Respiratory Physiology I (Lectures 42- 45 ) Flashcards
Name the 4 steps of the respiratory function overview
- Pulmonary ventilation– the movement of air into lungs (inspiration) and out of the lungs (expiration) by bulk flow
- Exchange between lung air spaces and blood by diffusion
- Transportation of O2 and CO2 between lungs and body tissues by the blood
- Exchange of O2 and CO2 between the blood and body tissues by diffusion
What is the difference between internal and external respiration
Internal = cellular respiration
External: oxygen exchange from body and environment
What does the upper airway refer to
nasal cavities, oral cavity, pharynx
Both the nasal and oral cavities lead to the _____
pharynx
After the pharynx, food enters the _____ and air enters the ______.
esophagus
larynx
What are the two components of the respiratory tract.
What is the main difference between the 2 components
conducting zone the respiratory zone
The conducting zone begins with the larynx and contains vocal cords. It functions to conduct air from the larynx to the lungs.
The respiratory zone is the site of gas exchange within the lungs
(T/F) Only airspaces with sufficiently thin walls can participate in gas exchange
True
The larynx opens into the _______ which in turn opens into _______, one of which enters each lungs
trachea
two bronchi
Each bronchi divides into _____. On the right side there are _______ and on the left there are _____
secondary bronchi
3
2
What is alveoli
Alveoli is the site of gas exchange between themselves and the blood.
The airways terminate in clusters called alveolar sacs
What are alveolar sacs
termination of alveoli.
It is surrounded with elastic fibers and a network of capillaries
The air-facing surface of a single wall is lined by a ____________ called ______.
continuous layer of one cell thick, flat epithelial cells
type 1 alveolar cells
Type I vs Type II alveolar cells
Type I alveolar cells are the site of gas exchange while Type II alveolar cells synthesize surfactant ( aids lung expansion when breathing)
how does gas pass between alveolar airspace and blood
They diffuse across the thin walls of alveolar cells
Each lung is surrounded by a fluid filled _____
pleural sac
What is the pleural sac
a double membrane surrounding each lung. One surrounds the chest wall and the other surrounds the lungs. ( think of it as a fluid filled balloon)
Ventilation occurs because of the presence of _____
pressure gradient between the alveoli and outside air
Inspiration occurs when ..
Expiration occurs when ..
Inspiration occurs when Palv < Patm
Expiration occurs when Palv > Patm
Name the four primary pressures that are associated with ventilation
Patm
Palv
Pip
transpulmonary pressure
What is Atmospheric Pressure and its characteristics
This is the pressure of the atmosphere
It is kept constant.
As elevation increases, Patm decreases. It increases under water .
At sea level Patm is 760 mmHg
However is it set to 0 mmHg for class
What is intra-alveolar pressure and its characteristics
The intra-alveolar pressure is the pressure within the alveoli
It is given relatively to the Patm.
During inspiration, Palv is negative and during expiration, Palv is positive
The difference between the Palv and Patm drives ventilation
What is intra-plural pressure and its function
The intra-plural pressure is the pressure within the plural sac.
The intra-plural pressure is always negative due to the opposing pulls on the intra-pleural space. The surface tension created is what hold the lungs and walls in place.
The intra-pleural pressure is always less than Palv.
At rest the intra-pleural pressure is about -4 mmHg
What is the transpulmonary pressure and its characteristics
The transpulmonary pressure is the pressure difference between the Palv and Pip (P alv - Pip )
It is the distending pressure across the lung wall.
An increase in transpulmonary pressure causes a larger pressure against the lung wall. (ex: lungs expanding increasing the volume inside)
How does pneumothorax happen
Pneumothorax happens when the negative pressure in the intrapleural pressure is not longer present.
This causes the lungs to collapse and recoil while the chest wall expands
Air flow into and out of the lungs is driven by _____ that the respiratory muscles create by _______
pressure gradient
changing volume in lungs
What is Boyle’s Law
Pressure and volume is inversely related.
What 2 factors determine the intra-alveolar pressure
Quantity of air in alveoli and
volume of the alveoli
Explain Inspiration Pressure
At the start of inspiration, inspiration muscles contract, causing the lung muscles to expand. This expansion results in the lower of alveolar pressure.
When alveolar pressure is lower than atmospheric pressure, air is drawn into the lungs
Due the the increase in air molecules flowing in, alveolar pressure increases. Air molecules stop flowing in when Palv = Patm.
Lung volume decreases, which causes air to flow out of the lungs. The quantity of air in the alveolar decreases, which lowers the pressure towards 0
Explain the Inspiration process ( muscle)
Inspiration is initiated by the simulation of inspiratory muscles ( ACh is released at the NMJ)
Contraction of diaphragms causes it to flatten and move downward. Contraction of the external interconstals causes the ribs to pivot outward and expanding the wall of the chest
As the chest expands, it pulls on the intrapleural fluid, causing a decrease in Pip
The decrease of Pip is an increase of transpulmonary pressure.
Increase in transpulmonary pressure leads to a larger distending pressure across lungs, therefore, the lungs expands to the chest wall
When lungs expand, Palv < Patm ; air flows in the alveoli in bulk flow
During quiet breathing, expiration is usually a ______ that ______ muscle contraction
passive process
does not require
Explain expiration process ( muscle)
When motor neurons in the inspiratory muscles stop firing, inspiratory muscles relax
The lungs and chest wall recoil to its original position
The volume of the thoracic cavities decrease, causing Palv > Patm
Air flows out till Palv = P atm
What are the two factors that affect pulmonary ventilation
Lung compliance and Airway resistance
What is pulmonary ventilation
Pulmonary ventilation is the rate at which air flows in and out of the lungs
Define lung compliance
Lung compliance is the change in lung volume that results from the given change in transpulmonary pressure
Is having a large lung compliance advantageous or not
Yes, it is advantageous
This is because only a small change in transpulmonary pressure is needed to bring in a given volume of air.
Less work is required for muscle contraction
What are factors that affect lung compliance
Surface tension and elasticity
Elasticity is present in the lungs due to the elastic connective tissue fibers. Forces by these fibers oppose lung expansion.
Surface tension is the work needed to increase surface area by a certain amount
What is emphysema
Emphysema is the destruction of these elastic fibers. This causes a high compliance within the lungs. However, they will not recoil to its resting position during expiration which can be very bad.
How does surface tension affect lung compliance . Explain the mechanisms
Work is needed to increase surface area of the fluid layer and also stretch the elastic tissue.
Pulmonary surfactants secreted by type II alveolar cells help decrease surface tension by interfering with hydrogen bonding between water molecules.
Surfactant stabilizes alveoli of different sizes (r) by differentially altering surface tension allowing the alveoli to have the same pressure.
______ decreases the surface tension in the alveoli. It is secreted at the ______.
Pulmonary surfactant // type II alveolar cells
The greater the surface tensions the _____ the compliant
less
Premature babies can develop _______ .
Explain and what is the treatment for it
Newborn respiratory distress syndrome
Surfactant synthesis develops about 25th weeks of development and is adequate by 34 weeks. Little surfactant causes alveoli to collapse with every breath, draining a lot of energy in addition to low-compliance lungs.
Treatment = administer steroid hormone to help stimulate surfactant production or artificial surfactant administration / artificial administration.
How does airway resistance affect pulmonary ventilation
In increase in resistance causes a high pressure gradient needed to produce airflow
What are the 3 parameters that contribute to resistance:
Radius – the major one
Length of the system ( constant)
viscosity of the air ( usually also constant )
_____ is the device used to measure the inspired and expired air volume. It works by …
Spirometer
It works by breathing in and out of a tube connected to a transducer that converts volume air to an electrical signal proportional to the volume
3 of the 4 non overlapping lung volumes measured include
tidal volume.
inspiratory volume
expiratory reserve volume
What are the 4 non overlapping lung volumes and explain each of them
Tidal Volume (VT): is the volume of air that moves in and out of lungs during a single unforced breath
Inspiratory reserve volume (IRV): is the maximum volume of air that can be inspired by the end of a normal inspiration
Residual Volume (RV): the volume of air that is left remaining in the lungs after a maximal expiration
Expiratory reserve volume (ERV): maximum volume of air that can be expired from the end of a normal expiration
Lung capacities are the _______
sums of two or more lung volumes
Inspiratory Capacity =
Vital capacity =
Functional residual capacity =
total lung capacity =
IC = tidal volume + IRV
VC = tidal volume + ERV
FRC (volume in lungs after passive exhale) = ERV + RV
TLC = tidal volume + ERV + IRV + RV
Minute ventilation is ____ than alveolar ventilation because of _____, which refers to the ______
greater
dead space
air at the upper airway that can’t be used for gas exchange
Minute ventilation = _____ * ______
tidal volume * respiratory rate
Alveolar ventilation = formula
(tidal volume - anatomical dead space) * respiratory rate
