Respiratory Physiology I : Volume And Pressures

Front 1

What is ventilation?

Back 1

The exchange of air between atmosphere and alveoli

Front 2

How are oxygen and carbon dioxide exchanged between alveolar air and blood in lung capillaries?

Back 2

By diffusion

Front 3

How are oxygen and carbon dioxide transported through pulmonary and systemic circulation?

Back 3

By bulk flow

Front 4

What is meant by bulk flow?

Back 4

When substrate is flowing through the tube and carries dissolved gas with it

Front 5

What forms the upper respiratory tract?

Back 5

Nasal cavity, mouth, pharynx, larynx

Front 6

What forms the lower respiratory tract?

Back 6

Front 7

Can the right lung and left lung function independently?

Back 7

Yes

Front 8

What are some functions of the upper respiratory tract?

Back 8

Filtration

Conditioning of air

Speech

Front 9

Filtration is an important defence mechanism against infection. Inhaled particles are trapped by hair and mucus in nasal passages. What do these inhaled particles activate?

Back 9

Irritant receptors triggering sneeze reflex

Front 10

What happens to excess mucus?

Back 10

passes back to the pharynx to be removed by swallowing

OR

is expulsed through nose

Front 11

Why is it necessary that air passing through the nasal cavity is warmed and humidified?

Back 11

Necessary for optimal gas exchange in the alveoli

(N.B nasal passages have a rich blood supply for this purpose)

Front 12

One function of the upper respiratory tract is speech. The larynx contains vocal cords: two folds of elastic tissue stretched across its lumen. What happens to them as air flows across them?

Back 12

They vibrate , producing sound

Front 13

The lower respiratory tract is divided functionally into two zones. What are these two zones?

Back 13

Conducing zone and respiratory zone

Front 14

What forms the conducting zone?

Back 14

Trachea, bronchi and bronchioles

Front 15

What keeps the airways open in the trachea and bronchi?

Back 15

C shaped bands of rigid cartilage

Front 16

What happens to the number of tubes in branch as you go from the trachea to bronchi?

Back 16

It increases

Front 17

Where does the trachealis muscle span and what is its function?

Back 17

Spans gap between ends of cartilage bands

It contracts to aid expulsion of blockages e.g coughing reflex

N.B narrowing of airway means air comes out faster so is more effective at dislodging blockages

Front 18

Describe the bronchioles

Back 18

No cartilage

Smooth muscle bundles. Normally relaxed, allowing air to reach alveoli

Contraction prevents irritants and particles from entering the alveoli

Front 19

What forms mucus?

Back 19

Front 20

Describe the process of mucociliary transport

Back 20

Front 21

How does the amount of cilia and mucus in upper airways compare to in the bronchioles?

Back 21

Bronchioles have fewer cilia and much less mucus

Front 22

How is bacteria and other small particles removed in bronchioles?

Back 22

Macrophages

Front 23

What forms the respiratory zone?

Back 23

Front 24

What happens in the respiratory zone that does not happen in the conducting zone?

Back 24

Gaseous exchange

Front 25

What do pulmonary arteries transport and from where to where?

Back 25

They carry deoxygenated blood from heart to lungs

Front 26

How many alveoli are in each alveolar sac?

Back 26

40-50

Front 27

Blood that goes through capillaries is supplied by branches what vessel?

Back 27

The pulmonary artery

Front 28

Approximately how many alveoli do the lungs contain?

Back 28

~300 x10 6

Front 29

What is the approximate diameter of the alveoli?

Back 29

0.2 mm

Front 30

What are the two types of alveolar cells orpneumocytes?

Back 30

Type I flattened epithelium(gaseous exchange)

Type II thicker cells(secrete surfactant)

Front 31

What is the function of the pores inside the alveoli?

Back 31

Gaps between alveoli that allow entry of air even if duct is blocked

Front 32

Other than providing oxygen and removing carbon dioxide, forming speech sounds, and protection from microbes and other foreign matter, what are some other functions of the lungs?

Back 32

Regulates blood hydrogen ion concentration

Removal or deactivation of circulating vasoactive (affecting the diameter of blood vessels) hormones e.g bradykinin

Activation of angiotensin II

Front 33

One function of the lungs is the removal of micro-thrombi arising in systemic veins. What is meant by this?

Back 33

The lungs removed small blood clots

Front 34

Angiotensin converting enzyme (ACE) on surface of pulmonary endothelium convertswhat into what?

Back 34

angiotensin I into angiotensin II

Front 35

Is angiotensin II a vasoconstrictor or vasodilator?

What does it trigger the release of?

Back 35

A vasoconstrictor

It triggers release of aldosterone from adrenal cortex

Front 36

In normal steady quiet breathing, the volume of air inspired is equal to the volume of air expired. What is this known as?

Back 36

Tidal volume

Front 37

What is the volume of tidal volume?

Back 37

500 ml

Front 38

What is the Inspiratory Reserve Volume (IRV)?

Back 38

The maximum amount that lung volume can be increased above tidal volume

3000 ml

Front 39

What is the Expiratory Reserve Volume (ERV)?

Back 39

After expiring the tidal volume, a further maximal exertion of the expiratory muscles a further volume can be expired

1200 ml

Front 40

What is the residual volume?

Back 40

Even after maximal expiratory effort, the lungs cannot be complete emptied, a sizeable volume always remains.

1200 ml

Front 41

Lung volumes vary between individuals. What factors can influence lung volume?

Back 41

Age

Gender

Height

Front 42

The sum of two or more volumes are known as what?

Back 42

capacities

Front 43

The sum of the inspiratory reserve volume plus the tidal volume is....?

Back 43

Inspiratory capacity

3500 ml

Front 44

The sum of inspiratory reserve volume plus the tidal volume plus the expiratory reserve volume is .....?

Back 44

Vital capacity

4700 ml

Front 45

The sum of expiratory reserve volume plus residual volume is......?

Back 45

Functional Residual Capacity

2400 ml

N.B this is what is left in the lungs after a normal breath out

Front 46

The sum of all four volumes (IRV+VT+ERV+RV) is ....?

Back 46

Total Lung Capacity

5900 ml

Front 47

Some lung volumes and capacities can bemeasured directly using a water Spirometer. Describe how this forms a trace.

Back 47

On inspiration, pen moves up On expiration, pen moves down

N.B modern versions of this decide use force transducers and record electronically

Front 48

Because the lungs cannot be completely emptied, no 'baseline' can be recorded. What is a consequence of this?

Back 48

Residual volume, and all capacities that include RV (FRC and TLC) cannot be measured directly using this device

Front 49

What is ventilation?

Back 49

The exchange of air between atmosphere and alveoli

Front 50

What is

Back 50

Total ventilation per minute

Front 51

What is

Back 51

Volume of fresh air reaching alveoli per minute

Front 52

How can minute ventilation be calculated?

Back 52

Tidal volume x breaths per minute

Front 53

Why is minute ventilation different from alveolar ventilation?

Back 53

Gaseous exchange occurs primarily in alveoli and minimally in respiratory bronchioles, while pharynx and conducing zone of lower respiratory tract do not contribute at all to this

The volume from the top of the pharynx down to the terminal bronchioles is known as the anatomical dead space

Of the 500ml tidal volume, 350 ml will reach the alveoli for gaseous exchange, while 150 ml will remain in the conducting zone and not be absorbed

Front 54

In adults, the anatomical dead space has a fixed volume. What is this?

Back 54

~150 ml

Front 55

How can alveolar ventilation be calculated?

Back 55

Front 56

Anatomical dead space is fixed. True or false.

Back 56

True

Front 57

Physiological dead space is fixed. True or false.

Back 57

False.

Front 58

In healthy lungs, anatomical dead space = physiological dead space.

However, in what instance would physiological dead space not be equal to anatomical dead space?

Back 58

If some alveoli are poorly perfused (with blood) then no gas exchange occurs in those areas. This is the alveolar dead space.

Physiological dead space = anatomical dead space + alveolar dead space

Front 59

What are the SI units of pressure?

Back 59

kPa

Front 60

What does mean?

Back 60

Fractional concentration of oxygen

Front 61

Flow can be defined by which equation?

Back 61

Front 62

In ventilation, which are the important pressures?

Back 62

Atmospheric pressure

Alveolar pressure

Front 63

When does movement of air into and out of the lungs occur?

Back 63

When P alv is smaller or larger than P atm

So in between breaths, when P alv = P atm, there is no flow of air

Front 64

The changes in pressure inside the lungs can be explain by Boyles Law. What is this?

Back 64

The pressure (P) of a fixed amount of gas ( at a constant temperature) is inversely proportional to the volume (V) of the container in which it is placed

Front 65

The lungs are enclosed in a fluid-filled pleural sac.Cohesive forces exerted by the fluid between the pleuralmembranes cause the lung to adhere to the thoracic cage andthus when the thorax changes its shape the lungs move with it.

True or false.

Back 65

True

Front 66

At Functional Residual Capacity (end of a normal breath out), all respiratory muscles are contracted/relaxed.

Back 66

Relaxed

Front 67

At the end of a normal breath out, inward recoil of the lungs is balanced by what?

Back 67

Outward recoil of the chest wall.

Front 68

At Functional Residual Capacity (end ofnormal breath out), all respiratory muscles arerelaxed and inward recoil of lungs isbalanced by outward recoil of chest wall.

What does this generate?

Back 68

Front 69

What is meant by P alv = 0

Back 69

Alveolar pressure is the same as atmospheric pressure

Front 70

What would happen if the chest wall was opened?

Back 70

Intra-pleural pressure would be normalised with atmospheric pressure

Lungs would collapse due to inward recoil

Chest wall would expand due to outward recoil

Front 71

The structure of the chest wall is such that elastic fibres in the chest tend to make the chest wall recoil ________, but _______ ______ of lungs makes lungs recoil inwards. Forces are balanced at ____

Back 71

outwards

elastic tissue

FRC

Front 72

What is trans-pulmonary pressure?

Back 72

The difference between alveolar pressure and intrapleural pressure

Front 73

How can trans-pulmonary pressure be calculated?

Back 73

Front 74

At FRC, what is trans-pulmonary pressure equal to?

Back 74

0.5 kPa

Front 75

What happens to intra plural pressure as the chest wall expands and why?

Back 75

It becomes more negative ( -0.7 kPa) as there is more of a force trying to pull the two membranes apart

Front 76

As the chest wall expands, intrapleural pressure becomes more negative.

How does this affect trans-pulmonary pressure and intra-pleural pressure?

Back 76

Trans-pulmonary pressure increases

Alveolar pressure decreases

Front 77

What are the sequence of events in inspiration?

Back 77

Nerves stimulate diaphragm and other inspiratory muscles to contract, expanding chest wall

Intrapleural pressure falls ( becomes more negative)

Alveoli are expanded

Pressure in alveoli falls

Increased pressure gradient from out the alveoli-air flows into lungs

Front 78

Why do the alveoli expand during inspiration?

Back 78

Due to increased trans-pulmonary pressure difference across the alveoli

Front 79

What are the sequence of events in normal expiration?

Back 79

Nerves decrease firing to diaphragm and intercostal muscles relax

Expanded chest wall recoils inwards

Intrapleural pressure goes back towards pre-inspiration level

Transpulmonary pressure decreases to pre-inspiration level

Expanded lungs which have a greater elastic recoil, reduce in size

Air in alveoli gets compressed

Air flows out of lungs

Front 80

In forced expiration or high ventilation: abdominal muscles contract which increases/decreases recoil of diaphragm and speed/slow down shrinkage of chest wall and lungs. Intrapleural pressure may be positive/negative

Back 80

increase

speed

positive

Front 81

When what two things are equal to each other is there no air flow?

Back 81

P alv = P atm

Front 82

In mid-inspiration, expanding chest wall _______ intra-pleural pressure, making trans-pulmonary pressure more _________. This ______ the lung, making P alv __________ and results in inward/outward airflow.

Back 82

decreases

postive

expands

negative

inward

Front 83

At the end of inspiration, chest wall is no longer expanding but has yet to passively _____. P alv = P atm and there is no ________

Back 83

recoil

airflow

Front 84

In mid-expiration, lung is collapsing, compressing ___________ gas. So P alv becomes ________ relative to P atm, causing _______ airflow

Back 84

alveolar

positive

outward

Front 85

What is the fractional concentration of nitrogen + inert gases in air ?

Back 85

~0.79 ( 79%)

Front 86

What is the fractional concentration of oxygen in air?

Back 86

~ 0.21 (21%)

Front 87

Why does humidified air alter the relative concentrations of other gases?

Back 87

The presence of water vapour dilutes oxygen

Front 88

The pressure exerted by a gas is directly proportional to what two things?

Back 88

Temperature

Number of gas molecules in a given volume (concentration)

Front 89

What is the definition of partial pressure as defined by Dalton's Law?

Back 89

Individual pressure of a particular gas (e.g oxygen) in a mixture of chemically non-reactive gases

Front 90

What is total pressure equal to?

Back 90

Front 91

What is the equation to calculate partial pressure (e.g of oxygen) ?

Back 91

P atm x fractional concentration

Front 92

Why are the volumes different?

Back 92

Oxidation of organic fuel products water as well as CO2.

CO2 produced / oxygen consumed =respiratory quotient = 0.8

Front 93

At rest, what is alveolar ventilation?

Therefore what is the volume of oxygen inhaled per minute?

Back 93

4.2 L/min

21% of 4200ml = 882 ml

Front 94

Of the 882 ml of oxygen in inhaled air, what happens to it?

Back 94

250 ml is absorbed into the blood and added to the reservoir of 750 ml

250 ml used by cells per min

Front 95

How much CO2 do cells produce per minute?

Back 95

200 ml

Front 96

What is the reservoir of CO2 in the body?

Back 96

2400 ml

Front 97

How much CO2 is expired per minute?

Back 97

200 ml

Front 98

How does the PO2 of oxygen vary in these places?

Back 98

PO2 reduced from atmospheric air to upper airways because of saturation

Front 99

How does PCO2 vary in each of these places?

Back 99

Front 100

How does PH20 vary in each of these places?

Back 100