lesson 6

• Disease

  A condition that disturbs the normal functioning of the organism
• Homeostasis

  The body's ability to maintain normal functioning
• Illness

  A deterioration in the state of normal health
• Infection

  The invasion of an organism's body tissue by disease-causing agents
• Immune system

  • Prevents infectious agents invading body tissues
  • Responds to successful infections in order to restore normal health
• Pathogen

  A disease-causing agent that disrupts normal physiology
• Types of pathogens

  • Cellular (living)
  • Acellular (non-living)
• Cellular pathogens

  • Parasites
  • Protozoa
  • Fungi
  • Bacteria
• Acellular pathogens

  • Viruses
  • Prions
• Lymphatic system

  Corresponding drainage system comprised of lymph that is responsible for filtering blood and tissue fluid
• Lymph

  A clear fluid containing white blood cells that arises from the drainage of fluid from blood and tissues
• Lymph nodes

  Points where lymph is filtered and pathogens are targeted for destruction and removal
• Lymphoid organs

  • Spleen
  • Thymus
  • Tonsils
  • Appendix
• White blood cells (leukocytes)

  • Neutrophils
  • Lymphocytes
  • Monocytes
  • Eosinophils
  • Basophils
• Mnemonic for white blood cells

  Never Let Monkeys Eat Bananas
• Innate immune response cells

  • Neutrophils
  • Eosinophils
  • Basophils
  • Monocytes
• Adaptive immune response cells

  Lymphocytes (B and T cells)
• Lines of defense in the immune system

  • Non-specific defences (innate immunity)
  • Specific defences (adaptive immunity)
• Non-specific defences (innate immunity)

  • First line of defense
  • Phagocytic leukocytes
  • Antimicrobial proteins
  • Inflammatory response
  • Fever
• Specific defences (adaptive immunity)

  • Second line of defense
  • Lymphocytes
  • Antibodies
  • Memory cells
• Surface barriers

  Skin and mucous membranes that protect against infectious agents
• Components of surface barriers

  • Thick and tough dead skin cells
  • Biochemical agents to inhibit microbial growth
  • Mucus secretions
  • Biochemical agents in mucus
  • Cilia to aid pathogen removal
• Clotting

  The process by which broken vessels are repaired to prevent blood loss and limit pathogenic entry
• Coagulation cascade

  The series of steps that lead to the formation of a blood clot
• Innate immunity

  The non-specific, non-adaptive second line of defense against infection
• Components of innate immunity

  • Inflammation
  • Phagocytosis
  • Antimicrobial proteins
  • Fever
• Inflammation

  The process that increases capillary permeability at infected sites to recruit leukocytes
• Phagocytosis

  The engulfment and destruction of pathogens by phagocytic cells
• Complement system

  Antimicrobial proteins that augment and enhance innate immune responses
• Fever

  An abnormally high body temperature associated with infection that reduces pathogen growth and activates heat-shock proteins
• Natural killer cells

  Lymphocytes that non-specifically target compromised host cells for apoptosis
• Adaptive immunity

  The specific, adaptive third line of defense against infection
• Lymphocytes in adaptive immunity

  • B lymphocytes
  • Cytotoxic T lymphocytes
  • Helper T lymphocytes
  • Regulatory T cells
• Antibodies

  Proteins produced by lymphocytes that are specific to a given antigenic fragment
• Antibody production

  1. Pathogen invades body and is engulfed

  2. Antigen fragments expressed by cell

  3. Helper T cell activates specific B cells

  4. B lymphocytes produce antibodies
• Antibiotics are compounds that specifically target prokaryotic metabolism
• Mechanisms of antibiotic action

  • Targeting metabolic enzymes
  • Targeting ribosomes
  • Targeting cell wall synthesis
  • Targeting DNA synthesis
• Antibiotic resistance

  Some bacterial strains have evolved genes that confer resistance to antibiotics, leading to the prevalence of resistant strains
• Antivirals

  Compounds that target viruses, which lack metabolism and instead take over the cellular machinery of infected cells
• Antibiotics

  Compounds that specifically target prokaryotic metabolism