Flashcards in Respiratory Physiology Deck (126)
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?
2) Hypertension - brain overcomes obstruction releases some ADR, over years get hypertension
What are the 2 clinical features of sleep apnoea?
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
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
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?
In what state is O2 pushed out of the Hb molecule?
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%
What is the Bohr shift?
decrease in pH - curve shifts to the right
Bohr shift is the effect of CO2 on the oxygen dissociation curve so is a RIGHT SHIFT
What is the effect of temperature of the Hb dissociation curve?
Increase in temperature - shift to the right
decrease in temperature - shift to the left
What is the effect of 2,3 DPG on the Hb dissociation curve?
Increase in 2,3 DPG - shift to the right
Decrease in 2,3 DPG - shift to the left
More 2,3 DPG in hypoxic conditions
What is methaemaglobin?
Have Fe3+ Fe atom - drug induced
What is a buffer?
Minimises changes in free H+ - usually a weak acid and its base in equilibrium
What is the most common buffer in the body?
H2CO3 H+ + HCO3-
Within what range should blood pH be held?
Other than bicarbonate, what are the 3 other body buffering systems?
1) Plasma proteins
What 3 ways can CO2 be carried in the blood and which is the main way?
1) Dissolved in blood
2) Carbamino compounds (bound to NH2 groups on proteins)
3) As carbonic acid/bicarbonate - main way