22.2 AP2
As the lungs expand during inhalation, the bronchioles ____ because the are being pulled in all directions This decreases resistance to flow
enlarge
Just before each inhalation, the pressure inside the lungs is ____- to the atmospheric pressure. 760mmHg
equal
Although Pip is always _____ than Ppul, Pip can sometimes exceed Patm during forced exhalation such as a cough
less
For air to flow into the lungs, the pressure in the alveoli must be ___ than atmospheric
less
The diameter of airways is regulated by ______ which, as previously discussed, is dependent upon parasympathetic and sympathetic interaction
smooth muscle tone
In Pulmonary Ventilation, or breathing, the changes in pressure are due to changes in _______.
thoracic volume
(Ppul - Pip) = ______ Keeps lungs open Greater transpulmonary pressure --> larger lungs
transpulmonary pressure
applies to containers with changeable volume - like our thoracic cage. It states that volume and pressure are inversely related. Thus if there is a decrease in volume, there will be an increase in pressure. P1V1 = P2V2
Boyles Law
Only about ___ of the tidal volume reaches the respiratory zone - the other 30% remains in the conducting zone (called the anatomic dead space).
70%
Sternocleidomastoid, Scaline, and Pectoralis minor are ____
Accessory muscles of inhalation
_______ varies greatly depending on the altitude and the temperature.
Air pressure
Differences in air pressure drive airflow, but 3 other factors also affect the ease with which we ventilate: The surface tension of alveolar fluid Compliance of the lungs and _______________.
Airway resistance
non-functional alveoli due to collapse, poor perfusion, or obstruction
Alveolar dead space
Amount of air that can be forcefully exhaled after a normal tidal volume expiration
Expiratory reserve volume (ERV)
Increases thoracic volume in addition to that of the diaphragm contraction Responsible for ~25% of the air entering the lungs during quiet breathing During inhalation, the ribs move upward and outward like the handle on a bucket
External intercostals
Second most important muscles of inhalation During contraction, these muscles elevate the ribs increasing the anteroposterior and lateral diameters of the chest cavity
External intercostals
Amount of vital capacity one can forcibly expel in 1 second In healthy adults this should be approximately 75-80% In obstructive diseases (asthma, COPD, chronic bronchitis, emphysema) FEV1 is diminished because of increased airway resistance to expiratory flow
FEV1
amount of gas expelled during specific time intervals of VC
Forced expiratory volume (FEV)
Amount of air that can be forcefully inhaled after a normal tidal volume inspiration
Inspiratory reserve volume (IRV)
Pleural cavity pressure becomes more negative as chest wall expands during inspiration. Returns to initial value as chest wall recoils.
Intrapleural pressure
Pneumothorax-air in pleural cavity _______ goes from -4 to 0 thus eliminating the transpulmonary pressure that keeps a lung open Inward forces dominate and lung collapses in on itself
Intrapleural pressure
Pressure in pleural cavity Pleural cavity is sealed Fluctuates with breathing This should always be a negative pressure (<Patm and <Ppul) in order to prevent lung collapse
Intrapleural pressure (Pip)
Forceful exhalation Playing a saxophone, yelling, or exercise Requires muscles, Abdominals, internal intercostals
active exhalation
Accessory muscles of inhalation Involved in __________ These assist in increasing thoracic volume during exercise or deep, forceful inhalations Do not really contribute quiet breathing
active inhalation
When the diaphragm contracts and the intrapleural pressure becomes slightly more negative generating a greater outward pull on the lungs, it causes the lungs to expand thus increasing their volume and _____ the pressure at the alveoli below that of atmospheric
decreasing
Most important muscle for inspiration Dome-shaped skeletal muscle innervated by the phrenic nerve Contraction of it causes it to flatten
diaphragm
Amount of _______ (flattening) correlates to the amount of air entering the lungs
diaphragm contraction
Air flows from ____ pressure to ___ pressure
high, low
If the bronchioles dilate even a little, the resistance drops by a power of ___ Constriction increases by power of __
4
condition that narrows or obstructs the airways increases resistance
COPD
This is responsible for about 75% of air that enters the lungs during resting (quiet) breathing
Diaphragm contraction
Lung compliance dependent upon 2 factors
Elasticity and surface tension
Pressure in alveoli Fluctuates with breathing Always eventually equalizes with Patm
Intrapulmonary (intra-alveolar) pressure (Ppul)
Pressure inside lung decreases as lung volume increases during inspiration; pressure increases during expiration.
Intrapulmonary pressure
May modify normal respiratory rhythm Most result from reflex action; some voluntary Examples include-cough, sneeze, crying, laughing, hiccups, and yawns
Nonrespiratory Air Movements
increased airway resistance (e.g., bronchitis) TLC, FRC, RV may increase
Obstructive pulmonary disease
during quiet breathing, no muscular contractions are involved, it results from inward forces; the elastic recoil of the chest wall and lungs the inward pull of the surface tension of the alveolar fluid
Passive exhalation
Pip can sometimes exceed ____ during forced exhalation such as a cough
Patm
Respiratory pressures are described relative to ____
Patm
Elevates ribs 3-5
Pectoralis minor
sum of anatomical and alveolar dead space
Physiological (total) dead space
______ consists of inhalation and exhalation.
Pulmonary ventilation
the movement of air between the atmosphere and the alveoli of the lungs
Pulmonary ventilation
Amount of air remaining in the lungs after a forced expiration
Residual Volume (RV)
The process of gas exchange in the body 3 basic steps: Pulmonary ventilation External (pulmonary) respiration Internal (tissue) respiration
Respiration
Deficiency of surfactant in premature infants Alveoli collapse due to high surface tension
Respiratory Distress Syndrome (RDS)
restrict lung expansion resulting in a decreased lung volume, an increased work of breathing, and inadequate ventilation and/or oxygenation Pulmonary fibrosis Deficiency in surfactant Pulmonary edema (fluid in the lungs) Impedance to expansion E.g. Ventilatory muscle paralysis, broken ribs Emphysema Decrease compliance
Restrictive disorders
Elevates the first two ribs
Scaline
instrument for measuring respiratory volumes and capacities can distinguish between Obstructive pulmonary disease and restrictive disorders
Spirometer
Elevates the sternum
Sternocleidomastoid
A mixture of phospholipids and lipoproteins present in the alveolar fluid
Surfactant
Allows for easier inflation of the alveoli and helps prevent alveolar collapse during exhalation
Surfactant
Reduces the alveolar fluid surface tension below the surface tension of pure water
Surfactant
Amount of air inhaled or exhaled with each breath under resting conditions
Tidal Volume (TV)
Maximum amount of air contained in lungs after a maximum inspiratory effort: TLC = TV + IRV + ERV + RV
Total Lung Capacity (TLC)
If unopposed, this force (surface tension of alveoli) would cause the alveoli to close with each expiration and make our "Work of Breathing" insupportable. True or False
True
______, or breathing, is made possible by changes in pressure at the alveoli relative to the atmospheric pressure
Ventilation
Maximum amount of air that can be expired after a maximum inspiratory effort: VC = TV + IRV + ERV
Vital Capacity (VC)
During each breath, the pressure gradients move 0.5 liter of air into and out of the lungs.
Volume of breath
instrument that measures atmospheric pressure.
barometer
During exhalation, the increase in pressure _____ the bronchioles This increases resistance to flow
compresses
Increased lung volume = ______ alveolar pressure
decreased
When the lungs expand and increase their volume, decreasing the pressure at the alveoli below that of atmospheric, air rushes in from the higher external atmospheric pressure to the lower internal alveoli pressure causing the lungs to fill in an effort to _____ the two pressures
equalize
During _______ the external intercostals relax and the ribs are depressed
exhalation
This causes an increase in alveolar pressure above that of atmospheric Air flows from high (lungs) to low (external environment) pressure
exhalation
This decreases the anteroposterior, vertical, and lateral diameters of the thoracic cavity Decreases lung volume
exhalation
begins when the inspiratory muscles relax The diaphragm relaxes and begins to rise superiorly and regain it's dome shape
exhalation
to _____ the pressure in the lungs is greater than that of the atmosphere
exhale
Boyles Law states that if there is a decrease in volume, there will be an ______ in pressure. ie. engine piston
increase
Contraction of the diaphragm lowers the dome, _____ the vertical volume of the thoracic cavity
increases
This decrease in alveoli pressure is accomplished by _____ the volume of the lungs through mechanical coupling to a change in thoracic volume
increasing
When the diaphragm contracts, the change in volume is transferred to the lungs via the _____ and the pressure within it
intrapleural cavity
At high altitudes, the atmospheric pressure is _____; descending to sea level, atmospheric pressure is _______.
less, greater
Plural fluid level must also be kept to a minimum Excess is pumped out by lymphatics If accumulates -> positive Pip pressure -> ____
lung collapse
If Pip = Ppul or Patm --> typically _____
lungs collapse
When the diaphragm contracts, Intrapleural pressure becomes slightly more _____ generating a greater outward pull on the lungs
negative
Advanced pregnancy, excessive obesity, and confining abdominal clothing can _______
obstruct diaphragm flattening
reduced TLC due to disease or fibrosis VC, TLC, FRC, RV decline
restrictive disorders
The ________ of alveolar fluid Found at all air-water interfaces Polar water molecules are more strongly attracted to each other than gas This means that when air tries to fill the alveoli, the fluid on the alveoli doesn't want to pull away from itself and produces an inward pull resisting expansion Causes the alveoli to assume the smallest possible diameter Accounts for 2/3 of lung elastic recoil.
surface tension