Basic Structure of the respiratory system

Question 1

Describe the flow of air into the lungs

Answer 1

Air is taken into the nasal or oral cavity- then enters the pharynx
Joins larynx
Trachea (terminates at T4/5 sternal angle)
bronchi
lungs

Question 2

Describe the nasal cavities

Answer 2

Nasal septum separates two halves, and largely made of cartilage, but lined by olfactory mucosa - very sensitive, with trigeminal nerve innervation
Olfactory bulb and tract present at top of cavity, with olfactory mucosa to allow sense of smell (olfactory nerves arise from the bulb)

Question 3

Describe the innervation of the nasal cavity

Answer 3

 Olfactory nerves.
 Nasopalatine nerve (V2).
 Medial internal nasal br of ant ethmoidal nerve (V1).

Question 4

Describe the nose

Answer 4

Part of the upper respiratory tract superior to the hard palate
Consists of the external nose and nasal cavities
The main function of these structures are olfaction and breathing
The lateral wall consists of conchae which provide a large SA covered in a highly vascuarlised mucous membrane to warm and humidify inspired air

Question 5

Why does the nasal cavity exist

Answer 5

The nasal cavity exists to warm the air before it goes down into the lungs as cold air is an irritant.

Question 6

What are the paranasal cavities also lines by

Answer 6

olfactory mucosa

Question 7

Where are the olfactory nerves found in the nasal cavity

Answer 7

At the top

Question 8

Describe the characteristics of the olfactory mucosa

Answer 8

very sensitive

even light can make you sneeze

Question 9

Describe the paranasal sinuses

Answer 9

Lateral wall of cavity is not smooth - three ridges (concha)
Frontal sinus present above the eyes (frontal bone)
Sphenoidal sinus found in sphenoid bone below pituitary gland
Ethmoid air cells found high in cavity on each side of septum
Maxillae have openings to sinus above upper teeth - opening high up inside maxillary sinus, so any infection/mucous cannot leave via the opening

Question 10

What is found underneath each concha

Answer 10

A groove or meatus
The paranasal air sinuses (frontal, sphenoid, ethmoid and maxillary) drain into these meatuses via small Ostia, or openings

Question 11

What are the concha covered in

Answer 11

Respiratory epithelium

Question 12

Describe the respiratory epithelium

Answer 12

Pseudostratified ciliated columnar epithelium

Question 13

Describe the structure of the paranasal air sinuses

Answer 13

 There are 3 major ridges known as the choncha – the inferior, middle and superior.
 The sphenoidal sinus sits just bellow the sella turcicia (pituitary gland bone).
 In the maxilliary sinus, the meatus that exits from it is located at the superior aspect which makes drainage difficult so this makes it difficult for the body to clear infection.
 The maxilliary sinus is also very close to the teeth meaning dentists have to be very careful.

Question 14

What are the functions of the concha

Answer 14

increase surface area of nasal mucosa to condition air before reaching the lungs (bone protrusions covered in respiratory epithelium - inferior concha lower in cavity with middle concha near the top)

Question 15

What are the functions of the sinuses

Answer 15

1. Lightens the skull by increasing strength to weight ratio.
2. Acts as an insulator by trapping warm air- double glazing
3. Protective for the brain- forms a crumple zone- at front of skull
4. Affects the resonant quality of voice- resonance of voice changes when clogged with mucous

Question 16

Why is it important that the air is humidified

Answer 16

cold, dry air is an irritant for the lungs

Question 17

Describe how respiratory infections can get into sinuses

Answer 17

Issue for maxillary sinuses
 In the maxilliary sinus, the meatus that exits from it is located at the superior aspect which makes drainage difficult so this makes it difficult for the body to clear infection.
 The maxilliary sinus is also very close to the teeth meaning dentists have to be very careful.

Question 18

What is the role of the mucosa

Answer 18

Warm or cool air
Moisten it
Capture bacteria and viruses

Question 19

What happens when we are cold

Answer 19

Nasal mucosa tries to take heat and moisture from the air going out- countercurrent mechanism
Why we see water vapour on a cold day

Question 20

What else do the concha do

Answer 20

aka turbinates
Disrupt smooth flow of air and direct it to the top of the nasal cavity to allow us to smell
increases contact between infiltrating air and the nasal mucosa, allowing particles in the air to be trapped before entering other parts of the respiratory system (e.g. the lungs).

Question 21

Describe the pharynx

Answer 21

from top of nasal cavity to opening of the larynx; can be divided to three areas: nasopharynx (nasal cavity to end of soft palate), oropharynx (soft palate to epiglottis) and laryngopharynx (epiglottis to opening of airway)

Question 22

What are the anterior aspects of each of the compartments of the pharynx

Answer 22

Nasopharynx- situated above the soft palate and opens anteriorly into the nasal cavities at the choanae
Orophaynx- mouth
Laryngopharynx- larynx
During swallowing, the nasopharynx is cut off from the oropharynx by the soft palate

Question 23

Describe the basic structure of the larynx

Answer 23

Continuous with the trachea at its inferior end
Attached to the U-shaped hyoid bone and lies below the epiglottis of the tongue
The larynx consists of a cartilaginous skeleton linked by a number of membranes
the cartilaginous skeleton comprises the epiglottis, thyroid, arytenoid and cricoid cartilage.

Question 24

Describe the anatomy of the larynx

Answer 24

All cartilage hangs from the hyoid bone
Epiglottis is attached posteriorly to the hyoid bone
Gives rise to thyroid cartilage via (thyrohyoid membrane)
Cricoid cartilage arise from thyroid cartilage via cricothyroid ligaments
Corniculate and arytenoid (vocal ligaments move medially) cartillages found posteriorly
Learn from diagram!

Question 25

What are the functions of the larynx

Answer 25

As an open valve, to allow air to pass through when breathing
Protection of the trachea and bronchi during swallowing. The vocal folds close, the epiglottis is pushed back covering the opening to the larynx, and the larynx is pushed upwards and forwards beneath the lungs
Speech production (phonation)

Question 26

Describe phonation

Answer 26

vocal ligaments vibrate to cause sound generation, and form sphincter to stop anything other than air going to airways
sphincter open in inspiration

Question 27

What are some key facts about the larynx

Answer 27

 Note the Hyoid bone, the only actual bone here.
 Tracheostomies are performed in the Cricothyroid ligament.
 Volume and pitch is controlled by the vocal ligaments (vocal folds)
 The trachea is made up of around 20 rings of cartilage in horseshoe shapes into which the oesophagus can expand during peristalsis.

Question 28

Describe the structure of the trachea

Answer 28

horseshoes of cartilage embedded in walls, but are deficient posteriorly; lined by same respiratory epithelium, with trachealis muscle posteriorly to join horseshoe; oesophageal muscle lies at back of trachea

Question 29

Where doe the trachea extend from

Answer 29

the larynx to its bifurcation at the carina

Question 30

Describe the tracheobronchiolar tree

Answer 30

 The primary bronchus go into the lungs and then secondary bronchi are located in each lobe.
 Tertiary bronchus go into bronchopulmonary segments.
 All of the bronchi are held open by cartilage to some degree, the bronchioles are supported by smooth muscle cells.
 The Corina is the name for the located of the bifurcation of the trachea into the bronchi. This occurs at the 2nd CC or T4/T5.
 The right lung is split into 3 lobes; the left is split into 2.
 The bronchiolar and alveolar surfaces are reduced by surfactant.

Question 31

Where will object obstructing the lungs most likely be found

Answer 31

inferior lobe of the right lung, as the right bronchi is more vertical

Question 32

Describe the bronchi

Answer 32

Bronchi held open by cartilage horseshoes and plates
Bronchiolar and alveolar surface tension reduced by surfactant
bronchiole has no cartilage (less cartilage as you go down)- so can present problems in asthma and related conditions; much smaller in diameter so greater resistance

Question 33

Describe what happens when the diaphragm moves down

Answer 33

The pericardium moved down

it flattens out

Question 34

Describe the basic structure of the pleura

Answer 34

Parietal faces the chest wall
Visceral faces the lungs
No difference structurally between the visceral and parietal pleura- changes at the hilum
Potential space between them- with serous fluid to allow the two pleura to move over each other and the lungs to expand

Question 35

What is meant by the costodiaphragmatic recess

Answer 35

space beneath lungs to expand downwards towards abdomen

as left lung inflates- it moves in front of the pericardium- it Does not move symmetrically downwards

Question 36

What can be seen in the hilum

Answer 36

Bronchi beginning to divide
Antero-inferiorly- veins
Superiorly- arteries
Can distinguish between bronchi and vessels due to cartillage
nerves
lymph nodes and lympahtic vessels
pulmonary ligament

Question 37

Why can we not see any differences in thickness of the pulmonary arteries and veins

Answer 37

Both are low pressure circuits

Question 38

Describe the topography of the lungs

Answer 38

 Right Lung (left side, 3 lobes):
o The grooves are for the azygous vein and oesophagus.
o In the hilum, the pulmonary arteries (blue) and veins (red) can be seen alongside the bronchi and lymph nodes.
 Left Lung (right side, 2 lobes):
o The arch of the aorta groove and the associated common carotid and subclavian can be seen.
 The right side image is of the bronchopulmonary segments, each with independent blood supply and bronchioles

Question 39

Where does vocalisation take place

Answer 39

The oral cavity

Question 40

What drives oxygen across the blood-air barrier

Answer 40

PO2 Air = 100 mm HG ➔ PO2 Blood = 40 mm HG

Diffusion takes place down considerable pressure gradient

Question 41

Describe the morphological barrier between the capillary and alveolus

Answer 41

1 cell thick epithelium (alveolar) and 1 cell thick endothelium (capillary)
It is exceedingly thin (average thickness of alveolar- capillary membrane is 0.4mm) and has an area between 50 and 100 square metres- making it well suited to gas exchange

Question 42

Describe the removal of inhaled particles in the alveoli

Answer 42

The alveoli have no cilia
Removed by macrophages
foreign material is removed from lungs via lymphatics or the blood flow
leukocytes also participate in the immune response

Question 43

Describe the diaphragm

Answer 43

 The white part must be a tendon otherwise when the diaphragm contracts, the IVC would be crushed and we would die.
 T10 is the level at which the oesophagus pierces the diaphragm.
 The phrenic nerve originates at C3, 4, 5 and provides innervation to the diaphragm; without it, we would die as we wouldn’t breathe.
 The vagus nerve passes anteriorly to the heart, the phrenic nerve runs posteriorly to the heart.
 Breathing is carried out like a bucket-handle motion with lateral expansion.

Question 44

Describe the position of the diaphragm

Answer 44

Margin attached to costal margin (lower edge of rib cage)
Centre of dome bulges up because of pressure difference between pleural and abdominal cavities
Highest in expiration

Question 45

Describe the stability of the alveoli

Answer 45

Because of the surface tension of the liquid lining the alveoli; relatively large forces develop that tend to collapse alveoli
Fortunately, some of the cells that line the alveoli secrete surfactant that lowers the surface tension of the alveolar lining layer, preventing collapse and increasing stability.

Question 46

What are the external intercostals involved in

Answer 46

inspiration

move the ribs upwards and outwards

Question 47

Why do ribs expand laterally

Answer 47

Middle parts lower than posterior and anterior
so they expand laterally
ribs 7,8,9 and 10

Question 48

What is meant by a plural cavity

Answer 48

Thin film of fluid between parietal and visceral layer- reduces friction to allow the pleurae to spill over each other in breathing
normally, no cavity is present, although in disease, the pathological potential may expand