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Medicine Year 1 > Immune and Lymphatic System > Flashcards

Immune and Lymphatic System Flashcards

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)

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2
Q

What are the normal flora bacteria found at the nose?

A

Staph. aureus
Staph. epidermidis
diptheroids
streptococci

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3
Q

What are the normal flora bacteria found on the teeth?

A 
Streptococcus mutans
Bacteroides
Fusobacterium
streptococci
Actinomyces
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4
Q

What are the normal flora bacteria found at the mouth?

A

Strep. mitis and other streptococci
Trichomonas tenax
Candida

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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
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6
Q

What are the normal flora bacteria found in the lungs?

A

Pneumocystis carinii

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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
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8
Q

What are the normal flora bacteria found in the urethra and vagina?

A

Staphylococcus epidermidis
diptherioids
streptococci
Gram negative rods

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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
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10
Q

Which type of bacteria have a thick pepeptidoglycan layer?

A

Gram positive

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11
Q

What colour do gram negative bacteria stain?

A

Blue/ purple

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12
Q

What colour do gram positive bacteria stain?

A

Red/ pink

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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)

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14
Q

Give an example of gram positive cocci bacteria

A

Streptococcus spp.

Staphylococcus spp.

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15
Q

Give an example of gram positive rod bacteria

A

Clostridium spp.

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16
Q

Give an example of gram negative cocci bacteria

A

Neisseria spp.

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17
Q

Give an example of gram negative rod bacteria

A

Bacteroides spp.

Escherichia spp.

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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.

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19
Q

Give some properties and examples of yeast fungi

A

Small and smooth
eg candida - athletes foot
trichophyton rubrum

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20
Q

Give some properties and examples of mould fungi

A

Mycelial growth

eg aspergillus - respiratory infection

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21
Q

How are fungal infections classified?

A

According to site of infection

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22
Q

How are cutaneous fungal infections spread?

A

Direct contact

Common - eg athletes foot and ringworm

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23
Q

How are subcutaneous fungal infections spread?

A

Puncture wounds/ trauma

These are rare

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24
Q

How are systemic fungal infections spread?

A

Inhalation then spread

Rare but serious
eg aspergillosis

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25
Q

Which type of patients are opportunistic fungal infections most likely to manifest in?

A

Immunocompromised patients

These are rare but serious
eg candida, cryptococcus infection

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26
Q

What are the properties of protozoa and metazoa?

A

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

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27
Q

What property are protozoa classified by?

A

Classified by the way they move:
Amoebae
Flagellates
Sporozoa

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28
Q

Give an example of an amoebae (protozoa)

A

Entamoeba

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29
Q

Give an example of a flagellate (protozoa)

A

Giardia

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30
Q

Give an example of a Sporozoa (protozoa)

A

Cryptosporidium

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31
Q

What property are metazoa classified by?

A

Classified by their shape:
Round worms - nematodes
Tape worms - cestodes
Flukes - trematodes

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32
Q

Give an example of a roundworm/ nematode (metazoa)

A

Ascaris

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33
Q

Give an example of a tape worm/ cestode (metazoa)

A

Taenia

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34
Q

Give an example of a fluke/ trematode (metazoa)

A

Schistosoma

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35
Q

What comprises a typical virus structure?

A

Nucleic acid
Protein coat - capsid
some have lipid envelope - usually originates from host cell
Viral proteins inserted

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36
Q

What is a nucleocapsid?

A

Nucleic acid + protein coat (capsid)

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37
Q

Where are lymphatic capillaries found?

A

Around the blood vessels

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38
Q

Where are lacteals found and what do they contain?

A

Found in the small intestine

Contain dietary fats and proteins

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39
Q

What are the constituent structures of the lymphatic system?

A 
Red bone marrows
Thymus
Lymph nodes
Spleen
Tonsils
Lymph Nodules (MALT, GALT etc)
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40
Q

Define primary lymphatic organs/ tissues

A

Sites where lymphocytes are produced, mature and become capable of immune response (immunocompetent)

eg Red bone marrow and thymus

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41
Q

Give some examples of primary lymphatic organs/ tissue. What are their functions?

A

Red bone marrows - site of T and B cell production and B cell maturation

Thymus - site of T cell maturation

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42
Q

Define secondary lymphatic organs/ tissue

A

Sites where most immune (adaptive) responses occur or develop.

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43
Q

Give some examples of secondary lymphatic organs/ tissue.

A

Lymph nodes
Spleen
Tonsils
Lymph nodules in the GIT, respiratory and reproductive systems (MALT, GALT etc)

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44
Q

What is lymph?

A

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.

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45
Q

What are the 4 cel types found in the lymphatic system?

A

Macrophages
Epithelial cells
Dendritic cells
Lymphocytes

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46
Q

What mechanisms aid the flow of lymph around the body?

A

skeletal muscle and respiratory pumps

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47
Q

What is the order of flow within the subdivisions of lymphatic vessels?

A

Lymphatic capillaries –> Lymph vessels –> Lymph nodes –> Lymph trunks –> Lymphatic Ducts –> Venous Blood

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48
Q

Name the two lymphatic ducts

A

Right lymphatic duct

Left (thoracic) lymphatic duct

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49
Q

Name the five lymphatic trunks

A 
Jugular lymphatic trunk
Subclavian lymphatic trunk
Bronchomediastinal lymphatic trunk
Lumbar lymphatic trunk
Intestinal lymphatic trunk
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50
Q

Where does the right lymphatic duct drain from?

A

Drains lymph from the right jugular, right bronchomediastinal and right subclavian trunks

Right duct just drains right arm and upper body

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51
Q

Where does the left lymphatic (thoracic) duct drain from?

A

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

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52
Q

What are venous angles?

A

Where the lymphatic ducts in most cases return lymph into the venous circulation.

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53
Q

What spinal level is the cisterna chyli located at?

A

between the level of T12 and L2

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54
Q

What are the difference between superficial and deep lymph vessels?

A

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

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55
Q

How do lymphatic vessels communicate with veins?

A

Via anastomoses

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56
Q

What are the 7 major groups of lymphatic nodes and where are they located?

A

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

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57
Q

What lymph vessels are involved in drainage of the face and scalp?

A

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.

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58
Q

What lymph vessels are involved in drainage of the anterio-lateral abdominal wall?

A

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.

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59
Q

How many lobes does the thymus have?

A

Two, with a fibrous connective tissue capsule

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60
Q

Where is the thymus located?

A

Extends from the superior to the anterior mediastinum and lies between the sternum and the great vessels

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61
Q

What is the spleen composed of?

A

Outer capsule and the stroma

Parenchyma:
White pulp - lymphatic tissue
Red pulp - blood filled venous sinuses

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62
Q

Give four functions of the spleen

A

Immune mediated response

Degradation of red blood cells

Haematopoesis in foetal life

Storage of blood

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63
Q

What comprises a lymph node?

A

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.

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64
Q

What are the two main viral structure types?

A

naked nucleocapsid and enveloped virus

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65
Q

How do viruses store genetic information?

A

Nucleic acids in the form of DS or SS RNA or DNA

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66
Q

What properties are viruses classified according to?

A

Size
Morphology
Type of nucleic acid in the genome
How they produce mRNA

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67
Q

In what form is the genetic material found in class I viruses?

Give an example of a class I virus.

A

dsDNA

Human papilloma virus
Herpes simplex

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68
Q

In what form is the genetic material found in class II viruses?

Give an example of a class II virus.

A

ssDNA

Parvouviri

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69
Q

In what form is the genetic material found in class III viruses?

Give an example of a class III virus.

A

dsRNA

Rotavirus

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70
Q

In what form is the genetic material found in class IV viruses?

Give an example of a class IV virus.

A

ssRNA (+)

SARS

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71
Q

In what form is the genetic material found in class V viruses?

Give an example of a class V virus.

A

ssRNA (-)

Influenza
Ebola

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72
Q

In what form is the genetic material found in class VI viruses?

Give an example of a class VI virus.

A

ssRNA (+) diploid

HIV

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73
Q

In what form is the genetic material found in class VII viruses?

Give an example of a class VII virus.

A

Gapped dsDNA

Hepatitis B

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74
Q

What is the mode of RNA production on class I viruses?

A

ds DNA virus - mRNA transcribed directly from DNA template

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75
Q

What is the mode of RNA production on class II viruses?

A

ssDNA virus - DNA converted to ds form before RNA transcribed

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76
Q

What is the mode of RNA production on class III viruses?

A

dsRNA virus - mRNA transcribed from RNA genome

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77
Q

What is the mode of RNA production on class IV viruses?

A

ssRNA (+) virus - genome functions as mRNA

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78
Q

What is the mode of RNA production on class V viruses?

A

ssRNA (-) virus - mRNA transcribed from RNA genome

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79
Q

What is the mode of RNA production on class VI viruses?

A

ssRNA (+) diploid virus - Reverse transcriptase makes DNA from RNA genome.
DNA then incorporated into the host genome.
mRNA transcribed from incorporated DNA.

(Think HIV.)

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80
Q

What is the mode of RNA production on class VII viruses?

A

Gapped dsDNA virus - viral genome is dsDNA, but viral DNA replicated through RNA intermediate

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81
Q

What does Saquinavir (antiviral) target?

A

Protein synthesis (an HIV protease inhibitor)

Used for HIV infection in combination with other antiretrovirals.

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82
Q

What does Acyclovir (antiviral) target?

A

Nucleoside analogue.

Used as a systemic and topic treatment for herpes simplex.
Systemic treatment for varicella zooster.
Does not eradicate the virus.

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83
Q

What is the molecular basis of the mechanism behind Saquinavir (antiviral)?

A

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.

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84
Q

What is the molecular basis of the mechanism behind Acyclovir (antiviral)?

A

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.

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85
Q

What does Amantadine (antiviral) target?

A

Viral uncoating.

Licensed for prophylaxis and treatment of influenza A.

86
Q

What is the molecular basis of the mechanism behind Amantadine (antiviral)?

A

Blocks ion channel which is formed by a membrane protein (M2) of influenza A, thus preventing viral uncoating within host cell.

87
Q

What are the physical barriers of the body to prevent infection?

A 
Skin
Cilia (respiratory and gut linings)
Hair
Mucosal surfaces (GI mucosal, respiratory tract)
Flushing action - urine and tears
Peristalsis
88
Q

How doe the gut architecture help the body overcome infection?

A

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
Q

What are the chemical barriers the body has against infection?

A

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
Q

What are the 3 lines of body defence in order?

A

1st line: Skin, mucous membranes, chemicals

2nd line: Innate - Phagocytosis, complement, interferon, inflammation, fever

3rd line: Adaptive - Lymphocytes, antibodies

91
Q

What cells are considered to be granulocytes?

A

Neutrophil
Basophil
Eosinophil
Mast cells

92
Q

What are the properties of red bone marrow?

A

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
Q

What are the properties of erythrocytes?

A

Red blood cells
contain haemoglobin
biconcave discs with no nucleus to maximise O2 carrying capacity
Life expectancy = 120 days

94
Q

Which cell types are capable of antigen presentation?

A

Macrophages, dendritic cells and B lymphocytes

95
Q

What cell lineage gives rise to cells of the adaptive immune system?

A

Lymphoid lineage

96
Q

What cell lineage gives rise to cells of the innate immune system?

A

Myeloid lineage

97
Q

Which cells are termed innate cells but are actually part of the lymphoid lineage?

Why are they termed innate?

A

Natural killer cells

Because they don’t require specific recognition to become activated

98
Q

Within what time frame is the innate immune system activated post infection?

A

0-12 hours

99
Q

Within what time frame is the adaptive immune system activated post infection?

A

After 12-24hrs, up to 7 days

100
Q

What is released when mast cells degranulate? What are the overall effects of this?

A

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
Q

What are the visual signs of inflammation?

A 
Rubor - Heat
Calor - Redness
Tumor - Swelling
Dolor - Pain
Loss of function
102
Q

What are dendritic cells under the skin called?

A

Langerhan cells

103
Q

What is the role of dendritic cells?

A

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
Q

What are the properties of neutrophils?

A

Recruited within minutes via chemotaxis
Phagocytic can engulf pathogen
Kill via respiratory burst

105
Q

How does chemotaxis work?

A

Chemokines released at site of infection

Inflammatory cells eg neutrophils follow chemotactic gradient towards infection site.

106
Q

What physical property of neutrophils make them easily identifiable under a microscope?

A

They have a multi lobed nucleus (three)

107
Q

What are p selectin and e selectin?

A

Adhesion molecules

108
Q

What is the respiratory burst?

A

Production of ROS and free radicals eg superoxide which break down pathogen within the cell once it has been phagocytosed

109
Q

What cell types do monocytes differentiate into?

A

Macrophages

110
Q

How do natural killer cells kill?

A

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
Q

What conditions/ diseases are basophils most commonly recruited against?

A

Allergy/ atopy

Resistance to internal parasites eg helminths and ticks

112
Q

What conditions/ diseases are eosinophils most commonly recruited against?

A

Allergic disease and helminth infections

113
Q

What colour do basophils appear under the microscope and why?

A

Purple because they take up basic dye

114
Q

What colour do eosinophils appear under the microscope and why?

A

Pink because they take up acidic dye (eosin)

115
Q

What do innate cells use to recognise pathogens?

A

PAMPs (recognised by PRRs)

116
Q

What elements of a bacterial cell can be recognised as PAMPs?

A 
Peptidoglycan
Lipoprotein
Lipoteichoic acid
LPS
Flagellin
Sugars eg mannose
DNA
117
Q

What elements of a viral cell can be recognised as PAMPs?

A

Envelope proteins
DNA
RNA

118
Q

What are TLRs?

A

Toll like receptors

A type of pattern recognition receptor (PRR)

119
Q

What does TLR-4 recognise?

A

LPS

120
Q

What is CRP?

A

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
Q

In what diseases is CRP measured in order to monitor progression and flare ups?

A

Rheumatoid arthritis
Vasculitides
Ankylosing spondylitis
Acute pancreatitis

122
Q

What do interferons do?

A

Type of cytokine that are important in preventing viral infections from spreading between cells

123
Q

Which cytokines are important for activating a t cell mediated response?

A

IL-12
IL-2
IFN-g
TNF-a

124
Q

Which cytokines are important for activating a humoral response (antibody production)?

A

IL-4
IL-5
IL-13

125
Q

Which are the key anti inflammatory cytokines?

A

IL-10

TGF-b

126
Q

Where are T lymphocytes produced?

A

Bone marrow

127
Q

Where do T lymphocytes mature?

A

Thymus

128
Q

Where are T lymphocytes activated?

A

Lymph node

129
Q

How do T cells undergo central tolerance?

A
  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
Q

What are the two possible classes of T cells?

A

CD4+ T helper cells

CD8+ Cytotoxic/ killer cells

131
Q

How are T helper cells activated?

A

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
Q

Exposure to which cytokine causes naive T cells to become Th1 CD4+ T helper cells?

A

IL-12

133
Q

Exposure to which cytokine causes naive T cells to become Th2 CD4+ T helper cells?

A

IL-4

134
Q

Exposure to which cytokine causes naive T cells to become Th17 CD4+ T helper cells?

A

IL-1b

IL-6

135
Q

Exposure to which cytokine causes naive T cells to become Treg CD4+ T helper cells?

A

TGF-b

IL-10

136
Q

What are Th1 CD4+ T helper cells effective at fighting?

A

Intracellular bacteria and viruses - cause a cell mediated immune response

137
Q

What are the downstream effects of activating Th1 CD4+ T helper cells?

A

They release IFN-g and IL-2 to stimulate macrophages, CD8+ and NK cells and cause B cells to become plasma cells.

138
Q

What are Th2 CD4+ T helper cells effective at fighting?

A

Extracellular bacteria, fungi or parasites - Humoral mediated response

139
Q

What are the downstream effects of activating Th2 CD4+ T helper cells?

A

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
Q

What are Th17 CD4+ T helper cells effective at fighting?

A

Defence against bacteria and fungi particularly in mucosal environments

141
Q

Are Th17 cells pro-inflammatory or anti-inflammatory?

A

Pro-inflammatory

142
Q

What are the downstream effects of activating Th17 CD4+ T helper cells?

A

IL-17 release promoting inflammatory mediators, as well as recruitment and increased production of neutrophils

143
Q

What are the downstream effects of activating Treg cells?

A

Down-regulate Th1 and Th2 cells - the ‘off’ switch.

Release anti inflammatory cytokines eg IL-10 and TGF-b, inhibiting ongoing responses.

144
Q

How are CD8+ T cells activated?

A

Dendritic cell expresses antigen on MHCI to CD8+ TCR.

Clonal expansion of activated CD8+ T cell.

145
Q

How do cytotoxic CD8+ T killer cells kill infected cells?

A

Death receptor signal - Fas/FasL binding

Perforin and granzyme - punch holes in the cell membrane and cause apoptosis

146
Q

Where are B cells produced?

A

Bone marrow

147
Q

Where do B cells reside and mature?

A

Bone marrow

148
Q

How does B cell tolerance work?

A

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
Q

How are B cells activated?

A

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
Q

What process allows plasma cells to produce different types of antibodies?

A

Isotype/ class switching

151
Q

What is the first antibody subset produced by plasma B cells?

A

IgM

152
Q

What are the names of the different sub classes of antibodies?

A

IgM, IgG, IgA, IgE, IgD

153
Q

What shape is IgM?

A

Pentameric

154
Q

What shape is IgA?

A

Dimeric with a J chain and secretory component

155
Q

What shape is IgG?

A

Monomeric

156
Q

What shape is IgE?

A

Monomeric

157
Q

What type of infection is IgE usually produced for?

A

Parasitic infections and allergy

158
Q

What are the properties and functions of IgM?

A

First Ab produced
High valency
Can activate complement
Can neutralise toxins

159
Q

What are the properties and functions of IgG?

A 
Opsonisation
Neutralisation
Activates complement
Ab with the highest affinity
Most abundant Ab
Important in ADCC
160
Q

What are the properties and functions of IgA?

A

The secretory Ab
Found at mucosal linings
Main function is neutralising
Second most abundant Ab

161
Q

What are the properties and functions of IgE?

A

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
Q

How does ADCC work?

A

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
Q

What are the different types of immunity that can be acquired? Give an example for each.

A

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
Q

Define infection

A

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
Q

What is a protist?

A

a eukaryote that is not an animal, plant, fungi.

166
Q

What is a protozoa?

A

a protist that is not photosynethetic.

167
Q

What is a local infection?

A

Confined to a small area of the body near the site of entry.
eg Hair follicle infected byStaphylococcus or a pneumonia confined to the lungs.

168
Q

What is a focal infection?

A

A pathogen spreads to a secondary location

eg Gum infected byStreptococcusthat gains access to the bloodstream and causes a secondary infection elsewhere.

169
Q

What is a systemic infection?

A

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
Q

Define pathogen

A

A microorganism that can cause disease

171
Q

Define pathogenicity

A

The ability of an organism to cause disease

172
Q

Define virulence

A

The degree of disease caused by an organism

173
Q

Define virulence factors

A

The molecules produced by the organism that add to their effectiveness in replicating within the host

174
Q

What is the ID50?

A

The number of bacterial, protozoal cells or virions required to cause active infection in 50% of inoculated animals.

175
Q

Give two examples of clinically significant spore forming organisms

A

Clostridium and Bacillus

176
Q

What is the process of biofilm formation?

A
  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

  1. detachment and reversion to planktonic growth, starting a new cycle
177
Q

What are exotoxins? Give an example

A

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
Q

What are endotoxins? Give an example

A

Integral part of the bacterial cell wall: released only if the microbe is destroyed

Eg Cholera

179
Q

What is the mechanism of the diseases causing exotoxin in cholera?

A

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
Q

What does toxic shock syndrome do?

A

Involves the production of superantigens.

Stimulate T cells non-specifically without normal antigenic recognition.
Cross link MHCII on APCs an TCR.

181
Q

What is the clinical effect of endotoxins?

A

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
Q

How do Staphylococcus aureus,Streptococcus pyogenes, andClostridium perfringens invade tissues?

A

produce hyaluronidase that degrades hyaluronic acid – open the cell junctions between connective tissue cells

183
Q

Which bacteria use a capsule to evade recognition by host?

A

Neisseria meningitidis
Haemophilus influenzae
Streptococcus pneumoniae

184
Q

How do capsules allow bacteria to evade host recognition?

A

Masks immunogenic antigens
Impairs complement pathways
Impairs opsonisation
Reduces phagocytosis

185
Q

How do Neisseria meningitidis, Streptococcus pneumonia and Haemophilus influenzae evade host recognition?

A

Produce protease enzymes that break down IgA allowing them to invade mucosal surfaces

186
Q

What are the ways in which bacteria or viruses can survive in the host?

A

Body armour - capsule
Fight - survive once captured
Biofilms
Antigenic variation

187
Q

How does antigenic variation allow survival within the host?

A

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
Q

What is always the first immune cell thats drawn in to the site of infection?

A

Neutrophils

189
Q

Production and binding of what cytokine causes production of CRP at the liver?

A

IL-6

190
Q

What are the two main types of inflammation?

A

Acute and chronic

191
Q

What is the duration of acute inflammation?

A

Less than 3 weeks

192
Q

What is the duration of chronic inflammation?

A

Greater than 6 weeks

193
Q

What are the features of acute inflammation?

A

Injury not necessarily associated with tissue destruction
Neutrophils often recruited in large numbers
Variable systemic effects, often minor

194
Q

What are the features of chronic inflammation?

A

Significant tissue destruction typically a prominent feature
Macrophages, lymphocytes and their derivatives characteristically predominate
Systemic manifestations often prominent

195
Q

What triggers a favour response?

A

Production of acute phase proteins by the liver eg CRP

196
Q

What is virulence?

A

How pathogenic something is.

197
Q

What is a pathogen?

A

Microorganism that causes disease.

198
Q

What is infection?

A

Problem caused by a pathogen.

199
Q

What is commensalism?

A

Part of normal flora.

200
Q

What is a microbiome?

A

Community or microorganisms.

201
Q

What is colonisation?

A

Microorganisms in or on the body that don’t cause problems.

202
Q

What is contamination?

A

Contamination is the action of something becoming unsterile which could cause harm

203
Q

What is normal flora?

A

Microorganisms normally found in a body site.

204
Q

What is subclinical infection?

A

Infection that does not cause symptoms e.g. influenza.

205
Q

What does latent mean?

A

An inactive and persistent infection and may react intermittently e.g. VSV.

206
Q

What are the 5 main types of pathogen?

A 
Bacteria
Fungi
Viruses
Parisites
Prions
207
Q

What shape are cocci bacteria?

A

Round

208
Q

What shape are bacilli bacteria?

A

Rod shaped

209
Q

What shape are spirachaotes?

A

Spiral

210
Q

What is the composition of blood?

A

55% is blood plasma which contains water, solutes, proteins and hormones.

45% is red blood cells.

Under 1% is white blood cells and platelets.

Medicine Year 1 (3 decks)

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