Resp Flashcards
What are the four main functions of the nasal cavity?
- warms and humidifies air
- removes and traps pathogens and particulate matter from the inspired air
- responsible for sense of smell
- drains and clears the paranasal sinuses and lacrimal ducts
What three sections can the nasal cavity be divided into?
- the vestibule
- the respiratory region
- the olfactory region
What are the functions of the nasal conchae?
increase the surface area of the nasal cavity and to create laminar flow, making the air slow and turbulent. So the air spends longer in the cavity so that it can be humidified.
What are the openings into the nasal cavity?
- the frontal, maxillary and anterior ethmoid sinuses open into he middle meatus.
- the middle ethmoid sinus opens into the superior meatus
- the sphenoid sinus drains into the posterior roof
- the nasolacrimal duct and gustation tube open into he inferior meatus
What are the branches of the internal carotid which supply the nose? (2)
-anterior ethmoidal artery
-posterior ethmoidal artery
They are a branch of the ophthalmic artery. They descend through the cribriform plate.
what are the branches of the external carotid which supply the nose?
-sphenopalatine artery
-greater palatine artery
-superior labial artery
-lasal nasal arteries
these arteries form anastomoses.
What are the veins of the nose?
the veins follow the arteries, they drain into the pterygoid plexus, facial vein or cavernous sinus.
Through which passage can a nasal infection pass to the cranial cavity?
Some individuals have veins which join to the sagittal sinus, allowing infections to pass form the nose to the cranial cavity.
through what nerve is the special sensory innervation of the nose carried?
the olfactory nerve which penetrates through the olfactory plate.
What nerves provide general sensory innervation to the nose?
Innervation of the septum and lateral walls is provided by the nasopalatine nerve (a branch of the maxillary nerve) and the nasociliary nerve (a branch of the ophthalmic nerve). innervation of the external skin of the nose is supplied by the trigeminal nerve.
How ay a fracture of the cribriform plate occur?
trauma, directly or by fragments of the ethmoid bone.
why may clear fluid leak from the nose after direct trauma to the face?
a fragment of a fractured cribriform plate can penetrate the meningeal lining of the brain, causing leakage of the cerebra-spinal fluid. This increases the risk of meningitis, encephalitis and brain abscesses.
What structures does the oropharynx contain?
- posterior 1/3 of the tongue
- the lingual tonsils
- the palatine tonsils
- superior constrictor muscles
what lymph node swelling commonly is associated with inflamed palatine tonsils?
jugulo-digastric lymph nodes
how is chronic inflammation of the palatine tonsils treated?
tonsillectomy
what two locations can objects become lodged at in the pharynx?
- the valleculae in the nasopharynx
- the piriform fuss in the laryngopharynx
What is a pharyngeal diverticulum?
Where the pharyngeal mucosa bulges between the thyropharyngeaus and cricopharyngeus.
how is a pharyngeal diverticulum caused and how does this differ from normal?
The cricopharynxgeus doesn’t relax, so inter pharyngeal pressure rises. usually the thyropharyngeus usually contracts and the cricopharynxgeus relaxes allowing food to be propelled into the oesophagus.
What structures can be found medially to the left lung?
- heart
- aortic arch
- thoracic aorta
- oesophagus
What structures can be found medially to the right lung?
- oesophagus
- heart
- inferior vena cava
- superior vena cava
- azygous vein
What are the lung fissures called and how do they differ between the left and right lungs?
Horizontal and oblique fissures. The left lung only has an oblique fissure.
What structures can be found in the lung root?
bronchus, pulmonary artery, two pulmonary veins,bronchial vessels, pulmonary plexus of nerves and lymphatic vessels
In the hilum which is more superior, the vein or artery?
Artery
Why is the right bronchus at a greater risk of blockage?
due to its wider shape and more vertical course
What nerve is the parasympathetic supply of the lungs derived?
the vagus nerve, it stimulates secretion from the bronchial glands, contraction of the bronchial smooth muscle, and vasodilation of the pulmonary vessels.
What nerve is the sympathetic supply of the lungs derived?
the sympathetic trunks, they stimulate relaxation of the bronchial smooth muscle, and vasoconstriction of the pulmonary trunk.
What role does the visceral afferent fibres have not the lung?
Conduct pain impulses to the sensory ganglion of the vagus nerve.
What are the three most common types of emboli?
fat
air
thrombosis
when would you be concerned about a fat emboli?
after a fracture or orthopaedic surgery
what are the types of pleura?
visceral- covers the lungs
parietal- covers the internal surface of the thoracic cavity
What sections can the parietal pleura be divided into?
mediastinal, cervical, costal and diaphragmatic
what is the space between the parietal and visceral pleura called?
the pleural cavity
what’s contained in the pleural cavity?
serous fluid
what are the two main functions of the serous fluid?
lubricates the surface of the pleurae allowing them to move over each other. it also produces surface tension, pulling the parietal and visceral pleura together- ensuring that when the thorax expands, so do the lungs.
During swallowing are the rim glottides, rims vestibule and vestibule open or closed?
closed
in which direction does the larynx move during swallowing?
up and forward, which helps to open the oesophagus for the passage of the swallowed material.
During respiration are the rim glottides, rims vestibule and vestibule open or closed?
open
What happens to the vocal folds during forced inspiration?
further abducted by the action of the posterior cricoarytenoid muscles.
during phonation, what position are the vocal cords in?
adducted
how is sound produced during phonation?
air is forced through the closed rim glottidis, the vocal cords vibrate against one another, producing sound.
which ribs can be classified as ‘typical’ and what makes them so?
3-10
a wedge shaped head with two articular facets. The neck contains no bony prominences. The internal surface has a groove for the neuromuscular supply to the thorax, protecting nerves and vessels from damage.
which ribs are a-typical and why?
1- shorter and wider than the other ribs, it only has one facet on it’s head for articulation with the vertebrae. The superior surface is marked by two grooves, which make way for the subclavian vessels.
2- thinner and longer than rib 1. It has a roughened area on its upper surface, where serrates anterior attaches
11/12- have no neck, and only contain one facet which articulates with the corresponding vertebrae.
What joints do the ribs form posteriorly with the vertebrae?
- costotransverse joint- between the tubercle of the rib, and the transverse costal facet of the corresponding vertebrae
- costovertebral joints- two for each rib, where the ribs articulate with the costal facet of the rib above and below.
which ribs are classed as floating ribs?
11+12 as they don’t attach anywhere, only to the abdominal muscles.
what tissues are at risk after a rib fracture?
the lungs, spleen and diaphragm
what happens when one or more ribs are broken in the same area?
the area is no longer under control of the thoracic muscles, a paradoxical movement can be seen- this is called ‘flail chest’
How is flail chest treated?
fixing the affected ribs
how does flail ribs affect oxygen content of the lung?
Expansion of the rib cage is impaired, so oxygen content is lower.
What direction do the external intercostals run?
inferoanteriorly
what nerves innervates the external intercostals?
the intercostal nerves
where do the external intercostals end and what do they become?
at the start of the sternocostal cartilage and become a membrane.
what direction do the fibres of the internal intercostals run?
inferoposteriorly
what abdominal muscle are the internal intercostals continuous with?
internal oblique
what abdominal muscle are the external intercostals continuous with?
external oblique
where do the internal intercostals end?
the angle of the rib and then it becomes a membrane.
what separates the internal and innermost intercostals?
the intercostal neuromuscular bundle
what direction do the innermost intercostals run?
inferoposteriorly
What are the two main functions of the diaphragm?
- separates the thoracic cavity from the abdominal cavity.
- it undergoes contraction and relaxation, altering the volume of the thoracic cavity and the lungs, aiding inspiration and expiration.
what are the three peripheral attachments of the diaphragm?
- the lumbar vertebrae and arcuate ligaments
- costal cartilages of ribs 7-12
- Xiphoid process of the sternum
from which vertebra does the right crus arise?
L1-3
what do some of the fibres of the right crus form around the oesophagus?
physiological sphincter
from which vertebrae does the left crus arise?
L1-2
which side of the diaphragm is higher ?
right, this is thought to be due to the liver
what openings are there in the diaphragm and what level are they?
- oesophageal opening: T10, transmits the oesophagus, vagus nerve and oesophageal branches of the left gastric vessels
- aortic opening: T12, transmits the aorta, thoracic duct and azygous vein
- caval opening: T8, transmits the inferior vena cava
what is the nerve innervates the diaphragm and the roots?
phrenic nerve: C3,4,5
What arteries supply the diaphragm?
inferior phrenic arteries, which arise directly from the abdominal aorta.
how can the phrenic nerve be injured?
- mechanical trauma e.g. ligation
- compression- tumor within the chest cavity
- myopathies- myasthenia gravis
- neuropathies- diabetic neuropathies
what happens to the movement of the diaphragm during paralysis of the diaphragm?
paradoxical movement- the affected side moves upward during inspiration, and downwards during expiration.
what are the common symptoms of bilateral diaphragmatic paralysis?
poor exercise tolerance, orthopnoea and fatigue. LFT will show a restrictive deficit.
how is diaphragmatic paralysis treated?
- treating the underlying cause
- symptomatic relief, usually via non-invasive ventilation, such as CPAP machine.
what is partial pressure?
as the constituents of a gas mixture don’t combine chemically, each component exerts a partial pressure which is the same proportion of the total pressure as the volume fraction in the gas mixture.
when is vapour pressure a maximum?
when a gas mixture is in equilibrium with water- as in most biological systems. This is called the saturated vapour pressure (SVP).
what is the SVP at normal body temperature?
6.28kPa
what is the mean pulmonary arterial pressure?
14-18mmHg
systolic: 20-25mmHg
diastolic: 4-12mmHg
what is the mean hydrostatic pressure in pulmonary capillaries?
9mmHg
What is the mean pressure int he pulmonary veins/ left atrium?
1-10mmHg
why is tissue fluid not formed in the lungs?
the capillary pressure in normal pulmonary circulation is always less than the colloid osmotic pressure. Except in the lung bases, where gravity can occasionally increase transmural hydrostatic pressure.
what is alveolar pO2 determined by?
a balance between rate of removal of O2 by the blood and the rate of replenishment of O2 by alveolar ventilation.
what is alveolar pCO2 determined by?
a balance between rate at which CO2 enters the alveoli from the blood and the rate at which it is removed from alveolar gas by ventilation
what is the normal partial pressure of oxygen in alveolar gas?
13.3kPa
what is the normal partial pressure of carbon dioxide in alveolar gas?
5.3kPa
what is the normal partial pressure of oxygen in venous blood?
6.0kPa
what is the normal partial pressure of carbon dioxide in venous blood?
6.5kPa
what does diffusion rate depend on?
- area
- diffusion gradients
- diffusion length/resistance
what structures does gas have to pass through to enter a red blood cell from the alveoli?
- alveolar gas
- alveolar epithelial cell
- interstitial fluid
- capillary endothelial cell
- plasma
- RBC membrane
what is the main limiting factor of diffusion in the lungs and why is this important?
the solubility of the gas in water, carbon dioxide diffuses much faster than oxygen as it’s more soluble.
how many times faster does carbon dioxide diffuse than oxygen?
21 times
how many times faster does carbon dioxide diffuse than oxygen?
21 times
define tidal volume. What is its typical value?
the volume that enters and leaves the lungs with each breath, typically 0.5l
define inspiratory reserve volume. What is its typical value?
extra volume that can be breathed in over that at rest, typically 2.5l
define expiratory reserve volume. What is its typical value?
extra volume that can be breathed out over that at rest, typically 1.5l
define residual volume. What is its typical value?
the volume of air left in the lungs after forced expiration, typically 0.8l
define inspiratory capacity. What is its typical value?
from the end of quiet expiration to maximum inspiration, typically 3l (inspiratory reserve+ tidal volume)
define functional residual capacity. What is its typical value?
the volume of air in the lungs at the end of quiet expiration, typically 2l.
define vital capacity. What is its typical value?
inspiratory capacity+ expiratory reserve
OR
inspiratory reserve volume+ TV+ expiratory reserve volume
typically 5l
define total lung volume. What is its typical value?
Vital capacity+ reserve volume, typically 5.8l
define ventilation rate.
the amount of air moved into and out of a space per minute, the product of volume moved per breath and respiration rate.
define pulmonary ventilation rate. What is its typical value?
tidal volume x respiratory rate
typically 8l/min but can but ca exceed 80l/min during exercise.
what is ‘dead space’
the volume of air inspired which isn’t in the alveoli so doesn’t undergo gas exchange
what is the anatomical dead space?
the volume of the conducting airways, upto and including the terminal bronchioles.
whats tha typical volume of anatomical dead space?
150ml
how can the anatomical dead space be measured?
nitrogen washout test
what is the alveolar dead space?
not all alveoli are perfused and some may be damaged by disease, the volume of these alveoli in which gas exchange doesn’t occur is the alveolar dead space.
what is physiological dead space?
anatomical dead space + alveolar dead space
how can physiological dead space be measured?
Helium dilution
how can physiological dead space be measured?
Helium dilution
what type of breathing wastes the least proportion of air due to dead space and why?
slow deep breathing
during shallow rapid breathing the majority of the air inhaled is lost in the anatomical dead space.
why don’t we just breath deeply and slowly all of the time then?
it requires a lot of energy, so at rest we adopt an intermediate
here’s a little calculation for you !
if TV= 0.25l & RR=33
calculate PVR, DSVR and AVR
so conclude what percentage of the air inhaled is wasted?
PVR=TVxRR=0.25x32=8l/min
DSVR=DSVxRR= 0.15x32=4.8l/min
AVR=PVR-DSVR=8-4.8=3.2l/min
so almost 2 thirds are wasted
here’s a little calculation for you !
if TV= 0.25l & RR=33
calculate PVR, DSVR and AVR
so conclude what percentage of the air inhaled is wasted?
PVR=TVxRR=0.25x32=8l/min
DSVR=DSVxRR= 0.15x32=4.8l/min
AVR=PVR-DSVR=8-4.8=3.2l/min
so almost 2 thirds are wasted
here’s a little calculation for you !
if TV= 0.25l & RR=33
calculate PVR, DSVR and AVR
so conclude what percentage of the air inhaled is wasted?
PVR=TVxRR=0.25x32=8l/min
DSVR=DSVxRR= 0.15x32=4.8l/min
AVR=PVR-DSVR=8-4.8=3.2l/min
so almost 2 thirds are wasted
why is the pressure in the lungs called ‘negative pressure’
as the chest recoils outwards, and the lungs elastic recoil causes them to pull inwards the balance is classed as negative pressure
what ensures that when the thoracic cavity moves the lungs follow?
the pleura and pleural fluid form a seal between the two
where in the respiratory cycle are the elastic forces of the lungs and chest balanced in equal directions?
FRC
what causes quiet inspiration?
contraction of the diaphragm and external intercostals, so it’s active
what causes quite expiration?
passive recoil of the lungs
what causes forced expiration?
contraction of the abdominal muscles and the internal intercostals
what causes forced inspiration?
same as quiet inspiration but also the SCM and other accessory muscles
what are the accessory muscles of breathing?
The sternocleidomastoid (elevated sternum) and the scalene muscles (anterior, middle and posterior scalene).
what are the accessory muscles of inspiration?
The sternocleidomastoid (elevated sternum), the scalene muscles (anterior, middle and posterior scalene), serratus anterior and pec major.
during inspiration where is the highest pressure?
in the mouth
during expiration where is the lowest pressure and why?
the alveoli, due to the elastic recoil of the lungs
why is the lowest pressure in the mouth, and not the pleural space during forced expiration?
as the pleural space is having pressure put on it by the abdominal contraction, whereas normally the recoil of the lungs makes the pressure negative
what are the accessory muscles of expiration?
internal intercostals and the abdominal wall muscles
what is compliance of the lungs?
the volume change per unit pressure change, but can be seen as the ‘stretchiness’ of the lung.
what two features make the lung elastic?
- elastic tissue in the lungs (duh)
- surface tension forces of the fluid lining the alveoli
what are type 1 alveolar cells?
squamous alveolar cells, that line the alveolar surfaces of the lungs
what are type 2 alveolar cells?
great alveolar cells or septal cells are granular and roughly cuboidal in shape. Type II pneumocytes are typically found at the alveolar-septal junction.
in which cells is surfactant produced?
type 2 alveolar cells
what molecules comprise surfactant?
phospholipids and proteins with detergent properties.
what is the role of surfactant?
the molecules disrupt the interactions between surface molecules and reduce the surface tension.
how does surfactant reduce surface tension?
the molecules disrupt the interactions between surface molecules and reduce the surface tension.
why does surfactant make ‘little breaths’ easy?
it reduces surface tension when the lungs are fully deflates, but not when fully inflated, so little breaths are easy. Hysteresis.
what are the 3 main roles of surfactant
- increases lung compliance by decreasing surface tension
- stabilises the lungs, by preventing small alveoli collapsing into bigger ones
- prevents the surface tension in alveoli creating a suction force, causing transudation fluid from pulmonary capillaries.
what is hysteresis?
the energy put into stretching a film of surfactant is not all recovered when the film recoils, this loss is greatest when tidal volume is high, so little breaths are easy due to this too.
how does surfactant work to stop smaller alveoli collapsing into larger ones?
the concentration of surfactant is
how does surfactant work to stop smaller alveoli collapsing into larger ones?
the concentration of surfactant is lower when an alveolus is expanded, so it has less effect. As an alveolus shrinks the surface area decreases, so the surfactant has more effect. This stabilises the lungs. so r and T increase together.
what is laplaces law?
P=2T/r
P=pressure in the alveolus, T=surface tension, r= radius of alveolus
why does laplaces law mean that smaller alveoli would empty into larger ones?
as T is constant, smaller bubbles would have a higher pressure within them than the larger ones, so would empty into the larger ones.
At how many weeks does a foetus have type 2 alveolar cells, and toreador surfactant?
25 weeks
what is respiratory distress syndrome?
premature babies and sometimes full term babies don’t have enough surfactant, so struggle with breathing
resistance increases with decreasing diameter, so how is it that the overall resistance for the small airways is low?
as they are connected in parallel
why does the pressure in some lung diseases such as asthma reach a point where the small airways occlude earlier?
the resistance of the airways is heightened, so a higher force has to be exerted to force air out of the lungs. This increased force causes some of the small airways to collapse.
why does the pressure in some lung diseases such as asthma reach a point where the small airways occlude earlier?
the resistance of the airways is heightened, so a higher force has to be exerted to force air out of the lungs. This increased force causes some of the small airways to collapse.
give two reasons why the lungs may not be filled fully
- compliance of the lungs is reduced
- the force of inspiratory muscles is reduced
give two reasons why the lungs may not be emptied fully
- increase in airway resistance
- the lungs are compressed
Describe a restrictive deficit inrelation to spirometry.
the lungs are difficult to fill e.g. weak intercostal muscles, so the lungs start f less full. FVC will be reduced but the air will exit normally, so FEV will be >70%
Describe a obstructive deficit inrelation to spirometry.
the airways are narrowed sot he lungs will be difficult to fill but the resistance will increase in expiration, so air will exit more slowly. FEV will be reduced but FVC will be relatively normal.
