1 Mechanisms of Ventilation Flashcards
What does the respiratory system consist of?
Nose and nasal cavity, pharynx, larynx, trachea, and lungs
What types of ribs are there (and how many of these are there?)
True (1-7), False (8-10), Floating (11-12)
What is pleura?
A serous membrane that surrounds the lung, containing pleural cavities. 2 types, separated by serous fluid.
Name the two pleural
Parietal and Visceral
Define Parietal pleura
The outer layer; lines the thoracic cavity
Define visceral pleura
The inner layer covers lung and follows the lung fissures
What is the upper respiratory tract made up of?
Nasal cavity, pharynx, larynx (epiglottis), trachea
Name the 3 parts of the pharynx
Nasopharynx, oropharynx, laryngopharynx
Role of epiglottis
Closes off the trachea when food is being swallowed, preventing it from entering the lungs. (It flattens posteriorly when food enters)
List the stages of respiration/breathing
At rest, the diaphragm is relaxed (dome-shaped)
Muscles of respiration contract + expand thoracic cavity - mainly diaphragm (flat)
This increases thoracic volume and decreases intra-thoracic pressure
Air is drawn into lungs from outside (where pressure is greater)
Air passes into terminal bronchioles + alveoli to oxygenate blood
The diaphragm relaxes (dome), lung recoils, thoracic volume decreases, intra-thoracic pressure increases, and the air is expelled
How does the thoracic cage interact with and expand the lungs
When the thoracic cage expands, so does the parietal pleura, which pulls the visceral pleura (and hence the lungs), thus expanding the lungs
What is the most important muscle in respiration?
The diaphragm; dome-shaped, which separates the thorax and the abdomen
What is the innervation of the diaphragm?
Phrenic nerve (C3,4,5 - keeps diaphragm alive)
List the attachments of the diaphragm
Anteriorly: xiphoid process and costal margin
Laterally: ribs 6-12
Posteriorly: T12 Vertebrae
What are intercostal muscles
Muscles which assist in inspiration and expiration, and have obliquely angled fibres from rib to rib
What is the role of the external intercostal muscles?
Contraction of external muscles raises each rib toward the rib above (RAISE RIBCAGE)
[face inwards]
What is the role of internal and innermost intercostal muscles?
Contraction of internal and innermost fibres depresses each rib toward the rib above
(LOWERS RIBCAGE)
[face outwards]
Name the accessory muscles of respiration + list their actions
- Sternocleidomastoid (SCM) muscle raises sternum
- Scalene muscles prevent rib 1 + 2 from descending
- Pecs and trapezius ‘fix’ pectoral girdle to raise rib cage
What is the movement of the rib cage during forced inspiration?
Upwards + Outwards
What is the movement of the rib cage during forced expiration?
Downwards and Inwards
Where are the ribs joined to?
The vertebral body and transverse process of vertebra
What movement do the ribs follow?
Bucket and pump handle movement
- Up movement = bucket handle
- Out movement = pump handle
List features of breathing in babies
Babies can only breathe via abdominal breathing:
- Newborn ribs are more horizontal, so can’t use pump/bucket handle movements
- Intercostal muscles are weak
This abdominal breathing is done by contracting the diaphragm
Why is there a high risk for respiratory failure in babies
Reliance on the diaphragm alone means if it cannot contract, there will be respiratory failure
