Lecture 9 - Respiratory System Flashcards
What is VO2 max
The maximum rate in which oxygen can be consumed,
transported and utilised by the respiratory, cardiovascular and
muscular systems
What is external respiration
the process of
drawing oxygen into the
body and expelling
carbon dioxide back into
the environment
What are the components in the respiratory system
Sphenoidal sinus
Frontal sinus
Nasal cavity + nose
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Alveoli
Lungs
Diaphragm
What laws is the process of ventilation dependant on
Boyle’s law
Fick’s 1st law of diffusion
What is Boyle’s law
As volume increases, pressure decreases
As volume decreases, pressure increases
What is Fick’s 1st law of diffusion
Gas goes from area of
a high concentration to
regions of a low
concentration; at a
magnitude that is
proportional to the
concentration gradient
What are the inspiratory muscles
diaphragm and external
intercostals
What are the expiratory muscles at rest
None - it is a passive process
What are the expiratory muscles during high demand (exercise, altitude, illness)
transversus abdominis,
internal and external obliques, rectus abdominis, internal intercostals and the triangularis sterni
What is the volume during inspiration and expiration
~3000 mL ins
~2000 mL exp
How will ambient air be drawn into the lungs
Ventilation
(oxygen will be drawn into the respiratory zone of the lungs by conc gradients)
What is the difference in mmHg between ambient air and alveolar pO2 and why
55-60
Humidification of gases in the lungs
CO2 mixing in alveolar air
What does the pulmonary artery do
the only
artery to carry deoxygenated
blood
What do pulmonary veins do
Conversely,
these veins carry oxygenated
blood
What do pulmonary capillaries do
Contain both oxygenated and
deoxygenated blood
What is perfusion
the transport of molecules to target tissues
How are capillaries in the lungs adapted to their function
One endothelial layer thick (0.0006 mm)
What is partial pressure
In a mixture of gases, the partial pressure is
pressure exerted by each individual gas
What is Henry’s law
The concentration of dissolved
gas equals the partial pressure
of the gas multiplied by its
solubility
What are the trends for the partial pressure of gas
Nitrogen > O2 > CO
mmHg
PN2 597.4
PO2 158.8
PCO2 0.3
Pother 3.5
Total 760.0 mmHg
Barometric Pressure
[at sea level]
What is the solubilities of gases in the air
O2 > CO2 > Nitrogen
What is a spirometer used for
Lung function
What are the steps for spirometry
1) Ask the patient to take
3-5 normal breaths;
2) After this, they rapidly
inhale as quickly and
deeply as possible;
3) As soon as they reach
peak inspiration, they
blow out for as hard
and long as possible
(or, for at least 6-
seconds)
What is Tidal Volume (Vt)
the amount of air that moves in or out of the
lungs with each respiratory cycle
What are normal values for Vt
Males: ~500 mL
Females: ~400 mL
What are normal values for breathing frequency (f)
12-20 breathes/min
How is ventilation (Ve) calculated
Vt x f
(mL/min or L/min)
What is Inspiratory Reserve Volume (IRV)
the amount of air that can be
inhaled, above that of the normal VT
What is the Expiratory Reserve Volume (ERV)
the amount of air that can be
expired, below that of the normal VT.
What is the residual volume
the volume of air that remains in the lungs
after a forced, maximal exhalation
Why is there a residual volume of air present in the lungs
A RV means that
there is always enough air
in the lungs, for alveoli to
participate in gas
exchange. A healthy person
cannot empty their lungs
during a maximal
ventilation
What is inspiratory capacity (IC)
maximal
volume of air that can be inspired
following a normal passive expiration
What is functional residual capacity (FRC)
volume of air in the lungs following a
normal passive expiration
What is the Forced Vital capacity (FVC)
the
total volume of air that can be
expired following a maximal
inspiration
What is the total lung capacity (TLC)
the total
volume of air in the lungs following a
maximal inhalation
What is a capacity
the maximal volumes of air in the lung parenchyma
(functional tissue) during a specific point in the respiratory cycle
What is forced expiratory volume over 1-second (FEV1)
the
amount of air that can be
expired within the 1st second
of a maximally forced
expiration, following a
maximal inhalation
At rest, what is ventilation controlled by
The brainstem (pons and Medulla
Oblongata)
Pneumotaxic center
Apneustic center
What are chemoreceptors
detect changes in O2 or
CO2, which feeds back to the back to the
respiratory centers in the brain
What do peripheral chemoreceptors do (carotid and aortic)
Emergency detection for low O2;
Carotid receptors provide rapid response;
pH / CO2 detection system
What do central chemoreceptors do (extracellular portion of the brain)
Slower response but more of a “steady state” control
What happens to tidal volume, breathing frequency and minute ventilation during exercise
Tv - increase ~225%
f - increase ~237%
Ve - Increase ~653%
Why does altitude cause ventilation limitation
Altitude results in a reduced ambient, alveolar
and arterial partial pressure of O2, which results
in ↓ bioavailability for cells
Hypoxic environment lead to vasoconstriction
within the lung’s microvasculature results in ↑
alveolar fluid content (leaking from blood)
