1. Lymphatic system and immunity
D- Chapter 16
Lecture PowerPoint
Lymphatic system and immunity
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2. Chapter 16 Lymphatic System and Immunity2

3. 16.1: Introduction
The lymphatic system is a vast collection of cells and biochemicals that travel in lymphatic vessels
It is a network of vessels that assist in circulating fluids
It is closely associated with the cardiovascular system
It transports excess fluid away from the interstitial spaces
It transports fluid to the bloodstream
It transports fats to the bloodstream
It helps defend the body against diseases 3

4. 16.2: Lymphatic Pathways 4 Lymphatic capillaries Pulmonary capillary
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Lymphatic
capillaries
Pulmonary
capillary
network
Lymph
node
Lymphatic
vessels
Blood
flow
Lymph
node
Lymph
flow
Systemic
capillary
network 4
Lymphatic
capillaries

5. Lymphatic Capillaries
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Lymphatic
capillary
Capillary
bed
Tissue cells
Venule
Arteriole
Lymphatic
vessel 5

6. © The McGraw-Hill Companies, Inc./Dennis Strete, photographer
Lymphatic Vessels
The walls are similar but thinner than those of veins
Lymphatic vessels are composed of three layers:
An endothelial lining (inner)
Smooth muscle (middle)
Connective tissue (outer)
Larger vessels lead to lymph nodes and then to larger lymphatic trunks
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© The McGraw-Hill Companies, Inc./Dennis Strete, photographer

7. Lymphatic Trunks and Collecting Ducts
The trunks drain lymph from the lymphatic vessels
They are named for the regions they serve such as lumbar, intestinal, intercostal, bronchomediastinal, subclavian, and jugular
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Jugular trunk
Internal jugular vein
Right lymphatic duct
Thoracic duct
Brachiocephalic vein
Subclavian trunk
Bronchomediastinal trunk
Thoracic duct
Intercostal
trunk
Intestinal
trunk
Lumbar
trunk
Lymphatic
vessels 7

8. 8 Right internal jugular vein Right lymphatic duct Right subclavian
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Right internal jugular vein
Right lymphatic duct
Right subclavian
vein
Left internal
jugular vein
Area drained
by right lymphatic duct
Thoracic duct
Right lymphatic
duct
Left subclavian
vein
Axillary lymph
nodes
Lymph nodes
Thoracic duct
Lymphatics of
mammary gland
Cisterna
chyli
Lymphatic
trunks
Lymphatic
vessels
(b)
(a) 8

9. Afferent lymphatic vessel
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Lymphatic capillary
Afferent lymphatic vessel
Lymph node
Efferent lymphatic vessel
Lymphatic trunk
Collecting duct 9
Subclavian vein

10. 16.3: Tissue and Fluid Lymph
Lymph is essentially tissue fluid that has entered a lymphatic capillary
Lymph formation depends on tissue fluid formation 10

11. Tissue Fluid Formation
Capillary blood pressure filters water and small molecules from the plasma
The resulting fluid has:
Much the same consistency as plasma
Contains water and dissolved substances
Contains smaller proteins which create plasma colloid osmotic pressure 11

12. Lymph Formation
Filtration from the plasma normally exceeds reabsorption, leading to the net formation of tissue fluid
This increases the tissue fluid hydrostatic pressure within interstitial spaces forcing fluid into lymphatic capillaries forming lymph
This process prevents accumulation of excess tissue fluid or edema 12

13. Lymph Function Lymphatic vessels play a role in:
Absorption of dietary fats
Delivering fats to the bloodstream
Collecting of excess interstitial fluids
Delivering excess fluids to the bloodstream
Delivering foreign particles to the lymph nodes
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Flow of lymph
Filaments
anchored to
connective
tissue
Epithelial
cell
Movement of
tissue fluid 13

14. 16.4: Lymph Movement
Hydrostatic pressure of tissue fluid drives the lymph into the lymphatic capillaries
Muscle activity largely influences the movement of lymph through the lymphatic vessels via:
Action of skeletal muscles
Respiratory movements
Smooth muscle in the larger lymphatic vessels
Valves in the lymphatic vessels 14

15. b: © The McGraw-Hill Companies, Inc./Al Telser, photographer
Lymph Flow
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Afferent
lymphatic
vessel
Subcapsule
(macrophages, B cells)
Lymph flow
Medulla
(macrophages, T cells)
Germinal
center
(B cells)
Sinus
Capsule
Nodule
Hilum
Artery
Lymph flow
Vein
Efferent lymphatic vessel
(a) 15
(b)
Germinal
center
Capsule
b: © The McGraw-Hill Companies, Inc./Al Telser, photographer

16. Obstruction of Lymph Movement
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Lymphatic
vessels
Lymph node
Blood vessels
Muscle 16
© Dr. Kent M. Van De Graaff

17. 16.5: Lymph Nodes
Lymph nodes or lymph glands are located along the lymphatic pathways
They contain lymphocytes and macrophages to fight invading pathogens 17

18. Structure of a Lymph Node
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Subcapsule
(macrophages, B cells)
Afferent
lymphatic
vessel
Lymph flow
Medulla
(macrophages, T cells)
Germinal
center
(B cells)
Sinus
Capsule
Nodule
Hilum
Artery
Lymph flow
Vein
Efferent
lymphatic
vessel 18
(a)

19. Locations of Lymph Nodes
Lymph nodes are found in groups or chains along the paths of the larger lymphatic vessels throughout the body, including the:
Cervical region
Axillary region
Supratrochlear region
Inguinal region
Pelvic cavity
Abdominal cavity
Thoracic cavity
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Thoracic
lymph
node
Cervical
lymph
node
Axillary
lymph
node
Supratrochlear
lymph node
Abdominal
lymph node
Inguinal
lymph
node
Pelvic lymph
node 19

20. Functions of Lymph Nodes
Lymph nodes have two primary functions:
Filter potentially harmful particles from the lymph
Act with immune surveillance provided by macrophages and lymphocytes
Along with the red bone marrow, the lymph nodes are centers for lymphocyte production 20

21. 16.6: Thymus and Spleen
These are two other lymphatic organs with functions similar to those of the lymph nodes 21

22. Thymus The thymus is: Larger in infancy and during puberty
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The thymus is:
Larger in infancy and during puberty
Small in an adult
Replaced by fat and connective tissue in the elderly
Site of T lymphocyte (or T cell) production
Secretes protein hormones called thymosins
Thymus
in fetus
Thymus
in adult 22

23. b: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Larynx
Thyroid gland
Trachea
Thymus
Lung
Heart
Diaphragm
Liver
Stomach
Spleen
(a)
Connective
tissue
Lobule
(b) 23
b: © The McGraw-Hill Companies, Inc./Dennis Strete, photographer

24. b: © The McGraw-Hill Companies, Inc./Al Telser, photographer
Spleen
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The spleen is:
The largest lymphatic organ
Located in the upper left abdominal quadrant
Has sinuses filled with blood
Contains two tissue types:
White pulp (lymphocytes)
Red pulp (red blood cells, lymphocytes and macrophages)
Spleen
Splenic
artery
Splenic
vein
Artery of pulp
White pulp
Venous sinus
Red pulp
Capillary
Connective
tissue
Capsule
(a)
Capsule
White pulp
Red pulp 24
(b)
b: © The McGraw-Hill Companies, Inc./Al Telser, photographer

25. 25

26. 16.7: Body Defenses Against Infection
The presence and multiplication of a pathogen in the body may cause an infection
Pathogens are:
Disease causing agents
Bacteria, viruses, complex microorganisms, and spores of multicellular organisms
The body can prevent entry of pathogens or destroy them with defense mechanisms such as:
Innate defenses :
These are general defenses
They protect against many pathogens
Adaptive defenses:
Known as immunity
More specific and precise targeting specific antigens
Are carried out by lymphocytes 26

27. 16.8: Innate (Nonspecific) Defenses27

28. Species Resistance
Refers to a given type of organism, or species, that develops diseases unique to it 28

29. Mechanical Barriers
The skin and mucous membranes create mechanical barriers
Mechanical barriers are considered the first line of defense (all other non-specific defenses are part of the second line of defense) 29

30. Chemical Barriers
Enzymes in body fluids provide a chemical barrier to pathogens, and they may include:
Interferons are horomone-like peptides and stimulate phagocytosis
Defensins are peptides produced by neutrophils and other granulocytes. They cripple microbes.
Collectins are proteins with broad protection against bacteria, yeast and some viruses
Complement is a group of proteins in plasma and other body fluids that stimulate inflammation, attract phagocytes and enhance phagocytosis 30

31. Natural Killer (NK) Cells
NK cells are a small population of lymphocytes defending against viruses and cancer by secreting cytolytic substances called perforins that destroy the infected cell
NK may also enhance inflammation 31

32. Inflammation
Inflammation produces local redness, swelling, heat and pain
Table 16.2 summarizes the process 32

33. Phagocytosis Phagocytosis removes foreign particles from the lymph
Phagocytes are also in the blood vessels and in the tissues of the spleen, liver or bone marrow
The most active phagocytic cells are neutrophils and monocytes
Chemicals attract these phagocytic cells to the injury and this is called chemotaxis 33

34. Fever
A fever begins when a viral or bacterial infection stimulates lymphocytes to proliferate, producing cells that secrete a substance called interleukin-1 (IL-1) 34

35. 16.9: Adaptive (Specific) Defenses or Immunity
This is the third line of defense and known as immunity
It is resistance to particular pathogens or to their toxins or metabolic by-products
It is based on the ability to distinguish molecules that are part of the body (“self” from “non-self”)
Antigens are molecules that can elicit an immune response 35

36. Antigens Antigens may be: Proteins Polysaccharides Glycoproteins
Glycolipids
The most effective antigens are large and complex
Haptens are small molecules that are not antigenic by themselves, but when they combine with a large molecule can stimulate an immune response 36

37. Lymphocyte Origins 37 1 Stem cells in red bone marrow give rise to
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Stem cells
in red bone
marrow give
rise to
lymphocyte
precursors.
Thymus 2
Some lymphocyte
precursors are
processed in the
thymus to become
T cells.
T cell
Blood
transport
Blood
transport
Red
bone
marrow
Lymphocyte
precursors
T cell
B cell
B cell
Lymph
node 3
Some lymphocyte
precursors are
processed within
the bone marrow
to become B cells.
Blood
transport 4
Both T cells and B cells are transported through the blood to lymphatic organs, such as the lymph nodes, lymphatic ducts, and spleen. 37

38. T Cells and the Cellular Immune Response
A lymphocyte must be activated before it can respond to an antigen
T cell activation requires antigen-presenting cell (accessory cell) and may include macrophages, B cells and several other types of cells
Requires major histocompatibility complex (MHC) or human leukocyte antigens (HLA) to recognize “non-self”
T cells can synthesize and secrete polypeptides called cytokines
Types of specialized T cells include:
Helper T cells
Cytotoxic T cells
Memory T cells 38

39. 39

40. B Cells and the Humoral Immune Response
B cells can be activated when an antigen fits the shape of its receptor
Most of the time B cell activation requires T cells
T cells release cytokines that stimulate B cells
Some B cells may become memory B cells while others differentiate into plasma cells and produce and secrete large globular proteins called antibodies or immunoglobulins 40

41. b: © Manfred Kage/Peter Arnold
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cytotoxic
T cell
Displayed
antigen
B cells
Cytotoxic T cell contacts
Displayed antigen 2
Macrophage displays ingested
antigen on its surface 3
Helper T cell contacts displayed antigen and proliferates
B cell combines
with antigen 1
Helper
T cells
Interleukin-2
Antigen
receptor
Cytokines
Cytotoxic
T cell
Antigen 4
Activated helper T cell interacts with cytotoxic T cell (which has combined with an identical antigen) and releases interleukin-2, which activates the cytotoxic T cell 5
Proliferation
and
Differentiation
Activated B cell
Memory
T cell
Cytotoxic
T cell
(a)
Macrophage
Helper T cell 41
(b)
b: © Manfred Kage/Peter Arnold

42. 42 Antigen Antigen receptor B cells 1 Activation 2 Stimulation by
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Antigen
Antigen
receptor
B cells 1
Activation 2
Stimulation by
activated helper T cell
Activated B cell
Cytokines 3
Proliferation
Clone of
B cells 42

43. 43 Antigen Receptor-antigen combination Antigen Receptor (antibody)
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Antigen
Receptor-antigen
combination
Antigen
Receptor
(antibody)
Cytokines
from helper
T cell
Activated
B cell
Proliferation
Clone of
B cells
Proliferation and
Differentiation
Proliferation and
Differentiation
Released
antibodies
Endoplasmic
reticulum
Clone of
B cells
Plasma cell
(antibody-secreting cell)
Memory cell
(dormant cell)
Plasma cell
(antibody-secreting cell)
Memory cell
(dormant cell) 43

44. 44

45. 45

46. 16.1 From Science to Technology
Immunotherapy 46

47. Immune Responses Secondary response Plasma antibody concentration
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Secondary response
Plasma antibody concentration
Primary response 10 20 30 40
Days after exposure to antigen 47

48. Practical Classification of Immunity48

49. Allergic Reactions Type I Immediate-reaction allergy
Occurs minutes after contact with allergen
Symptoms include hives, hay fever, asthma, eczema, gastric disturbances, and anaphylactic shock
Type II
Antibody-dependent cytotoxic reaction
Takes 1-3 hours to develop
Transfusion reaction
Type III
Immune-complex reaction
Antibody complexes cannot be cleared from the body
Damage of body tissues
Type IV
Delayed-reaction allergy
Results from repeated exposure to allergen
Eruptions and inflammation of the skin
Takes about 48 hours to occur 49

50. 50 Allergic reaction Allergen 1 Initial B cell contact with allergen
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Allergic
reaction
Allergen 1
Initial B cell
contact with
allergen
Histamine
and other
chemicals
B cell
Plasma cell
secretes
antibodies 2
Mast cell releases
allergy mediators 5
Allergen
Plasma cell
Released IgE
antibodies
Granule
IgE receptor
Subsequent
contact with
allergen 4 3
Antibodies
attach to
mast cell
Mast cell
(a) 50

51. Transplantation and Tissue Rejection
Successfully transplanted tissues and organs:
Cornea
Kidney
Liver
Pancreas
When the donor’s tissues are recognized as foreign there is a tissue rejection reaction
Resembles the cellular immune response against antigens
Important to match MHC antigens
Immunosuppressive drugs used to prevent rejection
Heart
Bone marrow
Skin 51

52. 52

53. Autoimmunity
The immune system fails to distinguish “self” from “non-self” and the body produces antibodies called autoantibodies, and cytotoxic T cells to attack the body’s tissues and organs 53

54. 16.10: Lifespan Changes
The immune system declines early in life as the thymus gland shrinks (only 25% as powerful as it once was)
There is a higher risk of infection
Antibody response to antigens becomes slower
IgA and IgG antibodies increase
IgM and IgE antibodies decrease
Elderly may not be candidates for certain medical treatments that suppresses immunity 54

55. Immunity Breakdown: AIDS
16.1 Clinical Application
Immunity Breakdown: AIDS 55

56. Important Points in Chapter 16: Outcomes to be Assessed
16.1: Introduction
Describe the general functions of the lymphatic system.
16.2: Lymphatic Pathways
Identify and describe the parts of the major lymphatic pathways.
16.3: Tissue Fluid and Lymph
Describe how tissue fluid and lymph form, and explain the function of lymph.
16.4: Lymph Movement
Explain how lymphatic circulation is maintained, and describe the consequence of lymphatic obstruction. 56

57. Important Points in Chapter 16: Outcomes to be Assessed
16.5: Lymph Nodes
Describe a lymph node and its major functions.
Describe the location of the major chains of lymph nodes.
16.6: Thymus and Spleen
Discuss the locations and functions of the thymus and spleen.
16.7: Body Defenses Against Infection
Distinguish between innate (nonspecific) and adaptive (specific) defenses.
16.8: Innate (Nonspecific) Defenses
List seven innate body defense mechanisms, and describe the action of each mechanism. 57

58. Important Points in Chapter 16: Outcomes to be Assessed
16.9: Adaptive (Specific) Defenses, or Immunity
Explain how two major types of lymphocytes are formed, activated, and how they function in immune mechanisms.
Discuss the origins and actions of the five different types of antibodies.
Distinguish between primary and secondary immune responses.
Distinguish between active and passive immunity.
Explain how allergic reactions, tissue rejection reactions, and autoimmunity arise from immune mechanisms.
16.10: Lifespan Changes
Describe lifespan changes in immunity. 58