Bio

• Bacteria


  Most types are free-living cells (perform most metabolic functions themselves) relying on the host primarily for nutrition. Pathogenic bacteria contain virulence genes.
• Virus


  Non living organisms outside the host. Built from short sequences of nucleic acid, either DNA (Adenovirus) or RNA (Retrovirus), wrapped in a protein shell. Rely on the host cell to synthesize their genetic and structural components causing cell death and disease.
• Viruses


  • Coronaviruses (CoV) are a large family of viruses that cause illness ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS-CoV).

  
• Fungi, Protozoa & worms


  A group of eukaryotic organisms. Some can cause superficial, cutaneous, subcutaneous, or systemic disease.
• Prions


  Infectious misfolded protein. Can replicate and kill the host. Can cause some rare neurodegenerative diseases including the mad cow disease.
• Pathogen


  An agent capable of causing host damage and disease.
• First line defenses


  • Chemical and physical barrier defenses. Act instantaneously to prevent pathogenic invasion into the body tissues. e.g: skin
• Pathogens have different antigens, and each antigen has a unique shape.
• Antigen


  Any substance that provokes an immune response. Large proteins or polysaccharides.
• Host


  A human host. Nutrient-rich, warm, and moist environment, with a uniform temperature and constantly renews itself => desirable niche for microorganisms.
• Immune system components


  • Barriers, Cells, Soluble proteins.
• Immune system function


  The collection interact with each other to recognize, destroy and neutralize pathogens and cancer cells.
• Immune system organization


  • Nonspecific (Innate) immune response, Specific (Adaptive) immune response, Cell mediated immune response, Antibody-mediated immune response.
• Cell mediated immune response

  • Depends mainly on T-lymphocytes that kill the pathogens (antigen).
• Antibody-mediated immune response


  • Depends mainly on B-lymphocytes that produce antibodies (that bind and neutralize specific antigens).
• Second line defenses


  • Phagocytes, Complement proteins, Early induced proteins (interferons), Inflammation.
• Lymphatic system


  Drains body fluids and returns them to the bloodstream. Transports dietary fats and fat-soluble vitamins absorbed from the digestive system to the cardiovascular system. Defends the body against infection.
• Lymph


  Interstitial fluid once it has entered the lymphatic system. Milky fluid containing white blood cells, proteins, fats and occasionally bacteria and viruses.
• Primary lymphoid organs


  • Bone marrow, Thymus.
• Secondary lymphoid organs


  • Lymph nodes, Spleen, Lymph nodules (Tonsils, Adenoids, MALT).
• Lymphatic capillaries


  The terminal lymphatics, are vessels where interstitial fluid enters the lymphatic system to become lymph fluid and empty into larger lymphatic vessels. Located in almost every tissue except in the central nervous system, bone marrow, bones, teeth, and the cornea of the eye. Contain endothelial flaps that prevent the "backflow" of lymph when interstitial pressure is low.
• Lymphatic vessels


  Large vessels, similar to veins. Drain into the cardiovascular system through the right lymphatic duct and thoracic duct. Have one-way valves to prevent backflow of lymph.
• Thymus gland


  A bilobed organ found in the space between the sternum and the aorta of the heart. It matures the T cell and secretes thymic hormones; e.g thymosins which are implicated in lymphocyte maturation and differentiation. Largest, most active during childhood and atrophies with age.
• Lymphoedema


  When the lymphatic system is damaged, protein-rich, interstitial fluid accumulates (sometimes "backs up" from the lymph vessels) in the tissue spaces. This inappropriate accumulation of fluid is referred to as lymphedema. This condition may lead to serious medical consequences.
• Bone marrow


  The red bone narrow is a loose collection of cells where hematopoiesis occurs. The yellow bone marrow is a site of energy storage, which consists largely of fat cells. It develops the B cell.
• The immature T cell, called a thymocyte, leaves the bone marrow and matures largely in the thymus gland.
• Lymph nodes


  Lymph filters located at intervals along lymphatic vessels. Remove debris and pathogens from the lymph. Dendritic cells and macrophages within the nodes internalize and kill many of the pathogens that pass through. Lymphocytes B and T are also present and mediate adaptive immune response.
• Spleen


  A fragile organ without a strong capsule. Highly vascularized which gives it a dark red color. Has two regions: Red pulp (contains macrophages and dendritic cells that remove microbes and other materials from the blood, including dying red blood cells) and White pulp (where adaptive T and B cell responses are mounted). The spleen is also the location of immune responses to blood borne pathogens.
• Lymphoid nodules


  Have more simple architecture than the spleen and lymph nodes. Include Tonsils, MALT (Peyer's patches), and BALT.
• Tonsils


  The palatine tonsils (faucial tonsils), nasopharyngeal tonsils, lingual tonsil, and tubal tonsils. Located along the inner surface of the pharynx. They are the first line of defense against ingested or inhaled pathogens. Enlarge during early childhood and start to atrophy after the first decade. Hypertrophy can pose a risk for disease pathologies in children.
• Mucosa-associated lymphoid tissue (MALT)

  Dome-shaped structures found underlying the mucosa of the gastrointestinal tract, breast tissue, lungs, and eyes. Important for immune responses against ingested substances. Contains specialized endothelial cells called M (or microfold) cells that transport material from the intestinal lumen toward the lymphoid follicles that activate or inhibit the immune response leading to either tolerance or systemic immune cell response.
• Bronchus-associated lymphoid tissue (BALT)


  Consist of lymphoid follicular structures with an overlying epithelial layer found along the bifurcations of the bronchi, and between bronchi and arteries. Are effective against inhaled pathogens.
• Adenoids

  The tonsils located on the roof and posterior wall of the nasopharynx.
• Cells of the Innate Immune Response

  • Macrophage (Agranulocyte, Irregular shape, Has pseudopodia, Primary location: Body cavities/organs, Function: Phagocytosis)
• Peyer's patches

  Specialized lymphoid follicular structures in the small intestine
• Peyer's patches

  • Contain MALT (mucosa-associated lymphoid tissue) in the small intestine
  • Are important for immune responses against ingested substances
  • Contain specialized endothelial cells called M (or microfold) cells
• M (or microfold) cells

  Transport material from the intestinal lumen toward the lymphoid follicles that activate or inhibit the immune response leading to either tolerance or systemic immune cell response
• Bronchus-associated lymphoid tissue (BALT)

  • Consist of lymphoid follicular structures with an overlying epithelial layer
  • Found along the bifurcations of the bronchi, and between bronchi and arteries
  • Are effective against inhaled pathogens
• Adenoids

  The tonsils located on the roof and posterior wall of the nasopharynx
• Cells of the Innate Immune Response

  • Macrophage
  • Neutrophil
  • Monocyte