8 T cells; most helper T cells carry the CD4 marker and are often called CD4 T cells. Note that CD4 is also a receptor for HIV, which explains why the virus infects helper T cells.

Major Histocompatibility Complex (MHC)

the host protein that displays the antigen fragment on the cell surface. MHC class 1-molecules that cells use to present antigen(present endogenous antigens (antigens made within the cell)). MHC class 2-molecules on the surface of antigen presenting cells (APC) (present exogenous antigens (antigens taken up by a cell). Cytotoxic T cells recognize antigen presented on MHC class I molecules, whereas helper T cells recognize antigen presented on MHC class II molecules. Because of these recognition characteristics, effector cytotoxic T (TC) cells respond to endogenous antigens, whereas effector helper T (TH) cells respond to exogenous antigens

Phagocyte

Cell type that specializes in engulfing and digesting microbes and cell debris (carries out phagocytosis)

Sentinel Cells

Cells that help immune cells detect signs of invasion by inducing cytokines when their PRR recognixe invading microbes

Combinational Association

Combinatorial association refers to the specific groupings of light chains and heavy chains that make up the antibody molecule. Both types of polypeptides independently acquire diversity through gene rearrangement and imprecise joining. Additional diversity is then introduced when these two polypeptides join, because the combination of the two chains creates the antigen-binding site

Oposins

Complement C3b and Certain antibody classes that bind to invading particles making it easier for phagocytes to engulf them

Membrane Attack Complexes (MACs)

Complement system components assembled to form pores in membranes of invading cells.

lysis of foreign cells

Complexes of complement system proteins (C5b, C6, C7, C8, and multiple C9 molecules) spontaneously assemble in cell membranes, forming doughnut-shaped structures called membrane attack complexes (MACs). creates pores in the membrane, causing the cells to lyse. MACs have little effect on Gram-positive bacteria because the thick peptidoglycan layer of these cells prevents the complement system components from reaching their cytoplasmic membranes.

IgG

the most abundant serum immunoglobulin (serum is the liquid portion of clotted blood), accounting for about 80% to 85% of the total serum antibodies. It circulates in the blood but exits the vessels to enter the tissues as well. provides the longest-term protection of any antibody class; its half-life is 21 days, meaning that a given number of IgG molecules will be reduced by about 50% after 21 days. In addition, IgG is generally the first and most abundant circulating antibody class produced during the secondary response. provides protection by neutralization, opsonization, complement activation, immobilization and prevention of adherence, cross-linking, and ADCC. transported across the placenta into the fetus's bloodstream, so it protects the developing fetus against infections. Women who are not already immune to a given pathogen lack IgG against that microbe, so they are warned to take extra precautions during pregnancy to avoid pathogens that can infect and damage a fetus. also in colostrum, the first breast milk produced after giving birth. The newborn's intestinal tract absorbs this antibody.

Sebum

the oily secretion of the sebaceous glands, flows up the hair follicules and protects the skin

Immunogenic

the relative ability of an antigen to elicit an immune response

Immunogenic

the relative ability of an antigen to elicit an immune response. Small molecules are usually not immunogenic, meaning that they do not elicit a response.

Inflammatory response

Coordinated innate response with the purpose of containing a site of damage, localizing response, eliminating the invader, and restoring tissue function

Fc region

the stem of an antibody

Interfon (IFN)

Cytokines that induce cells to resist viral replication, they also regulate immune response

Antibody functional regions

the two identical arms and the single stem of the Y-shaped molecule. ends of the arms are the parts that attach to antigens. By binding to antigens, the antibodies can neutralize their effects.the stem portion is functionally similar—it serves as a "red flag" that sticks out from the surface of an antibody-bound antigen. This tags the antigen for rapid elimination by macrophages or other components of the immune system

nucleic acid synthesis is most effective against

DNA viruses

Th cell

Effector form of a helper T cell; it activates B cells and macrophages, and releases cytokines that stimulate other parts of the immune system

Pharyns (throat) and Epilottis

throat is shared by the respiratory system and the digestive system. During swallowing, a small flap called the epiglottis covers the glottis, the opening that allows air to pass between the upper and lower respiratory tracts. This prevents swallowed material from entering the lungs. Inflammation of the epiglottis, called epiglottitis, can be life-threatening because the swollen flap can block the glottis and close the airway.Streptococci, including viridans streptococci (a group of α-hemolytic streptococci; viridis means "green") and non-hemolytic species, are common members of the normal microbiota of the throat. A variety of other bacteria are also found there, including Moraxella species, diphtheroids, and various obligate anaerobes. Some common opportunistic pathogens also colonize the throat, including Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis.