Term
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Definition
| Resistance to plant and many animal pathogens |
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Term
| The Three Lines of Defense |
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Definition
Non-specific: skin. phagocytosis.
Specific: lymphocites, antibodies. |
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Term
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Definition
| skin and mucous membranes of the respiratory, digestive, urinary, and reproductive systems |
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Term
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Definition
Epidermis
Epidermal dendritic cells |
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Term
| Epidermal dendritic cells |
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Definition
Also termed Langerhans cells
Phagocytize pathogens |
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Term
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Definition
Contains protein fibers called collagen
Give skin strength and pliability to resist abrasions that could introduce microorganisms |
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Term
| Skin – Chemical Components of Defense |
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Definition
Perspiration secreted by sweat glands
Sebum secreted by sebaceous (oil) glands |
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Term
| Perspiration secreted by sweat glands |
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Definition
Salt- inhibits growth of pathogen by drawing water from their cells
Lysozyme- destroys cell wall of bacteria |
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Term
| Sebum secreted by sebaceous (oil) glands |
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Definition
Helps keep skin pliable and less likely to break or tear
Lowers the pH of the skin to a level inhibitory to many bacteria |
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Term
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Definition
Line all body cavities open to the outside environment
Two distinct layers
Epithelium
Deeper connective layer that supports the epithelium |
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Term
| Skin – Chemical Components of Defense |
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Definition
Perspiration secreted by sweat glands
Sebum secreted by sebaceous (oil) glands |
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Term
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Definition
living
Tightly packed to prevent entry of pathogens
Continual shedding of cells carries attached microorganisms away |
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Term
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Definition
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Term
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Definition
Normal microbiota help protect the body by competing with potential pathogens
Various activities of the normal microbiota make it hard for pathogens to compete
Secrete antimicrobial substances that limit pathogen growth
Consumption of nutrients makes them unavailable to pathogens
Create an environment unfavorable to other microorganisms by changing pH
Helps stimulate the body’s second line of defense
Promote overall health by providing vitamins to host |
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Term
| Other First-Line Defenses |
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Definition
Many body organs secrete chemicals with antimicrobial properties
Lacrimal glands that bathe the eye
Saliva
Stomach acid |
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Term
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Definition
Operates when pathogens succeed in penetrating the skin or mucous membranes
Nonspecific defense
Composed of cells, antimicrobial chemicals, and processes but no physical barriers
Many of these components are contained or originate in the blood |
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Term
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Definition
Operates when pathogens succeed in penetrating the skin or mucous membranes
Nonspecific defense
Composed of cells, antimicrobial chemicals, and processes but no physical barriers
Many of these components are contained or originate in the blood |
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Term
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Definition
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Term
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Definition
Erythrocytes- carry oxygen and carbon dioxide in the blood (4.2-6.2x109/ml)
Platelets- involved in blood clotting and inflammation (1.3-4x108/ml)
Leukocytes- involved in defending the body against invaders (4.5-11x106/ml)
2 groups:
Granulocytes
Agranulocytes |
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Term
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Definition
Granulocytes:
Neutrophils: 50-70% of circulating WBC
Multi-lobed nucleus (>3 masses)
>1010 neutrophils made every day
Major phagocytes; Cells of acute inflammation
Eosinophils: 1-3% of circulating WBC
Bilobed nucleus; Parasite defense; Red granules
Basophils: 0.5-1% of circulating WBC
Bilobed nucleus; Contain histamine; Blue granules |
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Term
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Definition
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Term
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Definition
Phagocytic cells of the second line of defense
Monocytes leave the blood (via diapedesis), enter tissue, and differentiate into macrophages. Some become fixed in a particular tissue, some remain free to wander and phagocytize throughout the body
Fixed macrophages include microglial cells (central nervous system), mesangial cells (Kidney) and Küpffer cells (liver)
All macrophages, plus monocytes attached to endothelial cells, constitute the mononuclear phagocytic system (formerly called the reticuloendothelial system (RES)) |
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Term
| Lab Analysis of Leukocytes |
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Definition
The differential white blood cell count test can signal signs of disease
Increased eosinophils can indicate allergies or parasitic worm infection
Bacterial diseases often show increase in leukocytes, mostly neutrophils
Viral infections show increase in lymphocytes |
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Term
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Definition
Phagocytosis
Extracellular killing by leukocytes
Nonspecific chemical defenses
Inflammation
Fever |
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Term
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Definition
Cells capable of phagocytosis (certain leukocytes or their derivatives) are called phagocytes
Phagocytosis is performed chiefly by neutrophils (microphages) and macrophages.
Can be divided into 5 stages |
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Term
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Definition
The host’s cells are protected from destruction by the phagocytes
Some phagocytes have receptors for bacterial surface components, such as flagellar proteins or cell wall components, that are lacking on the body’s cells
Opsonins such as certain complement split products and antibody provide a handle for the phagocyte |
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Term
| Extracellular Killing by Leukocytes |
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Definition
Eosinophils
Natural Killer Lymphocytes (NK cells)
Neutrophils |
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Term
| Nonspecific Chemical Defenses |
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Definition
Lysozyme
Complement
Interferon
Defensins
Lactoferrin |
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Term
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Definition
Set of serum proteins designated numerically according to the order of their discovery
Complement activation results in lysis of the foreign cell
Complement can be activated in several ways:
Classical Pathway
Alternate Pathway |
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Term
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Definition
• Complement named for the events of this originally discovered pathway
• Various complement proteins act nonspecifically to “complement” the action of antibodies |
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Term
| The Alternate (Properdin) Pathway |
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Definition
• Activation occurs independent of antibodies
• Less efficient than the classical pathway
• Useful in early stages of infection before antibodies have been made
• Initiated by interaction between properdin factors B, D, and P and the endotoxins and LPS from bacteria and fungi
• Stabilizes molecules of C3b that are normally in the blood in small quantities |
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Term
| The Alternate (Properdin) Pathway |
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Definition
• Stabilized C3b combines with the properdin factors to form an enzyme that cleaves C3 to produce more C3b
• C3b combines with properdin B to form a different enzyme which cleaves C5 molecules
• The complement cascade then continues as in the classical pathway |
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Term
TEM of a Cell Damaged by Complement Membrane Attack Complexes
Interferons |
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Definition
• Protein molecules released by host cells to nonspecifically inhibit the spread of viral infections
• Particularly effective against viruses with RNA genomes
• Cause many phys. symptoms typically associated with viral infections
• 3 Classes
– Alpha
– Beta
– Gamma |
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Term
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Definition
• Alpha and beta interferons are present early in the infection
• Gamma interferon appears later in the course of infection |
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Term
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Definition
• It was thought that this might be a good antiviral treatment
• Many viral infections don’t respond to interferon therapy at all
• Only a slight effect is seen with those viral infections that do respond |
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Term
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Definition
• Small peptides that function nonspecifically to protect against a broad range of pathogens
• Act against pathogens in various ways
– Punch holes in cytoplasmic membranes
– Interfere with internal signaling and other metabolic processes
– Interfere with the protein that preserves the shape of bacterial proteins under heat stress
• In humans, inflammation increases the production of defensins |
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Term
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Definition
• Nonspecific response to tissue damage resulting from various causes
• Characterized by redness (rubor), heat (calor), swelling (tumor), and pain (dolor)
• Two types
– Acute
– Chronic |
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Term
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Definition
– Develops quickly and is short lived
– Is usually beneficial
– Important in the second line of defense
• Dilation and increased permeability of the blood vessels
• Migration of phagocytes
• Tissue repair |
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Term
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Definition
• Develops slowly and lasts a long time
– Can cause damage to tissues |
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Term
| Stimulation of Inflammation by C3a & C5a |
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Definition
Cardinal Signs of Inflammation:
Rubor = redness
Calor = heat
Tumor = edema
Dolor = pain |
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Term
Chemical Mediators of Inflammation
Fever |
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Definition
• A body temperature over 37C
• Results when chemicals called pyrogens trigger the hypothalamus to increase the body’s core temperature
• Various types of pyrogens
– Bacterial endotoxins
– Cytoplasmic contents of bacteria released by lysis
– Antibody-antigen complexes
– Interleukin-I (IL-1) |
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Term
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Definition
• IL-1 production causes the hypothalamus to secrete prostaglandin which resets the hypothalamic “thermostat”
• Communication with the brain initiates muscle contractions, increased metabolic activity, and constriction of blood vessels which raises the body’s temperature
• Chills associated with fever are due to the reduced blood flow of constricted vessels
• Decrease in IL-1 production results in the body’s temperature returning to normal |
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Term
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Definition
• Enhances the effects of interferons
• Inhibits growth of some microorganisms
• May enhance the performance of phagocytes, cells of specific immunity, and the process of tissue repair |
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