4. Components
• Lymph:
fluid that enters lymphatic capillaries composed
of water and some solutes
• Lymphocytes
• Lymphatic vessels
• Lymph nodes
• Tonsils
• Spleen
• Thymus gland
5. Lymphatic Capillaries and Vessels
• Carries fluid in one direction from tissues to
circulatory system
• Fluid moves from blood capillaries into tissue
spaces
• Lymphatic capillaries:
- tiny, closed-ended vessels
- fluid moves easily into
- in most tissues
- join to form lymphatic vessels
6. • Lymphatic vessels:
- resemble small veins
- where lymphatic capillaries join
- one way valves
• Right lymphatic duct:
- where lymphatic vessels from right upper
limb and right head, neck, chest empty
- empties into right subclavian vein
7. • Thoracic duct:
- rest of body empties from lymphatic
vessels
- empties into left subclavian vein
9. Lymphatic Organs
• Tonsils:
- palatine tonsils on each side of oral
cavity
- pharyngeal tonsils near internal opening
of nasal cavity (adenoid)
- lingual tonsils posterior surface of
tongue
- form a protective ring of lymphatic tissue
around nasal and oral cavities
11. • Lymph nodes:
- rounded structures that vary in size
- located near lymphatic vessels
- groin, armpit, neck
- lymph passes through lymph nodes before
entering blood
- lymph moves through and immune system
is activated (lymphocytes produced) if
foreign substances are detected
- removal of microbes by macrophages
13. • Spleen:
- size of clenched fist
- located in abdomen
- filters blood
- detect and respond to foreign substances
- destroy old red blood cells
- blood reservoir
- white pulp: lymphatic tissue surrounding
arteries
- red pulp: contains macrophages and red
blood cells that connect to veins
18. Immunity
• What is it?
- ability to resist damage from foreign
substances
- Ex. Microbes, toxins, cancer cells
• Types of immunity:
- innate
- adaptive
19. Innate Immunity
• What is it?
- present at birth
- defense against any pathogen
- accomplished by physical barriers,
chemical mediators, cells, inflammatory
response
20. Physical Barriers
• First line of defense
• Skin and mucous membranes to act as
barriers
• Tears, saliva, urine wash away pathogens
21. Chemical Mediators
• What are they?
chemicals that can kill microbes and prevent
their entry into cells
• Lysozyme:
found in tears and saliva to kill bacteria
• Mucous membranes:
prevent entry of microbes
22. • Histamine:
promote inflammation by causing vasodilation
• Interferons:
proteins that protect against viral infections by
stimulating surrounding cells to produce
antiviral proteins
23. Cells
• White blood cells:
produce in red bone marrow and lymphatic
tissue that fight foreign substances
• Phagocytic cells:
- ingest and destroy foreign substances
- Ex. neutrophils and macrophages
24. • Neutrophils:
first to respond to infection but die quickly
• Macrophages:
- monocytes
- leave blood and enter tissues
- can ingest more than neutrophils
- protect lymph in lymph nodes and blood in
spleen and liver
- given specific names for certain areas of
body (Kupffer cells in liver)
25. • Basophils:
- made in red bone marrow
- leave blood and enter infected tissues
- can release histamine
• Mast cells:
- made in red bone marrow
- found in skin, lungs, gastrointestinal tract,
urogenital tract
- can release leukotrienes
26. • Eosinophils:
- produced in red bone marrow
- release chemicals to reduce inflammation
• Natural Killer Cells:
- type of lymphocyte
- produce in red bone marrow
- recognize classes of cells such as tumor
cells or virus infected cells
- release chemicals to lysis cells
27. Inflammatory Response
• What is it?
- involves chemical and cells due to injury
- signaled by presence of foreign substance
- stimulates release of chemical mediators
29. Adaptive Immunity
• What is it?
- defense that involves specific recognition
to a specific antigen
- acquired after birth
- reacts when innate defenses don’t work
- slower than innate immunity
- has memory
- uses lymphocytes (B and T cells)
- 2 types antibody-mediated and cell-
mediated
30. Terms Related to Adaptive Immunity
• Antigen:
- substance that stimulates immune response
- Ex. Bacteria, virus, pollen, food, drugs, etc.
• Self-antigen:
molecule produced by person’s body that
stimulates immune system response
• Antibody:
proteins the body produces in response to
antigen
31. Origin and Development of Lymphocytes
• Stem cells:
- red bone marrow
- give rise to all blood cells
- give rise to some pre T cells and pre B
cells
32. • Lymphocytes:
- type of white blood cell
- involved in adaptive immunity
- develop from stem cells
- differentiate into specific lymphocytes
such as B or T cells
32
33. • B cells:
- type of lymphocytes
- involved in antibody-mediated immunity
- originate from stem cells
- mature in red bone marrow
- move to lymphatic tissue after mature
- lead to production of antibodies
33
34. • T cells:
- type of lymphocyte
- involved in cell-mediated immunity
primarily and antibody-mediated immunity
- mature in thymus gland
- move to lymphatic tissue after mature
- 4 types
34
36. Antigen Recognition
• Lymphocytes have antigen receptors on their
surface
• Called B-cell receptors on B cells and T-cell
receptors on T cells
• Each receptor only binds with a specific antigen
• When antigen receptors combine with antigen
the lymphocyte is activated and adaptive
immunity begins
37. • Major histocompatibility complex molecule
(MHC):
- contain binding sites for antigens
- specific for certain antigens
- hold and present a processed antigen on
the surface of the cell membrane
- bind to antigen receptor on B or T cells
and stimulate response
38. • Cytokines:
- proteins secreted by a cell that regulates
neighboring cells
- Ex. Interleukin 1 released by
macrophages stimulates helper T cells
39. Dual Nature of Immune System
• Lymphocytes give rise to 2 types of immune
responses: antibody-mediated and cell-mediated
• Antigens can trigger both types of responses
• Both types are able to recognize self vs. nonself,
use specificity, and have memory
39
40. 40
Antibody-Mediated
• What is it?
- effective against antigens in body fluids
(blood and lymph)
- effective against bacteria, viruses, toxins
- uses B cells to produce antibodies
41. 41
Antibody Structure
• Letter Y shape
• Variable region:
- V of Y
- bind to epitopes of antigen using antigen-
binding site
• Constant region:
- stem of Y
- each class of immunoglobulin has same
structure
43. 43
• Antigen-binding site:
site on antibody where antigen binds
• Valence:
number of antigen-binding sites on antibody
• 5 immunoglobulins used to destroy antigens:
IgG, IgM, IgA, IgE, IgD
44. Effects of Antibodies
• Inactivate antigen
• Bind antigens together
• Active complement cascades
• Initiate release of inflammatory chemicals
• Facilitate phagocytosis
46. Antibody Production
Primary response
• 1st
exposure of B cell to antigen
• B cell undergoes division and forms plasma
cell and memory cells
• Plasma cells:
- produce antibodies
- 3-14 days to by effective against antigen
- person develop disease symptoms
47. Secondary Response
• Memory cells:
- occurs when immune system is exposed
to antigen that has been seen before
- B memory cells quickly divided to form
plasma cells which produce antibodies
- produces new memory cells
48. 48
Cell-Mediated Immunity
• What is it?
- effective against antigens in cells and
tissues
- effective against bacteria, viruses, fungi, and
protozoa
- uses different types of T cells
49. 49
Types of T cells
• Helper T cells (TH):
- activate macrophages
- help form B cells
- promote production of Tc
50. 50
• Cytotoxic T cells (Tc):
precursor to cytotoxic T lymphocytes (CTL)
• Cytotoxic T lymphocytes (CTL):
destroys antigen on contact
• Regulatory T cells (Tr):
turn off immune system response when
antigen is gone
52. 52
Types of Adaptive Immunity
Naturally Acquired Immunity
• Active:
- natural exposure to antigens causes
production of antibodies
- can be lifelong immunity
- Ex. Mononucleosis
• Passive:
- transfer of antibodies from mother to child
- Ex. Breast milk or placenta
53. 53
Artificially Acquired Immunity
• Active:
- injection of antigens using vaccines which
cause the production of antibodies
- vaccine or immunization:
process of introducing killed, live, or
inactivated pathogen
• Passive:
injection of antibodies from another person
or animal
57. ASSIGNMENT:
1. Discuss briefly the proliferation of B cells.
2. Explain how production of antibodies occur.
3. Discuss briefly what is specificity and memory in
immunity.
4. Differentiate active natural immunity, active
artificial immunity, passive natural immunity and
passive artificial immunity.
