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The Lymphatic System.

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Presentation on theme: "The Lymphatic System."— Presentation transcript:

1 The Lymphatic System

2 Introduction The ability to ward off pathogens that produce disease is called resistance

3 Introduction Lack of resistance is called susceptibility

4 Lymphatic System Consist of; lymph (fluid) lymphatic vessels
lymphatic organs and tissues bone marrow

5 Lymphatic System Functions; Drain interstitial fluid

6 Lymphatic System 2. Return leaked plasma proteins to the blood

7 Lymphatic System 3. Protects against invasion by nonspecific defenses and specific immune responses

8 Lymphatic Circulation
Interstitial fluid drains into lymphatic capillaries thus forming lymph


10 Lymphatic Circulation
Lymph capillaries merge to form larger vessels, called lymphatic vessels

11 Lymphatic Circulation
Convey lymph into and out of structures called lymph nodes


13 Lymphatic Capillaries
Lymphatic capillaries are found everywhere except; 1. Avascular tissue

14 Lymphatic Capillaries
2. CNS

15 Lymphatic Capillaries
3. Portions of the spleen

16 Lymphatic Capillaries
4. Red bone marrow

17 Lymphatic Capillaries
Lacteal – lymphatic capillary in the villus of the small intestine which transport fats

18 Lymph Trunk and Ducts Thoracic Duct Right Lymphatic Duct


20 Thoracic Duct Main collecting duct of the lymphatic system


22 Thoracic Duct Receives lymph from the left side of the head, neck, and chest, the left upper extremity and the entire body below the ribs

23 Thoracic Duct It drains lymph into venous blood via the left subclavian vein

24 Right Lymphatic Duct Drains lymph from the upper right side of the body


26 Right Lymphatic Duct It drains lymph into venous blood via the right subclavian vein

27 Flow of Lymph 1. Fluid flows from arteries and blood capillaries to interstitial spaces (interstitial fluid)


29 Flow of Lymph 2. To lymph capillaries (lymph)


31 Flow of Lymph 3. To lymphatic vessels


33 Flow of Lymph 4. To lymph trunks


35 Flow of Lymph 5.To the thoracic duct or right lymphatic duct

36 Flow of Lymph 6. To the subclavian veins (blood)


38 Lymphatic Organs and Tissues
Lymphatic organs are classified as primary or secondary

39 Primary Lymphatic Organs
Red bone marrow Thymus gland

40 Secondary Lymphatic Organs
Lymph nodes Spleen Lymphatic nodules

41 Thymus Gland Lies between the sternum and the heart


43 Thymus Gland Functions in immunity as the site of T cell maturation

44 Thymus Gland Large in the infant and after puberty it is replaced by adipose and areolar connective tissue

45 Lymph Nodes Are encapsulated oval structures located along lymphatic vessels

46 Lymph Nodes Contain T cells, macrophages, follicular dendritic cells, B cells, and plasma cells

47 Lymph Nodes Lymph enters nodes through afferent lymphatic vessels and is filtered to remove damage cells and microorganisms

48 Lymph Nodes Exits through efferent lymphatic vessel

49 Lymph Nodes Foreign substances filtered by the lymph nodes are trapped by nodal reticular fibers

50 Lymph Nodes Macrophages destroys foreign substances by phagocytosis

51 Lymph Nodes Lymphocytes bring about the destruction of others by immune response

52 Lymph Nodes Site of proliferation of plasma cells (from B cells) and T cells Plasma cells make antibodies

53 Spleen Largest mass of lymphatic tissue in the body

54 Spleen Located between the stomach and diaphragm


56 Spleen Made up of white and red pulp

57 White Pulp Lymphatic Tissue


59 White Pulp Its T lymphocytes directly attack and destroy antigens in blood

60 White Pulp Its B lymphocytes develop into antibody producing plasma cells, and the antibodies inactivate antigens in blood

61 White Pulp Macrophages destroy antigens in blood by phagocytosis

62 Red Pulp Consists of; Venous sinuses Splenic cords


64 Red Pulp Venous sinuses are filled with blood

65 Red Pulp Splenic cords consist of; RBCs Macrophages Lymphocytes
Plasma cells granulocytes

66 Red Pulp Macrophages remove deffective RBCs, WBCs, and platelets

67 Red Pulp Stores blood platelets

68 Lymphatic Nodules Oval-shaped concentrations of lymphatic tissue

69 Lymphatic Nodules Scattered throughout the mucous membranes lining the GI tract, respiratory airways, urinary tract, and reproductive tract

70 Peyer’s patches Lymphatic nodules in the ileum of the small intestine

71 Tonsils Multiple aggregations of large lymphatic nodules at the junction of the oral cavity and the pharynx

72 Tonsils Include; Pharyngeal Palatine Lingual tonsils

73 Tonsils Participate in immune responses by producing lymphocytes and antibodies

74 Nonspecific Resistance to Disease
Involves a First line of Defense Second line of Defense

75 First Line of Defense Involves Mechanical Protection
Chemical Protection

76 Mechanical Protection
Include 1. Epidermis layer of the skin

77 Mechanical Protection
2. Mucous membranes in the nose and trachea

78 Mechanical Protection
3. Lacrimal apparatus

79 Mechanical Protection
4. Saliva

80 Mechanical Protection
5. Mucus

81 Mechanical Protection
6. Cilia

82 Mechanical Protection
7. Epiglottis

83 Mechanical Protection
8. Flow of urine

84 Mechanical Protection
9. Defecation

85 Mechanical Protection
10. Vomiting

86 Chemical Protection 1. The skin produces sebum, which has a low pH

87 Chemical Protection 2. Lysozyme in sweat has antimicrobial properties

88 Chemical Protection 3. Gastric juice in the stomach has a low pH

89 Chemical Protection 4. Vaginal secretions are also acidic

90 Second Line of Defense Involves Antimicrobial proteins
Phagocytic and natural killer cells Inflammation Fever

91 Antimicrobial Proteins
Interferons Complement System

92 Interferons Body cells infected with viruses produce proteins called interferons (IFNs)

93 Interferons IFN diffuses to uninfected cells and binds to surface receptors

94 Interferons This induces uninfected cells to synthesize antiviral proteins that inhibit viral replication

95 Complement System A group of 20 proteins present in blood plasma and on cell membranes

96 Complement System When activated, these proteins enhance immune, allergic, and inflammatory reactions

97 Natural Killer Cells Lymphocytes that lack the membrane molecules that identify T and B cells

98 Natural Killer Cells Can kill a variety of infectious microbes and some tumor cells

99 Natural Killer Cells Sometime release perforins that insert into the plasma membrane of a microbe and make the membrane leaky so that cytolysis occurs

100 Natural Killer Cells Sometimes they bind to a target cell and inflict damage by direct contact

101 Phagocytes Neutrophils and macrophages

102 Inflammation Four symptoms Redness Pain Heat Swelling

103 Inflammation Three stages Vasodilation and increased permeability

104 Inflammation 2. Emigration of phagocytes from the blood into interstitial fluid

105 Inflammation 3. Tissue Repair

106 Inflammation Vasodilation and increased permeability are responsible for heat, redness, and swelling

107 Inflammation Pain results from injury to neurons and from toxic chemicals released by microbes

108 Fever When macrophages respond to an infection, they release interleukin -1

109 Fever Interleukin-1 stimulates the hypothalamus to initiate a fever

110 Fever Inhibits some microbial growth and speeds up body reactions that aid repair

111 Major Histocompatibility Complex Antigens
Unique to each person’s body cells

112 Major Histocompatibility Complex Antigens
All cells except rbc display MHC class I antigens

113 Major Histocompatibility Complex Antigens
Antigen presenting cells (macrophages) also display MHC class II antigens

114 Pathways of Antigen Processing
For an immune response to occur, B and T cells must recognize that a foreign antigen is present

115 Pathways of Antigen Processing
Antigens are chemical substances that are recognized as foreign by antigen receptors when introduced into the body

116 Pathways of Antigen Processing
The body contains millions of different T and B cells each capable of responding to a specific antigen

117 Cell-Mediated Immunity
Refers to destruction of antigens by T cells

118 Cell-Mediated Immunity
Three main steps

119 Cell-Mediated Immunity
1. T cells recognize antigen fragments associated with MHC II class molecules on the surface of an antigen presenting cell (macrophage).


121 Cell-Mediated Immunity
Although CD8 cell receptors bind to the antigen associated with MHC class I molecules on the virus infected cell

122 Cell-Mediated Immunity
2. A small number of T cells proliferate and differentiate into a clone of effector cells


124 Cell-Mediated Immunity
2 continued … Clone of effector cells – a pop. of identical cells that can recognize the same antigen

125 Cell-Mediated Immunity
3. Antigen (intruder) is eliminated

126 Types of T Cells Helper T (TH) cells Cytotoxic T (TC) cells
Memory T cells

127 Helper T cells T4 cells

128 Helper T cells Display CD4 proteins

129 Helper T cells Recognize antigen fragments associated with MHC-II molecules

130 Helper T cells Secrete interleukin-2 which as a costimulator

131 Helper T cells Proliferation of T cells requires costimulation

132 Cytotoxic T cells Fight foreign invaders by killing the target cell

133 Cytotoxic T cells Target cell – the cell that bears the same antigen that stimulated proliferation

134 Cytotoxic T cells One killing mechanism uses perforin to cause cytolysis of the target cell.


136 Cytotoxic T cells The second mechanism uses lymphotoxin to activate damaging enzymes within the target cells

137 Cytotoxic T cells Main targets are virus infected cells

138 Memory T cells Programmed to recognize the original invading antigen

139 Antibody-Mediated Immunity
Refers to destruction of antigens by antibodies

140 Antibody-Mediated Immunity
There are 4 steps

141 Antibody-Mediated Immunity
1. An antigen binds to the surface of B cells


143 Antibody-Mediated Immunity
2. Some antigen is taken into the B cell, broken down into peptide fragments and combined with the MHC-II self antigen, and moved to the B cell surface


145 Antibody-Mediated Immunity
3. Hepler T cells recognize the antigen-MHC-II combination and secrete interleukins


147 Antibody-Mediated Immunity
The interleukins deliver the costimulation needed for B cell proliferation

148 Antibody-Mediated Immunity
4. Some activated B cells become antibody-secretion plasma cells. Others become B cells


150 Antibodies A protein that can combine specifically with the antigenic determinant on the antigen that triggered its production

151 Antibodies Five classes IgG IgA IgM IgD IgE

152 IgG It binds to bacteria and viruses

153 IgG It crosses the placenta until it can begin secreting its own.

154 IgA It is in blood, breast milk, tears, saliva, and intestinal secretions.

155 IgA Levels decrease during stress

156 IgA Protects our mucous membranes against infections with bacteria and viruses

157 IgM First antibody to be secreted by plasma cells after exposure to antigens

158 IgM Antibodies to A and B red cell antigens are IgM

159 IgM Cannot cross the placenta

160 IgD Activate B cells

161 IgE On the surface of mast cells and basophils

162 IgE Involved in allergic reactions

163 IgE When a person with pollen allergies inhales pollen, it combines with the IgE on their mast cells

164 IgE Causes mast cells to release histamine

165 AIDS A condition in which a person experiences infections as a result of the progressive destruction of cells by the humon immunodeficiency virus

166 HIV The only documented transmissions are by way of blood, semen, vaginal secretions, and breast milk

167 HIV A recent study in San Fran showed that 8% of their HIV-infected patients acquired it via oral sex

168 HIV Form of a retrovirus with a protein coat

169 HIV HIV enters CD4 positive T lymphocytes and macrophages where it sheds its protein coat

170 HIV New HIV DNA is produced in the T cell along with new protein coats and then released

171 HIV The T cells are ultimately destroyed

172 HIV Progression to AIDS occurs because of reduced numbers of T cells and resulting immunodeficiency

173 AIDS Person now susceptible to opportunistic infections

174 HIV Treatment of HIV infection with reverse transcriptase inhibitors has shown to delay the progression of HIV infection to AIDS

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