Respiratory System

Question 1

What is diffusion ?

Answer 1

Random motion of molecules in all directions through the respiratory membrane and adjacent fluids.
Diffusion needs a source of energy but is totally passive. The diffusion goes from both side but the rate of diffusion is bigger from the high concentration are to the low concentration area.

Question 2

What is the diffusion law ?

Answer 2

The surface area x the difference of concentration on both side x the diffusion coefficient of the gas

Divided by the distance on both side.

Question 3

What factors determine the rate of diffusion ?

Answer 3

Thickness of membrane
Surface of membrane
Diffusion coefficient of the gas

Question 4

What causes pressure ?

Answer 4

Multiple impact of moving molecules. Directly proportional to the concentration of molecule

Question 5

What is the partial pressure of a gas ?

Answer 5

It’s the pressure difference of the gas between the 2 side of the membrane. It tends to force molecule of that gas into the solution in the blood.
The rate of diffusion of a gas is proportional to its partial pressure.

Question 6

What happen to pressure when the airway is humidified ?

Answer 6

The total pressure stay the same but partial pressures of others gas will be reduced to be replaced by the water vapour.
A decreased partial pressure in the lungs means less diffusion towards the capillaries.

Question 7

Of what is composed the diffusion barrier of the lungs ?

Answer 7

Airway space
Alveolar epithelium
Epithelial basement membrane
Interstitial space
Capillary basement membrane
Capillary endothelium
Plasma

Question 8

How does the oxigen diffuse ?

Answer 8

There is a low partial pressure of O2 in the alveoli compared to the outside environnement because there is a constant movement of O2 diffusion towards the capillaries where the partial pressure is even lower.
This low pressure allow oxygen to be pumped into the lungs.

Question 9

How does CO2 diffuse ?

Answer 9

The partial pressure in the capillaries is much higher than in the alveoli which is lower than the external environment. CO2 follows the gradient of concentration and is exhaled.

Question 10

Where does the gas exchange take place in the lungs ?

Answer 10

Mainly in the alveoli but also in the last pat of the terminal bronchioles, the respiratory bronchioles.

Question 11

How is CO2 transported ?

Answer 11

Majority is transported as part as the bicarbonate system (bicarbonate buffer system).
After diffusion into the red blood cells, it is converted into carbon is acid then into bicarbonate and H+.
While H+ bind to the hemoglobin, bicarbonate is transported out of the red blood cell in exchange he for chloride ion. ==> chloride shift
Arrived at the lungs, the bicarbonate goes back to the red blood cell to be reconverted into CO2 and expelled into the capillaries first then into the blood.

Question 12

How is O2 transported ?

Answer 12

The deoxygenated is transported by binding to the haemoglobin because otherwise it is not very soluble.

Question 13

Why is the binding between O2 and haemoglobin important for its transport ?

Answer 13

After the 1st molecule of O2 binds to the heme group the shape of it will change making it easier to allow other bindings. The ability of the heme group to attach with dioxygen increase as the O2 binds to it.

Question 14

What is the Bohr effect ?

Answer 14

If the temperature increase, the pressure of CO2 will increase therefore the pH level will decrease. The ability of haemoglobin to bind with O2 will decrease.

Question 15

What is the Haldane effect ?

Answer 15

If the partial pressure of O2 increase it will induce the dissociation of CO2 from haemoglobin.

Question 16

Where is the ventilation the greatest and why ?

Answer 16

At the base o the lungs. Because of gravity the intrapleural pressure on the top of the lungs is lesser than at the base. The alveoli at the top will be less compliant and wont be able to expand as much as at base during inspiration therefore they will be less ventilated.

Question 17

Where is perfusion the greatest and why ?

Answer 17

Because of gravity, 2/3 of the blood vessels will perfuse the base of the lungs and only 1/3 the top.

Question 18

What is a pathological shunt ? What happens ?

Answer 18

It happens if a foreign object block the airway in one of the lungs. All the air conducting volume behind won’t be able to be ventilated.
In the capillaries, the partial pressure of O2 decrease and the partial pressure of CO2 increase slightly.
V/Q = 0
Mechanism of vasoconstriction will be put in place, the perfusion to the capillaries of this area will be reduced.

Question 19

What is an alveolar dead space ? What happen ?

Answer 19

It happens if a foreign object is blocking the blood vessels of the lungs : pulmonary embolism.
In the lungs, the partial pressure of O2 will increase and the partial pressure of CO2 will be close to 0.
V/Q = infinite
In the lungs bronchial constriction will happens, progressively ventilating only the area where blood is still flowing. The alveolar type 2 pneumocyte will stop the production of surfactant causing the alveoli of the dead space to shrink.

Question 20

What are the 2 function f the lungs ?

Answer 20

Conducting portion (ventilation) to get the air into the respiratory system.
Respiratory portion (gaz exchange) to couple the O2 to haemoglobin to supply energy to the cells.

Question 21

What happen to the other lung if one collapse ?

Answer 21

it will not collapse because both are independent from each other. Each possess its own pleura.

Question 22

What is thoracocentesis ? How do you do it ?

Answer 22

A procedure to remove pressure from the lungs by draining fluids or air possibly present in the pleural cavity.
Insertion of a needle at the 8th intercostal space (the lowest level to avoid damage to the diaphragm dont go under).
Used in pneumothorax or haemothorax.

Question 23

What is the physiological dead space in the lungs ?

Answer 23

A dead space is a conducting airway where there is no gaz exchange. The physiological dead space is the biggest, a combination between the anatomic and alveolar dead space.

Question 24

What is a physiological shunt ?

Answer 24

When a non ventilated alveoli remain perfused. It’s the reason why there is never a 100% oxygen saturation in the blood.

Question 25

What is the ribs respiration ?

Answer 25

Also called the chest or flank respiration it’s the movement of elevation and depression of the thoracic cage.
The costovertebrale joints linked to each ribs allow the cavity to be enlarged.

Question 26

What does each costovertebrale joints do ?

Answer 26

The joint T1 allow the rib to move up and down.
The joint T2 allow the rib to move from side to side.

Question 27

Which muscle contract during normal inspiration ?

Answer 27

The external intercostal muscle, interchondral (between the cartilage) part of internal and innermost intercostal muscle.
The diaphragm.

Question 28

Who are the accessory muscle of inspiration ?

Answer 28

The sternocleidomastoid muscle, the pectoralis major and minor. The scalene muscle.

Question 29

Which muscle activate during forced expiration ?

Answer 29

Internal and innermost intercostal muscles (except the cartilage part), the transverse thoracic muscle.
The oblique and rectus abdominis.

Question 30

What do you hear in pneumothorax ?

Answer 30

No sound in the affected lung.

Question 31

What is a pneumoctomy ?

Answer 31

The removal of lung or lung lobe.

Question 32

What are the first signs of tuberculosis ?

Answer 32

Mucoid sputum and productive cough.

Question 33

What is chest physiotherapy ?

Answer 33

The use of vibration and percussion to help dislodge the thick airway secretion.