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