Microbiology 10 Flashcards
what does the lymphatic system consist of?
lymphatic organs
- primary (bone marrow, thymus)
- secondary (lymph nodes, spleen)
lymphatic vessels
lymph (protein rich fluid from plasma)
why is the vascular system important in the immune system?
- carried lymph fluid towards heart via lymph nodes
- filters bacteria at lymph nodes
- site of some immune response
the lymphatic system is not a …. system
closed
what is haematopoiesis?
generation of blood cells
where does haematopoiesis happen?
bone marrow
in hematopoietic stem cells
T cells mature in the ..
thymus
…. have a role in determining cell type
cytokines
innate immune system
‘older’ in evolutionary terms compared to adaptive immune system
present in all multi cellular organisms
recognises lipids + carbs
defence against any pathogen
adaptive immune system
evolved
driven against specific pathogens + adapts over time
recognises protein conformations/peptides
has memory
what is the first line of immunity?
innate/natural immunity
- intact skin
- mucous membranes
- normal microbiota
what is the second line of immunity?
innate/natural immunity
- NK and phagocytic WBCs
- inflammation
- fever
- antimicrobial substances
what is the third line of immunity?
adaptive/acquired immunity
specialised lymphocytes
T and B cells
antibodies
…. cells act as a barrier to prevent the passage of pathogens
epidermal
what can pathogens do to the skin?
circumvent/ colonise
the skin works in combination with other factors
give an eg?
production of sebum
what 2 layers does the skin possess?
- epidermidis
- dermis
what is the human microbiota?
ecological community of commensal, symbiotic + pathogenic microorganisms
inc:
- bacteria
- virus
- fungi
- archaea
microbiota exist for different human anatomical areas
give eg of these?
- skin
- gut
- conjunctiva
- urethra + bladder
composition of microbiota is said to be important in infectious diseases
give eg of these?
- bacterial metabolites influence host signalling pathways
- type 1 diabetes
- asthma
- cancer
what are the 3 major events to inflammatory response?
- vasodilation
- capillary permeability increase
- phagocyte influx
one of the principle mediators of the inflammatory response is…
histamine
what are the physiological barriers that contribute to innate immunity?
- temp
- pH (most pathogens grow best at 7)
- various soluble + cell associated molecules
lysozymes cleave the …
peptidoglycan layer in bacterial cell walls
interferons are produced by …
virus infected cells
the complement system straddles …
both innate and adaptive immune systems
what 3 paths is the complement system activated by?
- classical (antigen/antibody)
- lectin (MBL binding to pathogen)
- alternative (spontaneous)
activation of the complement system can lead to…
- cell lysis
- opsonisation
- immune clearance
- binding specific receptors on immune cells
what are the classifications of receptors expressed mainly by the cells of the innate system?
- membrane bound (e.g. TLRs/CLRs)
- cytoplasmic (NRLs)
what are the 2 classes of molecules in pattern recognition receptors?
- pathogen associated molecular patterns (PAMPs)
- damage associated molecular patterns (DAMPs)
PAMPs
- associated with microbial pathogens
- LPS recognised by TLR4
- peptidoglycan recognised by TLR2
DAMPs
- associated with host cell components as a result of damage/death
- damaged RNA from UV-B exposed keratinocytes activates TLR3 on intact keratinocytes
what pathogen type are TLR1, TLR2 and TLR6?
gram positive bacteria
e.g. s aureus/ fungi
what pathogen type is TLR4?
gram neg e.g. e coli
what pathogen type is TLR5?
bacteria
flagellum
what pathogen type is TLR3, TLR7 and TLR8?
virus
what pathogen type is TLR9?
bacteria
dna
what pathogen type is Nod1 and Nod2?
gram pos/neg
give e.g. of WBC?
- neutrophil
- eosinophil
- basophil (mast cells)
- lymphocyte
- monocyte
what are mast cells?
type of granulocyte that resides in tissue
basophil is the … equivalent
blood
what do the granules of mast cells contain?
and what does this make it?
histamine + heparin
most inflammatory cell in body
also major target for anti inflammatory drugs
eosinophils
combat multicellular parasites + certain infections
has role in allergy + asthma
not overly phagocytic
functions by releasing basic + cationic proteins (superoxide, peroxide, hypobromite)
what are NK cells?
type of cytotoxic lymphocyte
function by binding to cells + releasing cytotoxic granules
what are neutrophils?
type of phagocytic granulocyte
neutrophils attracted by?
cytokines
they = among 1st responders to inflammation
what are the predominant cells in pus?
neutrophils
what are the 3 ways neutrophils can directly attack microorganisms?
- phagocytosis
- degranulation
- generation of neutrophil extracellular traps (NETs)
what 2 cells do phagocytes consist of?
neutrophils + macrophages
what do phagocyte contain that can kill compounds?
peroxidase
acid
alkali phosphatases
what are cytokines?
broad + loose category of small proteins
imp in cell signalling
immunodomulating
can be produced by multiple classes of cells —> mainly helper T cells + macrophages
what are the 4 main characteristics that adaptive immunity displays?
- antigenic specificity
- diversity
- immunologic memory
- self/non self recognition
what does adaptive immunity rely on?
t cells
B cells
receptors have to recognise and differentiate between different antigen ….
epitopes
what is V(D)J recombination?
- happens in lymphoid organs during early stages of T + B cell development
- combines gene segments to form single gene
- limited number of cells produced
immunological diversity + clonal selection
- differentiation of hematopoietic stem cells
- immature lymphocytes produced each with different antigen receptors
- immature lymphocytes exposed to self antigens
- maturation into inactive lymphocytes
- exposure to foreign antigens activate lymphocyte
- activated lymphocyte then produces clones of itself
where do T cells arise?
bone marrow
what are the 2 major TCRs on T cells?
cd4 (t helper cells)
cd8 ( cytotoxic T cells)
what are the 2 main classes of MHC (major histocompatibility complex)?
- class I - expressed by all nucleated cells
- present Tc cells
- class II - expressed by antigen presenting cells (dendritic cells, B cells, macrophages)
- present Th helper cells
what are dendritic cells?
antigen presenters
activation of B cells happens in…
secondary lymph organs
antibodies are known as …
immunoglobulin glycoproteins
the …. region recognises the antigen
variable
what are the 4 different ways antibodies work?
- neutralise
- agglutinate
- precipitate
- activate complement
what are the multiple selection processes that T cells undergo?
positive selection
- removes cells which bind too weakly to self antigen (most cells removed here)
negative selection
- removes cells which bind too strongly to self antigens
what are the types of hypersensitivities (allergies)?
type I - most common type mediated by IgE antibodies
what are the minor systems of allergies?
- sneezing
- runny/blocked nose
- red, itchy, watery eyes
- wheezing + coughing
- red, itchy rash
- worsening of asthma or eczema symptoms
what is a vaccine?
biological preparation which provides active acquired immunity to particular disease
what are the 4 main types of vaccines?
- live-attenuated vaccines (MMR)
- inactivated vaccines (Hep A
- subunit, recombinant, polysaccharide + conjugate vaccines (HPV)
- toxoid vaccines (tetanus)
what does herd immunity only work on?
diseases which spread between people
what is the herd immunity threshold?
proportion of immune individuals within a population that can prevent a particular disease
what is immunodeficiency?
state which the immune systems ability is compromised / absent entirely
what are the 2 types of immunodeficiency disorders?
primary
- rare genetic conditions (SCIDs)
- broken down by cell type
secondary
- more common
- acquired
- some diseases can cause AIDs
what is immunosuppression?
reduction of activation/ efficacy of immune system
what does cyclosporin A (immunosuppressant) do?
- block T cell activation, IL-2 production
- less effective on activated cells
what do steroids do (immunosuppressants) do?
- anti-inflammatory (block gamma IFN)
- suppress activated macrophages
