Lecture 17 Flashcards
what is the aim of the respiratory system?
Get oxygen into the lungs, transfer it across capillaries, transport it to necessary organs where it is used for metabolism and produce carbon dioxide which can be breathed out.
What is Boyle’s Law?
The pressure of a gas is inversely related to it’s volume (P = 1/V)
Why is a pressure gradient necessary?
Gas will move from high pressure to low pressure.
What allows more space for the lungs to expand?
The diaphragm contracts which increases vertical diameter of thoracic cavity and at same time the rib cage expands.and moves outwards.
What happens as you inhale?
Your diaphragm drops while your rib cage expands. This increases the volume in your chest which lowers the pressure in lungs. Pressure outside is now greater than inside, so air rushes in. .
What happens as you exhale?
Diaphragm relaxes/rises and rib cage shrinks.
Pressure inside lungs increases so that it is greater than pressure outside, as a result air rushes out.
What are the two opposing forces that must be overcome to take a breath?
Stiffness and and Resistance of lungs
Explain Compliance/ stiffness?
Lungs must expand and be compliant to overcome the surface tension that holds them in place.
Explain Resistance
Need to overcome the resistance put on the movement of air air by the RT in order to move air from outside to Alveoli.
Define compliance?
The magnitude of change in the lung volume produced by given change in the pressure.
What can cause thickening and scaring of alveolar membrane?
Chronic inflammation or exposure to industrial chemicals.
How does compliance vary between normal and fibrous lungs?
More work is required to reach the same volume in the fibrous lung as it is less compliant
How can surface tension be overcome in order to expand the lungs?
Fluid from Alveoli
Alveoli thin walls
Surfactant
What is Surfactant?
MAde up of proteins and phospholipids and helps reduce surface tension in alveoli so they can expand easily.
How is surfactant produced?
Alveolar type 2 pneumocytes
How does surfactant lower surface tension?
Reduces attractive forces between fluid molecules lining alveoli.
What is Respiratory distress syndrome (RDS) ?
Results when premature infants do not produce surfactant
Where is air conducted?
Through the bronchi (main area of airway resistance) and bronchioles
What does a spirometer d?
Measures volume inspired/ exhaled
Measures how much and how fast you breathe
What is Tidal Volume (VT) ?
Volume of air moved in and out during normal quiet breath.
What is Inspiratory reserve volume (IRV)?
Extra volume that can be inhaled over and above the tidal volume.
What is expiratory reserve volume (ERV)?
Extra volume that can be exhaled voluntarily after completion of a normal, quiet respiratory cycle.
What is Residual volume?
Volume remaining in lungs after maximal exhalation.
What is Minimal Volume?
Volume remaining in lungs if they collapsed.
What is Vital Capacity?
Inspiratory reserve + Expiratory reserve + Tidal volume
Volume of air that can be moved in and out of your lungs.
What is Tidal lung capacity?
Vital capacity + Residual Volume.
Total Volume in lungs when it is filled to max
What is Inspiratory capacity?
Inspiratory reserve + Tidal volume.
Total volume of air that can be inspired from rest
What is Functional residual capacity?
Expiratory reserve + Residual; volume
Volume remaining in lungs after normal exhalation.
What is FEV?
Forced Expiratory Volume - How much of the forced vital capacity comes out in first second.
What affects FEV?
Diseases causing resistance to airflow
FEV1/FVC Ratio?
Normal = 80%
< 70% indicates airway obstruction
