Anatomy of the Resp. System Flashcards
Where does the trachea divide?
At the carina which is under the manubrium sterni junction and at the second right costal cartilage
Which lung is inhaled material more likely to end up in?
The right lung because the right main bronchus is more vertical
Bronchi (which are roughly the first 7 divisions after the trachea) have:
Walls consisting of cartilage and smooth muscle, epithelial lining containing cilia and goblet cells and endocrine cells
What endocrine cells are found in the bronchi?
Kulchitsky and amine precursor and uptake decarboxylation (APUD) cells which contain 5-hydroxytryptamine (5HT, serotonin)
Bronchioles (approx. divisions 8-25) have:
No cartilage and a muscular layer which progressively gets thinner, a single layer of ciliated cells, no goblet cells and contains granulated Clara cells which produce surfactant-like substances
Small airways refers to:
Bronchioles < 2mm in diameter
What is the main cell type lining the alveoli (covers largest area)?
Type 1 pneumocytes
What are the properties of type I pneumocytes?
They have a very thin layer of cytoplasm, thin barrier to gas exchange. They are also joined by tight junctions which limit the movement of fluid in and out of the alveoli
How to alveoli of adjoining lobules communicate?
Through pores of Kohn (holes joining them)
Where are type II pneumocytes normally found?
They are found generally in the borders of the alveoli
What are the properties of type II pneumocytes?
They contain lamellar vacuoles which are the source of surfactant, they are more numerous than type 1 but cover less epithelium.
Where are type I pneumocytes derived from?
Type II pneumocytes
What 3 cell types are present in the alveolus?
Type I pneumocytes
Type II pneumocytes
Large alveolar macrophages – to assist with defending the lung
What is a lung fissure?
An invagination in the pleura which separates the lung into lobes
What divides the bronchopulmonary segments?
Fibrous septa which extend inwards from the pleura – each segment is supplied by its own segmental bronchus
What does a terminal bronchiole supply?
An acinus which is just an area of lung within this further divisions in the terminal bronchioles cause alveoli to arise
What are the bronchopulmonary segments divided into?
Individual lobules which are 1 cm diameter pyramidal in shape with their apex at the bronchiole supplying them
Which lobe of the lung is in the front?
The upper lobe is anterior to the lower lobe so the sounds heard from the front relate to the upper lobe (and middle lobe in the right)
Where is the oblique fissure?
It begins just below the T4 vertebrae, moves laterally and inferiorly until it reaches the 6th rib and then follows its curvature anteriorly
Where is the horizontal fissure?
Begins in at the right 4th intercostal space and extents posteriorly until it meets the oblique fissure as it crosses the 5th intercostal space
What is the pleura?
A layer of connective tissue which is covered by a simple squamous epithelium
Where is the visceral pleura?
The pleura which lines the lungs, it lines the interlobar fissures, is continuous at the hilum with the parietal pleura and continues on the bronchial tree until it joins the parietal pleura again
Where is the parietal pleura?
Lines the body wall, and lines the inside of the hemithorax
What way are the visceral and parietal pleura held in health?
They are in apposition except for a small amount of lubricating fluid which also hold them together in tension
What covers the diaphragm?
The parietal pleura above and the peritoneum below
What is the nature of the diaphragm’s muscle fibres?
They arise from the lower ribs and insert into the central tendon, half of the muscle fibres are slow-twitch and have a low glycolytic capacity so are relatively resistant to fatigue
What nerve supplies the diaphragm?
The phrenic nerve from C3 C4 and C5
How does the pulmonary artery reach the alveoli?
It divides to accompany the bronchi then the arterioles follow the bronchioles, they have thin walls and contain little smooth muscle
How is the oxygenated blood drained?
The venules drain laterally to the lobules periphery, then pass centrally in the inter-lobular and intersegmental septa and eventually join to form the 4 main pulmonary veins
How is the lung tissue supplied?
Bronchial arteries arise from the descending aorta and supply tissues down to the level of the bronchioles, the bronchial circulation drains to the pulmonary veins
What are the tracheobronchial lymph nodes?
Pulmonary Bronchopulmonary Subcarinal Superior Tracheobronchial Paratracheal
What is the parasympathetic innervation of the respiratory system?
Comes from the vagus, stimulation of cholinergic postganglionic fibres causes the M3 receptors on the smooth muscle to cause muscle contraction and increased mucus secretion by goblet cells, when postganglionic noncholinergic fibres are stimulated the smooth muscle relaxes due to the mediation from nitric oxide (NO) and vasoactive intestinal peptide (VIP)
What is the sympathetic innervation of the respiratory system?
The sympathetic nervous division stimulates the B2 receptors which cause bronchial smooth muscle relaxation and decreased mucus secretion and increased mucociliary clearance. Sympathetic stimulation also causes contraction of the vascular smooth muscle, this is mediated by A1-ADR on the vascular smooth muscle
What comprises the upper respiratory tract?
nasal cavities
oral cavity
pharynx
larynx
What makes up the lower respiratory tract?
the respiratory tree - trachea right and left main bronchus lobar bronchi segmental bronchi bronchioles alveoli
what happens to the respiratory tract at the level of the C6 vertebrae?
the larynx becomes the trachea
and the pharynx becomes the oesophagus
how many bronchopulmonary segments does each lung have?
10
what lines the inside of the bronchial tree up to but not including the distal bronchioles?
mucous glands which secrete mucous onto the epithelial surface
cilia - eyelashes which beat to sweep the mucous and anything stuck in the mucous superiorly to the pharynx to be swallowed - the mucociliary escalator
Name 2 things which interfere with the normal beating of cilia
cooling/ drying of the mucosa
toxins in cigarette smoke
what is a wheeze?
the sound of air passing through constricted or narrowed airways
what is the hyaline cartilage and what is it’s purpose?
it supports the walls of the trachea and the bronchi
helps to keep them patent
as you progress down the respiratory tree there is progressively less cartilage
no cartilage in most distal bronchioles and alveoli
where is there smooth muscle in the lungs?
there is progressively more smooth muscle as you go distally and is the most prominent in the bronchioles allowing them to constrict and dilate
there is no smooth muscle in the alveoli because it would inhibit diffusion
what is needed to ensure enough O2 and CO2 can diffuse between the alveolus and blood at the pulmonary capillary beds?
- sufficient functioning lung tissue
- sufficient O2 in the air we breathe in
- no CO2 in the air we breathe in
- minimal thickness of the walls of the alveoli (air sacs) to facilitate gaseous diffusion
- minimal tissue fluid in the tissue spaces around the alveolar capillaries to facilitate gaseous diffusion
What are the 2 main ways air can be stopped from moving freely in and out of the lungs?
- the respiratory tract narrowing e.g. because bronchioles constrict, there is a swelling of mucosa - over production or a tumour externally pressing
- foreign bodies which have been inhaled
what makes up the nasal septum?
the bony (posterior) part which is the ethmoid bone superiorly and vomer inferiorly the cartilagionous (anterior) part of the nasal septum
how many nasal cavities are there and what do the contain?
there are 2 nasal cavities each with
a relatively featureless medial wall
an interestingly featured lateral wall
a floor (formed from the palate)
a roof (formed by the midline part of the floor of the anterior cranial fossa)
What are the functions of the larynx?
- Cartilages help to maintain the patency of the URT
- Helps to prevent the entry of foreign bodies into the LRT (the vocal cords)
- Produces sound (the vocal cords
what cartilages make up the skeleton of the larynx (voice box)?
the epiglottis
the thyroid cartilage
the cricoid cartilage
the 2 arytenoid cartilages (posteriorly)
what is the narrowest part of the larynx?
the rima glottidis
where in the URT do large foreign bodies tend block?
at the rima glottidis
how do the vocal cords protect the airway?
they can approximate in the midline to close the rima glottidis and prevent the foreign body being inhaled into the trachea directly inferior
a cough reflex can then be stimulated to expel the body
how do the vocal cords produce voice?
2 steps
Phonation - producing sound - air is expired over the vocal cords and they vibrate to produce sound
Articulation - producing speech - the sound is modified in the nose or mouth to make vowels and consonants
What are the aims of the heimlich manoeuvre?
for when there is a body lodged at the rima glottidis and an intake of breath for a cough is not possible
- raise the abdominal pressure
- which will force the diaphragm superiorly
- which will raise the pressure in the chest
- which will raise the pressure in the lungs
- which will force air from the lungs into the trachea
- which will force air through the rima glottidis to expel the foreign body out of the URT
What can inhibit the warming, moistening and cleaning of air in and out of the lungs?
- cooling and drying out of the respiratory tract - damages the mucociliary escalator & predisposes to infection
- breathing in infected foreign bodies or bacteria/viruses etc. - causes infection (commonly of the nose/throat/larynx/lungs)
How is the air warmed, humidified and cleaned when we breathe in?
- the conchae greatly increase the surface area of the lateral walls of the nasal cavities and produce turbulent flow bringing the air into contact with the walls
- the respiratory mucosa lining the walls of the nasal cavities has a very good arterial blood supply providing warmth
- the respiratory mucosa produces mucous providing moisture
- the “sticky” mucous traps potentially infected particles
- the cilia of the mucosa waft the mucous to the pharynx to be swallowed (into gastric acid)
what are the parts of the pharynx?
nasopharynx - posterior to the nasal cavities
oropharynx - posterior to the oral cavity
laryngopharymx - posterior to the larynx
what is the normal route for air when breathing in?
nasal cavities nasopharynx oropharynx laryngopharynx larynx trachea