chapter 43 the immune system -...
TRANSCRIPT
THE IMMUNE SYSTEM
Chapter 43
What you must know:
• Several elements of an innate immune
response
• The differences between B and T cells
relative to their activation and actions.
• How antigens are recognized by immune
system cells
• The differences in humoral and cell-mediated
immunity
• Why Helper T cells are central to immune
responses
Types of Immunity
Innate Immunity Adaptive Immunity
• Non-specific
• All plants & animals
• Pathogen-specific
• Only in vertebrates
• Involves B and T cells
Barrier Defenses: •Skin
•Mucous membranes
•Lysozyme (tears,
saliva, mucus)
Inflammatory Response: • Mast cells release histamine
• Blood vessels dilate, increase
permeability (redness,
swelling)
• Deliver clotting agents,
phagocytic cells
• Fever
Phagocytic WBCs: •Neutrophils (engulf)
•Macrophage (“big eaters”)
•Eosinophils (parasites)
•Dendritic cells (adaptive
response)
Natural Killer
Cells: •Virus-infected and
cancer cells
Proteins: • Interferons (inhibit viral
reproduction)
• Complement system (~30 proteins,
membrane attack complex)
Innate
Immunity (non-specific)
Phagocytosis
Lymphatic System: involved in adaptive immunity
Inflammatory Response
Adaptive Response
• Lymphocytes (WBCs):
produced by stem cells in
bone marrow
– T cells: mature in thymus
• helper T, cytotoxic T
– B cells: stay and mature
in bone marrow
• plasma cells antibodies
• Antigen: substance that elicits lymphocyte
response
• Antibody (immunoglobulin – Ig): protein made by
B cell that binds to antigens
Major Histocompatibility Complex (MHC)
• Proteins displayed on cell surface
• Responsible for tissue/organ rejection (“self” vs.
“non-self”)
• B and T cells bind to MHC molecule in adaptive
response
• Class I: all body cells (except RBCs)
• Class II: displayed by immune cells; “non-self”
Humoral Immune Response
(antibodies)
Cell-Mediated Immune
Response
(T Cells)
Antigen-
presenting
cell
Helper T
cell B cell Cytotoxic T
cell
Plasma
cell
Infected
cell Antibodies
Identify and
destroy
tag for
destruction
Immunological Memory
• Primary immune response: 1st exposure to antigen
• Memory cells:
– Secondary immune response: repeat exposure
faster, greater response
Antigen Antigen receptor
Antibody
Plasma cells Memory cells
B cells that differ in antigen specificity
Figure 43.14
• Immunizations/vaccines: induce immune
memory to nonpathogenic microbe or toxin
• Passive immunity: via antibodies in breast milk
• Allergies: hypersensitive responses to
harmless antigens
• HIV: infect Helper T cells
– AIDS = severely weakened immune system
• Immunological Diseases:
– Lupus, rheumatoid arthritis, Type I diabetes,
multiple sclerosis