Biol 251 Chapter 16

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  1. Examples of PAMPs
    • Lipopolysaccharide (LPS) of the outer membrane of gram-negative bacteria
    • The flagellin in the flagella of motile bacteria
    • the peptidoglycan in the cell wall of gram-positive bacteria
    • The DNA of bacteria and the DNA and RNA of vuruses
  2. Toll like receptor (TLR)
    • TLRs also attach to components of fungi and parasites
    • When the TLR's on the cells encounter the PAMPs of microbes, such as the LPS of gram-negative bacteria, the TLRs include the defensive cells to release chemicals called cytokines
  3. Cytokines
    Proteins that regulate the intensity and duration of immune responses
  4. What are the physical factors in the first line of defense?
    • Skin
    • Mucous membranes
    • Epiglottis
    • Earwax
    • Urine
    • Vaginal secrets
    • Peristalsis (muscle contraction moving), defecation, vomiting an diarrhea
  5. Skin
    • Skin is human's largest organs in terms of surface area and weight
    • Dermis - the skin's inner, thinker layer portion is composed of connective tissue
    • Epidermis - the outer, thinner portion is in direct contact with the external environment
    • Epidermis consists of many layers of continuous sheets of tightly packed epithelial cells with little or no material between cells
    • Keratin - the top layer of epidermis cell is dead and contains a protective protein keratin
    • The periodic shedding of the top layer helps remove microbes at the surface
    • Dryness of the skin is major factor in inhibiting microbial growth on the skin
    • The bacteria most likely to cause infection are the staphylococci that normally inhabit the epidermis, hair follicles and sweat and oil glands of the skin
  6. Mucous membrane
    • Mucous membrane consist of epithelial layer and an underlying connective tissue layer
    • Mucous membranes line the entire gastrointestinal, respiratory, and genitourinary tracts
    • Mucous membrane secretes a fluid called mucus, a slightly thick (viscous) glycoprotien produced by goblet cells of a mucus membrane - prevent the tracts from drying out
  7. Locrimal Apparatus
    • One mechanism that protects eyes is the locrimal apparatus, a group of structures that manufactures and drains tears
    • Continual washing action helps keep microorganisms from settling on the surface of eye
    • This protection is a protective mechanism because the excess tears dilute and wash away the irritating substance or microorganisms before infection can occur
  8. Saliva
    In a cleaning action very similar to that tears, saliva, produced by the salivary glands, helps dilute the numbers of microorganisms and wash them from the surface of the teeth and the mucous membrane of the mouth
  9. Ciliary escalator
    • The respiratory and gastrointestinal tracts have many physical forms of defense
    • Mucus traps many of the microorganisms that enter these tracts
    • The mucous membrane of the nose also has mucous-coated hairs that filter inhaled air and trap microorganisms, dust, and pollutants
    • The cells of the mucous membrane of the lower respiratory tract are covered in mucus upward toward the throat, this called ciliary escalator - coughing and sneezing speed up the escalator
  10. Epiglottis
    Microorganisms are also prevented form entering the lower respiratory tract by a small lid of cartilage called epiglottis, which covers the larynx (voice-box)during swallowing
  11. Ear wax
    Cerumen, prevents microorganisms from entering ear
  12. Urine
    Cleaning of he urethra by flow of urine, prevents microbes colonization
  13. Vaginal secrets
    Microorganisms out of the female body
  14. What are chemical factors in the first line of defense?
    • Sebum
    • Lysozyme
    • Ear Wax
    • Saliva
    • Gastric juice (Stomach acid)
    • Vaginal secretions
    • Urine
  15. Sebum
    • Sebaceous (oil) glands of the skin produce on oily substance called sebum that prevents hair from drying and becoming brittle
    • Sebum also forms a protective film over the surface of the skin
    • Component of sebum is unsaturated fatty acids, which inhibits the growth of certain pathogenic bacteria and fungi (pH 3 - pH 5)
    • Skin's acidity probably discourages the growth of many other microorganisms
  16. Lysozyme
    • In perspiration, tears, saliva, and urine destroys bacteria cell walls
    • Lysozyme breaks chemical bonds on peptidoglcan which destroy cell walls
    • Lysozyme is also found in tears, saliva nasal secretions, tissue fluids, and urine where exhibits its antimicrobial activity
  17. Perspiration
    • Helps maintain body temperature, eliminates certain wastes, and flushes microorganisms fro the surface of the skin
    • Perspiration contains lysozyme, an enzyme capable of breaking down cell walls of gram-positive bacteria and to a lesser extent, gram-negative bacteria
  18. Ear wax
    • Physical barrier also functions as a chemical protectant
    • Rich in fatty acids, giving the ear canel a low pH, between pH 3 - pH 5, which inhibits the growth of many pathogenic microbes
  19. Saliva
    • Contains the enzyme salivary amylose
    • Contains antibody (IgA) that prevents attachment of microbes so that they cannot penetrate mucous membrane
  20. Gastric juice (stomach acid)
    • Low pH (1.2 - 3.0) of gastric juice kills most of bacteria and toxins
    • Cannot destroy Clostridium botulium and Staphylococcus aureus
    • Helicobacter pylori neutralizes stomach acid - an immune response that results in gastritis and ulcers
  21. Vaginal secretions
    Low pH (3-5) of vaginal secretions inhibit microbes
  22. Urine
    In addition to containing lysozyme, urine has an acidic pH (average 6) that inhibits microbes
  23. What is fever?
    an abnormally high blood temperature, a third component of the second line defense
  24. How fever work?
    • The brain's hypothalamus is sometimes called the body's thermostat; and it is normally set as 37°C (98.6°F)
    • Cytokines cases the hypothalamus to release prostaglandins that reset the hypothalamic thermostat at a higher temperature, thereby causing fever
    • Assume that the body is invaded by pathogens and that the thermostat setting is increased to 39°C
    • To adjust to the new thermostat setting, the body responds by constricting blood vessels, increasing the rate of metabolism and shivering all of which raise body temperature
    • As the infection subsides heat-losing mechanisms such as vasodilation and sweating go into operation
    • The skin becomes warm and the person begin to sweat. This phase of the fever called the crisis, indicates that body temperature is falling
  25. What is the reason we have fever?
    • Mesophiles optimal temperature is 37°C. By increasing temperature, create unfavorable environment for bacteria to slow down growth and reproduction
    • Therefore, we can have under control of bacteria from growing
  26. Pyrogens
    A substance, typically produced by a bacterium that produces fever when introduced or release into the blood is pyrogens
  27. What are TLRs?
    • Toll-like receptors (TLRs) on the host cell attaches to pathogen-associated molecular patterns (PAMPs)
    • TLRs bound to PAMPs induce the release of cytokines form the host cell that regulate the intensity and duration of immune responses
    • Humans have 10 different TLRs
    • From heterodimers to increase PAMPs recognition
    • Also associate with other proteins to increase PAMPs recognition
    • TLRs can located on monocytes, macrocytes, dendric cells, epithelial cells (lungs, intestines) T. cells, and B cells
    • If TLRs activated, something need to be pay attention (pathogen)
    • It is important to have epithelial cells to have TLR's because lungs and intestines are exposed to outside world, they are first line of exposures
  28. What are PAMPs?
    • PAMPs are include the lipopolysaccharide (LPS) of the outer membrane of gram-negative bacteria, the flagellin in the flagella of motile bacteria, the peptidoglycan in the cell wall of gram-positive bacteria, the DNA of bacteria and DNA and RNA of viruses
    • When TLRs on cells encounter the PAMPs of microbes, such as the LPS of gram-negative bacteria, the TLRs induce the defensive cells to release chemicals call cytokines

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biologyhelp
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319914
Filename:
Biol 251 Chapter 16
Updated:
2016-05-09 01:13:49
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innate immunity
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Biol 251 chapter 16
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