Ventilation & Compliance 1-2 Flashcards
(26 cards)
What is the definition of tidal volume & what is the figure ?
Tidal volume: How much air is breathed in & out of the lungs each breath (500ml)
Define Expiratory Reserve Volume
The maximum volume of air which can be expelled from the lungs at the end of a normal expiration (1100ml)
Define Inspiratory Reserve Volume
The maximum volume of air which can be drawn into the lungs at the end of a normal inspiration
Define Residual Volume
The amount of gas left in the lungs/alveoli at the end of a maximum expiration (cannot expel this from the lungs its always present) (1200ml)
Define Vital Capacity
Tidal volume + inspiratory reserve volume + expiratory reserve volume (total lung capacity -residual volume)
Define Total Lung Capacity
The total volume of air that the lungs can hold upon maximum inspiration and maximum expiration.
Define inspiratory Capacity
Tidal volume + inspiratory reserve volume
Define Functional Residual Capacity
Expiratory reserve volume + residual volume
What is pulmonary ventilation ?
Total air movement in & out of the lungs (Anatomical dead space isn’t counted)
What is alveolar ventilation ?
Fresh air getting into the alveoli and therefore available for gas exchange (includes 150ml of dead space in the conduction airway)
What is Dalton’s law ?
The total pressure of a gas is the sum of all the individual gasses
What role does sufactant play in respiration ?
It reduces the surface tension of the Alveoli meaning they do not collapse and are more easily filled up.
What is the law of Laplace ?
P=2T/r (where P= pressure, T=Surface tension & r= radius of alveoli) surfactant works best within alveoli with a small radius
Define the term compliance
Compliance: The change in volume is relative to the change in pressure.
What does high compliance and low compliance mean ?
High compliance: Large increase in lung volume for small decrease in Pip (normal)
Low compliance: Small increase in lung volume for small decrease in Pip (fibrotic lungs)
What causes loss of lung compliance ?
lung stiffness and incomplete lung expansion
What is the normal FEV1/FVC ratio ?
80%
What are the two forms of spirometry & what do they measure ?
static: Volume exhaled
Dynamic: Time taken to exhale a certain volume (most common form)
Name the two main respiratory groups found within the medulla
The Dorsal respiratory group & the ventral respiratory group.
What are the receptors in the medulla called ?
The central chemo receptors
What are the DRG and VRG responsible for >
DRG: Inspiration muscles via phrenic & intercostal nerves.
VRG: Responsible for expiatory muscles & stops tongue from blocking airway
Explain how the central chemo receptors serve to regulate arterial PCO2
1: PCO2 increases in the bloodstream
2: This increases the amount of H ions in the CSF
3: This is picked up by the central chemo receptors
4: Brain then tells brain to increase ventilation until normal levels are reached
What is the condition caused by too many H ions ?
Acidosis
What is the condition caused by a decrease in H ions ?
Alkalosis
