Week 1 Flashcards
Thoracic cage is comprised of?
- 12 thoracic vertebrae
- 12 pairs of ribs
- Sternum
Function of thoracic cage
House and protect the internal organs
Thoracic cavity is limited superiorly by?
First ribs (surrounding the thoracic inlet)
Thoracic cavity is limited inferiorly by?
Muscular diaphragm (closing off the thoracic outlet)
Domes of the diaphragm lie at approximately the?
5th intercostal space during expiration
Between the ribs, the intercostal space is bridged by?
External, internal and innermost intercostal muscles
Between internal and innermost intercostal muscle layers resides a neurovascular bundle consisting of?
- Intercostal vein
- Intercostal artery
- Intercostal nerve
Intercostal vein drains into?
Azygous and hemi-azygous venous systems
Intercostal artery is supplied by the?
Aorta
Intercostal nerve branches off the _____ and passes through the _______.
Thoracic spinal cord segments; sympathetic trunk
Principle muscle of respiration
Diaphragm
Diaphragm is innervated by?
2 phrenic nerves (left and right)
2 phrenic nerves originates from?
Cervical spinal cord segments C3-5
Pneumonic for C3-5
C3-4-5 keeps the diaphragm alive
What happens to diaphragm during quiet inspiration?
Diaphragm descends to increase the thoracic volume and produce a corresponding decrease in intrathoracic pressure
Decrease in intrathoracic pressure promotes?
Promotes passage of air into the lungs
During passive expiration, what happens to diaphragm?
Diaphragm recoils to decrease the thoracic volume producing a corresponding increase in intrathoracic pressure causing air expulsion.
Contraction of the intercostal muscles causes?
Increases intrathoracic volume by elevating and separating the ribs
During periods of increased oxygen requirement (e.g. exercise, airway obstruction), which muscles become active?
Accessory muscles of inspiration activate and elevate the ribs to further increase intrathoracic volume.
Accessory muscles of inspiration include
- Pectoralis minor
- Scalenes
- Sternocleidomastoid
- Intercostal muscles
During forced expiration (e.g. blowing up a balloon, playing a trumpet), which muscles activate?
Contraction of abdominal muscles increases intrathoracic pressure facilitating air exit from the lungs
Air passes to the lungs from the upper respiratory system via the?
Trachea
Trachea begins at ?
At the inferior border of the larynx (CV6)
Trachea is kept patent (held open) by?
16-20 C-shaped rings of hyaline cartilage that are open posteriorly and completed by the trachealis muscle (smooth).
C-shaped rings of hyaline cartilage and trachealis muscle permits what?
Permits expansion of the posteriorly related oesophagus during swallowing
Trachea bifurcates at?
At the carina to form 2 cartilage ring reinforced primary bronchi behind the manubriosternal joint (sternal angle)
Two primary bronchi is located behind?
Behind the manubriosternal joint
Inhaled objects are more likely to be trapped in which bronchus?
Right primary bronchus as it is shorter, wider and more vertically oriented than the left.
Cartilage-containing primary bronchi further divide to form?
Cartilage-containing secondary bronchi
Cartilage-containing secondary bronchi further divide to form?
Cartilage-containing tertiary bronchi
Cartilage-containing tertiary bronchi divide to form?
Cartilage-deficient terminal bronchioles
Terminal bronchioles go on to form?
Respiratory bronchioles
Respiratory bronchioles ultimately end in the?
Alveoli
Left lung comprises an?
Upper and lower lobe separated by an oblique fissure
Right lung comprises an?
Upper, middle and lower lobe separated by oblique and transverse fissures
Bronchi and pulmonary vessels form the?
Lung root
Lung root passes through the?
Pulmonary hilum of the lung
Space between lungs is the?
Mediastinum
Lungs and thoracic wall are intervened by?
2 layers of pleura
Parietal pleura lines?
Lines the inner aspect of the thoracic wall
Visceral pleura invests the?
Lungs, intervening betweent he lobes
2 layers of pleura are held together by ?
Surface tension due to a small amount of fluid in the pleural space (pleural cavity)
Pleural fluid allows?
The visceral and parietal pleura to slide over one another but resists separation of the pleural layers.
Liquid surface tension between the pleural layers counteracts the tendency for?
For thoracic wall to expand outwards and the elastic lungs to recoil inwards.
The presence of air in the thoracic cavity is referred to as a ?
Pneumothorax
Pneumothorax is due to a?
Direct communication of the pleural space with atmospheric air
Pneumothorax disrupts?
Disrupts the fluid surface tension and results in separation of the pleural layers and a consequential recoil or collapse of the related lung
Lungs and visceral pleura only receive autonomic innervation with the parasympathetic control arising from?
Vagus nerves (cranial nerve X)
Sympathetic control of lungs and visceral pleura is governed by?
Sympathetic trunks
The parietal pleura is innervated by?
Nociceptors (detectors of noxious stimuli, usually perceived as painful)
Nociceptors send signals regarding?
Pleural stretch, inflammation or trauma to the brain via the intercostal nerves (within the intercostal space) and the phrenic nerves (around the hilum)
Sub-pleural lymphatic plexus drains to the?
Hilar lymph nodes
Lungs receive deoxygenated blood from the heart via the?
Pulmonary arteries
Oxygenated blood return to the heart via the?
Pulmonary veins
Surface of the lungs is covered by a?
Thin layer of connective tissue and mesothelial cells which is in close contact with a similar layer of tissue covering the interior surface of the chest wall
Between the parietal pleura and visceral pleura, what is the total volume of the pleural space?
2 ml in total volume which spreads over the surface area of the lungs
Thickness of pleural layer is only about?
10-30 um
Surface mesothelial cells of the visceral pleura have a ?
High density of microvilli to enhance absorption
Parietal mesothelial cells have a?
Lower density of microvilli
Microvilli function on mesothelial cells?
They also trap glycoproteins which act as a lubricant between the surfaces of the constantly moving lungs and chest wall
Pleural pressure changes with lung volume during the breathing cycle because?
Lung becomes stiffer (less compliant) with expansion
In the erect position, lower thoracic pleural changes from?
-0.5 to -33 cm H2O
In erect position, upper thoracic pleural pressure changes from?
-8.5 to -40 cm H2O as the lung expands from functional residual capacity (FRC) to total lung capacity (TLC).
The lower parts of the lung expand more during
Inspiration, because they operate on a more compliant part of the volume pressure relationship