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Terms in this set (34)
Disease-producing organisms or their toxins
Ability to ward off disease through body's defenses
Lack of resistance, vulnerability
Defense mechanisms that provide a general response against invasion by a wide range of pathogens
Production of specific antibody or activation of T cells against a particular pathogen or other foreign substance
First line of defense
Part of non-specific resistance to disease
Skin & mucous membranes are both mechanical & chemical
Mechanical first line of defense
Epidermis (skin) provides physical barrier
Mucous membranes-epithelial layer and CT layer, line cavities to outside
Lacrimal apparatus-manufactures and drains away tears
Saliva-dilutes number of microorganisms and washes them away from surfaces of teeth and mouth
Flow of urine-cleansing of urethra
Vaginal secretions-defecation and vomiting
Chemical first line of defense
Sebum-oily substance from sebaceous gland
Perspiration-contains lysozyme, enzyme that breaks down bacterial cell walls; also found in tears, saliva, nasal secretions and tissue fluid
Hyaluronic acid-in areolar connective tissue; gel-like consistency that slows spread of noxious agents in localized infections
Gastric juice-stomach glands; increase acidity
Second line of defense
Part of non-specific resistance to disease
When microbes pass first line of defense-antimicrobial substances
Interferons, complement system & transferrins
Protein hormones produced by body cells
1. type I (includes alpha and beta IFN)
2. type II (includes gamma-IFN)
Functions of interferons
IFN diffuses to uninfected neighboring cells and binds to surface receptors this induces non-infected cells to synthesize antiviral proteins that interfere with or inhibit viral replication
Gamma IFN enhances the cell-killing activity of phagocytic cells and natural killer cells
Type I (aplha & beta IFN) inhibit cell growth and suppress tumor formation
Was supposed to be the thing that curried cancer
Where are interferons produced? Released from?
Lymphocytes, macrophages & fibroblasts of virus-infected cells produce & release IFNs
What is missing in people that have some types of leukemia?
The gene that codes for alpha IFN
Comprised of about 20 normally inactive blood proteins and cell membrane proteins
Cascade effect when activated-they compliment or enhance certain immune, allergic, and inflammatory reactions
Once activated, activates other C' proteins which attach and destroy microbes
Iron-binding proteins inhibit bacterial growth by reducing available iron
Natural killer cells
When 1st & 2nd lines of defense fail
Large granular lymphocytes
Ability to kill a wide variety of infectious microbes and certain tumor cells
Present in spleen, lymph nodes, bone marrow & blood
Releases gamma IFN to increase cytolytic activity
Can act spontaneously against any target by recognizing cell surface changes that occur in some tumor or virus infected cells
Release cytolytic chemicals which attack target cell's membrane
Very effective at killing tumors
Can now isolate & grow in culture
Starting to lean towards specific immunity
Nonspecific defense as well as specific
Ingest microbe or particulate matter
What do macrophages develop from?
Stand guard in specific tissues
Macrophages-spleen, red marrow and lymph nodes
In most tissues
Response to stress of tissue damage
What is the function of inflammation?
To trap microbes, toxins or foreign material & begin tissue repair
What are the 5 signs of inflammation?
Loss of function
What are the 3 stages of inflammation?
Vasodilation & increased permeablility of blood vessels
What happens during the first stage of inflammation?
Vasodilation caused by histamine from mast cells, kinins from precursors in the blood, prostaglandins from damaged cells, and leukotrienes from basophils and mast cells
Occurs within minutes producing heat, redness and edema
Pain can result from injury, pressure from edema or irritation by toxic chemicals from organisms
Blood-clotting factors lead into tissues trapping microbes
What happens during the second stage of inflammation?
Within an hour, neutrophils and then monocytes arrive and leave blood stream (emigration)
Abnormally high body temperature that occurs because the hypothalamic thermostat is reset
Occurs during infection and inflammation
Bacterial toxins trigger release of fever-causing cytokines such as interleukin-1
What are some benefits of a fever?
Intensifies effects of interferons
Inhibits bacterial growth
Speeds up tissue repair
What are the 2 properties that distinguish specific immunity from nonspecific immunity?
Specificity-self vs non-self identification
Formation of T & B cells
Develop from stem cells in bone marrow
Before leaving site of maturation, cells acquire surface proteins; some function as AG receptors
Where do B cells mature?
In bone marrow
Where do T cells mature?
In the thymus
Name 3 types of T cells.
T cd4+ (T helper)
T cd8+ (T cytotoxic)
Major Histocompatibility Complex (MHC)
Antigens (proteins) that identify each individual as unique
No two animals have the same MHC (except identical twins)
Distinguishes self cells from non-self
RBC do not have MHC
Primates do not have Rh factors
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