What happens when immune system Goes wronge
How deos the skin act as a physical barrier againts organisms
-
Physical barrier - Tightly packed keratinised cells which can constantly replace themselves
-
Physiological barrier - Low PH and low oxygen tension
- Sebacous glands - Secretes
-
Hydrophobic oils
- Lysozyme
- Ammonia
- Antimicrobia peptides
How does mucous act as a barrier to prevent infection
- Physical barrier - traps invadors
-
Secretion of IgA - Prevent attachment and penetration of cells by organisms
-
Lysozymes, definsins, antimicrobial peptides - directly kill invading pathogens
-
Latoferin - starves invading bacteria or Iron
-
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
- Phygocytes: neutrophils, macrophages, monocytes and dendritic cells
- Lymphocytes: B, T cells and natural killer cells
- 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
-
Paracrine signaling - Acting on local cells causes a quick reponse and lasting for a short period
-
Endocrine signalling - Acting on distant cells causing a slower but longer lasting responce
-
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
- Helper T cells - regulate immune system
- 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
Phagocytes
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
