Resp Flashcards
Define tidal volume
volume of air that is displaced between normal inspiration and expiration when extra effort is not applied
List the order of the tubes of the respiratory tract
trachea main bronchi lobar bronchi bronchioles terminal bronchioles alveolar ducts alveoli
describe the epithelium of the trachea
pseudostratified ciliated with goblet cells
seromucus glands
c shaped cartilage ring
Describe the cartilage in the primary bronchi
completely encircling rings
What is the difference between the right and left bronchi?
right more vertical
objects more likely to lodge
Describe the cartilage in lobar bronchi
crescent
How are the bronchioles held open?
`surrounding elastic alveoli
What are clara cells?
found in bronchioles
produce surfactant lipoprotein
prevents walls sticking together during expiration
produce CC16 -
lowered marker in bronchoalveloar lavage = lung damage
raised marker in serum = leakage across blood-air barrier
What are the differences between bronhi and bronchioles?
bronchus
- cartilage in small islands
- glands in submucosa
Bronchiole
- no cartilage
- no glands
Describe the alveolar epithelium
elastic and reticular fibres type I pneumocytes - simple squamous - 90% type II pneumocytes - simple cuboidal - produce surfactant - 10%
What is the pleural cavity?
The potential space between the parietal and visceral layers of pleura
Describe the surface marking of the pleural cavity
• Apex – 3cm above medial 1/3rd of the clavicle
• 2nd to 4th ribs - vertically behind the sternum, up to 4th costal cartilage level
• At 4th rib
- Right pleura continues vertically down to 6th rib
- Left pleura deviates laterally to the edge of the sternum, then descends lateral to the border of the sternum up to the 6th costal cartilage
• 6th costal cartilage both sides turn laterally and pass around the chest wall
• Cross the 8th rib at the mid clavicular line
• The 10th rib at the mid axillary line
• The 12th rib at the medial border of the scapula
Describe the surface marking of the lungs
• Apex – 3cm above medial 1/3rd of the clavicle
• 2nd to 4th ribs - vertically behind the sternum, up to 4th costal cartilage level
• At 4th rib
- Right pleura continues vertically down to 6th rib
- Left pleura deviates laterally to the edge of the sternum, then descends lateral to border of the sternum to the 6th costal cartilage
• Crosses the 6th rib at the mid clavicular line
• The 8th rib in the mid axillary line
• The 10th rib at the medial border of the scapula
What is the costodiaphragmatic recess?
inferior part of the pleural cavity that is not occupied by the lungs
Describe the lobes and fissures of lungs
Right
- superior lobe
- horizontal fissure
- middle lobe
- oblique fissure
- inferior lobe
Left
- superior lobe
- oblique fissure
- inferior lobe
State the surface markings of the lobes of the lungs
The oblique fissure
- from the T2 spinous process to the 6th costal cartilage
The right lung horizontal fissure
- along the 4th rib from the mid axillary line to the anterior edge of the lung
What is the sternal angle?
junction between the manubrium and the body of the sternum
allows for identification of the second rib
What are the parts of a typical rib?
head - two articular facets for articulation with body of corresponding vertebra and superior vertebra
neck
tubercle - articular facet for articulation with transverse process of vertebrae
shaft - with costal groove on lower border for intercostal vessels and nerve
What are the features of a typical thoracic vertebra?
bilateral costal facets on body
costal facets on transverse process
long inferiorly slanting spinous process
what is the costovertebral joint?
articular facets on head of rib
corresponding vertebra and vertebra above
What is the costotransverse joint?
articular facet on tubercle of rib
transverse process of corresponding vertebra
Name the intercostal muscles, superficial to deep
external intercostal
internal intercostal
innermost intercostals
Describe the external intercostal muscles and their action
used in inspiration
fibres run downwards and anteriorly
contraction leads to rib elevation in bucket handle movement
increases AP and transverse diameters of the chest
Describe the internal intercostal muscles and their action
used in forced expiration
fibres run downwards and posteriorly
contraction pulls ribs down
Describe the innermost intercostal muscles and their action
used in forced expiration
fibres run downwards and posteriorly
contraction pulls ribs down
What happens in contraction of the diaphragm?
diaphragm descends
increase in vertical diameter
Describe the right crus of the diaphragm
arises from L1-L3
surrounds oesophagus
Describe the left crus of the diaphragm
arises from L1-L2
There are three openings in the diaphragm
What level?
For what?
T8 - vena cava (IVC)
T10 - oesophagus
T12 - aorta
What is the sensory and motor innervation of the diaphragm?
sensory
- phrenic nerve C3,4,5
motor
- phrenic nerve C3,4,5
Where do the intercostal vessels and nerves lie?
Why is this important to remember?
in the intercostal groove on the inferior surface of the rib
between the internal and innermost intercostals
pleural aspiration/chest drain
needle inserted at upper border of the rib
What are the four parts of the parietal pleura?
cervical
mediastinal
diaphragmatic
costal
What is the blood supply and innervation of the parietal pleura?
intercostal arteries and veins
intercostal and phrenic nerves, so somatic and autonomic innervation
What is the blood supply and innervation of the visceral pleura?
bronchial arteries and veins
no somatic innervation, only autonomic
What is the importance of the fluid in the pleural space?
surface tension
prevents the parietal and visceral surfaces of the pleura being pulled apart
lungs expand along with the thorax on inspiration
What is the significance of the bronchopulmonary segmental lobes of the lung?
supplied by one segmental bronchus
supplied by segmental branches of the pulmonary artery and vein
can be removed with little damage to other segments
Where do the bronchial arteries arise from?
two left bronchial arise from the thoracic aorta
single right bronchial arises from the 3rd intercostal
What do the bronchial arteries supply?
nutrition of the bronchial tree, visceral pleura and connective tissue
What muscles are used in forced inspiration?
diaphragm external intercostals SCM scalene serratus anterior pec major
What muscles are used in forced exhalation?
internal intercostals
abdominal muscles
What is compliance in the lungs?
the stretchiness!
volume change per unit pressure change
high compliance = easy to stretch
What is the role of surfactant in the lungs?
increases compliance
reduces surface tension
less so when lungs are fully inflated as surfactant is spread out more thinly
so as alveolus expands, the surface tension increases
prevents large alveoli eating smaller alveoli by equalising pressure
pressure = 2xsurface tension/radius
Define inspiratory reserve volume
extra volume that can be breathed in when extra effort is applied
Define expiratory reserve volume
extra volume that can be breathed out when extra effort is applied
define residual volume
the volume that remains in the lungs after maximal expiration
define inspiratory capacity
biggest breath that can be taken from resting expiratory level
define functional residual capacity
volume of air in the lungs at resting expiratory level
define vital capacity
biggest breath that can be taken in
measured from max expiratory capacity to max inspiratory capacity
define total lung volume
volume of gas in the lungs at the end of maximal inspiration
= vital capacity + residual volume
What is the FVC?
Forced vital capacity
= maximum volume that can be expired by the lungs
What is the FEV1.0?
Forced expiratory volume in one second
= volume expired in the first second
What is the normal FEV1.0/FVC ratio?
70%
What will obstructive diseases look like on spirometry?
narrowed airways
volume same, so FVC normal
resistance increased, so FEV1.0 is reduced
FVC/FEV1.0 ratio
What will restrictive diseases look like on spirometry?
lungs difficult to fill
FVC reduced
FEV1.0 normal
FVC/FEV1.0 ratio >70%
What type of cancer are most primary lung tumours?
bronchial carcinomas
What percentage of primary lung cancers are small cell carcinoma?
15%
What are the features of SCLCs?
manufacture polypeptides which act as hormones/neurotransmitters
rapidly growing
almost always inoperable at presentation
What are the types of non small cell lung cancer?
squamous
adenocarcinoma
large cell
What are the features of squamous NSCLCs?
most present as obstructive lesions of the bronchus
local spread common
What are the features of adenocarcinoma NSCLCs?
arise from mucous cells in bronchial epithelium
invasion of pleura and mediastinal lymph nodes common
What are the features of large cells NSCLCs?
less differentiated forms of squamous and adenocarcinomas
metastasise early
What are the risk factors for lung cancer?
active or passive smoking occupational exposures - industrial dust, asbestos, chromium, radiation increased age COPD previous history of cancer
Describe the signs and symptoms of lung cancer
cough dyspnoea weight loss chest pain haemoptysis finger clubbing fever weakness superior vena cava obstruction pleural effusion consolidation
Describe the signs and symptoms of metastatic disease as a result of lung cancer
bone tenderness hepatomegaly confusion fits focal neurological deficit cerebellar syndrome proximal myopathy peripheral neuropathy
Explain the T staging of lung cancer
o T1 – Cancer contained within lung ( 7cm diameter) Invading chest wall, mediastinal pleura, diaphragm, pericardium or has caused complete lung collapse. Or > 1 cancer nodule in the same lobe of lung
o T4 - Cancer invading mediastinum, heart, major blood vessel, trachea, carina, oesophagus, spine, recurrent laryngeal nerve Cancer nodules in more than one lobe of the same lung
Explain the N staging of lung cancer
o N0 – No cancer in lymph nodes
o N1 – Cancer in lymph nodes nearest the affected lung
o N2 – Cancer in lymph nodes in mediastinum on the same side
o N3 – Cancer in lymph nodes on the opposite side of the mediastinum / supraclavicular lymph nodes
Explain the M staging of lung cancer
o M0 – No evidence of distal cancer spread
o M1 – Lung cancer cells in distant parts of the body, such as pleura, opposite lung, liver or bones etc
What tumour markers are used in the management of lung cancer?
EGFR gene mutation analysis - NSCLC
How is the pCO2 of the blood controlled?
by the pCO2 in the alveoli
determined by breathing rate
How does CO2 react in RBCs?
CO2 reacts with water to form H+ and HCO3
H+ ions bind to negatively charged Hb, drawing the reaction towards HCO3- production as H+ is removed and [H+] decreases
The chloride bicarbonate exchanger transports HCO3- out of the RBC
Explain the buffering capacity of RBCs
If less O2 binds, more H+ binds
so more HCO3- can be produced and be exported to the plasma.
So plasma pH is changed only very slightly as both pCO2 and [HCO3-] have increased!
If more O2 binds, less H+ ions bind
so Hb gives up eh extra H+ it took on at the tissues when it reaches the lungs. H+ reacts with HCO3- to form CO2 which is then breathed out!
What do the central chemoreceptors detect?
arterial pCO2
detect changes in [H+]
How do the central chemoreceptors detect changes in arterial pCO2?
blood brain barrier ( CO2 can cross but not HCO3-)
The [HCO3-] in the CSF is fixed short term.
So falls in pCO2 lead to rises in CSF pH.
A rise in pCO2 leads to a fall in CSF pH.
How do the central chemoreceptors accept a persistent altered pH as normal?
choroid plexus cells
selectively add HCO3- or H+ to CSF
What is type 1 respiratory failure?
o Respiratory Rate high
o pO2 low
o CO2 normal or low
- Not enough oxygen enters the blood, so pO2 of arterial blood is below 8kPa and O2 saturation is below 90%.
- CO2 removal is not compromised, so pCO2 is normal or even lower! (as increased ventilation leads to more CO2 being blown off)
What is type 2 respiratory failure?
o Respiratory Rate high
o pO2 low
o CO2 high
- Not enough oxygen enters the blood, so pO2 of arterial blood is below 8kPa and O2 saturation is below 90%.
- Not enough CO2 leaves the blood, so pCO2 is raised.
describe the reaction of CO2 and H2O
CO2 + H20 H+ + HCO3-
What is the Henderson-Hasselbalch Equation?
pH = 6.1 + Log( [HCO3-] / (pCO2 x 0.23) )
What is the normal CO2 content of arterial blood?
21.5mmol/litre
What is the normal CO2 content of arterial blood?
23.3mmol/litre
State the proportion of CO2 travelling in various forms in the blood
60% HCO3-
30% carbamino compounds
10% dissolved CO2
How are carbamino compounds formed?
CO2 binds directly to amine groups on Hb
What physiological effect does a pH below 7 cause?
enzymes become denatured
ACIDOSIS
What physiological effect does a pH above 7.6 cause?
calcium forms insoluble salts serum calcium concentration drops nerves become hyper-excitable tetany ALKALOSIS
How does hypoventilation lead to respiratory acidosis?
CO2 produced more rapidly than it is removed by the lungs
alveolar pCO2 rises
[dissolved CO2] increases more than [HCO3-]
decrease in pH
How does hyperventilation lead to respiratory alkalosis?
CO2 removed from alveoli more rapidly than it is produced
alveolar pCO2 falls
[disssolved CO2] decreases more than [HCO3-]
increase in pH
How do the kidneys compensate for respiratory acidosis?
reduce excretion HCO3-
increases [HCO3-]
restores pCO2 : HCO3-
restores pH
How do the kidneys compensate for respiratory alkalosis?
increase excretion HCO3-
decrease [HCO3-]
restores pCO2 : HCO3-
restores pH
How does metabolic acidosis arise?
metabolic acids react with HCO3-
decreased [HCO3-]
pH falls
How does metabolic alkalosis arise?
during vomiting or diarrhoea, plasma [HCO3-] rises
pH rises
How is metabolic alkalosis compensated for by the lungs?
decreased ventilation rate
increases pCO2
restores pCO2 : HCO3-
restores pH
How is metabolic acidosis compensated for by the lungs?
increased ventilation rate
decreases pCO2
restores pCO2 : HCO3-
restores pH
What causes type 1 respiratory failure?
ventilation perfusion mismatch
- PE
- pneumonia
- acute asthma
- COPD
- RDS
diffusion impairment
- interstitial lung disease
- emphysema
- pulmonary oedema
How does a PE lead to type 1 respiratory failure?
part of pulmonary circulation disrupted
blood diverted to other parts of lung
ventilation to affected parts wasted so V/Q>1
excess perfusion to healthy areas not matched by increased ventilation so V/Q
How do pneumonia, asthma and COPD lead to type 1 respiratory failure?
poor O2 uptake in poorly ventilated alveoli cannot be compensated for by increased uptake in others
decreased O2 uptake
pO2 falls
How does interstitial lung disease lead to type 1 respiratory failure?
fibrous tissue in interstitial space between alveolus and capillary basement membrane
increases diffusion distance
How does emphysema lead to type 1 respiratory failure?
elastin broken down in alveolar walls reduced elastic recoil airspaces distal to terminal bronchioles dilated compliance increased hyperinflation reduced surface area for gas exchange
What causes type 2 respiratory failure?
hypoventilation
- respiratory centre depression (narcotics, head injuries)
- muscle weakness
- chest wall problems
- pneumothorax
- stiff lungs
- high airway resistance (COPD, asthma)
How does hypoventilation result in type 2 respiratory failure?
not enough oxygen enters and not enough CO2 leaves
low pO2, high pCO2
Why do patients with type 2 respiratory failure hyperventilate?
high pCO2 stimulates central chemoreceptors
What are the symptoms of CO2 retention?
flapping tremors
warm hands
