structure, function and lung ventilation Flashcards
The respiratory system is organized in 2 zones
conducting and respiratory
components of conducting zone
nasal cavity, paranasal tissues, larynx, pharynx, trachea, bronchi, bronchioles, terminary bronchioles
components of respiratory zone
respiratory bronchioles, alveoli, alveolar duct and sacs
function of lungs
respiration and ventilation
respiration refers to
gas exchange
ventilation refers to
Lung volumes and capacities
Volume dead space and physiological dead space
Inhalation and exhalation
Regional differences in ventilation
The conducting zone is responsible for
leading inspired air to the gas exchanging regions of the lungs
t/f the conducting zone has no part in gas exchange
true
The transitional zone is part of the respiratory zone. What are part of that zone?
respiratory bronchioles
the respiratory zone is responsible for
gas exchange occurs
Makes up most of the lungs
volume of respiratory zone at rest
2.5 – 3 l at rest
airways are organized in
generations
conduting zone is up to what # generation
16
Respiratory zone is up to what # generation
17-23
volume of gas present in the conducting zone, DOES NOT TAKE PART IN GAS EXCHANGE is known as
anatomical dead space
3 types of resistance
airways
lung tissue
chest wall
t/f Nasal cavity, pharynx and larynx provide more than 50% of the total resistance
true
t/f Air flows with more resistance the terminal bronchioles to the alveoli
false, less resistance
describe the anatomical features of the trachea
tubular, dependent in size depending on species
C shaped cartilaginous rings
contains smooth muscle = trachealis muscle
PSNS and SNS inn = vagus n.
trachealis muscle
regulates diameter of trachea
PSNS stimulation via ACATHYLCOLINE of trachea causes
bronchospasm
SNS stimulation via EPINEPHRINE of trachea causes
BRONCHODILATION
Acinus
anatomical unit –
Portion of lung distal to a terminal bronchioles
Pores of Kohn
holes in the alveolar wall
facilitate collateral ventilation
collateral ventilation
Ventilation of the alveoli through these passages or channels bypassing the normal airways
channels that make possible collateral ventilation
pores of kohn
Intrabronchial Martin’s channels
Bronchoalveolar Lamberts channels
Alveoli Structure , 2 types of epithelial cells
Alveolar Type I or Type I pneumocyte
Alveolar Type II or Type II pneumocyte
Alveolar Type II or Type II pneumocyte produces
surfactant
surfactant functions by
Decreases collapsing pressure in the alveoli
Increases gas exchange
Increased lung compliance
Decreased work of breathing
What substance is responsible for this?
surfactant
structure of surfactant
Lipoprotein mixture
lung functions
Respiratory Function
Ventilation
Metabolic function (Non- respiratory)
Respiratory Function
total process by which oxygen is supplied to and used by the body cells and CO2 is eliminated
Ventilation
movement of gas in and out of alveoli
Metabolic function (Non- respiratory)
Manufacture of the surfactant – keeps alveoli open
Metabolism of some anesthetic drugs: lidocaine, fentanyl and propofol
Inactivation of vasoactive substances like serotonin
Acid-based balance
Angiotensive Converse Enzyme (ACE)
In Pulmonary Endothelium
Angiotensin I to Angiotensin II
factors that affect ventilation
body size
level of activity
body temperature
oxygen consumption depends on
metabolic rate
VO2 max describes
Maximal Oxygen consumption
gas exchange occurs by diffusion due to
pressure gradient
from high pressure to low pressure
Fick’s law of diffusion
Amount of gas that moves across a sheet of tissue is proportional to the area of the sheet but inversely proportional to its thickness
3 factors that determine Fricks law
Driving force
Surfacer area
Wall thickness
the driving force in fricks law refers to the
pressure gradient
In which clinical situation gas exchange will be compromise?
Emphysema
MINUTE VENTILATION OR TOTAL VENTILATION (VE)
total volume of air breathed per minute
MINUTE VENTILATION OR TOTAL VENTILATION (VE) is calculated by 2 factors
Tidal volume and number of breaths per minute
Tidal Volume
Volume of each normal breath (inspiratory tidal volume or expiratory tidal volume) during resp. cycle
Number of breaths/minute
respiratory frequency
lower than normal ventilation
Hypoventilation
hyperventilation
higher than normal ventilation
How can you increase ventilation?
by increasing Respiuratory rate or tidal vol. or both
Inspiratory reserve volume
Maximum volume of air inhaled above the TV
3L
Expiratory reserve volume
Volume of gas expired from the end of the expiratory TV
1.2 L
Residual Volume
air remaining in the lung after a forced ventilation
1.2 L
lung volumes
inspiratory reserve vol.
expiratory reserve vol.
tidal vol.
residual vol.
lung capacities
Inspiratory capacity
Functional residual capacity
Vital capacity
Total lung capacity
Functional residual capacity
amount of air remaining in the lungs after a normal expiration
volume reminding
Sum of Expiratory Reserve Vol. +Residual Vol.
Functional residual capacity
Inspiratory capacity
Amount of air that can be inhaled after a normal expiration and distending the lungs to the maximum amount.
Sum of Tidal Vol.+ Inspiratory Reserve Volume
Inspiratory capacity
Vital capacity
max. amount of air in the lungs after a forced inspiration and expiration
Sum of Tidal Vol. +Inspiratory Reserve Vol+Expiratory Reserve Vol.
vital capacity
Total lung capacity
max. volume to which the lungs can be expanded with the greatest inflation
suma of all the volumes =
Total lung capacity
ventilation is measured with
Classic spirometer
Electronic spirometer
t/f No all volume from the total ventilation (VE) reaches the lungs
true
Alveolar ventilation
gas from the total ventilation which reaches the alveoli
Participates in the gas exchange
Volume alveolar Dead space
all that volume of gas which DO NOT participate in the gas exchange – It remains constant
formula to determine total ventilation
Volume of gas in the dead space + Volume of gas in the alveoli
2 types of physiological dead space
Anatomical dead space
Alveolar dead space
where there is alveolar dead space, there is no
blood perfusion
Clinical scenarios where dead space can be increased??
Decreased in CO – less blood sent into the lungs
Alveoli no well perfused
Embolism/ Thromboembolism
diaphragm is inn. by
phrenic nerve
exhalation is passive process in all animals except in
horses
vetilation realtionship between pressure and volume
Things move from high pressure to low pressure
Inspiration – Thorax cavity and lung volume increases
pressure decreases volume increases
Expiration – Thorax cavity and lung volume decreases
pressure increases volume decreases
Lower regions of the lungs
ventilate better than upper zones
Alveoli in the dorsal part
more distended, less compliant compared with the alveoli from ventral
ventilation occurs in a
vertical gradient
top alveoli are
less ventilated
