Host Defense Mechanisms and the Immune Response Flashcards
What is the order of the body’s defense mechanisms?
Invading microorganisms > physical barriers > innate immunity > specific immunity
What is included in the physical barriers (first line of defense)?
- Skin
- Coughing/sneezing
- Mucus flow
- Saliva
- Tears
- Vomiting/diarrhea
- Urine
How does the integument work to protect the body?
Through four different mechanisms:
- Desquamation
- Desiccation
- Low pH
- Resident bacteria flora
What is desquamation?
The cells on the skin continuously slough off to prevent bacteria from becoming attached to the body
What is desiccation?
Keeps the cells on the skin dry; bacteria thrive in warm, moist areas
What is low pH?
More acidic; sebaceous glands of the skin secrete sebum to keep pH low
What is resident bacteria flora?
Normal bacteria on the skin that takes up space so no abnormal/pathogenic bacteria can reside
How does the GI tract work to protect the body?
- Saliva
- Normal bacterial flora
- Low pH
- Lysozyme
How does the urinary tract work to protect the body?
- Low pH
- Urine flow
- Glycogen
Why is glycogen important for urinary tract of adult reproductive females?
Because the vagina is lined with squamous epithelium containing glycogen, therefore when cells slough off, it provides a substrate for lactobacilli
What is lactobacilli?
It produces lactic acid which keeps the pH of the vagina low
How do the mammary glands work to protect the body?
- Milk flow
- Lactenins
- Keratin plug
What is the keratin plug of the mammary glands?
It blocks T-Orifice when animal is not lactating
What is lactenins in regards to the mammary glands?
They contain compliment protein, lysozyme, and lactoferrin, which binds to bacteria so they can’t reproduce
How does the respiratory tract work to protect the body?
- Turbulence
- Particle filtration
What is turbulence in the respiratory tract?
- Turbinate bones - cause irregular airflow and warms the air
- Mucous - bacteria get caught and then either become swallowed or expelled
Why is particle size important in the respiratory tract?
It provides filtration through out
- upper respiratory - 15 um
- bronchi - 10 um
- bronchioles - 5 um
- alveoli - 1 um
Where are antibodies produced?
On mucosal surfaces
What is another work for antibodies?
Immunoglobulins
What are the four most important immunoglobulins produced in the body?
- IgA
- IgM
- IgE
- IgG
What is IgA?
- It protects body surfaces and neutralizes viruses, viral and bacterial enzymes
- Found in saliva, intestinal fluid, nasal and tracheal secretions, tears, milk, colostrum, urine and urogenital secretions
- Does not activate a compliment
What is the most important function of IgA?
Immune exclusion; it keeps things out!
What is IgM?
- Made and secreted by plasma cells in the spleen, lymph nodes, and bone marrow
- Major immunoglobulin produced in the primary immune response and with the 2nd highest concentration in blood
What is IgE?
- Backs up IgA and works through immune elimination
- Causes degranulation of mast cells and basophils by releasing histamine
- Extremely low concentrations in serum
What is the most important function of IgE?
Allergic responses to food and inhaled antigens
What is IgG?
- Found in highest concentration in the blood
- In ruminants, it is the major secretory immunoglobulin in milk and colostrum
- Smallest immunoglobulin
What is innate defense?
Immunity the animal is born with
- Complement
- Cytokines
- Lysozymes
How does complement work?
It covalently binds to specific proteins to the microbial surface to destroy invading organisims
Where is complement synthesized?
The majority is in the liver or macrophages and neutrophils store large quantities
How is complement activated?
Through binding antigen (foreign material) and antibody (immunoglobulin)
What does complement form?
MAC (membrane attack complex) at the end of the pathway to cause cell death
What are cytokines?
Chemical messengers that help to communicate through normal cells and cells of the immune system
What kinds of cells are considered cytokines?
- Interleukins
- Interferons
- Tumor Necrosis Factors (TNF)
What are interleukins?
The communicate between leukocytes and other cells in the immune system; specifically lymphocytes
What are interferons?
They are synthesized in response to viral infection, immune stimulation and to other chemical stimulus
What is the purpose of interferons?
To inhibit viral replication by stopping viral RNA and protein synthesis
What do tumor necrosis factors do?
Kills tumors by apoptosis (programmed cellular death)
Where are lysozymes found?
In all body fluids including the GI tract, but not including cerebral spinal fluid, sweat or urine with the highest concentration being in saliva, tears and neutrophils
What do lysozymes do?
Destroy bacterial peptidoglycans in the cell walls of gram positive bacteria and also act in conjunction with gram negative bacteria
What is a potent opsonin?
A lysozyme that covers an antigen to cause it to be more appetizing to phagocytic cells of the immune system
Where would you find more lysozymes?
In areas of inflammation due to their optimum pH being low (3-6) of a more acidic environment
What is inflammation?
Response of the body’s tissues to the presence of microorganisms or injury
What is inflammation triggered by?
Bacterial products or molecules produced by tissue damage
What is the body’s predominant vasoactive mediator?
Histamine except in ruminants and rodents, it’s seratonin
What is diapedesis?
The passage of blood cells through the intact walls of the capillaries, typically accompanying inflammation
What is chemotaxis?
The directed movement under the influence of a chemical gradient (aka chemical signal)
What are the cardinal signs of inflammation?
- Redness
- Heat
- Pain
- Swelling
What causes pain?
Tissue damage by an antigen which releases vasoactive factors such as histamine or serotonin
What causes redness and heat?
Vasodilation
What causes swelling?
Increased vascular permeability, as well as neutrophil margination
What was recently added as a cardinal sign of inflammation?
Loss of function
What is a neutrophil?
The major cell of the myeloid (bone marrow) system
What is the main purpose of a neutrophil?
To capture and destroy foreign particles
What is the zeta potential of a neutrophil?
Both neutrophils and bacteria suspended in blood have a degree of repulsion between adjacent, similarly charged particles, and they can be neutralized by complement and lysozymes