Respiratory System

Question 1

What is the superior thoracic aperture?

Answer 1

The opening of the thoracic cage, at the neck containing blood vessels and nerves

Question 2

What is contained in the superior compartment of the mediastinum?

Answer 2

The ascending aorta, the aortic arch, the thymus

Question 3

What is contained in the posterior compartment of the mediastinum?

Answer 3

the oesophagus and descending aorta

Question 4

what is the first branch of the aortic arch and what does this supply?

Answer 4

Brachiocephalic trunk - right common carotid and right subclavian artery

Question 5

What vessels drain into and make up the superior vena cava?

Answer 5

Right and left brachiocephalic vein - which the right and left jugular and subclavian veins drain into

Question 6

What nerve supplies the diaphragm?

Answer 6

Phrenic Nerve from C3-5

Question 7

What structures pass through the diaphragm?

Answer 7

Oesophagus and IVC, aorta does not

Question 8

What is the respiratory epithelium?

Answer 8

Pseudostratified ciliated columnar

Question 9

What is the role of the conchae?

Answer 9

To humidify air, so it is not too cold and damages the trachea and bronchus

Question 10

What is the role of the paranasal sinuses?

Answer 10

to lighten skull and voice resonance

Question 11

Why is the structure of the paranasal sinus flawed?

Answer 11

these drain into the internal nose, however the drainage duct is at the top of the sinus. Therefore, the infection or tumour has to grow all the way to the top before it is drained and the symptoms are seen

Question 12

What is the name given to the abnormal connection of the epithelium between the oral mucosa and the paranasal sinus?

Answer 12

oro-antral fistula

Question 13

what is the only cartilage at the larynx that is a complete ring?

Answer 13

cricoid cartilage

Question 14

what is the connection between cricoid cartilage and thyroid cartilage and how can this be useful clinically?

Answer 14

crico-thyroid ligament, if airway blocked (food, chocking at thyroid) membrane can be pierced and a tube inserted through here to provide an airway

Question 15

Where does the trachea begin?

Answer 15

at c6, after the cricoid cartilage

Question 16

what muscle is associated with the trachea and where is this situated?

Answer 16

trachealis, lies at the posterior trachea, no cartilage here

Question 17

why is the right bronchus more susceptible to pneumonia?

Answer 17

it is more vertical from the bronchus, so anything swallowed, e.g. foreign objects, are more likely to end here

Question 18

when is a tracheostomy used?

Answer 18

in terminally ill patients that require mechanical ventilation

Question 19

What is the pressure of oxygen in the alveolar sacs?

Answer 19

100mmHg

Question 20

What are the differences between quiet breathing and strenuous breathing?

Answer 20

Diaphragm is contracted more in strenuous - only 1cm in quiet, 10cm in strenuous
Accessory respiratory muscle required in strenuous inhalation - sternocleidomastoid e.g.
Exhalation is active during strenuous breathing, abdominal muscles and internal intercostal muscles required. In quiet breathing, it is passive - elastic recoil

Question 21

What is the transpulmonary pressure in the lungs and what does this cause in breathing?

Answer 21

transpulmonary pressure is the difference between alveolar pressure and the pleural pressure. In inhalation, alveolar pressure is equal to the atmospheric pressure, but the pleural pressure decreases even further as the diaphragm contracts, increasing the transpulmonary pressure which causes the lungs to expand

Question 22

What pulls air into the lungs?

Answer 22

The pressure difference, as the volume increases in the thorax with the diaphragm and external intercostal contracting, the pressure decreases, so air flows from a high pressure outside to a low pressure inside the lungs

Question 23

What drives exhalation of air, in terms of pressure difference?

Answer 23

As the diaphragm stops contracting, air flows in to the lungs, the alveolar pressure is equal to the barometric pressure. The lungs then elastic recoil, and the pleural and transpulmonary pressure return to normal. The air is then compressed in the alveoli, the pressure here is larger than the pressure in the barometric pressure and air flows out of the lungs.

Question 24

What is the functional residual volume?

Answer 24

The volume of air left in the lungs after exhalation

Question 25

What forces are acting on the FRV?

Answer 25

elastic recoil of the lungs is forcing the air out of the lungs, the recoil of the chest wall is retaining air in the lungs - these are equal and cancel one another out so the air is kept in the lungs

Question 26

What is the anatomical dead space in the lungs?

Answer 26

The conducting airways, bronchus containing cartilage and non-respiratory bronchioles, don't participate in gas exchange, but 30% of the air in each breath stays here

Question 27

How can the volume of air increase during exercise?

Answer 27

during exercise, more muscles contracting, increasing the pressure changes so recruits more capillaries and alveolar sacs, not normally used in quiet breathing

Question 28

What is the pressure of gases in the pulmonary artery?

Answer 28

O2 - 40mmHg CO2 - 45mmHg

Question 29

What is the pressure of gases in the alveolar sac?

Answer 29

O2 - 100mmHg CO2 - 40mmHg

Question 30

What is the pressure of gases in the pulmonary vein?

Answer 30

O2 - 100mmHg CO2 - 40mmHg

Question 31

Describe how exercise can alter the oxyhaemoglobin saturation.

Answer 31

During exercise, pH decreases due to lactic acid formation. At low pH, for the same given PO2, haemoglobin saturation is reduced. Also, the core temperature increases during exercise. At higher temperatures, for a given PO2, the haemoglobin saturation is also reduced.

Question 32

Below which partial pressure of O2 is a big reduction seen in haemoglobin saturation.

Answer 32

Below 60mmHg

Question 33

What is the main way in which CO2 is transported around the body?

Answer 33

In bicarbonate - CO2 + H2O gives carbonic acid, bicarbonate can be formed

Question 34

Define the respiratory exchange ratio.

Answer 34

The number of molecules of CO2 expired to the number of molecules of O2 uptake, normally 0.8

Question 35

What are chemoreceptors and where are they located?

Answer 35

Receptors that detect levels of PO2, PCO2 and pH in the blood. Peripheral receptors are located in the aortic arch and carotid sinus, these respond to decrease in PO2 - hypoxia. Central chemoreceptors are located at the brainstem and detect increase in PCO2 or decrease in pH

Question 36

What is different in the functioning of the central and peripheral chemoreceptors?

Answer 36

Central are very sensitive, a small increase in PCO2 results in a change in ventilation. Whereas, peripheral receptors don't alter ventilation until PO2 drops below 60mmHg

Question 37

What do mechanoreceptors detect in the lungs?

Answer 37

A stretch in the lungs, the alveolar epithelium or respiratory epithelium

Question 38

How do mechanoreceptors control breathing?

Answer 38

When stretch on epithelium detected, signal to NTS to stop inhalation and stop respiratory muscles contracting

Question 39

When do mechanoreceptors and chemoreceptors send their signals to?

Answer 39

The nucleus tractus solitarius, in the dorsal respiratory group at the medulla in the brainstem

Question 40

What controls normal, quiet breathing?

Answer 40

The central pattern generator, the ventral respiratory group in the brainstem. Produces a constant signal to the respiratory muscles via inhalation neurones or exhalation neurones, even if removed from body, signal is constant

Question 41

How can the CPG be modified to alter ventilation?

Answer 41

The NTS (receiving signals from chemo and mechanoreceptors) can send signals to the NTS, to tell it to change the firing to respiratory muscles. Can also receive input from the pontine respiratory group for volitional control of breathing

Question 42

Describe how ventilation is distributed throughout the lungs.

Answer 42

At the apex of lungs, due to gravity, pleural pressure is more negative resulting in a larger transpulmonary pressure. This causes the alveolar sacs to be more distended, therefore the change in volume of the sacs is much less, pressure difference is reduced so less air is drawn in here

Question 43

How can compliance change the ventilation

Answer 43

If the alveoli are less compliant, cannot stretch as much so cannot take in a high volume of air. Less air - less gas exchange

Question 44

How can resistance alter the ventiliation

Answer 44

A blockage or narrowing of airways results in a higher resistance, so it takes longer for air to flow in to alveoli. Although the same volume can be reached, there is not enough time in a breath to allow it, so less air taken in and less gas exchange

Question 45

What is physiological dead space?

Answer 45

The alveolar capillaries that are ventilated but not perfused

Question 46

Describe the distribution of blood flow through the lungs

Answer 46

The apex of the lungs have a much lower blood flow than the base of the lungs due to gravity and pressure difference

Question 47

How does the V/Q relationship differ throughout the lungs?

Answer 47

At apex - lower perfusion to ventilation, so blood comes out saturated with oxygen, high VQ ratio At base - perfusion much higher but ventilation not increased as much, blood is less saturated and VQ ratio lower - these balance out to give overall 0.8 ratio

Question 48

Describe an antaomical shunt in regards to ventilation

Answer 48

When blood is being shunted from right to left to avoid it from being oxygenated. Results in deoxygenated blood mixing with oxygenated blood. Patent foramen ovale - mixing of blood from right atria to left atria

Question 49

describe a disease that has a low VQ ratio

Answer 49

low VQ ratio occurs when ventilation is blocked but perfusion is maintained. Bronchitis is where mucous is produced in the airways, blocking the air coming in so ventilation is decrease

Question 50

describe a disease that has a high VQ ratio

Answer 50

high VQ when ventilation is maintained but blood flow through alveoli is poor. Emphysema - the alveolar sacs are inflammed, damage the capillaries so flow is poor despite good ventilation. exhalation is difficult as lungs have lost elastic ability

Question 51

where does the apex of the lung lie

Answer 51

1 inch above the medial 3rd of the clavicle

Question 52

what forms the pulmonary ligament

Answer 52

a double folding of pleura