Fundamental principles Flashcards
List the types of lung volume and explain them
Tidal volume - volume of air entering and leaving the lungs in each quiet breath
Inspiratory reserve volume - extra volume of air capable of breathing in if forced.
Expiratory reserve volume - air that can be forced out of the lung that is not usually breathed out in quiet breathing
List and explain the different types of lung capacities
Inspiratory capacity - the inspiratory reserve volume and the tidal volume. Maximum amount of air in lungs
Functional residual capacity - volume of air in lungs at the end of a quiet expiration (residual volume + expiratory reserve volume)
Viral lung capacity - inspiratory capacity and expiratory reserve
Total lung capacity - vital capacity + residual volume
List the types of dead space
Anatomical dead space - upper airways, trachea, bronchi etc
Alveolar dead space - damaged or non perfumed tissue
Physiological dead space - anatomical + alveolar dead space
Name the muscles of inspiration
Which muscles aid them in forced inspiration?
Diaphragm and external intercostal muscles
Sternocleidomastoid, scalenes, serratus anterior, pectoralis major
Which muscles aid forced expiration?
Internal intercostal muscles and abdominal wall muscles (rectus abdominis, internal and external obliques)
What is compliance?
What two factors affect it?
The ability of the lung to stretch (distensibility) or volume change per unit pressure change.
Elastic lung tissue (increase) and surface tension of fluid in the alveoli (decrease).
What is the purpose of surfactant in the lungs?
Where is it secreted?
Surfactant floats on surface alveolar fluid and decrease the surface tension, allowing for a greater compliance of the tissue. Also stabilises lungs and prevents suction forces.
Secreted by type 2 pneumocytes into alveolar fluid
Why is Respiratory Distress Syndrome often seen in premature newborns?
Foetuses younger than 25 weeks cannot produce surfactant and therefore their lungs have much lower compliance, resulting in difficulty breathing.
What characterises interstitial lung disease?
Thickening of the interstitium, collagen deposition and pulmonary fibrosis.
This leads to decreased compliance, however airways are not traditionally narrowed.
Elastic recoil is increased, as collagen wants to keep its original shape much more than elastic tissue.
What are the signs and symptoms of interstitial lung disease?
Shortness of breath, dyspnoea, reduced excercise tolerance, fatigue
Tachypnoea, tachycardia, diffuse ‘velcro’ crackles
What characterises emphysema?
Loss of elastin and breakdown of alveolar walls causing increased compliance and decreased elastic recoil, leading to loss of surface area and poor perfusion.
What are the signs and symptoms of emphysema?
Cough, shortness of breath,reduced exercise tolerance, Barrel chest sign
What is Pneumothorax?
A disorder where air enters the pleural space will loss of pleural seal and lung collapse. Often caused by trauma
What is Atelectasis?
What are the two common types in adults?
Incomplete expansion of the lungs or full collapse of a previously inflated lung.
Compression atelectasis - secondary to a rise in pressure exerted on the lung causing alveolar collapse. Caused by pneumothorax or pleural effusion.
Resorption atelectasis - complete obstruction of an airway, where air is resolved from alveoli that then collapse. Caused by carcinomas
What is the defining feature of hypoventilation?
Hypercapnia - elevated CO2
