Mechanisms of ventilation Flashcards
What is the upper tract of the respiratory system
nasal cavity, pharynx, larynx
What is the lower tract of the respiratory system
trachea downwards
What keeps the trachea open at all times
rings of cartilage
Right lung structure
3 lobes: superior, middle, inferior
2 fissures: horizontal, oblique
Left lung structure
2 lobes: superior, inferior
1 fissure: oblique
Difference between right and left bronchus
left is shorter, more horizontal and wider
Respiratory tract from nose to trachea
nasal cavity superior an dinferior concha opening of pharyngotympanic tube Pharynx: naso, oro, laryngo epiglottis larynx trachea (oesophagus)
Epiglottis role
covers the laryngeal inlet so food passes into the oesophagus and not the trachea
How do we breathe?
diaphragm contracts and flattens, increasing thoracic volume and decreasing pressure
air is drawn into the lungs from outside
air passes into terminal bronchioles/alveoli to oxygenate blood
diaphragm relaxes, lungs recoil, thoracic volume decreases, intrathoracic pressure increases and air expelled
What is the most important muscle in respiration?
diaphragm
What innervates the diaphragm?
phrenic nerve (C3-5)
Attachments of diaphragm
anterior: xiphisternum and costal margin
lateral: ribs 6-12
posterior: T12
Accessory muscles of respiration
intercostal muscles sternocleidomastoid scalenus anterior pecs trapezius
How do the icms assist respiration?
contraction of obliquely angled external and internal fibres raises each rib toward the rib above to rasie ribcage
innermost and inner depresses each rib to the rib below, lowering the rib cage
How does the sternocleidomastoid muscle assist respiration?
attaches to manubrium and clavicle and mastoid process on the skull
raises sternum
How does scalenus anterior assist respiration?
prevent rib 1 and 2 from descending
How does do the pecs and trapezius assist respiration?
fix the pectoral girdle to raise rib cage
Movement of the ribs and sternum when breathing
sternum: pump
ribs: bucket handle
lower ribs expand ribcage most for sternum to move
Where are the apex of the lungs and what are they covered by?
above 1st rib
covered by suprapleural membrane (so lungs don’t dip in and out of neck)
What allows the thoracic cavity and lungs to expand?
surface tension between the parietal and visceral pleura
Difference between adults and babies breathing
babies can only breathe via abdominal breathing
newborn ribs more horizontal - no pump/bucket movement
weak icms, use only diaphragm
Dangers of relying on the diaphragm for breathing
high risk for respiratory failure if it is unable to contract
Difference between adults and children breathing
nasal breathers until 4-6 wks shorter neck and narrower airways larger tongue smaller lung capacity, underdeveloped chest muscles higher respiratory rate
Dangers of breathing as a child
narrower airways: more susceptible to blocked airways and respiratory distress
larger tongue: obstruct when unconscious
Where is the costodiaphragmatic recess and what is its clinical relevance?
bottom of right lung
where fluid in the cavity gathers first
Where is the costomediastinal recess?
cardiac notch
What is the carina?
ridge at the point of bifurcation in the trachea to form left and right bronchi
Main types of respiratory distress
- neonatal respiratory distress syndrome: premature babies
- acute respiratory distress syndrome: fluid/proteins leak from blood vessels into alveoli (most common cause is infection eg pneumonia)
Symptoms of respiratory distress
blue coloured extremities, rapid and shallow breathing, rapid heart rate
use of accessory muscles at rest can be a sign
Types of pneumothorax
- non-tension
2. tension
Non-tension pneumothorax
hole in pleural cavity and therefore air can enter and leave
can partially expand, not full capacity
Tension pneumothorax
more severe, hole covered by flap of tissue
lungs can’t expand, air can enter but not escape
mediastinum and heart deviated - arrhythmia and heart pain
Emphysema
type of COPD
inflammatory response, destruction of alveoli
over-inflated alveoli have ineffective gas exchange
on x-ray: hardly any difference between expiration and inspiration
