Respiratory physiology 1 Flashcards
Anatomic dead space begins at the mouth and ends in the:
a. small airways
b. terminal bronchioles
c. respiratory bronchioles
d. alveolar ducts
b. terminal bronchioles
The airway is functionally divided into 3 zones:
conducting
respiratory
transitional
Ventilation is the process of
exchanging gas (O2 & Co2) between the atmosphere and the lungs
A coordinated effort between the brain and the respiratory muscles is required to produce
cyclic pressure changes that allow air to move into and out of the lungs
___________ & ________________ during inspiration
The diaphragm and external intercostals contract
Exhalation is usually
passive
Accessory muscles for inspiration include
the sternocleidomastoid and scalene muscles
Accessory muscles for active expiration include
the rectus abdominis, transverse abdominis, internal obliques, and external obliques
A vital capacity of _________ is required for an effective cough
at least 15 mL/kg
What is the action of the conducting zone?
does not participate in gas exchange
function: bulk gas movement
What is the transitional zone?
serves a dual function of air conduit and gas exchange
What is the respiratory zone?
participates in gas exchange
The transpulmonary pressure is
the difference between alveolar pressure and pleural pressure
Alveolar pressure is the
pressure inside an airway
Pleural pressure is the
pressure outside of the airway
An airway stays open if transpulmonary pressure is
positive
An airway collapses when transpulmonary pressure is
negative
The _____________ increases the superior-inferior dimension of the chest
diaphragm
The ________ increase the anterior-posterior diameter
external intercostals
What is the mnemonic for active exhalation?
I let the air out of my TIREs
transverse abdominis, internal oblique, rectus abdominis, external oblique
Exhalation becomes an active process when
minute ventilation increases or in patients with lung disease such as COPD
What anatomical structures are included in the conducting zone
trachea
bronchi
bronchioles
What anatomical structures make up the transitional zone?
respiratory bronchioles
What anatomic structures make up the respiratory zone?
alveolar ducts
alveolar sacs
To prevent airway collapse, the pressure inside the airway must be
greater than the pressure outside the airway
During tidal breathing, transpulmonary pressure
is always positive (keeps tha airway open)
During tidal breathing, intrapleural pressure is always
negative (keeps the lungs inflated)
Aside from pathologic states, such as pneumothorax, the only time that intrapleural pressure becomes positive is during
forced expiration
What is the primary determinant of carbon dioxide elimination?
a. minute ventilation
b. tidal volume
c. alveolar ventilation
d. respiratory rate
C. alveolar ventilation
A tidal volume is
the amount of gas that is inhaled and exhaled during the breath (6-8 mL/kg)
What is minute ventilation?
tidal volume x respiratory rate
What is alveolar ventilation?
(tidal volume- dead space) x respiratory rate
When you take a breath, only part of the Vt is delivered to the _________ while the remainder sits in the ____________
respiratory zone; conducting zone (dead space)
When you exhale, ______________ gas is removed first.
conducting zone
Any condition that increases the volume of the conducting zone (Vd) makes it more
difficult to eliminate expiratory gases from the lungs
-if alveolar ventilation is not increased, then the patient will retain CO2
In a healthy, 70 kg adult, the normal dead space is
~2 mL/kg or 150 mL
Alveolar ventilation removes _________ from the minute ventilation equation.
dead space
Alveolar ventilation is directly proportional to
Carbon dioxide production
(a higher CO2 production stimulates the body to breathe deeper and faster so it can eliminate more CO2)
Alveolar ventilation is inversely proportional to
PaCO2 (faster & deeper breathing reduces PaCO2)
Which conditions will MOST likely increase the PaCO2 to EtCO2 gradient? (select 3).
a. positive pressure ventilation
b. laryngeal mask airway
c. hypotension
d. endotracheal tube
e. neck flexion
f. atropine
a. positive pressure ventilation
c. hypotension
f. atropine
Why does hypotension increase dead space?
hypotension reduces pulmonary blood flow, which increases alveolar dead space
Why does atropine increase dead space?
atropine is a bronchodilator, so it increases anatomic dead space by increasing the volume of the conducting zone
Why does positive pressure ventilation increase dead space?
increases alveolar pressure, which increases ventilation relative to perfusion.
Dead space is reduced by anything that
reduces the volume of the conducting zone
or increases pulmonary blood flow
What are the four types of dead space?
anatomic
alveolar
physiologic
apparatus
What is anatomic dead space?
air confined to the conducting airways
What is alveolar deadspace?
alveoli that are ventilated but not perfused
What is physiologic dead space?
anatomic Vd + alveolar Vd
What is apparatus dead space?
Vd added by equipment
