The Upper Respiratory Tract

Question 1

Why is the upper respiratory tract important

Answer 1

Often get infections here (rhinitis, laryngitis, bronchitis)

Generally less severe than lower resp tract where infections here can kill (pneumonia :( )

Question 2

Describe the structure of the nasal cavities

What is the function of the nasal cavity and the structures inside

Answer 2

Ant nares => Vestibule with vibrisae => Nasal cavity => Post nares

Warms the air
Keeps it moist, both ensure that the moisture in the lungs is 100% saturated with O2

Vibrisae, filters inspired air

Question 3

Describe the general structure of the whole pharynx

Answer 3

Muscular tube made up of nasal pharynx, oropharynx and hypopharynx

Question 4

Where can the nasal pharynx be found

Answer 4

Extends from the base of the skull to the upper surface of the soft palate

Opening of auditory tube found here

Question 5

Where can the oral pharynx be found

Answer 5

Between the soft a palate and superior border of the epiglottis

Question 6

Where can the hypopharynx be found

Answer 6

Where the pharynx splits into the larynx and oesophagus

Question 7

Describe the structure and function of the larynx

Answer 7

Made up of hyaline and elastic cartilage

Predominantly a sphincter for the airway, prevent food and fluids entering the lungs
Voice box also found here but not its main role

Question 8

What is the function of the oesophagus

Answer 8

Food and fluids enter here => GBS

Question 9

Describe the structure and function of the trachea

Answer 9

20C shaped cartilage rings, keeps airway open

Leads to carina (bifurcation of trachea => 2 bronchi at T4)

Question 10

How does the bronchus divide and what changes as a result?

Answer 10

Pulmonary bronchus => Lobar bronchus => Segmentary bronchus => etc

23 divisions in total
As you divide, amount of hyaline cartilage decreases, amount of smooth muscle increases, amount of connective tissue increases

Epithelium transitions from ciliates pseudostratified columnar => simple squamous

Start to lose smooth muscle and connective tissue as you approach alveoli, site of gas exchange

Question 11

Describe the pulmonary circulation (pulmonary arteries, veins, bronchial arteries and veins)

Answer 11

Pulmonary arteries branch along bronchiole very closely
Forms a plexus around alveoli with pulmonary vein capillaries
O2 in solution diffuses across 2nm
Pulmonary vein normally further away from bronchioles
Alveoli don’t need a blood supply, get their O2 from diffusion

Thoracic aorta => bronchial arteries => veins => pulmonary veins, azygos

Question 12

What are the protective mechanisms of the upper respiratory tract

Answer 12

Mechanical (mucus and hairs)
Goblet cells and serous glands
Mucociliary escalator and cilia
Macrophages
WBCs
Mast cells and histamine release

Question 13

How does mechanical protection (mucus and hairs) protect the URT

Answer 13

Moistens air and traps pathogens

Question 14

How do the goblet cells and serous glands protect the URT

Answer 14

Watery submucosal antibacteriocidal secretions

Question 15

How does the mucociliary escalator and cilia protect the URT

Answer 15

On top of pseudocolumnar cells, wafts mucus up to oesophagus => stomach from bronchi

Question 16

How do macrophages help protect the URT
How do WBCs help protect the URT
How do mast cells help protect the URT

Answer 16

Digests unwanted pathogens, travel up to pharynx to dispose of them
Aids in immune response
Mast cells release histamine, decreases lumen in airway, prevent pathogens from entering the lumen

Question 17

Describe how airflow is directed from the nasal cavity to the nasopharynx

Answer 17

Upper, middle and lower conchae directs air flow to post nares
Warm because heat from blood vessels is close enough to the wall

Question 18

Describe the 5 ways that ventilation is controlled

Answer 18

Peripheral and central chemoreceptors
Proprioception
Irritant/C receptors
Stretch receptors
Hypothalamus (pain, emotion)

Question 19

How do peripheral and central chemoreceptors change ventilation

Answer 19

+ve

Conc of gases in blood (PO2, PCO2) altered by increased ventilation rate

Question 20

How does proprioception change the rate of ventilation

Answer 20

+ve
When muscles move more, increased O2 needed
Ventilation rate increased

Question 21

How do irritant/C receptors change the rate of ventilation

Answer 21

-ve

Causes a change in breathing pattern, reduces ventilation rate to remove source

Question 22

How do stretch receptors change ventilation

Answer 22

-ve

Tells you when to stop inspiring and start expiring

Question 23

How does the hypothalamus alter the rate of ventilation

Answer 23

+-ve

Pain and emotion affects the way we breathe

Question 24

What controls our afferent responses to ventilation?

Answer 24

Pons/respiratory centres of medulla oblongata

Question 25

How does the cough reflex change as the irritation goes down the resp tract

Answer 25

If irritation in upper tract, violent reaction | If irritation in lower tract, less of a reaction

Question 26

What receptors trigger the cough reflex

Answer 26

Rapidly adapting irritant receptors | Non myelinated C fibres

Question 27

What afferent reflexes are triggered as a result of the afferent receptors being triggered

Answer 27

Bronchial submucosal glands produce more mucus to trap irritation

Question 28

What nerve do the sensory afferents go up in the cough reflex

Answer 28

Ipsilateral vagus

Question 29

Where is the cough center

Answer 29

Integration of afferent fibres in medulla, separate to breathing centres

Question 30

What are the efferent nerves in the cough reflex and what do they trigger

Answer 30

Via phrenic and other somatic nerves, stimulates breath and sudden chest wall mv Recurrent laryngeal vagal efferents to bronchial tree

Question 31

What muscles are effected by the nervous efferents from the cough center

Answer 31

Expiration muscles Larynx Trachealis Bronchial SM

Question 32

What can stimulate the cough reflex

Answer 32

``` Sinusitis Asthma Laryngotracheatis Tuberculosis Emphysema Foreign body ```

Question 33

Describe the structures in the larynx

Answer 33

Larynx, behind the tongue Oesophagus, most posterior Aryepiglottic fold surrounds epiglottis False/vestibular fold => true vocal fold => glottis Arytenoid cartilage found at the bottom of the aryepiglottic fold

Question 34

What structures are found in the aryepiglottic folds and what is the function

Answer 34

Aryepiglottic muscles found in aryepiglottic folds, acts as sphincter of airway, prevents foods from going down lung

Question 35

How can the glottis be altered

Answer 35

Glottis diameter can be altered by rotation of artenoid cartilage => abduction and addiction of the vocal folds

Question 36

How do the different positions of the glottis affect the possible range of functions

Answer 36

When arytenoid cartilages adduct => vocal folds come together => glottis closed For swallowing food, prevent food from falling into lung Arytenoid cartilage rotated => vocal folds separate => glottis open For breathing Arytenoid cartilage rotated and abducted => vocal folds separate => glottis really open For deep breathing Arytenoid cartilage abducted only, no rotation => vocal folds closed => glottis open For whispering

Question 37

Describe the structure of the larynx

Answer 37

Hyoid bone Thyrohyoid membrane between hyoid and thyroid cartilage. Membrane has opening for vagus to enter Thyroid cartilage Muscles between thyroid and cricoid cartilage Cricothyroid membrane Trachea

Question 38

How is the cricoid cartilage different from the tracheal cartilage

Answer 38

Cricoid, complete cartilage ring, thicker at the back | Tracheal, C shaped cartilage rig

Question 39

Where are the false folds, laryngeal ventricles and true folds in relation to the larynx in a coronal section

Answer 39

All at level of thyroid cartilage False fold Laryngeal ventricle True fold

Question 40

How to do an emergency laryngotomy and what to watch out for

Answer 40

Target cricothyroid membrane However, some people have a pyramidal 3rd thyroid lobe covering this membrane, don’t puncture the artery here If they do have a 3rd lobe, move it out of the way before puncturing membrane

Question 41

When would you do a tracheotomy and why

Answer 41

Opening made in trachea in surgery | Keep the airways open

Question 42

What nerves innervate the larynx

Answer 42

From inf vagal ganglion => sup laryngeal Sup laryngeal branches into int and ext laryngeal Inf vagal ganglion => L vagus => L recurrent laryngeal Inf vagal ganglion => R vagus => R recurrent laryngeal

Question 43

What is innervated by the int laryngeal

Answer 43

Thyrohyoid membrane => sensory above vocal folds

Question 44

What is innervated by the ext laryngeal

Answer 44

Cricothyroid muscle

Question 45

Describe the route of the L vagus | What does it innervate

Answer 45

L vagus => through superior thoracic aperture => chest => branch comes off the bottom and passes up groove between trachea and oesophagus (L recurrent laryngeal) Sensory to lower half of larynx, below vocal folds and supply muscles

Question 46

Describe the route of the R vagus | Describe the innervations of the R vagus

Answer 46

From inf vagal ganglion => passes in front of and behind R subclavian artery => larynx Supplies trachea and oesophagus on route Sensory to lower half of larynx, below vocal folds to supply muscles

Question 47

Describe the relative structures of the R and L bronchi and the importance of this

Answer 47

R bronchi = straighter and wider than L | Foreign objects more likely to fall down into R

Question 48

What is the level of the cricoid cartilage and the carina

Answer 48

Cricoid C6 | Carina T4-5

Question 49

Describe the structure of a cross section of the trachea | Function of each section

Answer 49

C shaped cartilage Submucus glands Trachealis muscle between cartilage and oesophagus Trachealis muscle innervated by PNS vagus Submucus gland release mucus for protection