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Flashcards in lecture 1 Deck (28):

What happens when immune system Goes wronge


How deos the skin act as a physical barrier againts organisms 

  1. Physical barrier - Tightly packed keratinised cells which can constantly replace themselves 
  2. Physiological barrier - Low PH and low oxygen tension 
  3. Sebacous glands - Secretes 
  • Hydrophobic oils
  • Lysozyme
  • Ammonia
  • Antimicrobia peptides 



How does mucous act as a barrier to prevent infection

  1. Physical barrier - traps invadors 
  2. Secretion of IgA - Prevent attachment and penetration of cells by organisms
  3. Lysozymes, definsins, antimicrobial peptides - directly kill invading pathogens 
  4. Latoferin - starves invading bacteria or Iron 
  5. Cillia - Traps pathogen and leads to clearance of mucous assisted by sneezing and coughing 


How does commensal bacterial act as a defence againts other pathogens

  • Production of bactericidins - influence other bacteria
  • Synthesis of vitamins - Vitamin K and B12 
  • Anti-microbial short-chain fatty acids 
  • Compition for nutrients 
  • Reduction of PH in bowel 


What can happen if we use broad-spectrum antibiotics 

Eradication of normal bowel flora and leading to opportunistic infections

  • Oral, vaginal candidiasis - after oral antibiotics
  • C. diff after IV antibiotics 


How can these barriers be breached by iatrogenic causes 

  • Insertion of hardwire - IV lines, catheters and nasogastritubes
  • Antibiotics 
  • Anti-acid medication 
  • Antimicrobial wipes
  • Nasal decongestants 


What are all cells of the immune system 

  1. Phygocytes: neutrophils, macrophages, monocytes and dendritic cells
  2. Lymphocytes: B, T cells and natural killer cells  
  3. Mast cells, eosinophils and basophils 


What are all the soluble factors/proteins of the immune system 

  • Antibodies
  • Acute phase proteins 
  • Cytokines 
  • Complement system proteins 


What are cytokines 

Diverse collection of proteins and peptides which are activated in responce to infection, inflammation or tissue damagw 


What are the key features of cytokines 

  • Multiple functions 
  • Short half-life
  • can act locally or systemically 


What are the types of cytokines and whats there function

  • Interferons -                              Anti-viral activity 
  • Tumour necrosis factor           Pro-inflammatory cytokines 
  • Chemokines                             Cell migration 
  • Interleukines                            Various functions 


What are the 3 different types of signalling that can be carried out by Cytokines 

  1. Paracrine signaling - Acting on local cells causes a quick reponse and lasting for a short period
  2. Endocrine signalling - Acting on distant cells causing a slower but longer lasting responce 
  3. Autocrine signalling - Acting on the same cells that produced them- signaling and target cell can be the same or similar 


Where do B and T cells constantly circulate 

Blood lymph and secondary lymphoid tissue 


What are the 2 types of T-cells and whats their function

  1. Helper T cells - regulate immune system
  2. Cytotoxic T cells - kill virally infected Body cells 


What are Natural killer cells and whats their function 

  • Large granular lymphocytes - release lytic granules that kill some virally infected cells 
  • Detecting and killing tumour cells and virally infected cells
  • Can also kills antibody bound pathogens 



What are mast cells 

Live in tissues and protect mucosal surfaces 


What are basophils and eosinophils 

Circulate in the blood in small amounts - Recruited to the site of infection by inflammatory signals 


Whats the function of basophils, eosinophils and Mast cells 

  • Granular cells 
  • Release heparin, histamine and pro-inflammatory cytokines 
  • Important defense againts pathogens which are too big - Parasitic worms 
  • Key role in mediating allergic responce 


What is the complement system 

  • Family of 30 proteins produced in the liver
  • Circulate as inactive precursor proteins - upon entering infected/inflammed tissue become activated 
  • cleave each-other downstream in a biological cascade 
  • Promote inflammation and defending againts bacterial species 


What are macrophages, monocytes and neutrophils 



What are the functions of phagocytes 

  • Ingesting and killing bacteria + fungi 
  • Clearing debris - dead/dying cells and immune complexes 
  • Production of cytokines 


Desctribe the role of monocytes 

Circulates in blood - migrate into peripheral tissue and become macrophages


Describe Macrophages 

long-lived tissue resident phagocytes



what are the different types of macrophages 

  • Kupffer cells
  • Alveolar macrophages - lungs 
  • Mesangial cells - kideny
  • Microglial cells - nervous system


What are functions of macrophages 

  • phagocytosis
  • Limit inflammation 
  • Tissue repair and wound healing 
  • Antigen presentation 


Describe neutrophils/ Polynuclear cells 

  • Phagocytic cells that ciruclate the blood 
  • Short-lived
  • rapidly recruited to inflammed, damage and infected cells 


Describe dendritic cells 

  • In peripheral tissue as immature
  • Phagocytose antigens
  • Become mature and migrate into secondary lymphoid tissue where they have a role in antigen presentation 


Compare neutrophils, denritic cells and macrophages