Respiratory system anatomy Flashcards
What is the function of the respiratory system?
Ventilation and gas exchange - absorbing oxygen and removing carbon dioxide,
Immunological role - trapping inhaled pathogens. e.g. the tonsils monitor and detect pathogens and bacteria in the inspired air.
What is the upper respiratory tract?
Nasal cavity
Pharynx
Larynx
What is the lower respiratory tract?
Trachea
Bronchi
Lungs
Where are the lungs?
The lungs and trachea are located in the thoracic cavity, surrounded by a bony thoracic wall.
Has functions of protection of the heart and lungs.
Muscles pull on the bones and cause changes in the shape and dimensions of the thoracic cavity, important for breathing.
What are the functions of the bony thoracic cage?
Respiration
Protection
Conduit for passage of other structures in and out of the cavity.
What are the components of the thoracic cage?
The sternum is anterior, down the midline.
Attached are 12 pairs of ribs, that are typical and atypical.
There are also 12 thoracic vertebrae, 1 for each pair of ribs to attach to posteriorly.
What are the regions of the vertebrae?
The vertebrae are the individual bones that make up the vertebral column.
Cervical region
Thoracic region
Lumbar region
What is the superior thoracic aperture of the thoracic cage?
This is the superior (top) opening.
This contains the T1 vertebra, and the 1st rib, and 1st costal cartilage.
It also contains the upper part of the sternum - the manubrium of sternum.
What is the inferior thoracic aperture?
This is where the diaphragm attaches, inferiorly.
This contains the T12 vertebra, the inferior border of rib 12 and the tip of rib 11.
It also has the costal (lower) margin of ribs 7-10.
It contains the lowest part of the sternum - the xiphoid process.
What is the thoracic cavity?
This is the cavity where the organs sit.
The cavity is smaller than the thoracic cage because of the diaphragm.
The diaphragm is a fibromuscular partition which divides the thoracic cavity from the abdominal cavity.
The diaphragm domes upwards superiorly into the thoracic cavity, so it is smaller than the cage.
What is the diaphragm supplied by?
Supplied by the left and right phrenic nerve from C3,C4,C5, which enters through the superior thoracic aperture, to the diaphragm muscle fibres for contraction.
If this is damaged it will impact on breathing.
The diaphragm is also pierced by structures passing through the thoracic cavity to or from the abdominal cavity - arteries, veins and nerves.
What is the diaphragm?
The main muscle of respiration.
It is shaped like a dome, so when it contracts, it pulls the central tendon downwards, and increases the space within the chest wall.
This increase volume creates a negative pressure, so air rushes in to fill this space.
When the diaphragm relaxes, the tendon returns to its position, so volume decreases.
What are the structures passing through the diaphragm?
The inferior vena cava, which will then ascend upwards through the diaphragm to the heart.
The oesophagus.
The thoracic aorta, which then crosses through the diaphragm and becomes the abdominal aorta.
The heart sits on top of the diaphragm, and the pericardium blends with the diaphragm to hold the heart in place.
What are typical ribs?
The head attaches to the vertebrae.
Rib curves round anteriorly towards the costal cartilage which attaches to the sternum.
Costal groove on underside of rib - important as where vessels and nerves pass in.
Ribs 2-11.
What are atypical ribs?
Rib 1 - short and broad, many muscles attach so has grooves.
Rib 12 is short and thin, it has no costal cartilage, and doesn’t curve.
How do the types of ribs differ?
True ribs, have their own individual costal cartilage to attach to the sternum.
False ribs attach to the common cartilage from rib 7, then attach to the sternum.
Floating ribs do not attach to the sternum - no costal cartilage.
What is the movement of the ribs?
The movement of the ribs change the pressure and volume in the thoracic cavity.
When inspiring, the muscles elevate the ribs medially to laterally, and increases the space.
The ribs are also moved posteriorly to anteriorly.
What are the intercostal muscles?
External intercostals - elevates the rib when breathing in.
Internal intercostals - depresses the rib above while breathing out.
Innermost intercostals - depresses the rib while breathing out.
What are the vessels in the intercostal muscles?
Between the upper and lower rib there are vessels - intercostal vein, artery and nerve.
These are found in between the internal intercostal muscle and the innermost intercostal muscle.
How do the intercostal muscles contract during inspiration?
The external intercostal muscle contracts, and pulls the lower rib upwards and laterally.
This increases the space in the thoracic cavity.
How do the intercostal muscles contract during expiration?
The muscle fibres of internal and innermost intercostal muscle are orientated in the opposite direction to the external intercostal muscle.
So when the internal and innermost intercostals contract, they pull the rib above downwards and inwards, bring to original position.
This decreases the space in thoracic cavity.
What are the vessels in the ribs?
The vessels come from the front and back of the rib and join together to form a long continuous vessel that travels in the intercostal spaces.
The costal groove is where the intercostal nerve, vein and arteries travel in and provide additional collateral branches, down to superior border of the rib above it.
As they travel in intercostal spaces, supply blood and innervation to the intercostal muscles.
What are the inspiratory muscles?
Sternocleidomastoid elevate the sternum.
Scalenes elevate the ribs.
External intercostals elevate the ribcage.
The diaphragm.
What are the expiratory muscles?
The internal intercostals depress the ribcage.
The abdominal muscles compresses the abdominal cavity and pushes the diaphragm upward:
The external obliques
The rectus abdominus
Transverse abdominis
Internal obliques.
What happens in the nasal cavity?
Air passes into the cavity via the anterior nasal aperture, and becomes warmed and humidified by turbinates.
The nerves in the roof of the nasal cavity sense smell.
The paranasal air sinuses are beside the nasal cavity, they are large gaps that fill with air.
Sinuses can become inflamed and fill with mucous.
What is the pharynx?
Located behind the nasal and oral cavity.
It is used by both the digestive tract and respiratory tract.
What are the subdivisions of the pharynx?
Nasopharynx, behind the nasal cavity.
Oropharynx, behind the oesophagus.
Laryngopharynx, behind the larynx
What are turbinates?
These moisten and warm the air.
They are bones that form grooves, covered by a mucosal lining.
There are 3 grooves - superior, middle and inferior meatus.
Air flows through the grooves, and this creates a more complex path of breathing which slows air down, so it can be warmed and humidified.
What is the skeletal structure?
Air flows through the anterior nasal aperture.
The midline septum divides the left and right sides.
The middle and inferior concha form bony folds to humidify and warm the air.
What is the larynx?
The voice box - it contains the vocal cords.
It is made from cartilage.
The epiglottis cartilage closes over the supraglottis above the larynx to prevent food and drink going into the trachea.
What are the folds of the larynx?
There is a vestibular fold and a vocal fold.
When breathing, the vocal cords are open.
When you speak, the folds come together and vibrate the air as you breathe out, which produces speech.
What is the trachea?
Connects the larynx to the bronchi.
Surrounded by C-shaped cartilaginous rings, C-shaped so it doesn’t compress the oesphagus, so it can expand when eating.
What are the components of the bronchi?
Primary lobar bronchi - right is shorter, wider and more vertical.
Secondary lobar bronchi - which is divided into superior, middle and inferior bronchi which go to different lobes of the lung.
Tertiary lobar bronchi , which form 10 bronchopulmonary segments.
What is the bronchial tree?
Tubular structures which continuously divide and get smaller.
They divide the bronchi into the conduction airway and respiratory airway.
The conducting airway moves air, no gas exchange.
The respiratory airway is where gas exchange occurs, ends at the alveolar sacs.
How does the bronchial tree change structure?
It begins to lose cartilaginous support.
Smooth muscle surrounds the bronchioles, it can constrict and dilate.
The alveoli are surrounded by capillary networks for gas exchange.
What are the lungs?
The site of gas exchange.
They sit within the pleural cavity surrounded by the pleural membrane.
The pleural membrane has 2 layers - the parietal and visceral pleura.
What is the hilum of the lung?
This is where structures enter and leave - bronchi, pulmonary artery and veins.
What are the lobes of the left lung?
The left lung has 2 lobes, which is less because the heart takes up space.
The oblique fissure is a groove that separates the superior and inferior lobe of the left lung.
What are the lobes of the right lung?
The right lung has 3 lobes.
The oblique fissure separates the middle and inferior lobes.
The horizontal fissure separates the middle and superior lobes.
What are the pleura of the lungs?
The parietal pleura is in contact with the ribs and intercostal muscles.
The visceral pleura is in direct contact with the lungs, and goes deep into the fissures.
What is the space between the visceral and parietal pleura?
There is a pleural cavity which secretes fluid for lubrication and facilitates the movement of the lung.
It also produces a negative pressure against the elasticity of the lungs, which keeps the lungs attached to the walls of the thorax, and prevents the lungs collapsing.
The pleural cavity can fill with excess air or fluid in disease or injury and cause a collapsed lung.
