clinical relevance / extra pbl

Question 1

which airway is an aspirated object more likely to end up

Answer 1

right - it is less angulated

Question 2

ECG signs of sinus invertus

Answer 2

R axis deviation; Positive QRS complexes (with upright P and T waves) in aVR; Lead I: inversion of all complexes, aka ‘global negativity’; Absent R-wave progression in the chest leads

Question 3

what are the main defense mechanisms against inhaled pathogens

Answer 3

mucociliary escalator

Question 4

disease affecting cilia (4)

Answer 4

primary cilia diskinesia; cartagenous syndrome; CF; young’s syndrome (yellow nails, pleural effusion)

Question 5

4 components of the immune response to an infection and how to they work

Answer 5

cytotoxic T cells (respond to MHC1 and release perforin);
Natural killer cells (responds to downreg of MHC1 on cells, makes membrane porus);
Interferons (released later e.g. CRP, IL6);
Antibodies (B cells produce specific antibodies, work in numerous ways)

Question 6

3 actions of interferons

Answer 6

signal neighboring cells to put up barriers; signal infected cells to die; recruitment of white blood cells to stimulate long lasting immunity

Question 7

what should be considered along side CURB65 criteria when deciding whether to admit

Answer 7

O2 stats/score; CURB65 alone does not take into all factors

Question 8

which type pf H.influenzae is fata

Answer 8

HI B is fatal -> ear infections + meningitis can be seen in children

Question 9

what lobes does TB usually affect

Answer 9

upper lobes (due to V/Q ratio)

Question 10

tetracyclines MOA

Answer 10

protein synthesis inhibitors - inhibit the initiation of translation in variety of ways by binding to the 30S ribosomal subunit

Question 11

penicillin MOA (similar for other β-lactams e.g. amoxacillin, cephalosporin etc.)

Answer 11

specifically inhibiting the transpeptidase that catalyzes the final step in cell wall biosynthesis, the cross-linking of peptidoglycan (i.e. cell wall synthesis inhibition)

Question 12

antimycobacterials (Rifampicin) MOA

Answer 12

inhibition of the cell wall synthesis and RNA polymerase blockade

Question 13

quinolones (ciprofloxican) MOA

Answer 13

interfere with DNA replication by preventing bacterial DNA from unwinding and duplicating

Question 14

what is a B-lactam and give some examples

Answer 14

antibiotics are antibiotics that contain a beta-lactam ring in their chemical structure - e.g. penicillin, amoxacillin, Oxacillin, cephalosporin

Question 15

trimethoprim MOA

Answer 15

blocking the reduction of dihydrofolate to tetrahydrofolate, the active form of folic acid, by susceptible organisms - works best on gram +ve cocci

Question 16

Macroldies (erythromyocin, clarythromyocin etc.) MOA

Answer 16

binds to the bacterial 50S ribosomal subunit causing the cessation of bacterial protein synthesis

Question 17

what non-tuberculosis mycobacterium is essential to look out for in CF pts

Answer 17

Mycobacteroides abscessus
Bacteria

Question 18

what treatment cannot be given is M.abscessus is grown from the pt

Answer 18

lung transplant

Question 19

what can pts w an absent spleen not produce

Answer 19

loss of ability to filter out infected red blood cells;
reduced number of white blood cells as the spleen is also responsible for controlling the levels of blood cells

Question 20

asplenic pt vaccines (4)

Answer 20

Pneumococcal infections, such as pneumonia with a booster every 5 years;
Flu vaccine annually;
MenACWY;
MenB;

Question 21

asplenic pts antibiotics recommendation

Answer 21

recommended to take prophylactic antibiotics for the rest of the life to prevent bacterial infections

Question 22

what RTIs are HIV more likely to develop

Answer 22

sinusitis, bronchitis, bronchiectasis and pneumonia

Question 23

how does cough arise

Answer 23

postnasal mucous drip, also known as upper airway cough syndrome (UACS), other contributing factors may include bronchial hyperresponsiveness

Question 24

causes of chronic cough (8)

Answer 24

astroesophageal reflux disease (GERD); ACE Inhibitor use; asthma; bronchiectasis; COPD; chronic lung infection (e.g. tuberculosis); lung cancer and chronic micro aspiration

Question 25

how thick is the mucous blanket covering the RT

Answer 25

5 μm

Question 26

how is resistance reduced in cilia

Answer 26

Sublayer of water below mucus

Question 27

what does lactoferrin do?

Answer 27

binds to iron, limiting the growth of certain pathogenic bacteria that require it to create transport proteins; promotes the growth of beneficial low-iron requiring bacteria

Question 28

what are the 4 stages to macrophage defense in the alveoli

Answer 28

1. recognition - surface receptors or from complement cascade (C3b);
2. migration - neutrophils move from capillaries to alveolar space;
3. ingestion - Microbes englufed but not fully killed until certain signals are received (activation signals from NKCs releasing GMCSF or inteferons);
4. secretion of mediators - defensins (non-oxidative mech that kills many gram +/-ve species, fungi and certain viruses), surfactant proteins (type II Alveolar cells secrete surfactant proteins A and D to enhance phagocytosis)

Question 29

what is the main way in which neutrophils kills pathogens

Answer 29

Oxidation - Neutrophils phagocytose bacteria and kill them with reactive oxygen
metabolites like H2O2

Question 30

what is the effect of the enzyme elastase on the muco-cilia (secreted during an infection)

Answer 30

which causes excessive mucus, epithelial cell
damage and significant slowing of beat frequency in cilia

Question 31

what is the purpose of coughing

Answer 31

to clear material such as
sputum from the airways; It also helps protect the lungs against aspiration

Question 32

7 causes of cough

Answer 32

COUGHIN’
C - COPD
O - oedema
U - upper airways coughing syndrome
G - gastro-oesophageal reflux disease
H - hypertension medications (ACEi etc.)
I - infection
N - non-asthmatic eosinophilic bronchitis

Question 33

sensory components of cough

Answer 33

C fibres (affected by factors like bradykinin, histamines, prosoglandins etc.);
RAR (rapidly adapting airway mechanoreceptors) and SAR - mechanically driven due to bronchoconstriction, #oedema, high mucous levels etc.;
vagus nerve relays signals to brain

Question 34

“computing” component of cough

Answer 34

tractus solitarus (has nay afferent imputs incl ear, heart etc.); signal sent to pons -> cough signal recieved

Question 35

motor components of cough

Answer 35

Inspiratory centre: goes to muscle, pull diagram down, larynx closes -> pressure increase in lungs above 300 mmHg -> Expiratory phase: larynx open, and we cough as pressure changes

Question 36

4 phases of coughing

Answer 36

irritation, inspiraiton, compression, expulsion

Question 37

rifapentine side effects (7)

Answer 37

Black, tarry stools
coughing up blood
skin rash
sore throat
trouble breathing with exertion
ulcers, sores, or white spots in the mouth
unusual tiredness or weakness

Question 38

Rifampicin side effects

Answer 38

thrombocytopaenia; nausea; psychosis

Question 39

Isoniazid side effects

Answer 39

hepatic disorder; Severe cutaneous adverse reactions (SCARs)

Question 40

Ethambutol hydrochloride side effects

Answer 40

Hyperuricaemia; nerve disorders; visual impairment

Question 41

Pyrazinamide side effects (7)

Answer 41

Appetite decreased; arthralgia; dysuria; hepatic disorders; peptic ulcer aggravated; photosensitivity; skin reactions etc.