Nonspecific Defenses of the Host

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Nonspecific Defenses of the Host

• Chapter 16
• Lecture 15

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Introduction

• The ability of body defenses to ward off disease
  is _______________________
• Lack of Resistance is called ___________
• ___________ resistance is all body defenses
  protecting against any kind of pathogen
• ___________ resistance is immunity by means of
  antibodies against specific microorganisms (next
  lecture)

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Overview of the Bodys Defenses
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Mechanical Factors

• Intact skin with its waterproof ____________ do
  not allow microbial invasion
• Some pathogens can penetrate mucous membranes
• Tears wash the eyes continuously-and more when
  irritants are encountered
• Saliva ____________ organisms from teeth and gums
• Mucous traps microorganisms in respiratory and GI
  tract
• The __________ ___________
• Urine flow and the flow of vaginal secretions
  move microorganisms out of the body

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Intact skin
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The Ciliary Escalator
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The Ciliary Escalator
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The Lacrimal Apparatus
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Chemical Factors

• ____________ unsaturated fatty acids-inhibit
  growth of some pathogenic bacteria (acne organism
  can metabolize sebum)
• Perspiration washes microorganisms off the skin
• __________________ (can break down cell walls of
  G and to a lesser extent G-) is found in tears,
  nasal secretions, saliva and perspiration
• Gastric juice low pH prevents microbial growth in
  the stomach
• Normal microbiota prevent the growth of many
  pathogens

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Phagocytosis

• Ingestion of microorganism or foreign matter by a
  host cell
• Phagocytes are _______ __________ cells or
  derived from them

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Phagocytosis diagram
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Phagocytosis cell
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Formed Elements in Blood

• Blood consists of plasma (fluid) and cells and
  cells fragments (formed elements)
• Leukocytes (3 kinds) different ones increase
  during different kinds of infections!
  Differential Counts
• G______________( Eosinophils, Basophils,
  Neutrophils)
• M____________________ and
• L____________________ (lymphatic system)
• Infections increase in _____________ ( some
  decrease white cells!)
• Bacterial components, lipids and _________,
  activate phagocytes

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Formed Elements
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Leukocytes
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Lymphatic System
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Actions of Phagocytic Cells

• Neutrophils are the most important of the
  granulocytic phagocytes
• Enlarged _____________ become wandering
  macrophages (super phages) and fixed macrophages
  located in selected tissues
• During the early stages of infection,
  g__________________ predominate,
  m________________ predominiate as the infection
  subsides

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Macrophages
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Mechanisms of Phagocytosis

• C_____________ chemical signals which attract
  phagocytes
• Phagocyte then adheres to the microbial cells
• Process enhanced by coating the microbe with
  __________________ proteins
• Pseudopods of the phagocyte engulf the microbe
  and enclose it in a ________ vesicle
• Many phagocytized microorganisms are killed by
  lysosomal enzymes and oxidizing agents
• Some microbes are not killed and even
  ____________________ in phagocytes

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Phagocytosis
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The Inflammatory Response

• Inflammation is a bodily response to cell damage
• R_________, pain, heat, swelling
• Vasodilation and Increased Permeability of Blood
  Vessels cause by histamines, kinins,
  prostaglandins
• Blood ________________ around an area of
  infection (an abcess) to inhibit the spread of
  infecting

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The Inflammatory Response

• Phagocyte migration
• Phagocytes stick to the lining of blood vessels
  and squeeze through into inter- cellular space
• Pus is the accumulation of damaged tissue and
  dead microbes, g____________ and
  m_________________________

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The Inflammatory Response

• Fever Caused by bacterial _________ and
  interleukin-1 which is released by phagocytes
  when they ingest G- bacteria
• A chill indicates a ________ fever, crisis or
  sweating indicates that the body temperature is
  falling

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The Inflammatory Response
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The Inflammatory Response (2)
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Tissue Repair

• Tissue is repaired when the supporting tissue or
  _____________ produces new cells (functioning
  tissue)-a perfect repair
• Supporting tissues repairs produce scar tissue
• Last part of the inflammatory process

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Antimicrobial Substances

• The complement system a groups of serum proteins
  which activate one another to destroy invading
  microorganisms
• C1 binds to antigen-antibody complexes to
  eventually activate C3 protein. Factor B, f
  factor D, factor P, and C3 bind to cell wall
  polysaccharides to activate C3b
• C3 activation can result in cell lysis,
  inflammation or coating the microbe with protein
• Complement deficiencies lead to increased
  susceptibility to disease

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Diagram of Complement System
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Cytolysis
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Interferons

• Interferons are antiviral proteins produced in
  response to viral infection
• Three types of Interferon A_______, B_________
  and G_______________
• Alpha and Beta interferons induce uninfected
  cells to produce ______________ proteins that
  prevent viral replication
• Gamma Interferon activates n______________ to
  kill bacteria
• Interferons are ______________ specific, but not
  _____________specific

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Alpha and Beta Interferons