resp Flashcards
(182 cards)
alveolar macrophages - features + function
where do they go
- main feature: live in the alveoli - outside the body!
- > eat particles that didnt get trapped by mucous
either move up mucociliary escalator; or move back through into alveolar wall and stay there till death
Alveolar-capillary membrane
- thickness
- surface area
- alveolar volume
- capillary volume
- 0.5 micron
- 50-100m2
- 3-6 L
- 80mL (increases with increased CO)
around how many dichotomous branchings are there in the lungs?
23
At what level do bronchioles start
around 10-15th dichotomous branch
Clinical signs of acute pneumonia? (11)
Relatively well; then acutely ill
- resolves by crisis
signs:
- abrupt onset
- unrelenting cough
- lots of sputum
- fever
- raised WBC
- pleuritic chest pain
- sputum may be blood-stained
- G+ diplococci in sputum
- bacteraemia
- consolidation
- bronchial breathing
Clinical signs of atypical (interstitial) pneumonia (5)
“flu-like”
- symptoms are symptomatic and not as debilitating
- “walking pneumonia” - slower onset; cough a long time
- malaise
- headache
- diarrhoea
- aches; pains
- dry cough
Common cold - is lab diagnosis necessary?
- treatment
unnecessary
supportive treatment
componets of blood-gas barrier
lung: surfactant; type 1 pneumocyte; basal lamina connective tissue
capillary: basal lamina; endothelial cell; plasma
(sometimes basemet membranes are fused and there is no connective tissue)
Crepitations indicate pathology of which site(s) in the lungs?
what is the best test for this area?
terminal lung units - alveoli; parenchyma; interstitium
best test - ct scan (CXR will show gross abnormality)
croup (LTB)
- is lab diagnosis necessary?
- treatment
seldom necessary - clinical diagnosis and usually viral
if severe - inhaled steroids; otherwise no treatment
Definition of asthma
- 2 word
- longer
2 word: reversible bronchoconstriction
longer: increased responsiveness of airways to various stimuli; leading to episodic bronchoconstriction which is at least partially reversible
epiglottitis
- is lab diagnosis necessary?
- treatment
yes - whenever possible
-> be careful - irritation of the area -> inflammation -> closed off airways
treatment
- essential
- always bacterial
- very severe
features of type I pneumocytes - predominance (how much surface area they take up) - function - what are the junctions between cells and basal lamina - can they reproduce
95% of surface area gas exchange tight junctions - prevent leak of ECF into alveoli; basal lamina is thick and prominent - no - die and must be replaced (by type II)
features of type II pneumocytes - how much surface area do they take up? - function - structure - features - can they reproduce
- 5% (though more numerous than type I) - secrete surfactant - cuboidal cells - short microvilli + lamellar bodies that contain surfactant - yes - divide and give rise to both type I and II pneumocytes
How do antibodies neutralise influenza virus?
influenza - binds receptors via receptor-binding site on HA - receptor binding site - surrounded by 5x antigenic sites - antibody binds to one of these -> sterically inhibits binding of HA to receptor (ab is similar size to HA)
How does antigenic drift occur in influenza? in epidemics?
- mutations in antigenic sites are selected for if they prevent the binding of antibodies - antigenic drift = mutation + selection mutation: error of replication of viral RNA-dependent RNA polymerase epidemic - change in all 5 sites - point mutations - or reassortment -> swapping of gene segments on co-infection of a single cell -> get totally different HA/NA (problem: avian have specificity for a2-3 binding; and we have receptors with a2-6 -> but if avian + human co-infect a mixing vessel - eg pig - then we could have recombination such that genes are adapted for human growth; but HA and NA are avian. then there is mutation + selection for a2-6 specificity)
How does consolidation in lobar pneumonia spread through the lung?
Moves through pores between alveoli - get the whole lobe
How does diffusion limitation of oxygen occur in high-altitude environment?
High altitude - have lower atmospheric PO2 -> the gradient between partial pressures is lower -> have slower diffusion across membrane https://onenote.officeapps.live.com/o/GetImage.ashx?Fi=SDFD3144C4D713EDE3%21370&C=1__BAY-SKY-WAC-WSHI&ak=m%3Den%2Dau&ObjectDataBlobId=%7B52701cc9-9860-8048-b1c5-cc06599fc06b%7D%7B1%7D&usid=8e68f0f2-010c-446e-b7c9-63d80c9d17ee&build=16.0.2430.1026 also - the rate of rise of PO2 for a given increase in blood O2 is lessened - steep slope of O2 dissociation curve when PO2 is low => exercise may result in diffusion impairment of O2
how does influenza spread between people?
droplet infection - coughing; sneezing doesn’t spread too far (cf measles)
How does the pulmonary system maintain low P when CO increases?
- recruitment of pulmonary vessels that are not normally perfused - dilatation of vessels
How many subtypes of influenza A and B are there?
B - no subtypes A - subtypes according to which HA; NA combo it has - HA1-17 - NA1-10
If there are signs that abnormality is respiratory; but the chest sounds clear - what could this indicate? examples?
pathology is VASCULAR ** - PE - infarct can irritate pleura (pleuritic pain); cause haemoptysis; but chest sounds clear - pulmonary hypertension; pulmonary vasculitis -r are
Influenza virus - family - genome structure - envelope? what are the different types?
- Orthomyxoviridae family - genome: segmented ssRNA; -ve sense; arranged as 8 RNP’s RNP = ribonucleoprotein (genome wrapped in helix; nucleoproteins; attached RNA-dependent RNA polymerase) - enveloped 3 types - A; B; C - structurally similar; but no immunological cross-reactivity - only A and B are major human pathogens - A can also infect other species
Influenza: ion channel blockers - name drugs - influenza A or B? - how does it work? - administration - populations
- adamantanes - amantadine; rimantadine - only A - blocks M2 ion channel - no acidification of virus interior; RNP’s remain fused to matrix - oral; daily - children; prophylactic in nursing homes - but developing drug resistance so used rarely