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Respiratory > Basic Science > Flashcards

Basic Science Flashcards

1
Q

By which means is most oxygen transported in the body?

A

Bound to Hb

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2
Q

By which means is most CO2 transported in the body?

A

As bicarbonate

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3
Q

Where is a small amount of oxygen transported?

A

In solution

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4
Q

What shape is the myoglobin dissociation curve?

A

Hyperbolic

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5
Q

What shape is the haemoglobin dissociation curve?

A

Sigmoid

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6
Q

What is the shape and direction of the Bohr effect on the Hb dissociation curve?

A

Sigmoid, shifted right

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7
Q

What is the processes that exchange oxygen and CO2 between the external environment and the cells of the body?

A

External respiration

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8
Q

What comprises ventilation, gas exchange between the alveoli and blood, gas transport, and gas exchange at the tissues?

A

Internal respiration

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9
Q

Maintains alveolar patency through the elastic recoil of surrounding alveoli preventing alveolar collapse?

A

Alveolar interdepencence

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10
Q

What is the anatomical surface marking of the beginning of the lower respiratory tract?

A

C6 vertebra

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11
Q

What is the Bohr effect?

A

The oxygen dissociation curve is shifted to the right due to conditions in the tissues, meaning more oxygen is released

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12
Q

What is the Haldane effect?

A

As O2 is removed from Hb, Hb’s ability to pick up CO2 and CO2 generated H+ ions is invcreased

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13
Q

What is Henry’s law?

A

The amount of gas dissolved in a given type and volume of liquid at constant temperature is proportional to the partial pressure of the gas in equilibrium with the liquid

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14
Q

What is the anatomical site used for decompressing a tension pneumothorax?

A

2nd intercostal space

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15
Q

What is the anatomical site of the oblique fissure anteriorly?

A

Rib 6

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16
Q

What is Ficks law of diffusion?

A

Gas diffusion across a surface is inversely proportional to surface thickness and proportional to area

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17
Q

What is Dalton’s law?

A

The total pressure of a mixture of gases equals the sum of the partial pressures of each component gas

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18
Q

What is the law of LaPlace?

A

Smaller alveoli have a greater tendency to collapse

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19
Q

What vessel carries deoxygenated blood, drains into the superior vena cava and arches round the right lung root?

A

Azygous vein

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20
Q

What arise from the anterior surface of the ascending aorta?

A

Bronchial arteries

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21
Q

What is a major inspiratory muscle containing crura?

A

Diaphragm

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22
Q

What are thoracic muscles involved in active expiration?

A

Internal intercostals

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23
Q

what is a substance produced by alveolar type II cells that opposes alveolar surface tension?

A

Alveolar surfactant

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24
Q

What keeps the visceral and parietal pleura closely opposed and can be overcome by pneumothorax?

A

Transmural pressure gradient

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25
Q

What keeps the visceral and parietal pleurae closely opposed and is dependent on water molecule polarity?

A

Intrapleural fluid

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26
Q

What is boyles law?

A

At a constant temperature, the pressure exerted by a gas varies inversely with the volume of gas i.e. as the volume of a gas increases, the pressure exerted by the gas decareses

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27
Q

What is the anatomical site of the horizontal fissure?

A

Right 4th rib

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28
Q

What is the level of the oblique vertebra posteriorly?

A

T3 vertebra

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29
Q

What is the level at which the lower respiratory tract begins?

A

C6 vertebra

30
Q

What carries oxygenated blood and are sited inferoposteriorly within the lung root?

A

Pulmonary veins

31
Q

What carries deoxygenated and are sited superomedially within the the lung root?

A

Pulmonary arteries

32
Q

What are thoracic muscles involved in active expiration?

A

internal intercostals

33
Q

What is the volume of air breathed in and out per minute?

A

Pulmonary ventilation

34
Q

What is the volume of air exchanged between the atmosphere and alveoli per minute?

A

Alveolar ventilation

35
Q

What is the inspired air that is available for gas exchange?

A

Alveolar ventilation

36
Q

What particles does the mucus contain?

A

Macrophages
Cell debris
Inhaled particles
Bacteria

37
Q

What are the two types of cell found in the alveoli?
What is their function?
How common are they?

A

Type I pneumocytes
- Extremely thin cytoplasm, which offers a thin barrier to gas exchange
Type II pneumocytes
- Produce alveolar surfactant
- Are slightly more numerous than type I cells but cover less of the epithelial lining

38
Q

Why is giving high flow oxygen to a patient with COPD potentially dangerous?
Clues
1. What is the strongest stimulation to ventilation?
2. What happens to this in COPD?
3. What would oxygen treatment do?

A

The strongest stimulation to ventilation is PaCO2.
Sensitivity to this may be lost in patients with COPD, therefore in these patients hypoxaemia is the chief stimulus to respiratory drive.
Oxygen treatment may therefore reduce respiratory drive and lead to a further rise in PaCO2.

39
Q

What is physiological deadspace?
How do ventilation and perfusion relate in this?
What are causes of this?

A

Physiologic dead space is the sum of anatomical dead space (parts of the bronchial tree which are not perfused) and alveolar dead space (alveoli which are ventilated but not perfused.
This ventilation with reduced perfusion.
Causes include PE, necrosis, fibrosis (loss of capillary bed)

40
Q

What is a physiological shunt?
How does this relate to ventilation and perfusion?
What are causes of this?

A

There is adequate perfusion with reduced ventilation.
Causes include asthma, COPD, lung collapse or consolidation, loss of elastic tissue (emphysema), disease of the chest wall

41
Q

What are the four stages of external respiration?

A
  1. Ventilation - the mechanical process of moving air into and out of the lungs
  2. Ges exchange between the alveoli and blood
  3. Gas transport in the blood
  4. Gas exchanged at tissue level
42
Q

What two forces hold the thoracic wall and lungs in close opposition?
Which is more important?

A
  1. The Intrapleural fluid cohesiveness - the water molecules in the intrapleural fluid are attached to each other and resist being pulles apart, hence pleural membranes stick together
  2. The negative intrapleural pressure - creates a transmural pressure gradient across the lung wall ad across the chest wall
    THE SECOND ONE IS MORE IMPORTANT THAN THE FIRST
43
Q

What three pressures are important in ventilation?

A
  1. Atmospheric pressure
  2. Intra-alveolar pressure
  3. Intrapleural pressure
44
Q

Which intercostal muscles lift the ribs up and outwards in a “bucket handle” mechanism during inspiration?

A

External intercostals

45
Q

What is alveolar surfactant?
How does alveolar surfactant work?
Clue - which law of respiration does it follow?

A

Surfactant reduces the alveolar surface tension.
According to the law of LaPlace: the smaller alveoli (with smaller radius - r) have a higher tendency to collapse. Pulmonary surfactant is a complex mixture of lipids and proteins secreted by type II alveoli. It lowers alveolar surface tension by interspersing between the water molecules lining the alveoli. Surfactant lowers the surface tension of smaller alveoli more than that of large alveoli. This prevents the smaller alveoli from collapsing and emptying their air contents into the larger alveoli.

46
Q

Definition of tidal volume

A

Volume of air entering of leaving the lungs during a single breath

47
Q

How does a volume time graph differ from normal in obstructive lung disease?

A

Graph begins and ends at the same point, but takes longer to reach plateau.

48
Q

How does a volume time graph differ from normal in restrictive lung disease?

A

Starts slightly later; doesn’t reach as high a plateau; both FCV & FEV1 are low, giving a normal FEV1/FVC

49
Q

Why is active expiration difficult in patient with obstructive airway disease?

A

Dynamic airway compression - the rising pleural pressure during active expirayio compreses the alveoli and airway

50
Q

What is pulmonary compliance?

A

Compliance is a measure of effort that has to go into stretching or distending the lungs.
It is a measure of the volume change per unit of pressure change across the lungs.
The less compliant the lungs are, the more work is required to produce a given degree of inflation.
It shows a restrictive pattern on spirometry.

51
Q

What mechanisms are in place for large perfusion but small ventilation?

A

Large perfusion –> decreased O2 in area –> contraction of local pulmonary arteriolar SM –> constriction of local blood vessels -> increased vascular resistance –> decreased blood flow.
Small ventilation –> increased CO2 in area –> relaxation of local airway SM –> dilation of local airways –> decreased airway resistance –> increased airflow.

52
Q

What mechanisms are in place for large airflow but small perfusion?

A

Large airflow –> decreased CO2 in area –> contraction of local airway SM –> constriction of local airways –> increased airway resistance –> decreased airflow.
Small perfusion –> increased O2 in area –> relaxation of local pulmonary arteriolar SM –> dilatation of local blood vessels –> decreased vascular resistance –> increased blood flow.

53
Q

What four factors influence the rate of gas exchange across the alveolar membrane?

A
  1. Partial pressure gradient of O2 and CO2
  2. Diffusion coefficient for O2 and CO2
  3. Surface area of alveolar membrane
  4. Thickness of alveolar membrane
54
Q

PAO2 = PiO2 - [PaCO2 / 0.8]

What do these things mean?

A 
PAO2 = partial pressure of oxygen in the alveolar air
PiO2 = partial pressure of O2 in inspired air
PaCO2 = partial pressure of CO2 in arterial blood
0.8 = repiratory exchange ratio i.e. ratio of CO2 produced/O2 consumed
55
Q

What offsets the partial pressure gradient for CO2 and O2?

A

CO2 is more soluble in membranes than O2. The solubility of gas in membranes is known as the Diffusion Coefficient for the gas. The diffusion coefficient for CO2 is 20 times that of O2.

56
Q

How does foetal haemoglobin differ from adult haemoglobin?

Why?

A

It has twp alpha and two gamma subunits - hence it has a higher affinity for O2 compared to adult Hb, allowing O2 to transfor from mother to foetus even if the PO2 is low

57
Q

Where is myoglobin present?
How does it differ form Hb?
What is the shape of it’s curve?
Why is it there and how does it work?

A

Myoglobin is present in skeletal and cardiac muscles. There is one haem group per myoglobin molecule.
Dissociation curve is hyperbolic
Myoglobin releases O2 at very low PO2
-Provides a short-term storage of O2 for anaerobic conditions
Presence of myoglobin in the blood indicates muscle damage

58
Q

How is carbonate made in the red blood cells?

What does Hb have to do with this?

A

CO2 moves into the cell and reacts with water in the presence of carbonic anhydrase to form carbonate ions. The negatively charges ions then move out of the RBC and chloride ions move in – called chloride shift.
H+ then binds with haemoglobin to form HbH.

59
Q

What role does the medulla oblongata have in breathing?

A

The medulla oblongata detects the levels of oxygen and carbon dioxide concentrations and signals the muscles in the heart, the lungs and diaphragm to increase or decrease the breathing. The pons controls the speed of inhalation and exhalation or respiration rate depending on the need of the body

60
Q

What is breathing rhythm generated by?

A

A network of neurons called the Pre-Botzinger complex. These neurons display pacemaker activity. They are located near the upper end of the medullary respiratory centre.

61
Q

Name and explain four involuntary modifications of breathing.

A
  1. Pulmonary stretch receptors - mechanoreceptors found in the lungs which initiate the Herin-Bruer reflex, reducing the respiratory rate when the lung expands
  2. Joint receptors - impulses from moving limbs reflexly increase breathing
  3. Factors that may increase ventilation during exercise - e.g. adrenaline release, impulses from cerebral cortex, increase in body temp
  4. Cough relex
62
Q

Where are peripheral chemoreceptors and what do they do?

A

The are clusters of cells located in the carotid and aortic bodies.
They sense tension of oxygen and carbon dioxide and H+ in the blood

63
Q

Where are central chemoreceptors and what do they do?

A

They are situated near the surface of the medulla of the brainstem.
They respond to the [H+] of the cerebrospinal fluid

64
Q

What are the four main centers in the brainstem that regulate respiratory rate?
Where are they located?

A
  1. Inspiratory centre - medulla oblongata
  2. Expiratory center - medulla oblongata
  3. Pneumotaxic center - various nuclei of the pons
  4. Apneustic center - nucleus of the pons
65
Q

What is the role of the ventral respiratory group?

A

The ventral respiratory group controls voluntary forced exhalation and acts to increase the force of inspiration. Regulates rhythm of inhalation and exhalation.

66
Q

What is the role of the dorsal respiratory group?

A

The dorsal respiratory group controls mostly inspiratory movements and their timing.

67
Q

What is the role of the pneumotaxic center?

A

Coordinates speed of inhalation and exhalation
Sends inhibitory impulses to the inspiratory area
Involved in fine tuning of respiration rate

68
Q

What is the role of the apneustic center

A

Coordinates speed of inhalation and exhalation.
Sends stimulatory impulses to the inspiratory area – activates and prolongs inhalate (long deep breaths)
Overridden by pneumotaxic control from the apneustic area to end inspiration

69
Q

What lung volume increases with age?

A

Residual volume

70
Q

Does acidosis of alklalosis shift the oxygen dissociation curve to the right or left?

A

Alkalosis shifts left

Acidosis shifts right

Respiratory (15 decks)

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