introduction

• immune system can distinguish self from non self
• immune system can distinguish harmful and harmless
• the overreaction of immune system causes hypersensitivities
• first line of defence

  physical, mechanical, chemical, and biological barriers
• second line of defence

  activation of innate immunity
• third line of defence

  adaptive immunity with B lymphocytes and T lymphocytes
• cilia move mucous and trapped particles upwards towards the throat, to be expelled by coughing
• airway clearance through coughing is essential to reduce infections in the lungs
• mechanical barriers


  cilia in respiratory tract, coughing, vomiting, defecation, urinary tract flushing
• physical barriers

  skin, epithelial cells, mucous
• chemical barriers

  lysosomes, acid, antimicrobial peptides
• biological barriers

  commensal microorganisms
• cellular barriers

  lung alveolar macrophages
• secondary proteins

  complement and interferon
• secondary cellular response

  phagocytes and natural killer cells
• blood and urine are sterile
• microbiome exists so pathogens cant take control
• bone marrow contains stem cells
• thymus contains T cells that migrate into the periphery
• lymphocytes arise from stem cells in the bone marrow
• b cells complete their maturation in the bone marrow
• t cells leave bone marrow in an immature state and complete their maturation in the thymus
• plasma that is leaked from blood is collected by lymphatics as lymph and returned to the blood via thoracic duct, emptying into left subclavian vein
• dendritic cells will pick up pathogen and go to lymph nodes for an immune response
• adaptive immunity is highly antigen specific
• innate immune cells (dendritic cells) are essential for activation of naive lymphocytes (adaptive immune response)
• innate immunity influences the type of adaptive immune response generated
• adaptive immune response can enhance the antimicrobial activities of innate immune cells
• macrophages are activated by cytokines
• antibody produced by B lymphocytes can augment phagocytosis
• average human has 37.2 trillion cells
• microbe

  organism that is too small to be seen with naked eye eg. bacteria and viruses
• commensal microorganism = normal flora
• microbiota

  all microorganisms living in an environment
• microbiome

  ecosystem made up of microbes within and on human body
• composition of microbiome is influenced by:

  antibiotic use, moisture, diet, hormones, hygiene products
• candita albicans causes oral thrush
• staphlococcus epidermis inhibits s. aureus colonisation
• helicobacter pylori causes gastritis, ulcers, and gastic carcinomas
• escherichia coli causes diarrhea, UTI, and pnemonia