Respiratory physiology Flashcards
What is the pressure of the atmosphere?
760mmHg or 101kPa
What is the air pressure in the alveoli?
13kPa oxygen and 5kPa CO2
How is maximum oxygen consumption abbreviated?
VO2max
What is ATP catalysed by?
Large protein molecules
How is ATP formed?
Degradation of hydrocarbons
How is air drawn in to the body?
By the nose and mouth via trachea and bronchioles
Where do the lungs sit?
In a double layered bag of membranes known as the pleura
Why is there a small fall in pleural and alveolar pressure during inspiration?
Because cavities are expanding
What is the role of the respiratory tract?
Makes air warm and wet to decreases oxygen pressure
What part of the respiratory system is known as dead space?
Everything up to the bronchioles
What must air do before entering the alveoli?
Mix with air in the dead space
What is the gas exchange reservoir?
Air in the respiratory bronchioles, alveolar ducts and sacs
What is tidal volume?
Volume of normal inspirations and expirations (350-500ml)
How does volume increase during exercise?
Taking up reserve volumes
How can reserve volumes be used?
Contraction of intercostal muscles
Where does gas exchange occur?
Respiratory bronchioles and alveoli
What are alveolar sacs?
Thin-walled structures where gas exchange occurs via P1 cells
Role of P2 cells
Prevents internal collapse by reducing surface tension
Why does air in the airways have low oxygen content?
It is saturated with water vapour therefore it has to mix with air in the alveoli
What is the oxygen content of alveolar air?
13kPa
What is expired air?
Mixture of alveolar and inspired air at 16kPa
How much haemoglobin (Hb) is in a litre of blood?
150g
When does Hb have a greater affinity for oxygen?
At low pressures
What causes blood to fully oxygenate?
Respiratory pigment Hb and 2 and 3 diphosphoglycerate (DPG)
What are the 2 conformations of Hb?
T (tense) state and R (relaxed) state
Conditions of T state
De-oxygenated, blue
Conditions of R state
Oxygenated, red
What is the role of DPG?
Stabilising de-oxygenated Hb long enough for oxygen to bind
In what state does Hb bind more oxygen?
R state
What occurs if all sites of Hb are full?
DPG is released
Why does Hb favour T state when oxygen pressure is lower?
Temperature, acidity, CO2 and DPG are elevated
How is CO2 carried in the blood?
As bicarbonate
What is the chemical reaction for bicarbonate?
CO2 + H2O<>H+ + HCO3-
What is the bicarbonate reaction dependent on?
Gas pressure and ability of Hb in T state to bind H+
When is CO2 formed instead of bicarbonate?
When oxygen pressure is higher
Why can birds fly at higher altitudes and have high heart rates?
Because they have enhanced uptake by Hb and improved respiratory gas exchange
How do birds lungs vary to humans?
Finer air capillaries with surrounding blood vessels
Role of parabronchi
Lead to gas exchange membrane in air capillaries
When are parabronchi used?
During exhalation when posterior sacs empty
