Session 1.1a - Workbook Notes (Anatomy) Flashcards
Pre-Reading
Revise Body Logistics: Respiratory System (Session 9)
See Session
Explore the anatomy of the Respiratory System and relate its structure to function.
Session Aim
Describe how the structure of the nose and paranasal sinuses is conducive to warming, humidifying and filtering /trapping particles in inspired air
ILO
Describe how the larynx protects the airway during swallowing
ILO
Explain why hoarseness of voice/voice change may be a sign of intra-thoracic
disease
ILO
Describe the structure of the bony thorax including the features of a typical rib and thoracic vertebra.
ILO
Describe rib movements during respiration
ILO
Describe the external, internal and innermost intercostal muscles and the diaphragm, their nerve supply and actions in respiration.
ILO
Describe the course of the intercostal nerves, arteries and veins and how to avoid damaging them during pleural aspiration or insertion of a chest drain.
ILO
Describe the pleural cavity & pleura, including its nerve supply and the role of the pleural fluid and the pleural seal in lung expansion
ILO
Describe the lungs and the lower respiratory tract, its blood and nerve supply and lymphatic drainage.
ILO
Describe structures in the root of the neck and mediastinum, which are closely related to the lung and explain the effects of involvement of these structures by pathological processes in the lung or thoracic cavity
ILO
Describe the surface marking of the lungs & lobes of the lung, the extent of the pleural cavity (the lines of pleural reflection) and the dome of the diaphragm and understand the clinical implications of this information.
ILO
Describe the structure (histology) of the airways and alveoli and relate it to the functions and defence of the lungs. (covered in body logistics lecture)
ILO
Distinguish bronchi from bronchioles. Define what is meant by a terminal bronchiole, respiratory bronchiole, alveolar duct and alveolus. (covered in body logistics lecture)
ILO
Distinguish between the conducting zone and the respiratory zone of the airways. (Covered in body logistics lecture).
ILO
Describe the mechanisms which protect the lung from inhaled particles, including function of the muco-ciliary escalator. (Covered in body logistics).
ILO
Name and identify the following on a prosection: (detailed list on page 31)
- Diaphragm, intercostal muscles, intercostal arteries, veins and nerves
ILO
Name and identify the following on a prosection: (detailed list on page 31)
- The Parietal and visceral pleura and the costo-diaphragmatic recess
ILO
Name and identify the following on a prosection: (detailed list on page 31)
- Veins: Internal thoracic arteries and veins, azygous vein, SVC and aorta
ILO
Name and identify the following on a prosection: (detailed list on page 31)
- Nerves: intercostal nerves, phrenic nerves, Sympathetic trunk, Vagus nerves and left recurrent laryngeal nerve (if possible)
ILO
Name and identify the following on a prosection: (detailed list on page 31)
- Lung: surfaces & borders, oblique and horizontal fissures, lobes of the lungs, the hilum of the lungs and the main bronchus, pulmonary artery and pulmonary veins at the hilum.
ILO
What does the anatomy of the respiratory system contain?
- The upper respiratory tract (URT)
- Nose & Paranasal sinuses
- Pharynx
- Larynx
Where does the URT extend from?
The nostrils to the lower border of the cricoid cartilage of the larynx
Where does the URT begin?
The nostrils
What does the URT consist of?
It comprises the nose & paranasal sinuses, Pharynx and Larynx.
Note: These structures & their functions will be studied in depth in H&N. In this unit, focus is limited to their structure & function as relevant to respiration.
How is the nasal cavity divided into right & left cavities?
By the MEDIAN NASAL SEPTUM
The median nasal septum divides what?
The NASAL CAVITY into right & left cavities.
How many bony projections does the lateral wall of each nasal cavity contain?
3
What are the bony projections found on the lateral wall of each nasal cavity called?
CONCHAE or TURBINATES
The nasal conchae, or turbinates, are found where?
On the LATERAL WALL of each nasal cavity
What are the paranasal sinuses?
4 air containing cavities
What are the 4 air containing cavities that surround the nasal cavity called?
THE PARANASAL SINUSES
What are the paranasal sinuses called?
Named for the skull bones within which they are situated, the:
- frontal
- ethmoidal
- maxillary
- spheroidal
sinuses
What lines the paranasal sinuses?
PSEUDO STRATIFIED CILIATED COLUMNAR EPITHELIUM (respiratory epithelium)
What is pseudo stratified ciliated columnar epithelium sometimes known as?
Respiratory epithelium
(- because this type lines most of the URT
- however, it is a misnomer, because there is no significant exchange of O2 and CO2 here)
Where do the paranasal sinuses open into?
The spaces below the turbinates in the nasal cavity.
What does the mucosa lining the area presented by the turbinates and the paranasal sinuses do?
Allows inhaled air to be WARMED AND HUMIDIFIED.
Describe the mucosa lining the area presented by the turbinates and the paranasal sinuses. Hint: it allows the inhaled air to be warmed and humidified.
It is VASCULAR
Describe the area presented by the turbinates and the paranasal sinuses. Hint: it is lined by vascular mucosa
The turbinates and the paranasal sinuses present a LARGE SURFACE area.
As well as the vascular mucosa aiding in warming and humidifying inhaled air, how else is this achieved?
The turbinates also cause turbulence & slow down airflow, increasing the time available for warming and humidification.
Which structure(s) cause turbulence and slow down airflow to aid in warming and humidificaiton of inhaled air?
The turbinates
How do the turbinates warm and humidify inhaled air?
- They have VASCULAR mucosa which line the LARGE SURFACE area presented by them (and the paranasal sinuses)
- They cause turbulence & slow down airflow, increasing the time available for warming and humidification
Air is heated to what temperature on passage through the nose?
Approximately to body temperature
Inhaled air is heated approximately to body temperature. Where?
On passage through the nose
How is inhaled air humidified?
This is achieved by transudation of fluid through the epithelium and to a lesser extent by mucus secretion.
What is the main mechanisms of air humidification in the nose?
Transudation of fluid through the epithelium
The epithelium plays the main role in humidifying air in the nose. How else can it be humidified?
To a lesser extent, by mucus secretion.
What is transudation?
Passage of a fluid or solute through a membrane by a hydrostatic or oncotic pressure gradient.
What is each nostril lined with?
Coarse hairs
What is the function of the coarse hairs which line each nostril?
To trap large particles in inhaled air.
What is mucus secreted from?
Goblet cells
What do goblet cells secrete?
Mucus
What is the function of the mucus secreted by the goblet cells?
Traps almost all particles >5 micrometres.
How do we ‘dispose’ of the mucus?
The cilia waft the mucus to oropharynx where it is swallowed.
What structure gets rid of the mucus?
The cilia
Describe the role of the pharynx in the aerodigestive tract.
AIR & FOOD HAVE A COMMON PASSAGE THROUGH PARTS OF THE PHARYNX.
Air & food have a common passage through parts of the pharynx. Why is this important to note physiologically?
Mechanisms to prevent aspiration (inhalation) of food particles during swallowing are important (see later).
What complications can occur if physiological mechanisms to prevent aspiration fail?
Failure of these mechanisms can cause aspiration of food particles/liquid, leading to potentially life-threatening airway obstruction and/or infection (aspiration pneumonia).
What does the larynx link?
It links the pharynx to the trachea
What does the larynx contain?
The VOCAL CORDS
Where are the vocal cords found?
They guard the entrance to the trachea.
What are the vocal cords also known as?
The VOCAL FOLDS, OR VOCAL LIGAMENTS.
The vocal cords + the aperture (holes) between the cords are together termed as ___?
The ‘GLOTTIS’.
What is this glottis?
The vocal cords + the aperture between the cords together.
What happens to the laryngeal inlet during swallowing?
It becomes narrowed
What narrows during swallowing?
The laryngeal inlet
What happens to the epiglottis during swallowing?
It folds downwards (like a lid) over the laryngeal inlet
What happens to the vocal cords during swallowing?
They come together (are adducted)
Why do the vocal cords adduct during swallowing?
To act as a SPHINCTER CLOSING OFF THE ENTRANCE TO THE TRACHEA.
What happens during swallowing?
- The laryngeal inlet becomes narrowed
- The epiglottis folds downwards (like a lid) over the laryngeal inlet
- The vocal cords come together (are adducted) to act as a SPHINCTER CLOSING OFF THE ENTRANCE TO THE TRACHEA.)
The movements of the vocal cords are caused by the action of ___?
The INTRINSIC LARYNGEAL MUSCLES
The intrinsic laryngeal muscles control ___?
The movement of the vocal cords
What nerve supplies all intrinsic muscles (except the cricothyroid muscle)?
The RECURRENT LARYNGEAL NERVE
What does the recurrent laryngeal nerve supply?
All intrinsic muscles, except the cricothyroid muscle
The recurrent laryngeal nerve on the ____ side has a long course.
left
The recurrent laryngeal nerve on the left side has a ____ course.
long
The recurrent laryngeal nerve on the left side has a long course, part of which is ___?
inside the thoracic cavity
How can intra-thoracic disease result in a hoarse voice?
It can compress or infiltrate the left recurrent laryngeal nerve, which runs into the thoracic cavity, paralysing the left vocal cord and resulting in a hoarse voice.
Give examples of intra-thoracic disease.
- Aortic aneurysm
- Lung cancer
What can intra-thoracic disease do to the left recurrent laryngeal nerve?
It can compress or infiltrate it
What symptom, related to the larynx, can result from intra-thoracic disease?
A hoarse voice
Compression or infiltration of the recurrent laryngeal nerve can cause what ___?
Paralysis of the ipsilateral vocal cord.
What problems can occur if there is dysfunction in the vocal cords?
- Aspiration
- Cough reflex
- Airway obstruction
- Voice change
What occurs in aspiration?
If the larynx and vocal folds are dysfunctional, the trachea may not be properly closed off during swallowing, hence there is a risk of inhalation (aspiration) of food/liquid.
What should occur normally during swallowing?
The larynx and vocal cords come together, to close off the entrance to the trachea.
What can a dysfunctional larynx/vocal cord lead to?
Aspiration (inhalation) of food/liquid - as the trachea may not be properly closed off during swallowing.
How are the vocal cords involved in the cough reflex?
The ability to close the vocal cords is necessary to build up intra-thoracic pressure during the early part of the cough reflex. This is followed by the sudden opening of the vocal folds which then causes the air to be expelled at high velocity.
What is the cough reflex?
A protective mechanism to expel inhaled particles. It also serves as a clearance mechanism for disposing of excessive secretions from the airways.
How are the vocal folds involved in airway obstruction?
The opening between the vocal folds can present as airway obstruction & difficulty in breathing (choking), which can be an emergency.
Voice change can be one of the first signs of ___?
Serious intra-thoracic disease
Why is voice change one of the first signs of intra-thoracic disease?
Due to involvement of the left recurrent laryngeal nerve in the thorax.
The thoracic cavity and lungs include:
- The bony thorax: sternum, ribs, thoracic vertebrae, costovertebral joints and rib movements
- Intercostal muscles
- Pleura and pleural cavity
- The trachea and bronchial tree
How do the structures of the thoracic cavity work together?
The bony thorax, intercostal muscles and the diaphragm function together as a “respiratory pump” to ventilate the lungs, while the organisation of airways and blood vessels provides the interface for gas exchange.
Which bits of the thoracic cavity act as the respiratory pump, and which acts as an interface for gas exchange?
- Respiratory pump (for lung ventilation): bony thorax, intercostal muscles, diaphragm
- Gas exchange: organisation of airways and blood vessels
Describe the bony thorax
https://teachmeanatomy.info/thorax/bones/
What does the sternum consist of?
The manubrium, body and the xiphisternum
What happens to the xiphisternum?
It remains cartilaginous into adult life.
What do the manubrium, body and the xiphisternum make up?
THE STERNUM
What is the junction of the manubrium & body known as?
The STERNAL ANGLE
What is the sternal angle?
The junction of the manubrium & body.
How can you find your sternal angle?
It is felt as a transverse ridge on palpation of the sternum.
What articulates with the sternum at the level of the sternal angle?
The 2nd costal cartilage
What does the 2nd costal cartilage articulate with?
The sternum at the level of the sternal angle.
How can you identify which rib you are palpating?
Hint: think 2nd rib
The 2nd costal cartilage articulates with the sternum at the level of the sternal angle. This enables the 2nd rib to be identified, and the rest of the ribs can be counted downwards from here.
What are the bony landmarks of a typical rib?
THE RIBS: ‘A ‘typical’ rib (ribs 3-9) has a head, a neck, a turbercle, and a shaft. (see lecture slides)
Describe the head of the rib.
The HEAD has 2 articular facets which articulate with the body of the corresponding vertebra and the vertebra above.
What do the 2 articular facets at the head of the rib articulate with?
With the body of the corresponding vertebra and the vertebra above.
Describe the tubercle of the rib.
The TUBERCLE has one articular facet for articulation with the transverse process of the corresponding thoracic vertebra.
What does the articular facet at the tubercle articulate with?
The transverse process of the corresponding thoracic vertebra.
Describe the shaft of the rib.
The flat, CURVED SHAFT has a groove (the costal groove) on its inner aspect, near the lower border in which the intercostal vessels & nerve run.
Where do the intercostal vessels & nerve run?
In the costal groove, found on the inner aspect near the lower border of the flat, CURVED SHAFT.
Describe the costovertebral joints.
There are 2 synovial joints which connect the ribs with the thoracic vertebrae. The movements of the ribs during respiration take place at these joints.
What type of joint connects the ribs with the thoracic vertebrae?
Synovial joints.
The movements of the ribs during respiration occurs where?
At THE COSTOVERTEBRAL JOINTS.
How many intercostal muscles are there?
3 - external, internal and innermost.
What are the intercostal muscles innervated by?
The intercostal nerves
Describe the role of the intercostal muscle in respiration.
See other questions
What does each intercostal space contain?
3 muscles: the external, internal and innermost intercostal muscles.
Where are the intercostal muscles found?
All 3 are found in each intercostal space.
Name the intercostal muscles from superficial to deep.
- THE EXTERNAL INTERCOSTAL MUSCLES
- INTERNAL INTERCOSTAL MUSCLES
- INNERMOST INTERCOSTAL MUSCLES
Describe the fibres of the external intercostal muscles.
The fibres of these muscles run downwards & anteriorly from the inferior margin of the rib above to superior margin of the rib below.
What are the external intercostal muscles responsible for?
RESPONSIBLE FOR ABOUT 30% OF CHEST EXPANSION DURING QUIET RESPIRATION.
Which type of respiration are external intercostal muscles involved in?
QUIET RESPIRATION
How much of the chest expansion are the external intercostal muscles responsible for?
ABOUT 30%
What occurs when the external intercostal muscles contract?
Contraction of the muscles elevates the ribs in a ‘bucket handle’ type of movement to increase the antero-posterior and transverse diameters of the chest.
How are the ribs elevated when the external intercostal muscles contract?
In a ‘bucket handle’ type of movement
Why do the external intercostal muscles contract in a ‘bucket handle’ type of movement?
To increase the antero-posterior and transverse diameters of the chest.
Where do the fibres of the internal intercostal muscles lie?
The fibres of these muscles run downwards & posteriorly from the rib above to rib below.
What do the internal intercostal muscles do?
Their action pulls the ribs down from the position of chest expansion.
When are internal intercostal muscles active?
During FORCED expiration (quiet expiration is passive).
Which action is passive during respiration?
Quiet expiration.
What are innermost intercostal muscles?
They are similar to the internal intercostal muscle but are less well developed.
What do the innermost intercostal muscles do?
They act along with the internal intercostal muscles during forced expiration.
Describe the muscles of the thoracic cage.
https://teachmeanatomy.info/thorax/muscles/thoracic-cage/
What supplies the intercostal muscles?
The intercostal arteries, veins and nerves.
What do the intercostal arteries, veins and nerves supply?
They supply/drain the intercostal muscles, parietal pleura & overlying skin (see lecture).
Describe the diaphragm, its innervation and role in respiration.
https://teachmeanatomy.info/thorax/muscles/diaphragm/
What is the diaphragm the main muscle of?
Inspiration
What is the diaphragm responsible for?
RESPONSIBLE FOR >70% OF CHEST EXPANSION IN QUIET RESPIRATION.
What structures are involved in chest expansion during quiet respiration?
- Diaphragm (>70%)
- External intercostal muscles (~30%)
What is the main structure of inspiration?
The diaphragm
What structures are involved during forced expiration?
Internal intercostal muscles, helped by the innermost intercostal muscles.
What structures are involved during quiet expiration?
This is passive!
Describe the structure of the diaphragm.
The diaphragm is dome shaped and bulges into the thorax.
Where do the diaphragmatic peripheral muscular fibres arise from?
Its peripheral muscular fibres arise from the lower margin of the thoracic cavity (i.e. the inner aspect of the xiphisternum, inner aspects of the 7-12 costal cartilages, the arcuate ligaments and the crura of the diaphragm), and insert into the central tendon.
Which fibres of the diaphragm arise from the lower margin of the thoracic cavity?
Its peripheral muscular fibres.
Where are the peripheral attachments of the diaphragm?
- The inner aspect of the xiphisternum
- Inner aspect of the 7-12 costal cartilages
- Arcuate ligaments
- Crura of the diaphragm
Where do the muscle fibres of the diaphragm converge?
They combine to form and insert into the central tendon.
What does the central tendon fuse with?
It fuses superiorly with the inferior part of the fibrous pericardium.
What is the diaphragm innervated by?
The right and left phrenic nerves
Where do the phrenic nerves arise from?
C3-C5 (in the neck)
What happens to the diaphragm on contraction?
The diaphragm moves downwards to increase vertical diameter of thoracic cavity.
What can occur if you damage the phrenic nerve?
This causes paralysis of the affected side of the diaphragm.
How does a damaged phrenic nerve appear on an x-ray?
Damage to the phrenic nerve causes paralysis of the affected side of the diaphragm.
On a chest x-ray, this would appear as an elevated hemi-diaphragm.
The diaphragm has openings for which structures?
The IVC, the oesophagus and the aorta.
Where is the diaphragmatic opening for the IVC?
T8 level
Where is the diaphragmatic opening for the oesophagus?
T10 level
Where is the diaphragmatic opening for the aorta?
T12 level
Indicate where the diaphragmatic openings are and at which levels?
- T8: IVC
- T10: Oesophagus
- T12: Aorta
Where do the domes of the diaphragm lie?
- The right dome of the diaphragm lies at the level of the 5th rib
- The left dome is slightly lower at the level of the 5th intercostal space.
Which domes lie at the level of the 5th rib and 5th intercostal space?
Right and left respectively.
The right and left domes lie at the level of the 5th what?
Rib and intercostal space respectively.
Why is the thoracic cavity much smaller than the bony thorax would suggest?
Due to the the marked convexity (dome) of the diaphragm.
What implications does the marked convexity (dome) of the diaphragm mean for the thorax?
The thoracic cavity is much smaller than the bony thorax would suggest.
Which organs in the abdominal cavity are covered by the ribs?
The liver, spleen, parts of the stomach and upper kidneys.
Why is it clinically relevant to understand that some abdominal organs are covered by the ribs?
Because penetrating chest injuries of the lower chest can injure these abdominal organs (liver, spleen, parts of the stomach, upper kidneys)
Which organs lie in the lower chest?
The liver, spleen, parts of the stomach and upper kidneys.
What lines the inside of each hemi-thorax?
The PARIETAL PLEURA
What is the hemi-thorax?
The bony thoracic cage, diaphragm & mediastinal surfaces.
What is the parietal pleura continuous with?
The visceral pleura (which lines the outside of lung) at the hilum (of the lung)
What lines the outside of the lung?
The visceral pleura
Where does the visceral pleura extend to?
Between lobes of the lung into the depths of the oblique and horizontal fissures
The lungs do not __________ ____ the thoracic cavity.
completely fill
What lies around the outer edge of the diaphragm?
A peripheral gutter, into which only the parietal pleura extends.
What is the peripheral gutter space around the edge of the diaphragm called?
The costo-diaphragmatic recess.
Describe the lung pleura and pleural cavity
https://teachmeanatomy.info/thorax/organs/pleurae/
What is the function of the pleura?
To link the movement of the chest wall and lungs.
What is the pleural cavity?
A potential space between the parietal and visceral pleura
What does the pleural cavity contain?
A few millilitres (ml) of pleural fluid
What is important about the forced from pleural fluid?
The surface tension forces between the molecules of pleural fluid creates a ‘seal’ which ensures that when the thorax expands in respiration the lungs expand along with it.
(Self-Note: When the thorax expands, the surface tension means the pleural cavity stuck to the top comes with it. because it is also stuck to the bottom, this brings the lung along with it).
Which property of the pleural fluid allows the thorax and lungs to expand together in respiration?
The surface tension forces (between molecules of pleural fluid)
Describe the trachea and bronchial tree.
https://teachmeanatomy.info/thorax/organs/tracheobronchial-tree/
Where does the trachea commence?
At the LOWER BORDER OF THE CRICOID CARTILAGE (OF THE LARYNX) in the neck.
Where does the trachea terminate?
AT THE LEVEL OF THE STERNAL ANGLE
What does the trachea terminate into?
The right and left main bronchi
What is the angle between the right and left main bronchi known as?
The CARINA
What is the carina?
The angle between the right and left main bronchi.
What is different between the right and left bronchus?
The right main bronchus is wider, shorter and more vertical than the left.
What is the clinical significance of the difference in right and left bronchi structures?
Inhaled foreign bodies are more likely to lodge in the right main bronchus (because it is wider, shorter and more vertical)
What is the first structure you encounter after the trachea (not including the carina)?
The PRIMARY (LEFT & RIGHT MAIN) BRONCHI
What do the primary bronchi divide into?
LOBAR BRONCHI - one for each lobe.
How many lobes are there?
- 3 on the right (upper middle and lower lobar bronchi)
- 2 on the left (upper and lower lobar bronchi).
What are the lobes of the bronchi called?
- On both sides, upper and lower
- On the right, an additional middle
What do the lobar bronchi divide into?
SEGMENTAL BRONCHI
What do segmental bronchi supply?
A BRONCHOPULMONARY SEGMENT
What is a bronchopulmonary segment?
An area of lung supplied by a segmental bronchus., and the accompanying segmental branch of the pulmonary artery.
YOU SHOULD UNDERSTAND WHAT A BRONCHOPULMONARY SEGMENT IS, BUT DO NOT NEED TO NAME AND IDENTIFY THEM.
What blood vessel supplies a bronchopulmonary segment?
The accompanying segmental branch of the pulmonary artery.
What blood vessels drains the bronchopulmonary segment?
A segmental pulmonary vein
Describe the structure of a bronchopulmonary segment?
These segments are pyramid shaped, with the apex facing towards the segmental bronchus and the base toward lung surface.
http://meded.lwwhealthlibrary.com/data/Books/739/Moore-ch001-image035.gif
Describe the bronchial arrangement.
- Primary bronchi
- Lobar bronchi
- Segmental bronchi
- Bronchopulmonary segment
Each structure divides to produce the structure below it in the list.
Why do we know about bronchopulmonary segments?
Knowledge of them is surgically important
Why is knowledge of bronchopulmonary segments surgically important?
Because they can be isolated and removed without much bleeding, air leakage or interfering with other bronchopulmonary segments. it is the smallest resectable division of the lung.
What is the smallest resectable division of the lung?
Bronchopulmonary segments.
How can we visualise the airways clinically?
BRONCHOSCOPY
What can we visualise in bronchoscopy?
The whole of the INNER TRACHEA, THE CARINA, THE MAIN BRONCHI, LOBAR BRONCHI AND THE ORIGIN OF THE SEGMENTAL BRONCHI.
What is bronchoscopy used for?
In the diagnosis of bronchial carinoma
- to visualise the tumour
- obtain a tissue sample for histology
http://meded.lwwhealthlibrary.com/data/Books/739/Moore-ch001-bimage013.gif
What are the two areas of the respiratory system (from trachea to alveoli)?
The conducting zone and the respiratory zone
How many times does the airway divide, between the trachea and the alveolar sacs?
23 times
http://meded.lwwhealthlibrary.com/data/Books/782/PrestonLIRPhysio-ch022-image001.jpeg
The airway divides 23 times between the _______ and the _________ ____.
Trachea, alveolar sacs
Where do divisions 1-16 of the airways take place?
From the trachea up to, and including, the terminal bronchioles
Divisions between the trachea and terminal bronchioles are known as ___?
The CONDUCTING ZONE
Why is the conducting zone so named?
This area does not take part in gas exchange
Which divisions make up the respiratory zone?
17-23 (7 divisions)
How many divisions make up the respiratory zone?
7
Which structures make up the respiratory zone?
The respiratory bronchiole, alveolar ducts and alveolar sacs.
The respiratory bronchioles, alveolar ducts and alveolar sacs make up what?
The RESPIRATORY ZONE (7 divisions, between 17-23)
Why is the respiratory zone so named?
Gas exchange occurs here
Where does gas exchange occur - the conducting or respiratory zone?
In the RESPIRATORY ZONE (no gas exchange occurs in the conducting zone)
How many alveoli are there?
~3 million
What is the combined surface area of the alveoli
~70 m^2
What are the alveoli surrounded by?
A network of pulmonary capillaries
Where does gas exchange occur (specifically)?
Across the very thin (0.3 micrometre wide) alveolar capillary membrane.
How thin is the alveolar capillary membrane?
0.3 micrometre wide (very thin)
Describe the lungs.
http://teachmeanatomy.info/thorax/organs/lungs/
How is the left lung divided?
Into 2 lobes (upper and lower lobes)
How are the left lobes divided?
By the oblique fissure
How is the right lung divided?
Into 3 lobes (upper, middle and lower).
How are the right lobes divided?
- The horizontal fissure separates the right upper and middle lobes
- The oblique fissure separates the right middle (and upper) from the lower lobes
What does the oblique fissure separate?
- The upper from lower lobe of the LEFT LUNG
- The upper/middle from lower lobe of the RIGHT LUNG
What does the horizontal fissure separate?
- The upper from middle lobe of the RIGHT LUNG
Describe the lobe arrangement and what they are separated by in the lungs.
LEFT LUNG:
- upper and lower lobe (2)
- separated by oblique fissure
RIGHT LUNG:
- upper, middle and lower lobe (3)
- upper and middle separated by horizontal fissure
- middle (& upper) and lower separated by oblique fissure
Where does the apex of both lungs extend to?
Above the level of the 1st rib into the root of the neck
What is the top of the lungs called?
THE APEX, which extends above the level of the 1st rib into the root of the neck.
Where is the apex of the lung?
In the neck
What is the apex of the lung closely related to?
The subclavian vessels and the brachial plexus in the neck.
What can occur in tumours of the apex of the lung?
Neurological and vascular problems in the upper limb.
(Tumours of the apex of the lung can involve structures such as the subclavian vessel and the brachial plexus, due to its position. )
How can tumours of the apex of the lung cause neurological and vascular problems in the upper limb?
The apex is closely related to the subclavian vessels and the brachial plexus in the neck. Tumours can therefore involve these structures, causing pathology of the upper limb.
Where does the base of the lung rest?
On each hemi-diaphragm
Which part of the lung rests on each hemi-diaphragm?
THE BASE
Which part of the lung faces the mediastinum?
THE MEDIASTINAL SURFACE
What does the mediastinal surface contain?
THE HILUM
What is the hilum?
In human anatomy, the hilum (pl. hila) is a depression or fissure where structures such as blood vessels and nerves enter an organ.
What enters/leaves through the hilum?
- Main bronchi
- Branches of the pulmonary artery
- Pulmonary veins
- Lymphatics
- Pulmonary plexuses
Describe the mediastinal surface of the lung.
THE MEDIASTINAL SURFACE of each lung faces the mediastinum and contains THE HILUM through which the main bronchi, branches of the pulmonary artery, pulmonary veins, lymphatics and pulmonary plexuses enter/leave the lung.
Where do the mediastinal surfaces of the lung lie?
THE MEDIASTINAL SURFACES OF THE LUNG LIE ADJACENT TO SEVERAL IMPORTANT MEDIASTINAL STRUCTURES.
You should be able to identify these on a prosection.
What is the lung adjacent to on the left side (you should be able to identify all of these structures on a prosection)?
- the heart
- aortic arch
- descending aorta
- oesophagus
- several nerves
- —- phrenic nerve
- —- vagus nerve
- —– recurrent laryngeal branch of vagus nerve
The heart is adjacent to the lung on the _____ side.
Left
The aortic arch is adjacent to the lung on the _____ side.
Left
The descending aorta is adjacent to the lung on the _____ side.
Left
The oesophagus is adjacent to the lung on the _____ side.
Left
The phrenic nerve is adjacent to the lung on the _____ side.
Left
The vagus nerve is adjacent to the lung on the _____ side.
Left
The recurrent laryngeal branch of the vagus nerve is adjacent to the lung on the _____ side.
Left
The recurrent laryngeal is a branch of which nerve?
Vagus nerve
What is the lung adjacent to on the right side (you should be able to identify all of these structures on a prosection)?
- superior vena cava
- azygous vein
- right atrium
- oesophagus
- phrenic nerve
- vagus nerve
- sympathetic trunk
The superior vena cava is adjacent to the lung on the _____ side.
Right
The azygous vein is adjacent to the lung on the _____ side.
Right
The right atrium is adjacent to the lung on the _____ side.
Right
The oesophagus is adjacent to the lung on the _____ side.
Right
The phrenic nerve is adjacent to the lung on the _____ side.
Right
The vagus nerve is adjacent to the lung on the _____ side.
Right
The sympathetic trunk is adjacent to the lung on the _____ side.
Right
What is clinically relevant about mediastinal structures which are closely related to the lung?
These may be involved/damaged by pathologies such as:
- lung cancers
- enlarged hilar lymph nodes
- aortic aneurysm
Give 3 clinical conditions that could affect mediastinal structures related to the lung.
- lung cancer
- enlarged hilar lymph nodes
- aortic aneurysm
Give 3 structures that could be affected in pathologies affecting the mediastinal side of the lung (e.g. lung cancer, enlarged hilar lymph nodes, aortic aneurysm).
- phrenic nerve
- left recurrent laryngeal nerve
- superior vena cava (right side)
What would damage to the phrenic nerve cause?
Paralysis of the affected hemi diaphragm
What symptoms could a damaged phrenic nerve cause? Explain.
Breathlessness
Due to paralysis of the affected hemi diaphragm
What would damage to the left recurrent laryngeal nerve cause?
Paralysis of intrinsic laryngeal muscle on affected side –> vocal cord paralysis
What symptoms could a damaged left recurrent laryngeal nerve cause? Explain.
Hoarseness of voice
Due to paralysis of intrinsic laryngeal muscle on affected side, leading to vocal cord paralysis.
What would damage to the superior vena cava cause?
SVC obstruction
Describe the lungs blood supply, lymphatic drainage and nerve supply.
- Bronchial and pulmonary vessels
- Hilar nodes
- Parasympathetic and sympathetic fibres
What is significant about the lungs blood supply?
They have a dual blood supply
Where is the dual blood supply for the lungs from?
FROM BRONCHIAL ARTERIES AND THE PULMONARY ARTERIES.
What do bronchial arteries supply?
The bronchial tree (but not the alveoli) and visceral pleura with oxygenated blood.
The bronchial tree (bar alveoli) and visceral pleura is supplied by?
BRONCHIAL ARTERIES
Where does most of the blood from the bronchial artery return via?
Most of this blood returns via the pulmonary veins rather than the bronchial veins.
What do the bronchial veins drain into?
The small amount of blood returning via the BRONCHIAL VEINS drain VIA AZYGOUS VEIN INTO THE SVC ATRIUM.
How does blood from the lungs get into the SVC atrium?
Via the BRONCHIAL VEINS, which drain VIA AZYGOUS VEIN INTO THE SVC ATRIUM. Only a small amount of blood returns via the BRONCHIAL VEIN.
What does the pulmonary artery do?
It carries the entire output of the right ventricle (mixed venous blood) to the lungs for gas exchange. They also supply the alveoli.
What supplies the alveoli?
THE PULMONARY ARTERY
Where does blood from the right ventricle go?
PULMONARY ARTERY
What sort of blood from the right ventricle?
Mixed venous blood
How are bronchial and pulmonary arteries connected?
THERE ARE SOME ANASTOMOSES BETWEEN THE BRONCHIAL AND PULMONARY ARTERIES
Anastomoses between the bronchial and pulmonary arteries occur where?
At pre-capillary level and capillary level
Why are anastomoses between the bronchial and pulmonary arteries important clinically?
These maintain some blood supply to lung parenchyma in patients with pulmonary embolism
How do patients with pulmonary embolism maintain blood supply?
The ANASTOMOSES BETWEEN THE BRONCHIAL AND PULMONARY ARTERIES maintain some blood supply to lung parenchyma in patients with PE
What do pulmonary veins do?
RETURN OXYGENATED BLOOD TO THE LEFT HEART
Where do pulmonary veins run?
They do not closely follow the bronchi, but tend to run in the intersegmental septa.
How many pulmonary veins are there?
Two pulmonary veins leave each hilum
What do the pulmonary veins drain?
The upper and lower lobes
What do the bronchial and pulmonary blood vessels supply/drain?
- Bronchial arteries: supply the bronchial tree (not alveoli) and visceral pleura
- Bronchial veins: small amount of blood which drains via the azygous vein into the SVC
- Pulmonary arteries: carries entire output of right ventricle to lungs, supplies the alveoli
- Pulmonary veins: return oxygenated blood to the left heart
- Bronchial and pulmonary artery anastomoses: maintain some blood supply in patients with pulmonary embolism
Where is the lymphatic drainage from the lungs?
The lungs drain to the HILAR NODES
What are the hilar nodes also known as?
BRONCHOPULMONARY NODES
_________ from hilar/bronchopulmonary nodes run where?
Efferents, TRACHEOBRONCHIAL NODES
What can enlarged tracheobronchial nodes cause?
Widening of the (angle of the) carina
How can widening of the (angle of the) carine occur?
Due to enlarged tracheobronchial nodes.
What is the nerve supply to the lungs?
The lung receives fibres from the right and left vagus nerves and the sympathetic trunk.
What do the parasympathetic efferent fibres from the vagus do?
- Motor to the bronchial smooth muscle (bronchoconstrictor)
- Secretomotor to mucous glands
What supplies motor control to the bronchial smooth muscle?
PARASYMPATHETIC EFFERENT FIBRES from the vagus nerve
What supplies secretomotor control to mucous glands?
PARASYMPATHETIC EFFERENT FIBRES from the vagus nerve
What do the afferent fibres of the vagus nerve do?
Those are for the cough reflex and some subserving pain.
Which fibres are involved in the cough reflex?
Vagal AFFERENT fibres
Which fibres subserve pain?
Some of vagal AFFERENT fibres
What do the sympathetic efferent fibres do?
They are bronchodilator and vasoconstrictor
Which fibres enable bronchodilation?
SYMPATHETIC EFFERENT FIBRES
Which fibres enable vasoconstriction?
SYMPATHETIC EFFERENT FIBRES
Describe the nerve supply to the lungs:
The lung receives fibres from the Right and Left vagus nerves and the sympathetic trunk.
PARASYMPATHETIC EFFERENT
- from vagus
- motor to bronchial smooth muscle (bronchoconstrictor)
- secretomotor to mucous glands
AFFERENT
- cough reflex
- subserving pain
SYMPATHETIC EFFERENT
- bronchodilator
- vasoconstrictor
