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AP Biology, Chapter 43
The Body's Defenses
SUMMARY
INTRODUCTION
NONSPECIFIC DEFENSES AGAINST INFECTION
Introduction
The skin and mucous membranes provide first-line barriers to infection
1. Contrast the readiness of the immune system with that of the body's nonspecific
defenses.
a. Immune system: requires priming by initial exposure to antigen
b. Nonspecific: respond immediately to protect from all
2. Define the roles of physical and chemical surface membrane barriers.
a. Physical: skin and mucous membranes keep things out
b. Chemical
i. Acid in skin and vagina
ii. Stomach secretes HCl and proteases
iii. Saliva and tears contain lysozyme
iv. Stick mucus catches organisms
Phagocytic cells, inflammation, and antimicrobial proteins function early in infection
3. Contrast the roles of the nonspecific cellular defenses. [2 points]
a. Phagocytes engulf and destroy pathogens
b. NK cells punch virus-infected and cancerous cells
4. Rationalize the four cardinal signs of an acute inflammatory response.
a. Histamine and kinins released
b. Increased blood flow causes redness and heat
c. Leaky blood vessels cause swelling and pain
5. Describe the roles of chemotaxis and diapedesis in the inflammatory response.
a. Histamines and kinins attract phagocytes and WBCs
b. WBCs leave the capillaries at the site of inflammation for clean up
6. How is a fever initiated and how does it aid in fighting infection?
a. Pyrogens are secreted by macrophages
b. Liver and spleen confiscate Fe and Zn, raises metabolic rate
7. Contrast the roles of complement and interferon in nonspecific defense.
a. Complement
i. Proteins attach to foreign cells after activation
ii. Cause lesions, amplifies inflammatory response, opsinizes
b. Interferon
i. Released by virus-infected cells
ii. Interferes with virus replication
HOW SPECIFIC IMMUNITY ARISES
Introduction
8. Describe three important aspects of the immune response.
a. Anitgen specific: attacks particular pathogens
b. Systemic: body-wide defense, not restricted to site of infection
c. Memory: recognizes and mounts attAck on previously encountered pathogens
Lymphocytes provide the specificity and diversity of the immune system
9. What is the relationship between haptens and antigens.
a. Haptens are too small to be antigens
b. Reaction with our proteins creates antigen
Antigens interact with specific lymphocytes, including immune responses and
immunological memory
10. Contrast the roles of B lymphocytes, T lymphocytes, and macrophages in specific
defense.
a. B lymphocytes: humoral immunity
b. T lymphocytes: cell-mediated immunity
i. Cytotoxic T cells kill cancer, infected cells and attack foreign grafts
ii. Helper T cells regulate the immune response
c. Are phagocytes and activators of Ts and Bs
Lymphocyte development gives rise to an immune system that distinguishes self from
nonself
IMMUNE RESPONSE
Introduction
Helper T lymphocytes function in both humoral and cell-mediated immunity: an
overview
11. Define the role of macrophages in the development of cellular immunity.
a. Phagocytosis, processing and presentation of antigens
b. Binding to and activation of helper T
In the cell mediated response, cytotoxic T cells counter intracellular pathogens: a
closer look
In the humoral response, B cells make antibodies against extracellular pathogens: a
closer look
12. Describe the cellular basis of primary and secondary humoral responses.
a. Primary
i. Initial antigen exposure selects a clone making antibody specific to the
antigen
ii. Plasma cells die, memory cells remain
b. Secondary
i. Subsequent exposure activates memory cells to divide
13. Describe mechanisms of antibody action.
a. Neutralization: coats virus, prevents infection
b. Agglutination: clumping of foreign cells
c. Precipitation: clumping of soluble antigens
d. Complement fixation
Invertebrates have a rudimentary immune system
IMMUNITY IN HEALTH AND DISEASE
Introduction
Immunity can be achieved naturally or artificially
14. Contrast the acquisitions of active and passive humoral immunity.
a. Active: developed from B cells by natural exposure or vaccination
b. Passive: transfer of pre-made antibody in utero or serum
The immune system's capacity to distinguish self from nonself limits bloof transfusion
and tissue transplantation
Abnormal immune function can lead to disease
15. Describe examples of the three types of disorders of immunity.
a. Allergy: abnormally vigorous immune responses like to inhaled pollen
b. Immunodeficiency: inherited as SCID or by HIV infection
c. Autoimmune diseases: rheumatoid arthritis, myasthenia gravis
16. Differentiate the symptoms of immediate hypersensitivity, anaphylactic shock, and
delayed hypersensitivity.
a. Inhaled: mast cells release histamine causing mucous membrane inflammation
b. Anaphylactic shock: system-wide inflammation with fluid loss
c. Delayed hypersensitivity: contact dermititis from haptens in poison ivy, metals,
and the swelling from a TB test
17. List three possible triggers for autoimmune disease.
a. Inefficient lymphocyte programming
b. Loose self-antigens
c. Cross-reaction of antibodies with self-antigens
AIDS is an immunodeficiency disease caused by a virus