Respiratory Physiology Flashcards
What kind of condition are Asthma, COPD and Lung cancer?
Obstructive
What kind of conditions are pulmonary fibrosis, pneumothorax, scoliosis (intrinsic/extrinsic)?
Pulmonary fibrosis = intrinsic restrictive
Pneumothorax, scoliosis = extrinsic restrictive
What extra muscles do you use for inspiration with increasing effort?
Neck muscles
Shoulder muscles
What extra muscles do you use for expiration with increasing effort?
Abdominal muscles
What does a spirometer measure?
Volume of air in and out of lungs during ventilation
What happens to the TLC, VC, FRC and RV in restrictive conditions?
All reduced
What happens to TLC, RV, and FRC in obstructive conditions?
RV is increased (cant get last bit of air out)
TLC is reduced (COPD) or increased (emphysema)
FRC is increased in emphysema
Are pulmonary fibrosis, kyphyscoliosis and circuferential burn associated with increased or reduced compliance?
Reduced (less stretchy)
Is emphysema associated with increased or reduced compliance?
Increased (more stretchy)
What is Laplaces law?
pressure = (2x surface tension)/radius of bubble
Why does surfactant prevent atelectasis?
Spread thicker in smaller alveoli so decreases the surface tension more greatly in them than larger alveoli so you end up with the same pressure
What is the make up of surfactant?
90% phospholipid
10% protein
In what syndrome is surfactant deficient?
Respiratory distress syndrome
From laminar flow to turbulent flow by how much is the work increased?
Power of 2
How much of energy expenditure is spent on respiration in health at rest>?
2-5%
How much energy expenditure is spent on respiration at maximum hyperventilation?
30%
How is work of respiration minimised in restrictive conditions?
Rapid slow volume breaths
How is work of respiration minimised in obstructive conditions?
Large volume, slow breaths
Why are breath sounds greater in larger airways than smaller airways?
Higher flow rate and therefore more turbulent flow in large airways
What is Dalton’s law about partial pressure of gas?
Partial pressure = total pressure x fraction of that gas
Why is partial pressure of oxygen in the alveoli lower than in inspired air? 3
1) Inspired air humidified
2) O2 taken up into blood stream while CO2 is added
3) Body consumes more O2 molecules than is produces CO2
What is the relationship of partial pressure of a gas and its solubility?
Partial pressure of a gas in solution is inversely proportional to its solubility
Why in someone with pulmonary fibrosis would the partial pressure of oxygen in the blood decrease if rate of respiration and heart rate increased?
Capillary transit time is shorter than the time take for diffusion of O2
What is carbon monoxide diffusing capacity used for?
To establish if someone with reduced exercise capacity has a problem with diffusion across the alveoli
What is adult respiratory distress syndrome?
Inflammatory process, difficult to distinguish from pulmonary oedema
What muscle holds the tongue against the palate in nasal breathing?
Genioglossus muscle
What muscle lifts the soft palate away from the back of the pharynx in mouth breathing?
Tensor palati
How does the pharyngeal dilator reflex work?
1) Pressure receptors in the mucosal lining of the pharynx detect air flow
2) Send a message to the brainstem
3) Brain stem causes pharyngeal muscle contraction to open pharynx and allow air flow
What is the problem in obstructive sleep apnoea?
Pharyngeal dilator reflex doesnt work properly or pharynx cant be help open (fat deposits around the muscle in obesity)
What substances can make sleep apnoea worse? 2
Drugs and alcohol
What is the treatment for sleep apnoea? 2
1) Weight loss
2) CPAP - constant positive air pressure
What 2 conditions is obstructive sleep apnoea associated with?
1) obesity
2) Hypertension - brain overcomes obstruction releases some ADR, over years get hypertension
What are the 2 clinical features of sleep apnoea?
1) Snoring
2) Daytime somnolence (sleepiness)
What are the 2 layers of airway lining fluid?
Mucous layer and periciliary layer
What 4 things can inhibit cilia in the airway?
1) Cigarette smoke
2) Infections
3) Air pollution
4) Inhaled anaesthetics
What are the 2 functions of airway lining fluid?
1) Humidification - affected by breathing pattern, heat and moisture exchanger on way out and in, does so through active control of pericilliary layer depending on humidity of air
2) Airway defence - mucociliary escalator and expectoration
Where are very large, large, small and very small inhaled particles caught?
Very Large (>8um) - nose and pharynx
Large (3-8um) - large airways
Small (0.5-3um) - bronchioles
Very small (
What are the 3 types of non immunological pulmonary defences?
1) Physical barrier and removal
2) Chemical inactivation (lysozyme, protease, antimicrobial peptides eg. beta defensins)
3) Alveolar macrophages (engulph carbon - move to lymphatic system)
What are the 2 immunological pulmonary defences?
1) Humoral - immunoglobulins
2) Cell mediated
What are the immunoglobulins involved in pulmonary defense?
1) IgA - nose and large airways
2) IgG - small airways
3) IgE - allergic disease
What are the 4 types of cell involved in immunological pulmonary defences?
1) Epithelial cells
2) Macrophages
3) Neutrophils (infection)
4) Eosinophils (allergy)
What is the relationship between protease enzymes in pulmonary defences and alpha-1 anti trypsin deficiency?
Protease enzymes are not pathogen specific so we have an anti protease system to protect body cells
If deficient in this then have alpha 1 anti trypsin deficiency
What are the 2 ways that oxygen can be carried in the blood, in which way is it mainly carried?
1) Dissolved in the blood
2) Carried by haemoglobin - main way
How is oxygen saturation (SO2) calculated?
HbO2 / (HbO2 + HHb) basically the percentage of Hb carrying oxygen
How is the volume of O2 carried in the blood by Hb calculated?
Volume of O2 = SO2 x [Hb] x 1.39
1.39 is the Huffner constant
What is the roughly normal amount of oxygen carried in the blood a) dissolved and b) combined with Hb?
Dissolved = ~0.29ml/dl
Combined with Hb = ~19ml/dl
In what state is it easier for O2 to bind to haemaglobin?
Relaxed state
In what state is O2 pushed out of the Hb molecule?
Tense state
What is P50?
PO2 at which SO2 = 50% (~3.5kPa)
What is the rough PO2 and SO2 of arterial and venous blood?
Arterial - PO2 = 12.5kPa, SO2 = 97%
Venous - PO2 = 6.3kPa, SO2 = 75%