compendium 11

• What are the functions of the lymphatic system?

  -Fluid balance: excess interstitial fluid enters lymphatic capillaries, becomes lymph

  -Fat absorption; absorbs fat and other substances from the digestive tract via lacteals

  -Defence; fights infection, Microorganisms and foreign substances are filtered from lymph by lymph nodes and from blood by spleen
• What are the 8 structures of the lymphatic system?

  -Lymph

  -Lymphatic Vessels

  -Lymphatic tissue

  -lymphatic nodules

  -lymphatic nodes

  -Tonsils

  -Spleen

  -Thymus
• Describe Lymph


  -Water plus solutes from two sources

  -Plasma: ions, nutrients, gases, some proteins

  -Cells: hormones, enzymes, waste products

  -returns to circulatory system via veins; essential for fluid balance
• describe the lymphatic capillariies

  -carry lymph away from tissues

  -Lymphatic capillaries: more permeable than blood capillaries, epithelium, found in all part of the body except N.S, bone and avascular tissues
• What is a pathogen?

  -A microorganism that causes disease, they introduce foreign proteins into the body called antigens
• What are the 5 different types of pathogens?

  Bacteria, Virus, Fungi, Protozoa, Parasites
• What are some examples of pathogens?

  Bacteria: infections such as Staphylococcus or food poisoning such as salmonella

  Fungi: Candida

  Protozoa: amoeba

  Parasites: Worms

  Viruses: Influenza family, HIV
• How are Pathogens and Antigens detected?

  -Antigenic receptors on T cells and B cells recognise these foreign proteins and aim to remove them
• What is immunity?

  -Ability to resist damage from foreign substances and internal threats

  -immunity can distinguish between external micro-organisms such as bacteria and internal threats such as cancer cells
• What are the different categories of immunity?

  -Innate/ non-specific

  -Adaptive/specific

  -both are fully integrated into the body
• What are the differences between the immune and lymphatic systems?

  -The lymphatic is the transport system for cells of the immune system and antigens to move around the body

  -tissues where immune system cells "hang out"

  -Immune system is a collection of proteins, cells, tissues and organs widely distributed throughout the body
• Describe Innate Immunity


  -non-specific defence that is present at birth

  -each time body is exposed, response is the same (no memory)

  -provides immediate protection from pathogens and antigens

  -first (physical barriers) and second lines of defence (Chemical mediators and White blood cells)
• What are the physical barriers in innate immunity?

  -First line of defence, prevent entry or remove microbes

  -skin

  -mucous membranes (such as respiratory passageway)

  -Saliva

  -Tears

  -Stomach acid, urinary tract, vagina

  -Urine flushes urinary passageways

  -Cilia in respiratory tract, coughing/sneezing
• Chemical Mediators in innate immunity

  -second line of defence and promote phagocytosis and inflammation

  -Histamine

  -Cytokines

  -Complement

  -Interferons
• Describe Histamine


  -chemical mediator in innate immunity

  -causes vasodilation, increased vascular permeability, attract WBC, stimulates phagocytosis

  -causes allergy symptoms and reactions
• Describe cytokines

  -chemical mediator in innate immunity

  -secreted by one cell, and stimulates a neighbouring cell to respond, stimulate intensity and length of immune response
• Describe Complement


  -chemical mediator in innate immunity

  -stimulate lysis (break down) of invading pathogens
• Describe Interferons

  -chemical mediator in innate immunity

  -Anti-viral activity
• Describe White blood cells

  -produced in bone marrow and lymphatic tissue

  -released into blood and transported around the body

  -when a tissue is damaged, it releases chemicals that attract WBC to site of injury/invasion
• Role of white blood cells in innate immunity

  -ingest foreign particles-phagocytosis

  -produce chemicals to attract other immune cells to local area
• What are the 6 Types of White blood cells

  -Neutrophils

  -Macrophages

  -Basophils

  -Eosinophils

  -Natural Killer Cells

  -B and T lymphocytes
• Describe neutrophils


  -Type of WBC

  -Neutrophils; first to arrive at site of injury, acute inflammation, phagocytosis
• Describe Macrophages

  -Type of WBC

  -most effective phagocyte, important in later stages of inflammation and repair

  - help activate cells of the specific immune system
• Describe Basophils


  -type of WBC

  -Immunosurveillance; produces histamine during an allergy, which helps to heel the area through increased blood flow
• Describe eosinophils


  -type of WBC

  -attack parasitic infections and lessen allergy attacks
• Describe Natural Killer Cells

  -type of WBC

  -cause lysis (breakdown) of virus-infected cells or cancer cells
• B and T lymphocytes

  -type of WBC

  -adaptive immunity

  -B cells produce antibodies
• Describe Inflammation


  -part of innate immunity

  -local tissue response to damage from pathogens or injury

  -Aims to rid the body of debris/invader and prevent further pathogen entry
• What are the characteristics of inflammation?

  -Redness and Heat: increased blood flow to the region

  -Swelling: capillaries become leaky (increased permeability)

  -Pain: increased fluid stimulates pain receptors; chemicals released by cells also stimulate pain receptors
• Describe Fever


  -Part of Innate Immunity

  -Generalised body response to tissue damage and infection

  -can cause macrophages to release chemicals

  -body temp abnormally high
• What is the purpose of the high body temp in Fever

  -high temp increase some antimicrobial substances, decrease microbial growth, increase body reactions that help tissue repair
• Describe Adaptive Immunity


  -Specific, ability to recognise a particular substance

  -memory, ability to remember previous encounters with a particular substance and respond rapidly

  -Acquired during lifetime, depending on exposure

  -fights invaders once innate immunity is over-run
• How is Adaptive Immunity Mediated

  -Adaptive immunity activates lymphocytes

  -lymphocytes must recognise antigen

  -after recognition, lymphocytes increase in number to destroy antigen

  -use helper t cells, effector (cytotoxic) T cells and B cells
• Describe Cell-mediated immunity


  -does not rely on antibodies

  -primarily driven by helper t-cells

  -activates antigen-specific cytotoxic t-cells that destroy infected cells, either foreign pathogen or cancer infected

  -activates macrophages and natural killer cells enabling them to destroy intracellular pathogens

  -stimulates cells to release cytokines
• Describe Cytotoxic T cells

  -Eliminate antigens (pathogens)

  -Make holes in cell wall, causes cells to explode
• Describe Memory Cells


  -if the same antigen re-appears, the response will be faster

  -most effective against intracellular pathogens
• Antibody-mediated/humoral immunity


  -involves B cells

  -phagocytosis of an extracellular pathogen that matches the specific B cell receptor on that B cell

  -requires co-stim by a helper T cell that also recognises same antigen
• B cells in Anti-Body mediated immunity

  -divides to form:

  -Plasma Cells; make antibodies

  -Memory B cells; if the same pathogen (antigen) is encountered again, the response is much faster
• 3 Effects of antibodies

  -inactivate the antigen

  -binds antigens together

  -facilitate phagocytosis
• Antibody production; Primary Response

  -Primary Response: when a B cell is first activated by an antigen

  -B cell multiply to produce plasma cells (antibody production) and memory cells