What is innate immunity?
The defenses that are present at birth. Does not involve specific recognition of a microbe and lacks a memory response. Memory provides a more rapid and stronger immune reaction to microbes that invade at a later date.
What are the first line defenses?
Skin and mucous membranes
What are the second line defenses?
Natural killer cells, phagocytes, inflammation, fever, antimicrobial substances.
What is adaptive immunity?
It is based on a specific response to a specific microbe once it has breached the innate mechanisms of defense. It is slower than innate mechanisms and characterized by its specificity and memory.
What are physical factors of innate immunity?
Barriers that prevent entry or remove microbes from the body’s surface.
What are chemical factors of innate immunity?
Substances made by the body that inhibit or destroy microbial growth.
What makes up intact skin?
Epidermis and dermis
What is the epidermis?
The outer thinner component that is in direct contact with the external environment. Outer most layer contains a protective protein called keratin.
What are mucous membranes?
Consists of an epithelial layer and an underlying connective tissue layer. Lines the entire gastrointestinal, respiratory and genitourinary tracts. Secretes mucous (thick glycoprotein produced by goblet cells).
What are some examples of physical factors of first line defense?
Epiglottis covers the larynx during swallowing, urethra is cleansed by the flow of urine, peristalsis, defecation and vomiting expel microbes.
What is the lacrimal apparatus?
A group of structures that manufactures and drains away tears. Helps to keep microorganisms from settling on the surface of the eye.
How does saliva provide a defense against microorganisms?
Helps to dilute the numbers of microorganisms and washes them from the surface of the teeth.
How do sebaceous glands provide a chemical defense against microorganisms?
Secretes sebum. One component of sebum is unsaturated fatty acids, which inhibits the growth of certain pathogenic bacteria and fungi. The low pH of skin (between 3 and 5) is caused in part by the secretion of fatty acids and lactic acids.
How does perspiration defend against microorganisms?
Contains the enzyme lysozyme that targets and breaks the cell wall of gram positive bacteria.
How does saliva protect the body from microorganisms?
Contains lysozye, urea and uric acids (contributes to the control of microbial growth). Has a pH of 6.55-6.85 which inhibits some microbes and contains immunoglobulin A (antibody).
How does gastric juice protect the body from microorganisms?
the low pH (1.2-3) is sufficient to destroy bacteria and most bacterial toxins. Also contains hydrochloric acid, enzymes and mucus.
How do vaginal secretions protect the body from microorganisms?
Glycogen produced by vaginal epithelial cells is catabolized into lactic acid. The resulting pH of 3-5 inhibits the growth of many microbes.
What are macrophages?
Phagocytes that come from monocytes that are capable of leaving circulation and enter into tissues.
How can a macrophage respond to a pathogen?
Engulf the pathogen and destroy it with lysosomal enzymes, bind to or remove a pathogen from the interstitial fluid, destroy target by releasing toxic chemicals such as tumor necrosis factor, nitric oxide or hydrogen peroxide.
What are free macrophages?
Macrophages that can wander throughout the tissue spaces in search of cellular debris of foreign invaders.
What are fixed macrophages?
Also called histiocytes. Permanent residents of specific tissues and organs. Microglia are macrophages in the CNS, kupffer cells are in the liver and langerhans cells are in the skin
What are neutrophils?
The most abundant white blood cell. Usually the first to come to a site of infection. Become phagocytic on encountering infectious material in the tissues.
What are eosiniphils?
A white blood cell that is important in defending the body against parasitic infections. Discharges cytoplasmic granules over destructive content found in body.
What are the mechanisms of phagocytosis?
Cytoplasmic extensions bind to the particle and then pull it inside, enclosed within a membrane-lined vacuole called a phagosome. The phagosome fuses with lysosome to form a phagolysosome.
How can adherence be made more probably and efficient?
Complement proteins or antibodies can coat foreign particles making them easier for phagocytes to adhere to. This process is called opsonization.
What is a respiratory burst?
An event that liberates large amounts of free radicals such as nitric oxide and superoxide, which have powerful cell-killing abilities.
What are natural killer cells?
Cells that are responsible for recognizing and destroying abnormal cells when they appear in peripheral tissues.
What is immunological surveillance?
The constant monitoring of normal tissue by NK cells.
How do NK cells activate?
NK cells recognize unusual components in call plasma membranes. This activates the NK cell which adheres to the target cell. The golgi appartus moves until it is pointed directly at the abnormal cell. Performins are released at the cell surface by exocytosis and diffuse across the gap between the NK cell and target cell. The performins interact with one another and create a network of pores in the membrane. These pores are large enough to move intracellular materials through it and the target cell disintegrates.
What is immunological escape?
The process of avoiding detection or neutralizing the NK cells.
What are interferons?
Small proteins released by the activated lymphocytes, macrophages and tissue cells infected with a virus. When the protein comes in contact with a normal cell, the interferon binds to surface receptors and triggers the production of antiviral proteins.
What are the three types of interferons?
Alpha interferons (produced by several types of leukocytes and attracts NK cells), beta interferons (secreted by gibrocytes. Slows inflammation in a damaged area) and gamma interferons (secreted by T cells and NK cells. Stimulates macrophage activity).
What are cytokines?
Chemical messengers release by tissue cells to coordinate local activities. Ex) Cytokines.
