Week 2 Flashcards
What are the functions of blood films?
Detecting blood cell abnormalities or if patients have disease detectable in blood cells e.g. malaria
What information do blood films give and when are they requested?
Information on RBCS, WBS and platelets
When a patient has returned from a country where a disease is endemic
Usually performed with full blood count
What is a white cell differential and what is it used for?
Shows the proportions of WBCs in blood
Helps determine type of infection (bacterial, viral, parasitic)
How would you do a blood film?
- Take two microscope slides and clean them with ethanol on tissue
- Place one drop of blood on one end of one of the slides - creates monolayer to examine microscopically
- Hold the other slide at a 45 degree angle and slide it on the other slide until it reaches the blood
- Draw back the slide along the other slide
- Slide is then dried
What effect is seen on the slide when doing a blood film?
Feathered effect
Which type of WBC is this?
Eosinophil - bilobed nucleus
Which type of WBC is this?
Lymphocyte: large nucleus, not grainy
Which type of WBC is this?
Neutrophil - multi lobed nucleus
Which type of WBC is this?
Basophil - grainy, single nucleus
Which type of WBC is this?
Monocyte - kidney bean nucleus
What is the difference between gram positive and gram negative cell walls?
Gram positive have a thicker peptidoglycan wall
What is the order of stains in gram staining and what colour are they a each stage?
Crystal violet: put on both samples then washed, both purple
Grams iodine: traps dye in cell, incubated then washed, both purple
Ethanol: decolours gram negative bacteria, rinsed with water, neg = colourless, positive purple
Safranin: pink counterstain, gram pos purple, neg pink
What should always be performed when doing gram staining and why?
Controls: to ensure staining process has been carried out correctly
Why is gram staining done?
To identify which type/species of bacteria is present
Which type of parasitic egg is this?
Trichuriasis
Which type of parasitic egg is this?
Schistosomasis
What type of parasitic egg is this?
Ascaris
Why is oil immersion used?
Used with light microscope to see bacteria to give x1000 magnification , prevents
How can the immune system be improved to reduce disease caused by an infection?
By getting the infection/vaccinayion
Which virus has been made extinct through vaccination?
Smallpox
Give examples of things there are vaccinations for
Flu, cholera, polio, chickenpox, hep B
Examples of some physical barriers to infection?
Epithelial cells joined by tight junctions
Movement of mucus by cilia
Normal flora
Low ph in gut
Where are WBCs made?
the bone marrow - mostly pelvic area in adults, leg bones in children
Which cells are produced from a common myeloid progenitor?
Erythrocytes, megakaryocyte, mast cells, myeloblasts, basophils, neutrophils, eosinophils and monocytes
Which cells are produced from a common lymphoid progenitor?
NK cells, T and B lymphocytes
Where do T lymphocytes mature and why?
Thymus - checked to ensure they aren’t auto reactive and won’t cause autoimmune disease
List the WBCs in order of most prominent in blood to least.
Neutrophils (65%), lymphocytes (30%), monocytes (5%), eosinophils (2%), basophils (0.5%)
How long do neutrophils, eosinophils, basophils, monocytes and b and t lymphocytes live?
N - 7 hours
E - 8-12 days
B - few hours to few days
M - 3 days
BT - years
How do neutrophils carry out their function?
Chemotactic and phagocytic: chase and eat bacteria
Which cells leave the blood and take up long term residence in tissues and why?
Dendritic cells, macrophages, mast cells
They survey the tissue to ensure its healthy and there is no presence of infection/not damaged
If infection sensed then they protect the body
Name some secondary lymphoid organs.
Tonsils, adenoids, Peters patches of intestines, appendix, lymph nodes
Which cells are involved in the innate immune response?
Mast cells, NK cells, basophils, neutrophils, eosinophils, monocytes
Which cells are involved in the adaptive immune response?
T and B lymphocytes
What is inflammation?
A reaction of the body to damage to its cells and vascularised tissue
What are the aims of inflammation?
- Expel foreign body/infection
- Prevent metastasis
- Structural/functional repair
What are the 5 clinical features of inflammation?
Redness/rubour: vasodilation
Heat/calor: vasodilation and fever
Swelling/tumor: fluid in ECM
Pain/dolor: pain mediators e.g. serotonin
Loss of function/functio lasea: limb movement inhibited by pain/swelling
What are some cells/molecules that can induce inflammation?
Bradykynin: pain mediator produced in fibrinolysis
C5a: produced in complement and causes inflammation
Mast cells release histamine which can cause inflammation, also cytokines e.g. IL-6 and TNF which cause inflammation
Function of macrophages?
Phagocytose pathogens and kill with acidic/degregative lysosomes
How do macrophages/neutrophils recognise and kill?
They have phagocytic receptors that bind microbes and their components
The bound material is internalised in phagosomes and broken down in phagolysosomes
Function of Toll Like Receptors (TLRs)?
Recognise different PAMPs (pathogen associated molecular patterns)
They then activate macrophages/dendritic cels to cause an immune response
How can inflammation be bad?
They can sometimes outlive the threat they’re dealing with, causes more damage to the body than the infection would have caused e.g. allergies, autoimmune disease
Which diseases does inflammation underly?
Cancer, diabetes, alzheimers, arthritis
Which systems is the lymphatic system a part of?
Circulatory and immune
What is capillary filtration?
Plasma (liquid part of blood) is continuously removed from and returned to blood vessels
What is interstitial fluid?
Plasma not returned to blood vessels after capillary filtration, returned to lymphatic vessels instead
What makes up the lymphatic system?
Lymphatic vessels, lymph, primary and secondary lymphoid organs
What are the functions of the lymphatic vessels?
Drain lymph back into blood
Where does lymph drain?
Right upper body: right subclavian vein
Left upper body and lower body: left subclavian vein
Functions of lymph?
Transports immune cells
Removes waste products
Transports proteins and fats from digestive system
Where do B lymphocytes mature?
Bone marrow and then spleen/lymph node
Function of lymph nodes in lymphatic system?
Drains lymph and collects antigens
Activates immune response
What is microbiology?
The study of microorganisms and their relationships with humans
What is a microorganism?
Any organism/replicating entity of microscopic size.
What are three classifications of cellular microorganisms?
Bacteria, fungi, protazoa
What are 2 classifications of acellular microorganisms?
Viruses and prions
What type of DNA do prokaryotes have?
Single, circular DNA
Draw a diagram of bacteria
What form is DNA in in bacteria?
Long circular form +/- plasmids
Are bacteria pro/eukaryotes?
Single celled prokaryotes
What makes bacteria gram stain unreliable?
Very small, atypical life cycle, atypical structure
PCR may be used instead
Name common GP cocci
Staphylococcus aureus
Streptococcus pneumoniae
Name common GP rod
Listeria monocytogenes
Corynebacterium diphtheriae
Name common GN cocci
Nesseria meningitis
Name common GN rods
E coli
Salmonella
What is colonisation?
Symbiotic and natural living arrangements between 2 species which may be beneficial and doesn’t cause harm
What are benefits of colonisation?
Competition inhibits infection establishment
Vitamins K and b in the gut are produced
Immune stimulation
Where in the body is most flora found?
Colon
What are some examples of sterile body sites?
Blood, tissues, organs
CNS
Lower respiratory tract
Sinuses
Eye
What is infection defined as?
Colonisation +/- multiplication of pathogens or organisms that may cause harm in a vulnerable host +/- disease
What is a nosocomial infection?
Hospital acquired infection
What are endotoxins and where are they found?
Bacteria that illicit strong immune response and make patients appear septic
Lipopolysaccharide in gram neg bacteria
How are exotoxins produced, where and what do they cause?
Produced intracellular and release as mature toxins on infection
Gram pos bacteria (staph A, strep P)
Toxic shock syndrome
What are some host and environmental factors causing infection?
Age, gender ethnicity, nutrition
Drugs
Immunocompromise
Precense of foreign objects
Vaccination history
Crowding, sanitation
What is classed as microbiological emergencies?
Infection of sterile site
Meningitis
Septic arthritis
Eye infections
What are some SIRS markers in sepsis?
2 of:
Temp outside 36-38 C
HR > 90
RR > 20
What is sepsis, severe sepsis and septic shock?
Sepsis: sirs with infection present
Severe: sepsis with organ hypo perfusion e.g. hyperaemia, oliguria, acidosis
Shock: severe sepsis with hypotension despite fluid resuscitation
Draw the chain of infection.
What are the first defences to infection in the body?
Epithelium
Cilia
Mucus
Defensins
What are defensins?
Ppetides produced by neutrophils and macrophages that defend against infection
What is opsonization?
The process of making a foreign cell more susceptible to phagocytosis
What are three outcomes of complement?
- inflammatory cells recruited
- opsonization of pathogens
- killing of pathogens
What is complement?
A cascade of proteins in serum
Activated by antibody or molecules from pathogens
Amplifies inflammatory response
Kills pathogens directly or attracts immune cells
What does higher numbers of neutrophils indicate?
Bacterial infection
What do primary neutrophil granules contain?
Bcatericidal enzymes:
- lysozyme
- proteases
myeloperoxidase
What do secondary neutrophil granules contain?
- lysozyme
- collegenase
lactoferrin
How exactly do neutrophils destroy bacteria? Dependent on?
- phagosome fuse with granules to destroy internalised bacteria
oxygen dependent respiratory burst
What are psuedopodia?
Finger like projections encapsulating apoptotic cells in macrophages
What are macrophages activated by? What do they develop from?
Inflammation
Precursors in tissues
What is the difference between innate and adaptive immunity?
Innate: always present, ready to attack
Adaptive: stimulated by exposure to microbe, more potent
Function of lymph nodes?
Initiates immune response
Antigen arrives via lymph and communicate with naive b and t cells
What is the humoral immune response?
Antibodies from B cells target foreign cells
What is the cell mediated immune response?
T cells attack and kill other cells
Why is clonal selection theory necessary?
To remove self reactive t cells that may cause autoimmunity
Describe cloncal selection theory
A single progenitor cell gives rise to large number of lymphocytes with different specificities
Removal of potentially self reactive immature lymphocytes by clona detecion in primary lymphoid organs
Mature naive lymhocytes are circulated to secondary lymphoid organs
Proliferation of activated specific lymphocytes forms clones of effector cells - by antigen in secondary lymphoid organs
What are the first defences to infection?
epithelium
mucus
cilia
defensins
What is complement?
A cascade of proteins in serum which amplifies the inflammatory response - forms complex which is inserted into wall of bacteria to kill them
What are the triggers and results of complement?
Triggered by antibodies or pathogen surfaces
Can recruit inflammatory cells, opsonize pathogens or kill pathogens
What is opsonization of pathogens?
Making the bacteria more susceptible to be phagocytosed by making it sticky
Which part of antibodies binds antigens?
The v/varible region at the end of the antibody
Which part of the antibody binds cells?
The bottom c/constant section
What are the things antibodies recognise called?
Epitopes
What makes antibodies able to bind to things easily?
Sticky and specific
What do antibodies do?
Agglutination: clump bacteria together to enhance phagocytosis by decreasing units to deal with
Opsonization: coating antigen with antibody enhances phagocytosis
Activates complement
What are functions of helper T cells?
Produce cytokines to direct the immune response by recognising antigen presented in MHC II on surface of APCs
What is the function of cytotoxic t cells?
Kill infected cells by recognising antigen presented in MHC I on many cells
Which surface molecules are on each T cell?
Helper: CD4
Killer: CD8
What is anamnesis?
Secondary enhanced response to antigen that the body has previously ancountered
What happens in immunological memory?
More cells ready to respond
Cells easier to activate
Cells more efficient
How is ebola transmitted?
bodily fluid e.g. sweat, kissing, hugging
Which infection can cause microcephaly?
zika virus
how is monkeypox transmitted? symptoms?
bodily fluids/close contact
fever, malaise, then rahs
what does malaria look like in RBCs?
circles or like plasmids
when does malaria virus cause fever?
when they erupt in RBCs
what happens when you have cerebral malaria?
death
how is elephantitis, yellow fever, dengue, zika and west nile virus transmitted?
mosquitoes
which infection is transmitted by fleas?
plague
what infection is transmitted by sandflies?
leishmaniasis
which disease is transmitted by tsetse flies?
african trypsomanisis
which diseases are transmitted by ticks?
relapsing fever
lyme disease
how do kissing bugs cause disease?
feeds fron your lips
defecates on you
parasites enter cells causing chronic intestinal problems
how is cholera transmitted?
contaminated water
name some water borne disease
salmonella
e coli
shigella
enterovirus
which drug is used against schistosomiasis?
praziquantel
how to prevent cholera?
purify and boil water
filter water
use bottled water
avoid salad washed in water
which 3 signals do t cells require to activate?
antigen presented in the context of MHC
surface molecule costimulation
cytokines
function of baterial capsule?
allows it to avoid phagocytosis
function of pilli on bacteria?
allows attachemnt to host cells to transfer genetic material
how do bacterial infections occur?
- bacteria enter via portal of entry
- pill stick to host cells
- adhesins on pilli bind to specific receptors on host cells
- bacteria produce toxins to kill immune cells
- leave through feces, coughing etc.
Which cells present MHC II?
dendritic cells
macrophages
B cells
what is the first antibody produced in response to infection?
IgM
Which cells present MHC I?
all nucleated cells
