Immune and Lymphatic System Flashcards
(210 cards)
1
Q
Why is normal flora important?
A
Protection from pathogen colonisation (competition with other microorganisms)
Development of immune function (helps to balance between immune system firing and dampening it down - hygiene hypothesis)
Nutritional capability - eg provision of vitamins and amino acids (important in vitamin k production)
2
Q
What are the normal flora bacteria found at the nose?
A
Staph. aureus
Staph. epidermidis
diptheroids
streptococci
3
Q
What are the normal flora bacteria found on the teeth?
A
Streptococcus mutans Bacteroides Fusobacterium streptococci Actinomyces
4
Q
What are the normal flora bacteria found at the mouth?
A
Strep. mitis and other streptococci
Trichomonas tenax
Candida
5
Q
What are the normal flora bacteria found at the throat?
A
Strep. viridans Strep. pyogenes Strep. pneumoniae Neisseria spp. Staphylococcus epidermidis Haemophilus influenzae
6
Q
What are the normal flora bacteria found in the lungs?
A
Pneumocystis carinii
7
Q
What are the normal flora bacteria found on the skin?
A
Staph. epidermis Staph. aureus Diptherioids Streptococci Psuedomonas aeruginosa anaerobes, Candida Torulopsis Pityrosporum
8
Q
What are the normal flora bacteria found in the urethra and vagina?
A
Staphylococcus epidermidis
diptherioids
streptococci
Gram negative rods
9
Q
Name some structural properties of bacteria
A
Cell membrane Cell wall Slime layer or capsule Plasmids 70s Ribosomes Flagella - movement Pilli - attachment to host cells
10
Q
Which type of bacteria have a thick pepeptidoglycan layer?
A
Gram positive
11
Q
What colour do gram negative bacteria stain?
A
Blue/ purple
12
Q
What colour do gram positive bacteria stain?
A
Red/ pink
13
Q
What is the process of application of chemicals to produce a gram stain?
A
Fixation –> Crystal violet –> iodine treatment –> Decolourisation –> counter stain (safronin)
14
Q
Give an example of gram positive cocci bacteria
A
Streptococcus spp.
Staphylococcus spp.
15
Q
Give an example of gram positive rod bacteria
A
Clostridium spp.
16
Q
Give an example of gram negative cocci bacteria
A
Neisseria spp.
17
Q
Give an example of gram negative rod bacteria
A
Bacteroides spp.
Escherichia spp.
18
Q
What is the purpose of bacterial spore formation?
A
Formed when conditions aren’t favourable, they’re a dormant phase with little or no metabolic activity. Ensures bacterial survival.
19
Q
Give some properties and examples of yeast fungi
A
Small and smooth
eg candida - athletes foot
trichophyton rubrum
20
Q
Give some properties and examples of mould fungi
A
Mycelial growth
eg aspergillus - respiratory infection
21
Q
How are fungal infections classified?
A
According to site of infection
22
Q
How are cutaneous fungal infections spread?
A
Direct contact
Common - eg athletes foot and ringworm
23
Q
How are subcutaneous fungal infections spread?
A
Puncture wounds/ trauma
These are rare
24
Q
How are systemic fungal infections spread?
A
Inhalation then spread
Rare but serious
eg aspergillosis
25
Which type of patients are opportunistic fungal infections most likely to manifest in?
Immunocompromised patients
These are rare but serious
eg candida, cryptococcus infection
26
What are the properties of protozoa and metazoa?
Eucaryotic - single celled or multi celled
DNA inside the nucleus
Organelles eg mitochondria, ER, golgi
Cell membrane
Sometimes an outer wall
Complex life cycles - may involve different hosts
Well developed sexual reproduction
Metabolic processes closer to human processes
27
What property are protozoa classified by?
Classified by the way they move:
Amoebae
Flagellates
Sporozoa
28
Give an example of an amoebae (protozoa)
Entamoeba
29
Give an example of a flagellate (protozoa)
Giardia
30
Give an example of a Sporozoa (protozoa)
Cryptosporidium
31
What property are metazoa classified by?
Classified by their shape:
Round worms - nematodes
Tape worms - cestodes
Flukes - trematodes
32
Give an example of a roundworm/ nematode (metazoa)
Ascaris
33
Give an example of a tape worm/ cestode (metazoa)
Taenia
34
Give an example of a fluke/ trematode (metazoa)
Schistosoma
35
What comprises a typical virus structure?
Nucleic acid
Protein coat - capsid
some have lipid envelope - usually originates from host cell
Viral proteins inserted
36
What is a nucleocapsid?
Nucleic acid + protein coat (capsid)
37
Where are lymphatic capillaries found?
Around the blood vessels
38
Where are lacteals found and what do they contain?
Found in the small intestine
Contain dietary fats and proteins
39
What are the constituent structures of the lymphatic system?
```
Red bone marrows
Thymus
Lymph nodes
Spleen
Tonsils
Lymph Nodules (MALT, GALT etc)
```
40
Define primary lymphatic organs/ tissues
Sites where lymphocytes are produced, mature and become capable of immune response (immunocompetent)
eg Red bone marrow and thymus
41
Give some examples of primary lymphatic organs/ tissue. What are their functions?
Red bone marrows - site of T and B cell production and B cell maturation
Thymus - site of T cell maturation
42
Define secondary lymphatic organs/ tissue
Sites where most immune (adaptive) responses occur or develop.
43
Give some examples of secondary lymphatic organs/ tissue.
Lymph nodes
Spleen
Tonsils
Lymph nodules in the GIT, respiratory and reproductive systems (MALT, GALT etc)
44
What is lymph?
Usually clear watery and slightly yellow interstitial (intercellular/extracellular) fluid
Made of tissue fluid, plasma proteins, bacteria, cellular debris and lymphocytes - similar in composition to blood plasma.
45
What are the 4 cel types found in the lymphatic system?
Macrophages
Epithelial cells
Dendritic cells
Lymphocytes
46
What mechanisms aid the flow of lymph around the body?
skeletal muscle and respiratory pumps
47
What is the order of flow within the subdivisions of lymphatic vessels?
Lymphatic capillaries --> Lymph vessels --> Lymph nodes --> Lymph trunks --> Lymphatic Ducts --> Venous Blood
48
Name the two lymphatic ducts
Right lymphatic duct
| Left (thoracic) lymphatic duct
49
Name the five lymphatic trunks
```
Jugular lymphatic trunk
Subclavian lymphatic trunk
Bronchomediastinal lymphatic trunk
Lumbar lymphatic trunk
Intestinal lymphatic trunk
```
50
Where does the right lymphatic duct drain from?
Drains lymph from the right jugular, right bronchomediastinal and right subclavian trunks
Right duct just drains right arm and upper body
51
Where does the left lymphatic (thoracic) duct drain from?
Starts from the cisterna chyli and drains lymph from the right and left lumbar and intestinal, left jugular, left subclavian and left bronchomediastinal trunks
Thoracic duct drains 3/4 of body
52
What are venous angles?
Where the lymphatic ducts in most cases return lymph into the venous circulation.
53
What spinal level is the cisterna chyli located at?
between the level of T12 and L2
54
What are the difference between superficial and deep lymph vessels?
Lymphatic vessels described as superficial and deep depending on their location in the body.
Superficial lymph vessels are more numerous than subcutaneous veins and drain into the deep lymphatic vessels
The deep lymphatic vessels accompany the arteries
55
How do lymphatic vessels communicate with veins?
Via anastomoses
56
What are the 7 major groups of lymphatic nodes and where are they located?
Pericranial ring - base f head
Cervical nodes - along course of internal jugular vein
Tracheal nodes - nodes related to trachea and bronchi
Axillary nodes - in axilla
Deep nodes - related to aorta and celiac trunk and superior and inferior mesenteric arteries
Inguinal nodes - along the course of the inguinal ligament
Femoral nodes - along femoral vein
57
What lymph vessels are involved in drainage of the face and scalp?
Mostly to the pericervical (pericranial) collar of superficial lymph nodes – submental, submandibular, parotid, mastoid and occipital.
Then finally to the deep cervical lymph nodes which lie along the internal jugular vein.
58
What lymph vessels are involved in drainage of the anterio-lateral abdominal wall?
Superficial vessels above the Transumbilical plane drain mainly to the Axillary lymph nodes and a few to the parasternal lymph nodes.
Superficial lymphatic vessels below the Transumbilical plane drain to the superficial inguinal lymph nodes.
The deep lymphatic vessels drain to the external iliac, common iliac, and right and left lumbar (caval and aortic) lymph nodes.
59
How many lobes does the thymus have?
Two, with a fibrous connective tissue capsule
60
Where is the thymus located?
Extends from the superior to the anterior mediastinum and lies between the sternum and the great vessels
61
What is the spleen composed of?
Outer capsule and the stroma
Parenchyma:
White pulp - lymphatic tissue
Red pulp - blood filled venous sinuses
62
Give four functions of the spleen
Immune mediated response
Degradation of red blood cells
Haematopoesis in foetal life
Storage of blood
63
What comprises a lymph node?
Several afferent vessels, one or two efferent vessels
Fibrous capsular
covering
Capsular trabeculae
Cortex, containing T cells
Medulla, containing B cells and anti-body producing plasma cells from the cortex.
Lymphatic sinuses.
64
What are the two main viral structure types?
naked nucleocapsid and enveloped virus
65
How do viruses store genetic information?
Nucleic acids in the form of DS or SS RNA or DNA
66
What properties are viruses classified according to?
Size
Morphology
Type of nucleic acid in the genome
How they produce mRNA
67
In what form is the genetic material found in class I viruses?
Give an example of a class I virus.
dsDNA
Human papilloma virus
Herpes simplex
68
In what form is the genetic material found in class II viruses?
Give an example of a class II virus.
ssDNA
Parvouviri
69
In what form is the genetic material found in class III viruses?
Give an example of a class III virus.
dsRNA
Rotavirus
70
In what form is the genetic material found in class IV viruses?
Give an example of a class IV virus.
ssRNA (+)
SARS
71
In what form is the genetic material found in class V viruses?
Give an example of a class V virus.
ssRNA (-)
Influenza
Ebola
72
In what form is the genetic material found in class VI viruses?
Give an example of a class VI virus.
ssRNA (+) diploid
HIV
73
In what form is the genetic material found in class VII viruses?
Give an example of a class VII virus.
Gapped dsDNA
Hepatitis B
74
What is the mode of RNA production on class I viruses?
ds DNA virus - mRNA transcribed directly from DNA template
75
What is the mode of RNA production on class II viruses?
ssDNA virus - DNA converted to ds form before RNA transcribed
76
What is the mode of RNA production on class III viruses?
dsRNA virus - mRNA transcribed from RNA genome
77
What is the mode of RNA production on class IV viruses?
ssRNA (+) virus - genome functions as mRNA
78
What is the mode of RNA production on class V viruses?
ssRNA (-) virus - mRNA transcribed from RNA genome
79
What is the mode of RNA production on class VI viruses?
ssRNA (+) diploid virus - Reverse transcriptase makes DNA from RNA genome.
DNA then incorporated into the host genome.
mRNA transcribed from incorporated DNA.
(Think HIV.)
80
What is the mode of RNA production on class VII viruses?
Gapped dsDNA virus - viral genome is dsDNA, but viral DNA replicated through RNA intermediate
81
What does Saquinavir (antiviral) target?
Protein synthesis (an HIV protease inhibitor)
Used for HIV infection in combination with other antiretrovirals.
82
What does Acyclovir (antiviral) target?
Nucleoside analogue.
Used as a systemic and topic treatment for herpes simplex.
Systemic treatment for varicella zooster.
Does not eradicate the virus.
83
What is the molecular basis of the mechanism behind Saquinavir (antiviral)?
In HIV, mRNA is translated into inert polyproteins. A viral protease then cleaves the polyproteins into functional proteins during budding of the virus from the host cell. HIV protease inhibitors prevent this step.
84
What is the molecular basis of the mechanism behind Acyclovir (antiviral)?
A 'prodrug', which is phosphorylated to acyclovir monophosphate by thymadine kinase (viral enzyme). Further phosphorylated by cellular kinases to acylovir triphosphate, which competes for viral DNA polymerase, becomes incorporated into the growing viral DNA chain and terminates it.
85
What does Amantadine (antiviral) target?
Viral uncoating.
Licensed for prophylaxis and treatment of influenza A.
86
What is the molecular basis of the mechanism behind Amantadine (antiviral)?
Blocks ion channel which is formed by a membrane protein (M2) of influenza A, thus preventing viral uncoating within host cell.
87
What are the physical barriers of the body to prevent infection?
```
Skin
Cilia (respiratory and gut linings)
Hair
Mucosal surfaces (GI mucosal, respiratory tract)
Flushing action - urine and tears
Peristalsis
```
88
How doe the gut architecture help the body overcome infection?
Lumen (villi) which increase surface area of the gut
Within lumen we have goblet cells (mucous secreting) - mucous lines gut & contains secretory proteins and immune cells which help fight infection.
Villi themselves also contain immune cells
89
What are the chemical barriers the body has against infection?
Lysozyme in tears and other secretions
Removal f particles by cillia in nasopharynx
Mucus lining in trachea
Skin surface (physical barrier), fatty acids, normal flora
Stomach (pH2)
Normal flora in gut
Flushing of urinary tract
90
What are the 3 lines of body defence in order?
1st line: Skin, mucous membranes, chemicals
2nd line: Innate - Phagocytosis, complement, interferon, inflammation, fever
3rd line: Adaptive - Lymphocytes, antibodies
91
What cells are considered to be granulocytes?
Neutrophil
Basophil
Eosinophil
Mast cells
92
What are the properties of red bone marrow?
Highly vascularised connective tissue
Primary site of haematopoesis
Present in bones of axial skeleton, pectoral and pelvic girdles, proximal epiphysis of humorous and femur (in adults)
0.05-0.1% of cells are pluripotent stem cells
93
What are the properties of erythrocytes?
Red blood cells
contain haemoglobin
biconcave discs with no nucleus to maximise O2 carrying capacity
Life expectancy = 120 days
94
Which cell types are capable of antigen presentation?
Macrophages, dendritic cells and B lymphocytes
95
What cell lineage gives rise to cells of the adaptive immune system?
Lymphoid lineage
96
What cell lineage gives rise to cells of the innate immune system?
Myeloid lineage
97
Which cells are termed innate cells but are actually part of the lymphoid lineage?
Why are they termed innate?
Natural killer cells
Because they don't require specific recognition to become activated
98
Within what time frame is the innate immune system activated post infection?
0-12 hours
99
Within what time frame is the adaptive immune system activated post infection?
After 12-24hrs, up to 7 days
100
What is released when mast cells degranulate? What are the overall effects of this?
Contains histamine, heparin, proteases
Cytokines, chemokines and growth factors
Lipid mediators eg prostaglandins
Recruits other immune cells, up regulates phagocytosis and promotes tissue repair and vascular permeability increases, causing leaky blood vessels.
101
What are the visual signs of inflammation?
```
Rubor - Heat
Calor - Redness
Tumor - Swelling
Dolor - Pain
Loss of function
```
102
What are dendritic cells under the skin called?
Langerhan cells
103
What is the role of dendritic cells?
Professional antigen presenting cells
Pick up antigens in tissue and travel to local lymph, present part of pathogen to T cells, triggering the adaptive response.
104
What are the properties of neutrophils?
Recruited within minutes via chemotaxis
Phagocytic can engulf pathogen
Kill via respiratory burst
105
How does chemotaxis work?
Chemokines released at site of infection
| Inflammatory cells eg neutrophils follow chemotactic gradient towards infection site.
106
What physical property of neutrophils make them easily identifiable under a microscope?
They have a multi lobed nucleus (three)
107
What are p selectin and e selectin?
Adhesion molecules
108
What is the respiratory burst?
Production of ROS and free radicals eg superoxide which break down pathogen within the cell once it has been phagocytosed
109
What cell types do monocytes differentiate into?
Macrophages
110
How do natural killer cells kill?
Death receptor signalling - binding of death receptor and death receptor ligand causes cell degranulation which causes apoptosis
Release of cytokines such as IFN-g which stimulate macrophages to engulf and kill infected cell
111
What conditions/ diseases are basophils most commonly recruited against?
Allergy/ atopy
Resistance to internal parasites eg helminths and ticks
112
What conditions/ diseases are eosinophils most commonly recruited against?
Allergic disease and helminth infections
113
What colour do basophils appear under the microscope and why?
Purple because they take up basic dye
114
What colour do eosinophils appear under the microscope and why?
Pink because they take up acidic dye (eosin)
115
What do innate cells use to recognise pathogens?
PAMPs (recognised by PRRs)
116
What elements of a bacterial cell can be recognised as PAMPs?
```
Peptidoglycan
Lipoprotein
Lipoteichoic acid
LPS
Flagellin
Sugars eg mannose
DNA
```
117
What elements of a viral cell can be recognised as PAMPs?
Envelope proteins
DNA
RNA
118
What are TLRs?
Toll like receptors
A type of pattern recognition receptor (PRR)
119
What does TLR-4 recognise?
LPS
120
What is CRP?
C reactive protein
An acute phase protein, produced by the liver in response to infection.
It activates other parts of the immune system, acts as an opsonin and signalling molecule.
Measure as a marker for inflammation
121
In what diseases is CRP measured in order to monitor progression and flare ups?
Rheumatoid arthritis
Vasculitides
Ankylosing spondylitis
Acute pancreatitis
122
What do interferons do?
Type of cytokine that are important in preventing viral infections from spreading between cells
123
Which cytokines are important for activating a t cell mediated response?
IL-12
IL-2
IFN-g
TNF-a
124
Which cytokines are important for activating a humoral response (antibody production)?
IL-4
IL-5
IL-13
125
Which are the key anti inflammatory cytokines?
IL-10
| TGF-b
126
Where are T lymphocytes produced?
Bone marrow
127
Where do T lymphocytes mature?
Thymus
128
Where are T lymphocytes activated?
Lymph node
129
How do T cells undergo central tolerance?
1. Thymus cortex - positive selection: Challenge with MHC and see if they recognise it, if they don't then they will undergo apoptosis.
2. Thymus medulla - negative selection: self peptides and proteins presented to T cells. If they react with self antigens then T cell is apoptosed.
If T cells pass both of these steps they are released to reside in local lymph.
130
What are the two possible classes of T cells?
CD4+ T helper cells
| CD8+ Cytotoxic/ killer cells
131
How are T helper cells activated?
Dendritic cells presents antigen on MHCII which binds TcR on Naive CD4+.
B7 binds CD28 (costimulatory pair).
IL-2 released by Naive CD4+ to help activate T cell.
Clonal expansion of activated T helper cell occurs.
132
Exposure to which cytokine causes naive T cells to become Th1 CD4+ T helper cells?
IL-12
133
Exposure to which cytokine causes naive T cells to become Th2 CD4+ T helper cells?
IL-4
134
Exposure to which cytokine causes naive T cells to become Th17 CD4+ T helper cells?
IL-1b
| IL-6
135
Exposure to which cytokine causes naive T cells to become Treg CD4+ T helper cells?
TGF-b
| IL-10
136
What are Th1 CD4+ T helper cells effective at fighting?
Intracellular bacteria and viruses - cause a cell mediated immune response
137
What are the downstream effects of activating Th1 CD4+ T helper cells?
They release IFN-g and IL-2 to stimulate macrophages, CD8+ and NK cells and cause B cells to become plasma cells.
138
What are Th2 CD4+ T helper cells effective at fighting?
Extracellular bacteria, fungi or parasites - Humoral mediated response
139
What are the downstream effects of activating Th2 CD4+ T helper cells?
They release IL-4, IL-13, IL-3, IL-5, IL-2 and IL-9. This causes naive B cells to
become plasma cells and produce antibodies, macrophages are activated, as well as eosinophils and basophils.
140
What are Th17 CD4+ T helper cells effective at fighting?
Defence against bacteria and fungi particularly in mucosal environments
141
Are Th17 cells pro-inflammatory or anti-inflammatory?
Pro-inflammatory
142
What are the downstream effects of activating Th17 CD4+ T helper cells?
IL-17 release promoting inflammatory mediators, as well as recruitment and increased production of neutrophils
143
What are the downstream effects of activating Treg cells?
Down-regulate Th1 and Th2 cells - the 'off' switch.
Release anti inflammatory cytokines eg IL-10 and TGF-b, inhibiting ongoing responses.
144
How are CD8+ T cells activated?
Dendritic cell expresses antigen on MHCI to CD8+ TCR.
| Clonal expansion of activated CD8+ T cell.
145
How do cytotoxic CD8+ T killer cells kill infected cells?
Death receptor signal - Fas/FasL binding
Perforin and granzyme - punch holes in the cell membrane and cause apoptosis
146
Where are B cells produced?
Bone marrow
147
Where do B cells reside and mature?
Bone marrow
148
How does B cell tolerance work?
Challenged with self peptides in the bone marrow.
If they don't recognise these they are released into periphery and travel to lymph nodes.
If they are self reactive, they undergo receptor editing and are challenged again.
If they continue to recognise self tissue they undergo apopotsis.
149
How are B cells activated?
B cells present antigen on MHCII which bind TCR on activated CD4+ T cell. CD40/CD40L bind as costimulatory pairs.
Cytokine (IL-4, IL-6, IL-10) release from T cell causes B cell activation.
Clonal expansion of activated B cell.
Differentiation either into plasma cells to produce antibodies or memory B cells which reside in the lymph until future infection encountered.
150
What process allows plasma cells to produce different types of antibodies?
Isotype/ class switching
151
What is the first antibody subset produced by plasma B cells?
IgM
152
What are the names of the different sub classes of antibodies?
IgM, IgG, IgA, IgE, IgD
153
What shape is IgM?
Pentameric
154
What shape is IgA?
Dimeric with a J chain and secretory component
155
What shape is IgG?
Monomeric
156
What shape is IgE?
Monomeric
157
What type of infection is IgE usually produced for?
Parasitic infections and allergy
158
What are the properties and functions of IgM?
First Ab produced
High valency
Can activate complement
Can neutralise toxins
159
What are the properties and functions of IgG?
```
Opsonisation
Neutralisation
Activates complement
Ab with the highest affinity
Most abundant Ab
Important in ADCC
```
160
What are the properties and functions of IgA?
The secretory Ab
Found at mucosal linings
Main function is neutralising
Second most abundant Ab
161
What are the properties and functions of IgE?
The largest antibody (size)
Useful for parasitic infections
Associated with allergic responses
Binds to mast cells and eosinophils, where cross linking of antibodies causes cell to degranulate
162
How does ADCC work?
Antibody dependant cellular cytotoxicity.
Ab eg IgG binds to the infected target cell.
Fc region of Ab binds FcR on NK cell.
This causes perforin and granzyme release, and triggers cell apoptosis.
163
What are the different types of immunity that can be acquired? Give an example for each.
Natural passive - breast milk passing IgG or IgA from mother to baby
Artificial passive - directly inject Igs into patient eg anti venoms
Natural active - encounter the pathogen and have an immune response which leads to immune memory
Artificial active - vaccinations, where a part/ killed pathogen delivered so patient elicits own immune response creating immune memory
164
Define infection
Invasion and multiplication of microbes in the hosts tissues that lead to cellular injury as a result of: their multiplication, production of toxins, immune response or competition in metabolism.
165
What is a protist?
a eukaryote that is not an animal, plant, fungi.
166
What is a protozoa?
a protist that is not photosynethetic.
167
What is a local infection?
Confined to a small area of the body near the site of entry.
eg Hair follicle infected by Staphylococcus or a pneumonia confined to the lungs.
168
What is a focal infection?
A pathogen spreads to a secondary location
| eg Gum infected by Streptococcus that gains access to the bloodstream and causes a secondary infection elsewhere.
169
What is a systemic infection?
A pathogen is disseminated throughout the body
| eg Varicella-zoster virus enters through the respiratory system and spreads throughout the body resulting in a rash
170
Define pathogen
A microorganism that can cause disease
171
Define pathogenicity
The ability of an organism to cause disease
172
Define virulence
The degree of disease caused by an organism
173
Define virulence factors
The molecules produced by the organism that add to their effectiveness in replicating within the host
174
What is the ID50?
The number of bacterial, protozoal cells or virions required to cause active infection in 50% of inoculated animals.
175
Give two examples of clinically significant spore forming organisms
Clostridium and Bacillus
176
What is the process of biofilm formation?
1. attachment to surface
2. formation of monolayer and production of matrix
3. microcolony formation - multi layer
Mature biofilm, with characteristic 'mushroom' formed of polysaccharide
5. detachment and reversion to planktonic growth, starting a new cycle
177
What are exotoxins? Give an example
Proteins coded for by the bacteria: released when the microbe is alive. Often target specific receptors to selectively target cells
eg Clostridium botulinum toxin
178
What are endotoxins? Give an example
Integral part of the bacterial cell wall: released only if the microbe is destroyed
Eg Cholera
179
What is the mechanism of the diseases causing exotoxin in cholera?
Activation of adenylate cyclase in intestinal cells
Increased levels of cAMP and secretion of fluids and electrolytes out of the cell, causing diarrhoea
Opens chlorine ion channels
Inhibits sodium uptake
Cholera toxin phage (CTX phage), which carries the cholera toxin gene and other virulence factors
180
What does toxic shock syndrome do?
Involves the production of superantigens.
Stimulate T cells non-specifically without normal antigenic recognition.
Cross link MHCII on APCs an TCR.
181
What is the clinical effect of endotoxins?
Shock
Low conc: produce inflammatory response that is an effective defence
High conc: produces excessive iinflammatory response (cytokine storm) - sever drop in BP, multiple organ failure
182
How do Staphylococcus aureus, Streptococcus pyogenes, and Clostridium perfringens invade tissues?
produce hyaluronidase that degrades hyaluronic acid – open the cell junctions between connective tissue cells
183
Which bacteria use a capsule to evade recognition by host?
Neisseria meningitidis
Haemophilus influenzae
Streptococcus pneumoniae
184
How do capsules allow bacteria to evade host recognition?
Masks immunogenic antigens
Impairs complement pathways
Impairs opsonisation
Reduces phagocytosis
185
How do Neisseria meningitidis, Streptococcus pneumonia and Haemophilus influenzae evade host recognition?
Produce protease enzymes that break down IgA allowing them to invade mucosal surfaces
186
What are the ways in which bacteria or viruses can survive in the host?
Body armour - capsule
Fight - survive once captured
Biofilms
Antigenic variation
187
How does antigenic variation allow survival within the host?
Viral mutation (antigenic shift or drift) allows rapid changes in appearance displaying different surface antigens. A range of bacteria and protists are also capable of doing this such as Plasmodium (malaria parasite)
188
What is always the first immune cell thats drawn in to the site of infection?
Neutrophils
189
Production and binding of what cytokine causes production of CRP at the liver?
IL-6
190
What are the two main types of inflammation?
Acute and chronic
191
What is the duration of acute inflammation?
Less than 3 weeks
192
What is the duration of chronic inflammation?
Greater than 6 weeks
193
What are the features of acute inflammation?
Injury not necessarily associated with tissue destruction
Neutrophils often recruited in large numbers
Variable systemic effects, often minor
194
What are the features of chronic inflammation?
Significant tissue destruction typically a prominent feature
Macrophages, lymphocytes and their derivatives characteristically predominate
Systemic manifestations often prominent
195
What triggers a favour response?
Production of acute phase proteins by the liver eg CRP
196
What is virulence?
How pathogenic something is.
197
What is a pathogen?
Microorganism that causes disease.
198
What is infection?
Problem caused by a pathogen.
199
What is commensalism?
Part of normal flora.
200
What is a microbiome?
Community or microorganisms.
201
What is colonisation?
Microorganisms in or on the body that don't cause problems.
202
What is contamination?
Contamination is the action of something becoming unsterile which could cause harm
203
What is normal flora?
Microorganisms normally found in a body site.
204
What is subclinical infection?
Infection that does not cause symptoms e.g. influenza.
205
What does latent mean?
An inactive and persistent infection and may react intermittently e.g. VSV.
206
What are the 5 main types of pathogen?
```
Bacteria
Fungi
Viruses
Parisites
Prions
```
207
What shape are cocci bacteria?
Round
208
What shape are bacilli bacteria?
Rod shaped
209
What shape are spirachaotes?
Spiral
210
What is the composition of blood?
55% is blood plasma which contains water, solutes, proteins and hormones.
45% is red blood cells.
Under 1% is white blood cells and platelets.
