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Applied Clinical Physiology > Respiratory > Flashcards

Respiratory Flashcards

1
Q

What are 5 stages of foetal lung development?

A
  1. Embryonic
    1-7 weeks
  2. Pseduoglandular Phase
    7-16 weks
  3. Canalicular Stage
  4. 25w
  5. Saccular Stage
    25-36w
  6. Alveolar Stage
    36+
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2
Q

Name 6 differences between adult and paeds airway?

A
  1. Tongue large in proportion to mouth
  2. Smaller pharynx
  3. Epiglottis larger and floppier
  4. Laynx more anterior and superior
  5. Narrowest at cricoid
  6. Trachea narrow and less rigid
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3
Q

What are reasons for respiratory issues in children?

A
  1. Nasal congestion can lead to significant respiratory distress until 6 months
  2. airway small <9 years
  3. Relatively little cartilaginous support
  4. Respiratory muscles may fatigue rapidly
  5. Large tongue, small oropharynx in infants and small children
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4
Q

What is respiratory drive?

A

Controlled by respiratory centre in the brainstem.

Inhaling and exhaling is automatic but can be voluntarily controlled.

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5
Q

Where is the respiratory centre?

A

pontine respiratory group in pons - upper pons = timing, lower pons = rhythm

then ventral (expiration) and dorsal (inspiration) respiratory group in medulla.

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6
Q

What is the conducting zone in respiration?

A

The trachea, primary bronchus and terminal bronchioles.

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7
Q

what is respiratory zone in respiration?

A

Respiratory bronchioles, leading to alveolar sacs and alveolus.

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8
Q

What is ventilation?

A

The movement of air through the conducting passageways between the atmosphere and the lungs.

Air flows because of pressure differences.

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9
Q

What happens in inspiration?

A

Diaphragm contracts and thoracic cavity increases in volume.

An active process, This makes intrathoraic pressure lower than atmospheric pressure so the air comes in

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10
Q

What happens in expiration?

A

A passive process, The diaphragm and intercostals relaxes, elastic muscles recoil which decreases the thoracic volume.

Results in increase in the intraalveolar pressure and air is expelled

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11
Q

How does gas exchange work in the lungs?

A

Oxygen and CO2 move between the air and blood by simple diffusion.

They move from high partial pressure to low partial pressure.

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12
Q

What is Fick’s law of diffusion?

A

The amount of gas that moves across the tissue is proportional to the area of the tissue but inversely proportional to its thickness.

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13
Q

What is surface area of the blood-gas barrier?

A

50-100m2 and is very thin

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14
Q

How many alveoli are in a human lung?

A

Approximately 300 million, giving about 85m2 surface area.

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15
Q

What is PO2?

A

The partial pressure of oxygen. The amount of O2 dissolved in the blood.

Low arterial PO2 means gas exchange in lungs is impaired.

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16
Q

What is typical pressure in pulmonary artery?

A

15mmHg

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17
Q

What is typical pressure in aorta?

A

100mmHg

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18
Q

Why is pulmonary pressure so much lower than other pressures?

A

Allows right side of heart to keep up with workload - the lungs receive the whole of the cardiac output in one go.

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19
Q

What adaptations does pulmonary circulation have?

A
  1. pulmonary arteries have thin walls
  2. Pulmonary capillaries mesh together in alveolar wall so blood flows through capillary bed
  3. It can decrease resistance as cardiac output increases
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20
Q

How can pulmonary circulation decrease resistance in response to increased cardiac output?

A
  1. Capillary recruitment (opening further capillaries)

2. Capillary distension

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21
Q

What benefits does decreasing pulmonary pressure for increased cardiac output have?

A
  1. Minimises load on right side of heart
  2. Prevents pulmonary oedema
  3. Maintains adequate flow rate of blood in the capillary
  4. Increases the capillary surface area
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22
Q

What is Henry’s law?

A

The amount of gas dissolved in the liquid is proportional to it’s partial pressure.

e.g. amount of oxygen dissolved in blood

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23
Q

What is structure of haemoglobin?

A

2 x alpha and 2 x beta chains.

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24
Q

What controls the red blood cell production and Hb in the body?

A

Erythropoietin. Produced by the kidneys.

Production stimulated when amount of oxygen delivered to the kidneys is lower than normal .

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25
Q

How much oxygen can bind with 1g Hb?

A

1.39ml

26
Q

How much Hb does normal blood have?

A

15mg/100ml

27
Q

What is partial pressure o2 in arterial and venous blood?

A

arterial 100mmHg

venous 40mmHg

28
Q

What is the Bohr effect?

A

The amount of O2 carried and released by Hb depends not only the pO2 but also on the pH.

Acidity causes HbO2 to dissociate to release O2 in the tissues.

H+ displaces O2 from the HbO2 thus increasing the O2 available to the tissues.

The release of O2 even when pO2 is relatively high is called the Bohr effect.

29
Q

What effect does CO2 have on dissociation curve?

A

High CO2 moves to right.

Because Carbonic anhydrase in RBC catalyses reaction between CO2 and H20 - resulting in HCO3 and H+.

(therefore decreases pH)

30
Q

What does temperature do to dissociation curve?

A

Increase temp moves curve to left

Higher temperature = less saturated the blood is with O2 (e.g. the Hb unloads more O2 to the tissues)

e.g. during exercise.

31
Q

How much air enters alveoli?

A

Adult - 4L/min
5kg child - 500ml/min
10kg - 800ml/min

32
Q

What is respiration?

A

the exchange of oxygen and carbon dioxide between an organism and the external environment.

33
Q

What is ventilation?

A

The exchange of air between the atmosphere and the alveoli

34
Q

What is Boyle’s law?

A

The pressure exerted by a constant number of gas molecules is inversely proportional to the volume of the container.

e.g. in respiration - change in lung volume generates pressure changes in alveoli driving flow of air in and out of lung.

35
Q

What are accessory muscles of respiration?

A

Inspiration: sternocleidomastoid and scalene (above the clavicle)

Expiration: Internal intercostals, abdominal muscles

36
Q

What effect does a pneumothorax have on respiration mechanics?

A

Loss of negative intrapleural pressure
Cannot overcome natural elastic recoil of lung.
Lung collapses

37
Q

How is oxygen transported in the blood?

A

Oxygen poorly soluble in blood.

For PO2 100mmHg - there is 3ml of O2 dissolved in 1L of blood.

But actually 200ml of oxygen in 1L of arterial blood.

Remaining 197mls (98%) is bound to haemoglobin

38
Q

What is oxygen saturation?

A

Fraction of all haemoglobin molecules bound to oxygen

39
Q

For what reasons would the oxygen dissociation curve move right?

A

Moving right means decreased affinity for oxygen at same partial pressure of O2.

Causes could be

  • increased temp
  • increased CO2
  • increased 2,3 DPG
  • decreased pH
40
Q

What is 2,3 DPG

A

product of glycolysis in RBC. If too much (in hypoxia) then will take up haemoglobin sites

41
Q

What reasons would cause oxygen dissociation curve to move left?

A

Increased affinity for O2 at same pressure

  • Decreased temp
  • Decreased CO2
  • Decreased 2,3 DPG
  • increased pH
42
Q

What is foetal haemoglobin?

A

Higher affinity for O2 than adult Hb. Allows foetus to take O2 across placenta

Has different chains - 2 alpha and 2 gamma

All HbF replaced by adult by 6months old.

43
Q

How is CO2 transported in blood?

A

CO2 more readily dissolved in water than O2.

So 10% travels dissolved in plasma
30% as carbamino haemoglobin
60%as bicarb ions - carbonic anhydrase in erythrocytes causes CO2 and H20 to become bicarbonate ions and H+.

44
Q

Why is pulmonary vascular resistance lower than systemic?

A
  • vessel walls thinner
  • less musculature in vessel walls
  • more distensible vessels
45
Q

What receptors aid respiratory control?

A

Mechanoreceptors - stretch receptors in weals of bronchi and bronchioles.
Prevent over distension of lung
Activated during inflation - sends signal via vagus nerve and inhibits inspiratory centre

Chemoreceptors - specialised neurones that are activated by changes in O2 or CO2.

CO2 most potent controller of respiration (e..g hypoxia is weaker stimulant of respiration than hypercapnoea)

46
Q

What is bronchiolitis?

A

Inflammation of bronchioles

Infection triggers increased mucous production, cell death and sloughing.

Then lymphocytic infiltrate, submucosal oedema.

Then distal airway obstruction

Decreased airflow

Increased end expiratory lung volume
Decreased lung compliance.

47
Q

What causes bronchiolitis?

A

RSV
Paraflu
Rhinovirus
Adenovirus

48
Q

What age is bronchiolitis common?

A

<3 years old

2-6months common

49
Q

What is treatment for bronchiolitis?

A 
suction upper airway
hypertonic saline nebulisation
If O2 less than 90%:
- bronchodilators
- adrenaline
- steroids
50
Q

What are signs and symptoms of bronchitis?

A 
URTI
Fever
Cough
SOB
Apnoea complication in 20%
51
Q

How do you assess for bronchiolitis?

A
  • Increased respiratory effort
  • NPA
  • Wheezing

Fine crackles

Dehydration

CXR - hyperinflation/consolidation in 25%

52
Q

What is cystic fibrosis?

A

Genetic condition - mutation of CF TR gene - regulates the chloride channel - it can be either absent or dysfunctional. Allows Na into cell which therefore decreases osmotic pressure gradient outside cell therefore decrease H2) outside of cell - therefore thickened mucus/dehydration

Severe damage to respiratory and digestive systems

Thick sticky mucus in organs

53
Q

What are signs and symptoms of CF?

A

depends on severity

will have strong salty sweat on skin

cough
wheezing
SOB
recurrent chest infection
stuffy nose/sinuses
constipated
nausea
swollen abdo 
loss of appetite 
delayed growth
54
Q

What is treatment of CF?

A 
Antibiotics for infections
Mucus thinning drugs
NSAIDS for pain/fever
Bonchodilaotrs to relax airways 
Lung transplant and bowel surgery

Chest physio and increased calorie consumption

55
Q

How do you assess CF?

A

Immunoreacive thypsingen test (IRT)
Sweat chloride test
Sputum (for lung infections)
CXR/CT/lung function tests

56
Q

What is asthma?

A

Common long term disease affecting 5 million people in UK. Affects 10-15% of children in UK.

IgE attaches to bronchial mast cells resulting in degranulation and release of pro-inflammatory mediators.

Lining of airways then inflamed and sputum = narrows them.

57
Q

How do you treat asthma?

A

Inhalers - preventative: steroids - control inflammation. low dose.

Reliever - short acting B agonists (SABAs) - relax muscles around tight airway e.g. Ventolin = salbutamol

Management = healthy weight, flu jab etc.

58
Q

What are signs and symptoms of asthma?

A 
SOB
Wheezing
Tight chest
Cough
Bronchial hyper reactive
Can be mild to severe
Worse in night/morning
Can. be worse if have trigger = e.g. environmental pollution, smoking, pollen, atopic, cold.
59
Q

What does atopic mean?

A

Prone to allergies.

60
Q

What is sleep apnoea?

A

Sleep induced collapse of pharyngeal airway.

Pharynx has nothing to hold it open - it is muscles that normally do.

Risk factors =being overweight/smoking/large tonsils.

Applied Clinical Physiology (14 decks)

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