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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
Q

Tonsils

A

Simplest lymphoid organs
Ring of lymphatic tissue around pharynx
Gather and remove pathogens in food or air

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26
Q

tonsillar crypts

A

Epithelium indents
Trap and destroy bacteria,particulate matter
Immune cells build memory for pathogens

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27
Q

Peyer’s patches

A

Clusters of lymphoid follicles in wall of small intestine
• Destroy bacteria, preventing them from breaching intestinal wall
• Generate “memory” lymphocytes

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28
Q

Innate Defense

A 
Surface Barriers - Mucous Membranes and Skin.
Internal defenses
• Phagocytes
• Natural killer cells
• Inflammation
• Antimicrobial proteins
• Fever
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29
Q

Adaptive Defense

A
  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

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30
Q

Skin

A

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)

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31
Q

Respiratory system modifications

A

Mucus-coated hairs in nose

Cilia of upper respiratory tract sweep dust/bacteria-laden mucus toward mouth

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32
Q

Internal Defenses: If deeper tissues invaded

A

Phagocytes
Natural killer (NK) cells
Interferons and complement proteins
Inflammatory response

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33
Q

Phagocytes

A

Neutrophils most abundant but die fighting
Macrophages chief phagocytic cells
-Free wander tissue spaces (alveolar)
-Fixed permanent residents (liver, brain)

34
Q

Natural Killer (NK) Cells

A

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
Q

Inflammatory Response

A 
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
Q

Cardinal signs of acute inflammation

A 
Redness
Heat
Swelling
Pain
Impairment of function
37
Q

Inflammatory mediators

A

Kinins, prostaglandins, complement
Dilate local arterioles (hyperemia)
Make capillaries leaky
Many attract leukocytes to area

38
Q

Innate Defense steps of Inflammatory response

A

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
Q

Interferons

A

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
Q

Complement Proteins

A

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

41
Q

opsonization

A

pathogen is marked for ingestion by a phagocyte

42
Q

Fever

A

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
Q

Antigens

A

Complex molecules not found in body

targets of all adaptive response

44
Q

Immunogenicity

A

ability to stimulate proliferation of specific lymphocytes

45
Q

Reactivity

A

ability to react with activated lymphocytes and antibodies

46
Q

MHC (Major Histocompatibility Complex)

A

glycoproteins, unique to individual, have groove holding self- or foreign antigen

47
Q

self-antigens

A

Protein molecules on surface of cells not antigenic to self but antigenic to others in transfusions or grafts

48
Q

Three types of cells in Adaptive Response

A 
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
Q

Positive Selection

A

T Cells must recognize a MHC. Failure to recognize MHC results in apoptosis, recognize results in survival.

50
Q

Negative Selection

A

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
Q

Steps of Lymphocyte Maturation

A

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
Q

Antigen-presenting Cells (APCs)

A

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
Q

Humoral Immunity Primary Response and Proliferation

A 
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
Q

Active Humoral Immunity

A

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
Q

Vaccines

A

Dead or attenuated pathogens

Provide antigenic determinants that are immunogenic and reactive

56
Q

Humoral Immunity Passive vs Active

A

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
Q

IgM

A

First antibody released
Potent agglutinating agent
Fixes and activates complement

58
Q

IgA (secretory IgA)

A

Monomer or dimer; secretions

Helps prevent entry of pathogens

59
Q

IgD

A

Monomer on surface of B cells

60
Q

IgG

A

Monomer; most of antibodies in plasma

Crosses placental barrier

61
Q

IgE

A

Monomer active in some allergies and parasitic infections

Causes release of histamine

62
Q

Neutralization

A

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
Q

Agglutination

A

Antibodies bind same determinant on more than one cell-bound antigen
Cross-linked antigen-antibody complexes agglutinate

64
Q

Precipitation

A

Soluble molecules are cross-linked then complexes are subject to phagocytosis

65
Q

Complement Fixation and Activation

A

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
Q

Two types of MHC proteins important to T cell activation

A

Class I MHC proteins – all cells except RBCs

Class II MHC proteins – APCs (dendritic cells, macrophages, and B cells)

67
Q

Class I MHC

A

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
Q

Class II MHC

A

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
Q

T cell Activation: Antigen Binding

A

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
Q

T cell Activation: Co-stimulation

A

Requires T cell binding to other surface receptors on an APC – co-stimulation
Cytokines trigger proliferation and differentiation of activated T cell

71
Q

T cell Activation Requires

A

Antigen Binding

Co-Stimulation

72
Q

Cytokines

A

Cell development and differentiation
Include interferons and interleukins
IL-2 key growth factor, acting on cells that release it and other T cells

73
Q

Helper T Cells

A

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
Q

Targets of Cytotoxic T Cells

A

Virus-infected cells
Cells with bacteria, parasites
Cancer cells
Foreign cells (transfusions, transplants)

75
Q

SCID

A

Severe combined Immunodeficiency Syndrome (Boy in the Bubble)
Genetic Defect in B & T cells, treated with bone marrow transplant and gene therapy

76
Q

Hodgkin’s Disease

A

Acquired immunodeficiency
Cancer of B cells
Leads to immunodeficiency by depressing lymph node cells, swollen lymph nodes

77
Q

Acquired Immune Deficiency Syndrome (AIDS)

A

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
Q

HIV

A

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

79
Q

Autoimmune Diseases

A

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
Q

Treatment of Autoimmune Diseases

A 
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
Q

Hypersensitivities

A

Immune responses to perceived (harmless) threat cause tissue damage

82
Q

Anaphylactic Shock

A

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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