Innate Immunity
This immunity is NON SPECIFIC. It refers to the defenses that are present at birth. They are always present, and provide rapid response to protect against disease. It does NOT involve SPECIFIC RECOGNITION, or MEMORY.
Memory
In immunity, this provides a more rapid and stronger immune reaction to the same microbe if it should invade the body at a later date.
Components of Innate Immunity
First Line Defense and Secondary Line Defense
First Line Defense Inclusions
The Skin; it acts as a barrier, and Mucous Membranes
Second Line Defense Inclusions
Natural Killer Cells, Phagocytes,Inflammation, Fever, and Antimicrobial Substances.
Innate Mechanical Immunity
Washing of the Eyes with tears, blinking, saliva.
First Cell That comes to the site of an infection:
Neutrophil, which are particulaly effective on Bacteria.
Diapedesis
Ability of WBC to leave circulation and go to the site of infection.
Adaptive Immunity
This type of immunity is SPECIFIC. It is based on a specific response to a specific microbe once it has breached innate mechanism defense. Although this is slower to respond than innate mechanisms, it is characterized by its SPECIFICITY and MEMORY.
Adaptive Immunity Involves...
T Lymphocytes and B Lymphocytes
Physical Factors Involving Immunity
These include barriers that prevent entry or remove microbes from the body's surface.
Chemical Factors Involving Immunity
These include substances made by the body that inhibit or destroy microbial growth.
Physical Factors: Skin
This is an important component in First Line Defense. Two Distinct Portions: The Epidermis and The Dermis.
Epidermis
This is the outer, thinner component, and is in direct contact with the external environment. The outermost layer contains a protective protein called Keratin. This layer periodically sheds, removing any microbes at the surface.
Dryness of the Skin
This is a major factor in inhibiting microbial growth on the skin. Microbes tend to be most numerous on moist areas of the skin. When the epithelial surface is broken, a subcutaneous infection may develop.
Mucous Membranes
These line the entire gastrointestinal, respiratory, and genitourinary tracts. The epithelial layer of this membrane secrets a fluid called mucus, a thick glycoprotein produced by goblet cells. This traps many microorganisms.
Respiratory Tract Mucosa
This also has structural modifications that counteract potential invaders. For example, tiny mucus-coated hairs inside the nose trap inhaled particles, and cilia on the mucosa of the Upper Respiratory Tract sweep dust and bacteria laden mucus toward the m
Urine Cleanse
The cleansing ot the Urethra by the flow of Urine is another example of a physical factors that prevents microbial growth in the genitourinary tract.
Additional Physical Factors:
Peristalsis, Defecation, and vomiting also expel microbes.
Lacrimal Apparatus
These are a group of structures that manufactures and drains away tears. These tears are spread over the surface of the eyeball by blinking. This continued washing by tears helps keep microorganisms from settling the surface of the eye.
Saliva
This also helps dilute the number of microorganisms and wash them from the surface of the teeth. It not only contains Lysozome, but also uric acid and urea which contribute to the control of microbial growth. The pH of this (6.55 - 6.85) also inhibits som
Sebaceous Glands
A chemical factor, these are oil glands of the skin that produce an oily substance called sebum that prevents hair from drying out and becoming brittle. One of the components of sebum is unsaturated fatty acids, which inhibit the growth of certain pathoge
Perspiration
The sweat glands of the skin also produce this, which helps maintain body temperature, eliminate certain wastes, and flush microorganisms from the surface of the skin.
Lysozyme
An enzyme found in perspiration which targets and breaks the cell walls of gram-positive bacteria and, to a lesser extent, gram-negative bacteria. It is also found in tears, nasal secretions, tissue fluids and urine.
Gastric Juices
This is another important chemical defense. It is produced by the glands of the stomach. It is a mixture of Hydrochloric Acid, Enzymes, and Mucus. The pH of this is between 1.2 and 3.0. The acidity pH is sufficient to destroy bacteria and most bacterial t
Vaginal Secretions
These play another important role in Chemical Immunity as it relates to antimicrobial activity. First, glycogen produced by the vaginal epithelial cells is catabolized by Lactobacillus Acidophilus into Lactic acid. Second, as a result of this lactic acid
Second line Defense
Our body uses a variety of nonspecific cellular devices to protect itself, these include the following: 1.) Phagocytes and 2.) Natural Killer Cells (NK Cells)
Phagocytes
Pathogens that get through the skin and mucous membranes into the underlying connective tissue are confronted by these. The chief ones are Macrophages.
Macrophages
These are derived from white blood cells called Monocytes that are capable of leaving circulation and enter the tissues. and develop into these. A classic antigen presenting cell.
Activated Macrophage Response to Pathogen: First
It may engulf a pathogen or other foreign object and destroy it with lysosomal enzymes.
Activated Macrophage Response to Pathogen: Second
It may bind to or remove a pathogen from the interstitial fluid, but be unable to destroy the invader until assisted by other cells.
Activated Macrophage Response to Pathogen: Third
It may destroy its target by releasing toxic chemicals, such as tumor necrosis factor, nitric oxide, or hydrogen peroxide into the interstitial fluid.
Two Classes of Macrophages
1.) Free Macrophages
2.) Fixed Macrophages
Free Macrophages
These wander throughout the tissues spaces in search of cellular debris or foreign invaders.
Fixed Macrophages
AKA Histiocytes; these are PERMANENT residents of specific tissue and organs. In some organs, these have special names.
Microgia
Fixed Macrophages in the CNS
Kupffer Cells
Fixed Macrophages in the Liver
Langerhans Cells
Fixed Macrophages in the Skin
Neutrophils
These are the most abundant type of white blood cell, and usually the FIRST to come to a site of an infection, become phagocytic on encountering infectious material in the tissues.
Eosinophils
This is another type of white blood cell, important in defending the body against parasitic infections. When they encounter parasites, such as worms, they position themselves against the worm and discharge the destructive contents of their large cytoplasm
Does a lack of fever rule out infection?
NO. Although we would expect a fever during an infections process, a lack of a fever DOES NOT rule out an infection. Some people (Diabetics, AIDS, the elderly) are so sick, they are immunocomprimised, and may not be able to elicit the fever response.
Mechanism of Phagocytosis
A Phagocyte engulfs particulate matter much in the way an amoebia ingests food particles. Cytoplasmic extensions bind to the particle and the pull it inside, enclosed within a membrane-lined vacuole called a Phagosome. The Phagosome then fuses with a lyso
Adherence
Phagocytic attempts are not always successful. In order for a phagocyte to accomplish ingestion, this must be done first. This is made possible by recognizing the pathogen's carbohydrate "signature''.
Opsonization
This is when complement proteins or antibodies coat foreign particles, making Adherence both more probable and more efficient. This coat provides a means to which phagocyte receptors can bind.
Respiratory Burst
An event produced when a macrophage is stimulated by chemicals released by immune cells and additional enzymes are produced. This event liberates large amounts of free radicals such as nitric oxide and super-oxide, both of which have a powerful cell-killi
Defensins
Antimicrobial chemicals produced by Neutrophils that pierce the pathogens membrane.
Natrual Killer Cells (NK Cells)
These are Lymphocytes that are responsible for recognizing and destroying abnormal cells when they appear in peripheral tissues. These are particularly good at removing tumor cells. Because of their versatility, single NK cell can attack bacteria in the i
Immunological Surveillance
The constant monitoring of normal tissues by NK cells.
Antigen Recognition
The plasma membrane of an abnormal cell generally contains antigens that are not found on the membranes of normal cells. NK Cells recognize an abnormal cell by detecting the presence of those antigens. Any membrane containing abnormal antigens will be att
Immunological Escape
...