Chapter 21 The Immune System

Front 1

What is the first line of defense for the immune system?

Back 1

The first line of defense for the immune system are the skin barriers, both the skin and mucosae.

Front 2

What is the second line of defense?

Back 2

The second line of defense is the internal defenses which include: proteins, cells, and inflammation.

Front 3

What is the third line of defense?

Back 3

The third line of defense are T cells, and B cells.

Front 4

What is the most important barrier to pathogen entry?

Back 4

The most important barrier to pathogen entry is the skin.

Front 5

What two features make skin so effective against fighting pathogens and how?

Back 5

The physical, keratin-a tough protein of the skin is dry and devoid of nutrients, and the acid mantle skin cells secrete lactic acid from sweat and fatty acids that lower the pH level on the surface of the skin 3-5.

Front 6

What kind of membrane besides the skin guards against pathogens?

Back 6

Mucus membranes also guard against pathogens.

Front 7

What kind of secretions guard against pathogens, what enzyme do these secretions have, and how does it work?

Back 7

Tears, saliva, earwax, and mucus all contain lysozyme, which is an enzyme that acts as an antibiotic by digesting bacterial cell walls.

Front 8

Part of skin is composed of this type of tissue, what is it called, and what does it contain that helps to protect against pathogens?

Back 8

Areolar tissue contains hyaluronic acid that gives the ground substance a viscous consistency.

Front 9

What are phagocytes, where are they found, and what do they do?

Back 9

A phagocyte is a cell that ingests and destroys foreign matter such as microorganisms or debris by a process known as phagocytosis.

Front 10

All bacteria have proteins that begin with what amino acid, and instead of what amino acid?

Back 10

All bacteria have proteins that begin with the amino acid N-formylmethionine, instead of methionine.

Front 11

What are macrophages also known as to Jim?

Back 11

Jim refers to macrophages as the Clint Eastwoods and Zenas of the immune system.

Front 12

Where do macrophages originate from?

Back 12

Macrophages are cells within the tissues that originate from specific white blood cells called monocytes.

Front 13

What do macrophages do?

Back 13

They can eat 100 bacteria cells, secrete cytokines which stimulate bone marrow to make and release additional neutrophils and macrophages.

Front 14

What does cytokine do, what are they also referred to as, and who produces it?

Back 14

Cytokines are also referred to as cell movers, they work by stimulating bone marrow to make and release additional neutrophils and macrophages, and they’re released by macrophages

Front 15

What does phago mean?

Back 15

Phago means eat.

Front 16

What do neutrophils do, and compare them to macrophages?

Back 16

Neutrophils can eat about 25 bacteria, are not as deadly as macrophages, secrete lysozyme, free radicals, NO, and ROIs like hydrogen peroxide.

Front 17

Where are neutrophils found and what are they doing?

Back 17

Neutrophils are found wandering around the connective tissues attacking bacteria.

Front 18

What is respiratory burst?

Back 18

Respiratory burst is the quick release of reactive oxygen species by phagocytes that degrade internalized particles or bacteria.

Front 19

What are eosinphils, where are they found, and what do they do?

Back 19

Eosinphils are a type of phagocyte cell found in the mucous membranes, and are specialized in attacking parasites, and involved in allergies and inflammation.

Front 20

What are basophils, what do they do, and what chemicals do they release?

Back 20

Basophils aid the mobility of other leukocytes by releasing the vasodialator histamine, and they also secrete the anticoagulant heparin.

Front 21

What are leukocytes?

Back 21

21. Leukocytes are another name for white blood cells.

Front 22

What affect does vitamin K have on blood, what cell produces the chemical that works against vitamin K clotting blood, and what is the name of the chemical?

Back 22

Vitamin K is an important blood-clotting factor, heparin is produced by basophil cells and heparin works as an anticoagulant.

Front 23

Roughly what portion of leukocytes are basophils?

Back 23

Basophils represent approximately .01%  .3% of all leukocytes.

Front 24

What are mast cells?

Back 24

Mast cells are a type of connective tissue cell similar to basophils, and contain granules of histamine and heparin.

Front 25

Describe the process of phagocytosis.

Back 25

The phagocyte engulfs a particle or bacteria through its cell membrane to form a phagosome, or food vacuole, the lysosome brakes it up with enzymes and toxic peroxides, and then the wastes are removed via exocytosis.

Front 26

What are natural killer cells, where are they found, and what do they do?

Back 26

Natural killer cells are large granular lymphocytes that continually patrol the body engaging in immune surveillance, detecting and destroying malignant cells by detecting the lack of “self” receptors and certain surface sugars on foreign cells.

Front 27

What are lymphocytes?

Back 27

Lymphocytes are a type of white blood cell.

Front 28

What are the four cardinal signs of inflammation?

Back 28

The four cardinal signs of inflammation are heat, redness, pain, and swelling.

Front 29

What are Toll-like receptors (TLRs), and how many known active toll-like receptors in human body?

Back 29

Each toll-like receptor can detects some essential component of a disease-causing agent, and there are approximately 10 different toll-like receptors found so far in the human body.

Front 30

Give three examples of things toll-like receptor can spot.

Back 30

Toll-like receptors can spot the flagellin in the tails of motile bacteria, bind to single stranded viral RNA, and bind to uniquely bacterial lipopeptites.

Front 31

What is a liptopeptide, where are they found, and what do they attract?

Back 31

A lipopeptide is a molecule that bacteria exhibit that consists of a lipid and a peptide, and Toll-like receptors are receptive to them.

Front 32

What does toll mean?

Back 32

Toll is a German word for amazing or far out.

Front 33

What does vasodialation and increased vascular permeability have to do with inflammation, and what cells help this to happen?

Back 33

Mast cells release chemicals that cause blood vessels near the wound to constrict, while their release of histamine induce vessels further from the wound to dialate.

Front 34

There are 5 steps to phagocyte mobilization, name and describe each one.

Back 34

• Leukocytosis: Inflammatory and vasoactive chemicals like histamine, kinins, and leukotrienes call out to the red bone marrow to rapidly release neutrophils.
• Margination (pavementing): Margination, which is also known as pavementingis when endothelial cells in amea of injury produce selectins that snag leukocytes by interacting with their intergrins.
• Diapedesis (emigration): Diapedesis, which is also known as emigration, prompts the leukocytes to exit blood via gaps between the endothelial cells of the capillary wall, (vasoactive chemicals cause the cells to separate a bit) and enter the tissue fluid.
• Chemotaxis: Leukocytes usually migrate randomly, but inflammatory chemicals act as homing devises.
• Phagocytosis: The phagocyte engulfs a particle or bacteria through its cell membrane to form a phagosome, or food vacuole, the lysosome brakes it up with enzymes and toxic peroxides, and then the wastes are removed via exocytosis.

Front 35

Briefly describe what phagocyte mobilization is.

Back 35

Phagocyte mobilization is when cells nearby tissues release chemokines, which are also known as chemical movers, that crate a chemical gradient that attracts neutrophils and other WBCs.

Front 36

What are chemokines, and what are they also known as?

Back 36

Chemokines are secreted by cells and have the ability to induce chemotaxis, and they’re also known as chemical movers.

Front 37

What are kinins, who produces them, and what do they do?

Back 37

Kinins are a plasma proteinfound in plasma, urine, saliva, and in lysosomes of neutrophils. They work like histamine by promoting vasodialation of local aterioles, increasing permeability of local capillaries, induce chemotaxis of leukocytes and prompt neutrophils to release lysosomal enzymes, and induce pain.

Front 38

What is histamine, what produces it, and what does it do?

Back 38

Histamine is found in the granules of basophils and mast cells, and are released in response to mechanical injury, presence of certain microorganisms, and chemicals released by neutrophils. Histamine promotes vasodialation of local arterioles, and increases permeability of local capillaries.

Front 39

What are prostaglandins, what produces them, and what do they do?

Back 39

Prostaglandins are fatty acid molecules produced from arachidonic acid, which is found in all cell membranes, generated by enzymes of neutrophils, basophils, and mast cells.

Front 40

What is PDGF, what produces it, and what does it do?

Back 40

Platelet-derived growth factor is secreted by platelets and endothelial cells, and stimulates fibroblast activity and repair of damaged tissues.

Front 41

What is a fibroblast?

Back 41

A fibroblast is a type of cell that maintains the extracellular matrix of many animal tissues and plays an important part in wound healing.

Front 42

What are leukotrienes?

Back 42

Leukotrienes are a type of inflammatory mediator and is usually produced as a result of produced histamine.

Front 43

What are selectins, and what are they also known as?

Back 43

Selectins are footholds that arise from within endothelial cells that latch onto selectins on neutrophils, they’re also known as cell adhesion molecules or CAMs.

Front 44

What are integrins.

Back 44

Integrins are the SOS signals sticking out from the endothial lining of the blood vessel that rally protective WBCs to a nearby infected injured area.

Front 45

What does di mean?

Back 45

Di means through.

Front 46

What does ped mean?

Back 46

Ped means use your feet.

Front 47

In what way can inflammation affect the heart?

Back 47

When cholesterol accumulates in arteries, WBCs may pull it into the arterial wall, weakening the wall &/or triggering formation of blood clots.

Front 48

In what way can inflammation affect cancer?

Back 48

The inflammatory response may cause the growth of too many new cells, including abnormal ones.

Front 49

How do interferons work, and what kind of protein are interferons?

Back 49

Certain cells secrete proteins called interferons which biind to receptors on neighboring cells and activate second-messenger mechanisms that inhibit viral replication.

Front 50

Describe interferon production and response of cell receiving interferon.

Back 50

Interferons are antimicrobial proteins produced when a virus enters a cell, interferon genes turned on, interferon molecules produced, interferon binding stimulates cell to turn on genes for antiviral proteins, antiviral proteins block viral reproduction.

Front 51

Especially which cells secrete interferon?

Back 51

Leukocytes and reticular epithelial cells of the thymus secrete proteins called interferons.

Front 52

What other kind of cells do interferons also activate?

Back 52

Interferons also activate natural killer cells, and macrophages.

Front 53

What is complement, where and how many are most made, and why is it called complement?

Back 53

Complement is a group of bloodborne proteins that when activated enhance the inflammatory and immune responses and may lead to cell lysis. A group of about 30 globulins are made by the liver, and its called complement because it completes the action of antibody.

Front 54

What is lysis.

Back 54

Lysis is the death of a cell by way of breaking the cell membrane.

Front 55

Describe complement in terms of pathogen destruction.

Back 55

Complement is the principal means of pathogen destruction in antibody-mediated immunity.

Front 56

What chemical is released by neutrophils and macrophages to induce fever, and what kind of chemical is this?

Back 56

Interlukin-1 (IL-1) is a type of pyrogen secreted from neutrophils and macrophages that signals the hypothalamus to increase body temperature.

Front 57

What affect does IL-1 have on the hypothalamus?

Back 57

Interlukin one stimulates the release of prostaglandin E (PGE), which resets the body’s thermostat.

Front 58

What affect does asprin and ibuprofen have on fever and how?

Back 58

Asprin and ibuprofen inhibit PGE synthesis and there fore stop the hypothalamus from raising the body’s temperature.

Front 59

What benefits are there to letting a fever run its course?

Back 59

Allowing a fever to run its course promotes interferon activity, increases tissue repair, decreases bacterial and viral reproduction.

Front 60

How does letting a fever run its course affect bacterial and viral reproduction.

Back 60

Letting a fever run it course causes the liver and spleen to sequester zinc and iron, which are both needed for bacterial and viral reproduction.

Front 61

What does the prefix immuno mean?

Back 61

The prefix immuno means free.

Front 62

Name and describe the three qualities of the adaptive immunity system.

Back 62

• Specific: It recognizes and is directed against particular pathogens or foreign substances that initiate the immune response.
• Systemic: Immunity isn’t restricted to initial infection site.
• Memory: After initial exposure, it recognizes and mounts even stronger attacks on the previously encountered pathogens.

Front 63

Does non-specific immunity system have memory?

Back 63

Non-specific immunity doesn’t have memory.

Front 64

Name and describe how two forms of immunity that interact extensively and respond to the same pathogen.

Back 64

• Humoral immunity: is antibody (Ab) mediated whose main weapon is antibodies, that don’t directly destroy a pathogen but “tags” them for destruction. Abs work against extracellular targets.
• Cellular immunity: is cell-mediated whose main weapon is lymphocytes that directly attack and destroy diseased host cells or foreign invaders. Ags work against intracellular targets.

Front 65

What are antibodies, and what are they also known as?

Back 65

A protein molecule released by a plasma cell, which is a daughter cell of a an activated B lymphocyte, that binds specifically to an antigen. Antibodies are also known as immunoglobulins (Igs), and they constitute the gamma globulin part of blood.

Front 66

What are antigens and what is their abbreviation?

Back 66

An antigen, abbreviated Ag, is a substance or part of a substance (living or not) that is recognized as foreign by the immune system, and reacts with immune cells or their products.

Front 67

What works against extracellular targets and what works against intracellular targets?

Back 67

The humoral response, which works by tagging pathogens with antibodies works against extracellular targets, and cellular immunity, which works to directly destroy diseased hosts or foreign invaders, works against intracellular targets.

Front 68

What does anti gen mean?

Back 68

Antibody generator.

Front 69

An antigen is any molecule that __________?

Back 69

An antigen is any molecule that triggers an immune response.

Front 70

What are exogenous antigens, and give some examples?

Back 70

Exogenous antigens are antigens that have entered the body from the outside. By phagocytosis, these antigens are taken into the antigen-presenting cells (APCs) and processed into fragments. APCs then present the fragments to T helper cells (CD4+) by the use of class II histocompatibility molecules[1] on their surface.

Front 71

What are endogenous antigens, and give some examples?

Back 71

Endogenous antigens are antigens that have been generated within the cell, as a result of normal cell metabolism, or because of viral or intracellular bacterial infection. The fragments are then presented on the cell surface in the complex with MHC class I molecules.

Front 72

What are complete Ags, and what is their weight?

Back 72

Complete antigens exhibit immunogenicity and reactivity, and have an approximate weight of 10,000 amu.

Front 73

What are incomplete Ags, and what are they also known as.

Back 73

Incomplete Ags are also known as Haptens. They’re not antigenic by themselves but can bind to a host macromolecule and be recognized as foreign.

Front 74

What is immunogenicity?

Back 74

Immunogenicity means to generate an immune response.

Front 75

What are antigenic determinants, and what are they also known as?

Back 75

Antigenic determinants are the certain parts of an entire antigen that are immunogenic, they’re also known as epitopes.

Front 76

What are self-antigens, and what are they called?

Back 76

Major histocompatibility complex (MHC) are a group of glycoproteins that mark the cell surface as “self”.

Front 77

What does reactivity mean when related to immunology?

Back 77

Reactivity is the ability to react with the activated lymphocytes and the antibodies released by immunogenic reactions.

Front 78

Where are haptens typically found?

Back 78

Haptens, also known as incomplete antigens, are found in penicillin, poison ivy, animal dander, detergents, cosmetics, etc.

Front 79

What marks the cell surface as “self”?

Back 79

MHCs mark the cell surface as self.

Front 80

What do class 1 MHCs do?

Back 80

Class 1 MHC proteins are found on virtually all body cells.

Front 81

When healthy, what do class 1 MHC display, and what do they display when they are infected?

Back 81

When healthy class 1 MHC display a diverse array of peptides from the breakdown of cellular proteins. When infected, the class 1 MHC binds to fragments of foreign antigens that come from within the infected cell.

Front 82

What do class II MHCs do?

Back 82

Class II MHCs display peptides that come from outside the cell.

Front 83

What are MACs?

Back 83

The membrane attack complex (MAC) is typically formed on the surface of intruding pathogenic bacterial cells as a result of the activation of the complement system, and it is one of the ultimate weapons of the immune system.

Front 84

What are B lymphocytes?

Back 84

Also called B cells, the B stands for blood, as they oversee humoral immunity.

Front 85

What are T lymphocytes?

Back 85

Also called T cells, they are non-antibody-producing lymphocytes that constitute the cell-mediated arm of adaptive immunity.

Front 86

What are APCs?

Back 86

An antigen-presenting cell (APC) or accessory cell is a cell that displays foreign antigen complexed with MHC on its surface. T-cells may recognize this complex using their T-cell receptor (TCR).

Front 87

Describe positive and negative selection, and where do they occur?

Back 87

• Positive selection occurs in the thymic cortex, and is an MHC restriction process. It identifiesT cells whose receptors are capable of recognizing self-MHC molecules. The molecules that make it through positive selection are tested to make sure they don’t react vigorously to self-antigens bound to self-MHC.
• Those who don’t pass this test are eliminated by apoptosis, and this is referred to as negative selection.

Front 88

What is apoptosis?

Back 88

Apoptosis is programmed cell death.

Front 89

Where do lymphocytes arise from?

Back 89

Lymphocytes arise from red bone marrow.

Front 90

Immature lymphocytes destined to become T cells go where to become competent?

Back 90

Future T cells go to the Thymus to become competent.

Front 91

Immature lymphocytes destined to become B cells go where to become competent?

Back 91

Future B cells stay in the red bone marrow to become competent.

Front 92

What 2 things must a mature cell be able to do?

Back 92

They must be able to recognize its one specific antigen by binding to it, this is called immunocompetence, and they must be relatively unresponsive to self-antigens, this is called self-tolerance.

Front 93

What is self-tolerance?

Back 93

Self-tolerance is an immune cells ability to recognize its body’s self-antigens.

Front 94

What is immunocompetence?

Back 94

Immunocompetence is the immune cell being able to recognize its specific antigen by binding to it.

Front 95

Describe the education process of a T cell.

Back 95

Education in the thymus ensures they’ll be able to bind MHC molecules whose antigens are presented to T cell for recognition, and not react strongly to self-antigens normally found in the body.

Front 96

Describe the three steps of lymphocyte traffic for T cells.

Back 96

• Those destined to become T cells migrate to the thymus and develop immunocompetence.
• After leaving thymus as naïve immunocompetent cells, they seed the lymph nodes, spleen, and othe lymphoid tissues where the antigen challenge occurs.
• Antigen-activated immunocompetent lymphocytes circulate continuously in the blood stream and lymph and through out the lymphoid organs of the body.

Front 97

Describe the three steps of lymphocyte traffic for B cells.

Back 97

• Those destined to become cells stay in the red bone marrow and develop immunocompetence.
• After leaving red bone marrow as naïve immunocompetent cells, they seed the lymph nodes, spleen, and othe lymphoid tissues where the antigen challenge occurs.
• Antigen-activated immunocompetent lymphocytes circulate continuously in the blood stream and lymph and through out the lymphoid organs of the body.

Front 98

What is the antigen challenge?

Back 98

The first encounter between an immunocompotent but naïve lymphocyte and an invading antigen, usually takes place in the spleen or in a lymph node, but could happen in any lymphoid tissue.

Front 99

Name and describe the function of the 4 APCs.

Back 99

• Dendritic cells (DCs): are immune cells and form part of the immune system. Their main function is to process antigen material and present it on the surface to other cells of the immune system, thus functioning as antigen-presenting cells.
• Langerhans’ cells: are dendritic cells abundant in epidermis, containing large granules called Birbeck granules. They are normally present in lymph nodes.
• Macrophages
• Activated B lymphocytes

Front 100

What are APCs?

Back 100

These professional APCs are very efficient at internalizing antigen, either by phagocytosis or by receptor-mediated endocytosis, and then displaying a fragment of the antigen, bound to a class II MHC molecule, on their membrane.

Front 101

What is the antigen challenge?

Back 101

The antigen challenge is when a naïve immunocompetent lymphocyte first encounters the antigen it’s been trained to recognize.