L06: Surfactant And Resistance Flashcards
What is compliance
Wanting to expand
What is elasticity
Wanting to recoil
What sets up the total system compliance
Chestwall compliance
Lung compliance
Where does surface tension occur
Where air and liquid meet
Which structure is surface tension present at
Alveoli
What happens to a bubble when surface tension acts down on it
Collapses
How does a bubble stop itself from collapsing due to a surface tension
It has a pressure inside that is equal, opposite and and positive
What does the laplace’s law describe
As a radius decreases and a bubble gets smaller the pressure increases to keep bubble inflated
What is laplace’s law in equation
P=2T/r
What is the role of a surfactant
Reduces surface tension in alveoli
If there is a high surface tension what happens to the compliance
Compliance decreases
With surfactant what happens to the compliance
Compliance increases
Which cells in the alveoli secrete surfactant
Alveolar type 2 epithelial cells
What is a surfactant made o
DPPC (a phospholipid)
Cholesterol
Other phospholipids
Proteins
What happens to the affect of surfactant as the surface area increases
Effect decreases so surface tension is not lowered much
When can you get reduced lung compliance
Infant respiratory distress syndrome
Damage to alveolar type 2 epithelial cells
Bronchopulmonary disease
What is infant respiratory distress syndrome
In premature baby’s there is a reduction of surfactant
Lungs have low compliance
Small alveoli collapse
Fibrounous membrane form which impairs diffusion across alveoli
What is the treatment for infant respiratory distress syndrome
Glucocorticoids
Instill surfactant into trachea
Name a syndrome associated with the damage of alveolar type 2 epithelial cells
Adult respiratory distress syndrome
Where does resistance come from in the lungs
Friction in airways
Lung tissue friction
What happens to the resistance as the radius increases
Resistance decreases
Is resistance greater in the lower or upper airway
Upper airway
Why is resistance less in the lower airway
Although the radius decreases as you get more branches, the total cross sectional are is highest in the lower airway
What are the common causes of increases airway resistance in the upper airways
Airway obstruction Bronchospasm (asthma) Mucus Oedema Tongue falling back in sleep/ unconsciousness
What is the most common cause of an increased resistance in the lower airway
Chronic obstructive pulmonary disease (COPD)
By which nervous system is the smooth muscle in the airways controlled by
Autonomic nervous system (sympathetic and parasympathetic)
Does parasympathetic or sympathetic nervous system cause bronchoconstriction
Parasympathetic
Which local mediators cause bronchoconstriction
Histamine
Does the sympathetic or parasympathetic nervous system crusade bronchodilation
Sympathetic nervous system
Which neurotransmitters act on beta2 receptors
Adrenalin or noradrenaline
What is oedema
Excess fluid accumulation
