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Anatomy & Physiology > Chapter 21 - Lymphatic & Immune System > Flashcards

Chapter 21 - Lymphatic & Immune System Flashcards

1
Q

Lymphatic System

A

Structural basis of immune system, houses phagocytes and lymphocytes. Returns fluid that leaked from blood vessels back to blood. Includes: Tonsils, Thymus, Spleen, Aggregated Lymphoid, Appendix

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2
Q

3 Parts of Lymphatic System

A
  1. Network of Lymphatic Vessels
  2. Lymph - fluid in vessels
  3. Lymph nodes - cleanse lymph, checkpoints
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3
Q

Differences between lymphatic vessels and capillaries

A
  1. Permeable (proteins, debris, pathogens)
  2. Endothelia cells have one way mini valves (flaps)
  3. Increased extracellular fluid volume opens mini valves
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4
Q

Where are lymphatic vessels absent in body?

A

Bones, teeth, bone marrow, central nervous system

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5
Q

Lacteals

A

Specialized lymph capillaries in intestinal mucosa that absorbs digested fat and deliver fatty lymph to the blood.

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6
Q

Lymph delivered into blood stream via 2 large ducts

A

Thoracic duct - Left subclavian Vein and left internal jugular vein ( Rest of body)
Right Lymphatic Duct - Right Subclavian Vein (Right head and arm)

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7
Q

Lymphatic Collecting vessels are similar to veins except for:

A

Thinner walls, more intestinal valves, anastomose more frequently, nutrients supplied from vaso vasorum

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8
Q

What is Lymph Propelled By?

A 
Milking action of skeletal muscle
Pressure changes in thorax during breathing
Valves to prevent backflow
Pulsations of nearby arteries
Contraction of smooth muscle in walls.
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9
Q

Lymphocytes

A

Main warrior of immune system that arise in red marrow, mature into 1 of 2 main varieties, T-Cell (thymus) or B-Cell (marrow)

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10
Q

Macrophage

A

Phagocyte foreign substances, help activate T-cells

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11
Q

Dendritic cells

A

capture antigens and deliver them to lymph nodes

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12
Q

Reticular cells

A

produce reticular fiber stroma; supports cells in lymphoid organs

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13
Q

Functions of Lymphoid Tissue

A

Houses and provides proliferation site for lymphocytes
Survellance vantage point for lymphocyte and macrophage
composed mainly of reticular connective tissue

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14
Q

Where are lymph nodes found

A

Principal lymphoid organs, embedded in CT, in clusters along lymphatic vessles, nearby surfaces in inguinal, axillary and cervical areas.

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15
Q

Functions of lymph nodes

A

Filter lymph: macrophages destroy microorganisms and debris

Immune system activation: lymphocytes activated and mount attack on antigens

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16
Q

Circulation of lymph

A

Lymph enters via afferent lymphatic vessels; to subcapsular sinus and smaller sinuses to medullary sinuses; exits at hilum via efferent vessels

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17
Q

Chyle

A

Fatty Lymph

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18
Q

Lymphoid follicles

A

solid, spherical bodies of tightly packed lymphoid cells and reticular fibers
• Germinal centers of proliferating B cells
• Isolated aggregations of Peyer’s patches and in appendix

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19
Q

Spleen

A

Largest lymphoid organ
Site of lymphocyte proliferation and immune surveillance and response
Cleanses blood of aged cells and platelets, macrophages remove debris
FUNCTIONS:
Stores breakdown products of RBCs
Stores blood platelets and monocytes
May be site of fetal erythrocyte production
Contains lymphocytes, macrophages, and huge numbers of erythrocytes

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20
Q

White pulp

A

around central arteries**

Mostly lymphocytes on reticular fibers

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21
Q

Red pulp

A

in venous sinuses and splenic cords

Rich in RBCs and macrophages

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22
Q

Thymus

A

increases in size, most active during childhood but stops growing during adolescence, then atrophies
-Slowly produces immunocompetent cells

Most thymic cells are lymphocytes
Cortex contains rapidly dividing lymphocytes and macrophages
Medulla contains fewer lymphocytes and thymic corpuscles (regulatory T cell dev.)

Thymus differs from other lymphoid organs:
-Has no follicles because it lacks B cells
-Functions strictly in T cell maturation
Stroma of epithelial cells provide place where T cells become immunocompetent

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23
Q

Mucosa-associated Lymphoid Tissue (MALT):

A

In mucous membranes

-Protects from pathogens entering body

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24
Q

Tonsils, Peyer’s patches, Appendix

A

Mucosa of respiratory, genitourinary organs; rest of digestive tract

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25
Tonsils
Simplest lymphoid organs Ring of lymphatic tissue around pharynx Gather and remove pathogens in food or air
26
tonsillar crypts
Epithelium indents Trap and destroy bacteria,particulate matter Immune cells build memory for pathogens
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Peyer's patches
Clusters of lymphoid follicles in wall of small intestine • Destroy bacteria, preventing them from breaching intestinal wall • Generate "memory" lymphocytes
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Innate Defense
``` Surface Barriers - Mucous Membranes and Skin. Internal defenses • Phagocytes • Natural killer cells • Inflammation • Antimicrobial proteins • Fever ```
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Adaptive Defense
1. Specific: recognizes specific antigens 2. Systemic: not restricted to initial site 3. Memory: stronger attacks to “known” antigens Two separate, overlapping arms Humoral (antibody-mediated) immunity Cellular (cell-mediated) immunity Humoral Immunity B-Cells Cellular Immunity T-Cells
30
Skin
Physical barrier to microorganisms Keratin resistant to weak acids and bases, bacterial enzymes, and toxins Acidity of skin and secretions – acid mantle – inhibits growth Enzymes - lysozyme of saliva, respiratory mucus, lacrimal fluid kill microorganisms Defensins – antimicrobial peptides Other- lipids (sebum), dermcidin (sweat)
31
Respiratory system modifications
Mucus-coated hairs in nose | Cilia of upper respiratory tract sweep dust/bacteria-laden mucus toward mouth
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Internal Defenses: If deeper tissues invaded
Phagocytes Natural killer (NK) cells Interferons and complement proteins Inflammatory response
33
Phagocytes
Neutrophils most abundant but die fighting Macrophages chief phagocytic cells -Free wander tissue spaces (alveolar) -Fixed permanent residents (liver, brain)
34
Natural Killer (NK) Cells
Nonphagocytic large granular lymphocytes Attack cells that lack "self" receptors Induce apoptosis in cancer and virus-infected cells Secrete chemicals that ↑ inflammation ``` Recognize Lack of class I MHC, antibody coating target cell, surface markers of stressed cells Use same key mechanisms as TC cells for killing their target cells ```
35
Inflammatory Response
``` Triggered whenever body tissues injured Prevents spread of damaging agents Disposes of cell debris and pathogens Alerts adaptive immune system Sets the stage for repair ```
36
Cardinal signs of acute inflammation
``` Redness Heat Swelling Pain Impairment of function ```
37
Inflammatory mediators
Kinins, prostaglandins, complement Dilate local arterioles (hyperemia) Make capillaries leaky Many attract leukocytes to area
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Innate Defense steps of Inflammatory response
Leukocytosis.Neutrophils enter blood from bone marrow. Margination. Neutrophils cling to capillary wall. Diapedesis.Neutrophils flatten and squeeze out of capillaries. Chemotaxis.Neutrophils follow chemical trail.
39
Interferons
immune modulating proteins Viral-infected cells secrete IFNs to "warn" neighboring cells IFNs enter neighboring cells produce proteins that block viral reproduction and degrade viral RNA
40
Complement Proteins
Unleashes inflammatory chemicals that amplify all aspects of inflammatory response Kills bacteria and other cell types by lysis Enhances innate and adaptive defenses Cell lysis begins when C3b binds to target cell insertion of complement proteins called membrane attack complex (MAC) -MAC forms hole, influx of water lysis of cell
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opsonization
pathogen is marked for ingestion by a phagocyte
42
Fever
Systemic response, leukocytes and macrophages secrete pyrogens whichact on body's thermostat in hypothalamus Benefits: liver and spleen sequester iron and zinc (needed by microorganisms) and increases metabolic rate faster repair
43
Antigens
Complex molecules not found in body | targets of all adaptive response
44
Immunogenicity
ability to stimulate proliferation of specific lymphocytes
45
Reactivity
ability to react with activated lymphocytes and antibodies
46
MHC (Major Histocompatibility Complex)
glycoproteins, unique to individual, have groove holding self- or foreign antigen
47
self-antigens
Protein molecules on surface of cells not antigenic to self but antigenic to others in transfusions or grafts
48
Three types of cells in Adaptive Response
``` B lymphocytes: humoral immunity T lymphocytes: cell-mediated immunity Antigen-presenting cells (APCs) Do not respond to specific antigens Play auxiliary roles in immunity ```
49
Positive Selection
T Cells must recognize a MHC. Failure to recognize MHC results in apoptosis, recognize results in survival.
50
Negative Selection
T Cells must not recognize self-antigens. Recognize self-antigen results in apoptosis. Gets rid of T Cells that could cause autoimmune diseases. Failure to recognize results in Survival
51
Steps of Lymphocyte Maturation
Seeding secondary lymphoid organs and circulation • Immunocompetent but still naive lymphocytes leave the thymus and bone marrow. • They “seed” the secondary lymphoid organs and circulate through blood and lymph. Proliferation and differentiation • Activated lymphocytes proliferate (multiply) and then differentiate into effector cells and memory cells. • Memory cells and effector T cells circulate continuously in the blood and lymph and throughout the secondary lymphoid organs.
52
Antigen-presenting Cells (APCs)
Engulf antigens Present fragments of antigens to T cells Dendritic cells, Macrophages, B cells Dendritic cells phagocytize pathogens, present antigens to T cells in lymph node Macrophages present antigens to T cells to activate themselves into voracious phagocytes secreting bactericidals.
53
Humoral Immunity Primary Response and Proliferation
``` Most clone cells become plasma cells Secrete specific antibodies at rate of 2000 molecules per second for 4-5 days, die. Others become memory cells Provide immunological memory Response to exposures to same antigen ```
54
Active Humoral Immunity
B cells encounter antigens and produce specific antibodies - Naturally acquired: response to bacterial or viral infection - Artificially acquired: response to vaccine of dead or attenuated pathogens
55
Vaccines
Dead or attenuated pathogens | Provide antigenic determinants that are immunogenic and reactive
56
Humoral Immunity Passive vs Active
Passive Naturally - Antibodies passed from mother to fetus via placenta; or to infant in her milk Artificially - Injection of exogenous antibodies (gamma globulin) Active Naturally - Infection; contact with pathogen Artificially - Vaccine; dead or attenuated pathogens
57
IgM
First antibody released Potent agglutinating agent Fixes and activates complement
58
IgA (secretory IgA)
Monomer or dimer; secretions | Helps prevent entry of pathogens
59
IgD
Monomer on surface of B cells
60
IgG
Monomer; most of antibodies in plasma | Crosses placental barrier
61
IgE
Monomer active in some allergies and parasitic infections | Causes release of histamine
62
Neutralization
Antibodies block specific sites on viruses or bacterial exotoxins Prevent these antigens from binding to receptors on tissue cells Antigen-antibody complexes undergo phagocytosis
63
Agglutination
Antibodies bind same determinant on more than one cell-bound antigen Cross-linked antigen-antibody complexes agglutinate
64
Precipitation
Soluble molecules are cross-linked then complexes are subject to phagocytosis
65
Complement Fixation and Activation
Main antibody defense against cellular antigens (bacteria, mismatched RBCs) Several antibodies bind close together on a cellular antigen complement-binding Complement fixation into surface lysis
66
Two types of MHC proteins important to T cell activation
Class I MHC proteins – all cells except RBCs | Class II MHC proteins – APCs (dendritic cells, macrophages, and B cells)
67
Class I MHC
Bind with fragment of protein made in the cell (endogenous-antigen) Crucial for CD8 cell activation Inform cytotoxic T cells of microorganisms hiding in cells (cytotoxic T cells ignore displayed self-antigens)
68
Class II MHC
Bind with fragments of exogenous antigens that have been broken down in a phagolysosome Recognized by helper T cells Signal CD4 cells that help is required
69
T cell Activation: Antigen Binding
T cell antigen receptors (TCRs) bind to antigen-MHC complex on APC surface TCR that recognizes the nonself-self complex linked to signaling pathways
70
T cell Activation: Co-stimulation
Requires T cell binding to other surface receptors on an APC – co-stimulation Cytokines trigger proliferation and differentiation of activated T cell
71
T cell Activation Requires
Antigen Binding | Co-Stimulation
72
Cytokines
Cell development and differentiation Include interferons and interleukins IL-2 key growth factor, acting on cells that release it and other T cells
73
Helper T Cells
play central role in adaptive immune response Once primed by APC presentation they Help activate, proliferate T and B cells Cytokines recruit other immune cells Without TH, there is no immune response Amplify responses of innate immune system Activate macrophages more potent killers Mobilize lymphocytes and macrophages and attract other types of WBCs
74
Targets of Cytotoxic T Cells
Virus-infected cells Cells with bacteria, parasites Cancer cells Foreign cells (transfusions, transplants)
75
SCID
Severe combined Immunodeficiency Syndrome (Boy in the Bubble) Genetic Defect in B & T cells, treated with bone marrow transplant and gene therapy
76
Hodgkin’s Disease
Acquired immunodeficiency Cancer of B cells Leads to immunodeficiency by depressing lymph node cells, swollen lymph nodes
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Acquired Immune Deficiency Syndrome (AIDS)
Cripples immune system by interfering with activity of helper T cells -Weight loss, night sweats, swollen nodes Opportunistic infections: pneumocystis pneumonia and Kaposi's sarcoma Caused by human immunodeficiency virus (HIV) transmitted via body fluids—blood, semen, and vaginal secretions Blood transfusions; blood-contaminated needles; sex, mother to fetus
78
HIV
HIV multiplies in lymph nodes throughout asymptomatic period, ~10 years HIV-coated glycoprotein complex attaches to CD4 receptor Enters cell and uses reverse transcriptase to produce DNA from its RNA
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Autoimmune Diseases
Immune system loses ability to distinguish self from foreign Production of autoantibodies and sensitized TC cells that destroy tissues MS, myasthenia gravis, Graves' disease, type 1 diabetes mellitus, lupus, glomerulonephritis, rheumatoid arthritis
80
Treatment of Autoimmune Diseases
``` Suppress entire immune system Anti-inflammatory drugs, Blocking cytokine action Blocking co-stimulatory molecules Activating regulatory T cells; inducing self-tolerance using vaccines; directing antibodies against self-reactive immune cells ```
81
Hypersensitivities
Immune responses to perceived (harmless) threat cause tissue damage
82
Anaphylactic Shock
Systemic response to allergen that circulates rapidly -Systemic histamine release may cause constriction of bronchioles; tongue swelling -Vasodilation, fluid loss from bloodstream may hypotensive shock, death Treatment: epinephrine

Anatomy & Physiology (26 decks)

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