Ch 45 The Immune System: Internal Defense Flashcards
Phagocytes, Natural killer (NK) cells, and Toll-like receptors
Nonspecific Responses
Engulf bacteria
– neutrophils
– macrophages
Phagocytes
Most common white blood cell
Neutrophils
Most common in other tissues
Macrophages
– release chemicals that destroy body cells – in both nonspecific and specific response
Natural killer (NK) cells
– cell-surface receptors on NK cells
– recognize common pathogen-associated molecular patterns (PAMPs)
• not specific pathogens
Toll-like receptors
• Target specific antigens
– molecules recognized as foreign or dangerous by immune system cells
• When it encounters antigens, immune system produces antibodies
– highly specific proteins
– recognize and bind to specific antigens
Specific Immune Responses
Two main types participating in specific responses are
- antigen presenting cells
- lymphocytes: T-cells and B-cells
• Display foreign antigens and their own surface proteins
– B cells
– macrophages
– dendritic cells:
-specialized to process, transport, and present antigens
-in skin and other body tissues that interact with environment
Antigen-Presenting Cells (APCs)
• Develop from stem cells in bone marrow
Lymphocytes
3 Types of Lymphocytes
– Natural Killer Cells
– B-cells
– T-cells
For non-specific response
Natural Killer Cells
Mature in bone marrow
B-cells
Mature in thymus gland
T-cells
Lymphocytes Participate in:
– Cell-mediated immunity
– Antibody-mediated immunity
T cells are responsible for
Cell-mediated immunity
– controls the establishment of immunocompetence in T cells (to distinguish between self and nonself)
Thymus gland
• T cells receive information from antigen presenting cells to target specific antigens remain for long term defense
– clones of T cells are formed for action
Cell-Mediated Immunity
• B and T cells are pre-made to recognize antigens; how is this possible?
• Millions of genetically different types of B and T cells are produced
– Due to rearrangement (a type of mutation) of preexisting DNA segments and new mutations during creation
– While the pathogens are evolving new antigen patterns (also through rearrangement & mutation), these semi-independent cells in our bodies are doing the same thing
• With millions of random options, one usually works
Antibody Diversity
- Previous exposure causes plasma cells to a make pollen-specific antibody.
- Antibody attaches to mast cells. 3. Pollen is inhaled.
- Pollen antigen combines with antibody on mast cell.
- Mast cell releases histamine.
- Histamine causes vasodilation and increased capillary permeability.
a) edema
b) redness
c) mucus
d) restriction of respiratory passages
• Systemic anaphylaxis: rapid, widespread allergic reaction. Can lead to death from low blood pressure, too much plasma lost from blood.
Allergic Reaction
• An immune response in which T cells destroy the transplant
• Stimulated by foreign antigens in transplanted tissues
• Often must suppress the immune system during transplant
– but may risk an infection without immune capabilities
Transplant Rejection
• Body reacts immunologically against its own tissues
- Rheumatoid arthritis
- Multiple sclerosis
Autoimmune Disease
Joint proteins attacked
Rheumatoid Arthritis
Myelin attacked
Multiple sclerosis
