HUBS192 Lecture 17 - The Work of Breathing Flashcards
what are the 4 things the physiology of the respiratory system needs to do?
1) get it in (get the air from from outside the body and down into the lungs to the alveoli)
2) get it across (gas exchange from the alveoli into the blood stream and then back into the alveoli)
3) get it around (transport the various gases to the cardiovascular system and to the cells that need them and back around to the lungs to be exchanged)
4) keep it going (keep the system running smoothly using neural input)
how do you quantify a liquid?
liquids are usually quantified in terms of volume
how do you quantify a gas?
gases are usually quantified in terms of pressure (result of collisions)
what is the relationship between the pressure of a gas and its volume?
the pressure of a gas is inversely related to its volume aka Boyles law
what happens to pressure if volume is decreased?
decreased volume results in increased pressure
what happens to pressure if volume is increased?
increased volume results in decreased pressure
what is Boyles law?
the pressure of a gas is inversely related to its volume
what is the function of a pressure gradient?
drives
when is there no pressure gradient?
when the amount of air within the lungs is equivalent to the atmospheric pressure
what is the equation for in the lungs pressure at rest?
Poutside=Pinside
what is the effect of Poutside=Pinside right before you take a breath?
because pressure outside and inside are equal no air movement will occur
what is the movement of gases in terms of pressure?
gases will more from high pressure to low pressure
what happens as you inhale in terms of the diaphragm , rib cage, volume and pressure
- as you inhale, your diaphragm drops while your rib cage expands
- this increases the volume in your chest, which lowers the pressure
what 3 things occur during inhalation?
1) volume is increasing
2) pressure inside the lungs is decreasing
3) pressure outside is now greater than inside, so air rushes in
what happens as you exhale in terms of the diaphragm , rib cage, volume and pressure
as you exhale, your diaphragm comes up while your rib cage comes in
-this decreases the volume in your chest , which increases the pressure
what 3 things occur during exhalation?
1) volume is decreasing
2) pressure inside the lungs is increasing
3) pressure outside is now lower than inside, so air rushes out
what is breathing rate highly correlated to?
highly correlated to heart rate
-breath once per every 4 heartbeats (approx.)
what are the 2 opposing forces that must be overcome to take a breath?
1) stiffness of the lungs
2) resistance of the airways to the lungs
what must the lungs do to take in air related to the stiffness of the lungs?
lungs must expand to take in air
-how compliant are the lungs? (lungs are highly compliant)
what holds the lungs in place?
surface tension holds the lungs in place
what does it mean by the resistance of the airways to the lungs?
need to move the air from outside to the alveoli
- how much resistance is the respiratory tract putting on the movement of air?
what is the relationship between lung stiffness and compliance?
lung stiffness is related to compliance (compliance= change in volume/change in pressure)
what is pulmonary fibrosis?
thickening and scarring of the alveolar membrane
- can arise from chronic inflammation or exposure to industrial chemicals
what is the effect of pulmonary fibrosis?
the fibrotic scarring is not as flexible or compliant than the normal cells within the lungs therefore it is more difficult to stretch the lung to accomodate a volume of air
what are the alveoli lined with and what is the function of this?
alveoli are lined with fluid (mostly water, strong H-bonding) that exert surface tension
what enhances the surface tension of the alveoli?
walls of the alveoli are very thin, enhancing this effect
what must be overcome to expand the lungs?
must overcome surface tension to expand the lungs
what is the function of surfactant?
molecule that disrupts the interaction between water molecules therefore prevent surface tension and allows the alveoli to expand during a breath
what do the alveoli secrete?
surfactant
what is the result of failure to produce adequate surfactant?
failure to produce surfactant results in difficulty in expanding the lungs and reduced oxygen intake
what does RDS stand for?
respiratory distress syndrome
what is RDS (respiratory distress syndrome)?
premature infants don’t produce surfactant therefore the can not over the surface tension by themselves
what are the 3 features of the airway resistance through the respiratory tract?
1) need to move air from outside to the alveoli
2) air is conducted through the bronchi and bronchioles
3) exert force (friction) on the air that must be overcome
what is the result of changing the radius of the bronchioles?
changes the resistance to air flow
-bronchioles are the most important for moving air from the outside to the inside
what is spirometry?
pulmonary functional test that measures volume inhaled / exhaled
-can measure how much and how fast you breathe
what are the 5 spirometry trace volumes?
1) tidal volume (Tv)
2) inspiratory reserve volume (IRV)
3) expiratory reserve volume (ERV)
4) residual volume
5) minimal volume
what is tidal volume (Tv)?
volume of air moved in and out during a normal quiet breath
what is inspiratory reserve volume (IRV)?
extra volume that can be inspired with maximal inhalation
what is expiratory reserve volume (ERV)?
extra volume that can be exhaled with maximal effort
what is residual volume?
volume remaining in lungs after maximal exhalation
what is minimal volume?
volume remaining in lungs if they collapsed
what are 4 spirometry trace capacities?
1) vital capacity
2) total lung capacity
3) inspiratory capacity
4) functional residual capacity
what is vital capacity?
inspiratory reserve + expiratory reserve + tidal volume
-volume of air you can shift in and out of your lungs (max amount)
what is total lung capacity?
vital capacity + residual volume
-total volume in lung when you’ve filled them to max (all the lungs in your lungs total)
what is inspiratory capacity?
inspiratory reserve + tidal volume
-total volume of air you can inspire (inhale) from rest
what is functional residual capacity?
expiratory reserve + residual volume
-volume remaining in lungs after normal exhalation
what does FEV1 stand for?
forced expiration volume in one second
-reduced with diseases causing resistance to air flow
what is the normal FEV1/VC ratio
80% of the air out of your lungs
what can spirometry identify between?
can discern obstructive and restrictive tissues
what is the restricture issue?
reduced lung capacity as there is reduced lung compliance (e.g fibrosis) by insufficient surfactant release
what is the obstructive issue?
resistance to airflow causes asthma and chronic bronchitis
