physio ch 16
passive forces exerted on the airways, smooth muscles in bronchioles, and secretions of mucous into airways
3 factors affecting resistance to airflow
atmospheric pressure, intra-alveolar pressure, intrapleural pressure, and transpulmonary pressure
Pulmonary pressures- the 4 primary pressure associated with ventilation
passive forces; tractive forces; decrease; increases
__________ are due to changes in the transpulmonary pressure that occurs during inspiration and expiration; _______ are exerted on the airways by the surrounding tissue during inspiration both forces act to _______ resistance while during expiration resistance _________
lung compliance
a measure of the ease with which the lungs can be stretched the greater it is the less work necessary to bring in a given volume of air
forced expiration volume
a measure of the percentage of forced vital capacity that can be exhaled within a certain period of time. A ____ that is less than 80% is characteristic of obstructive pulmonary disease
active expiration
a more forceful expiration results from contraction of the muscles of expiration in a process called
spirometry
a technique of measuring volumes of inspired and expired air
volume
air flow results from the muscles of respiration creating pressure gradients by changing the ______ of the lungs
bulk flow
air flows into the lungs by
intrapleural pressure
at rest it is -4 mmHg. pressure inside the pleural sac (it contains fluid not air); always negative and always less than Palv (intra-alveolar pressure) under normal conditions; negative due to the elasticity in lungs and chest wall the elastic forces are trying to open the intracellular space the tension resisting these elastic forces is the surface tension of the pleural fluid
tidal volume, inspiratory reserve volume, and expiratory reserve volume
can be measured directly
parasympathetic stimulation
causes contraction (bronchoconstriction) of smooth muscles in the lungs
sympathetic stimulation
causes relaxation of smooth muscle (bronchodilation)
the quantity (moles) of air molecules in the alveoli and the volume of the alveoli
determinants of intra-alveolar pressure
low; 2 mmHg
during eupnea, airway resistance in the conducting zone is ____ and only a pressure gradient of less than _______ is required to maintain sufficient air flow if airway resistance increases a much larger pressure gradient is needed to maintain a given airflow
greater
during expiration, intra-alveolar pressure is ________ than atmospheric pressure
less
during inspiration, intra-alveolar pressure is _____ than atmospheric pressure
passive process
during normal breathing, expiration is a ________ in which the muscles of inspiration release and the elastic properties of the chest wall and lungs cause lung volume to decrease
increasing tidal volume
during times of high oxygen demand it is more efficient to increase alveolar ventilation by _____________ _________ _________ than by increasing respiratory rate
bronchodilation
epinephrine causes broncho______
rate of flow
equals the pressure gradient created by the difference between atmospheric pressure and intra-alveolar pressure over the resistance encountered by air as it flows through the air passageways
external respiration
exchange of oxygen and carbon dioxide between the atmosphere and body tissues
restrictive pulmonary diseases
in these disorders, something interferes with lung expansion; there is a decrease in vital capacity and total lung capacity
chronic obstructive pulmonary diseases (COPD)
increase airway resistance; due to chronic diseases such as emphysema and chronic bronchitis
Palv-Pip; into; equals
increase in transpulmonary pressure is due to the difference in alveolar pressure and intrapleural pressure this increase in transpulmonary pressure causes the lungs to expand; the increase in the volume of the alveoli that accompanies this expansion decreases intra-alveolar pressure; the pressure difference between atmospheric pressure and intra-alveolar pressure (Patm-Palv) causes air to flow ______ the lungs; air flow continues until intra-alveolar pressure ______ atmospheric pressure
asthma
increases airway resistance by causing spastic contraction of smooth muscles of the bronchioles, increased mucous secretion, and inflammation of bronchioles
obstructive pulmonary diseases
involve abnormal increases in airway resistance; in these diseases the lungs become over inflated and the functional residual capacity and lung volume often increase
elasticity of lungs and surface tension of the liquid in alveoli
lung compliance depends on both factors tend to decrease the lung compliance
DV/(D(Palv-Pip))
lung compliance equation
forced vital capacity
lung test where the patient makes a maximum inspiration and then exhales as forcefully and rapidly as possible a low reading is indicative of restrictive pulmonary disease
tuberculosis; infant respiratory distress syndrome
lung tissue thickens decreasing lung compliance; lung compliance decreases due to loss of surfactant
vital capacity
max amount of air that can be expired following a max inspiration; sum of tidal volume + inspiratory reserve volume + expiratory reserve volume; ~4500 ml
inspiratory capacity
max volume of air that can be inspired at the end of a resting expiration; sum of tidal volume + inspiratory reserve volume; ~3500mL
alveolar ventilation
more important measure from a functional point of view because it is a measure of the volume of fresh air that reaches the alveoli each minute calculated by subtracting from the minute volume the air that does not reach the alveoli because of the anatomical dead space
pulmonary ventilation
movement of air in and out of the lungs
external respiration includes
pulmonary ventilation, exchange of gasses by diffusion between air and blood, transportation of gases by blood, exchange of gases by diffusion between blood and tissues
eupnea
quiet breathing
airway resistance
refers to the resistance of the entire system of airways in the respiratory
histamine
released during an allergic reaction and increases resistance by bronchoconstriction and increasing the secretion of mucus
pulmonary surfactant
secreted by type 2 alveolar cells in order to lessen the impact of surface tension on lung compliance
boyle's law
states that the pressure of gas in any container is inversely related to the volume of the container. when volume increases, pressure decreases and when the volume decreases, the pressure increases
tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume
the 4 non-overlapping lung volumes:
anatomical dead space
the combined volume of the non exchanging airways
increase in intra-alveolar pressure
the decrease in lung volume during expiration causes an __________ and creates the pressure gradient that causes an outflow of air
inspiratory muscles; expiratory muscles
the diaphragm and the external intercostal muscles are the primary ______ the internal intercostal and abdominal muscles are the primary ______
transpulmonary pressure
the difference between the intracellular pressure and the intra-alveolar pressure. this force operates across the walls of the lungs and causes the lungs to expand
neural and hormonal signals; local chemical mediators
the extrinsic control factors of contraction and relaxation of smooth muscle in lungs; the intrinsic control factors
pneumothorax
the lung collapses and the thoracic wall expands
expiratory reserve volume; 1000 mL
the maximum volume of air that can be expired at the end of a normal expiration. the average volume is about ______ mL
inspiratory reserve volume; 3000 mL
the maximum volume of air that can be inspired at the end of a normal inspiration. the average volume is about ______ mL
radius of the airways
the most important factor affecting resistance
airtight
the pleurae must be _______ to maintain its negative intrapleural pressure if the integrity of the airtight space is compromised by trauma or disease air enters this pace and the condition is called pneumothorax if the lung is ruptured, the Pip becomes 0 mmHg instead of -4 mmHg
atmospheric pressure
the pressure of the outside air at sea level is 760 mmHg. The remaining lung pressures are expressed relative to this pressure.
respiration
the process of gas exchange that occurs on two levels: internal and external
internal respiration
the use of oxygen by mitochondria to produce ATP by oxidative phosphorylation with the production of carbon dioxide as a waste produce
functional residual capacity (FRC)
the volume of air in the lungs when the lungs are at rest between breaths
residual volume; 1200 mL
the volume of air remaining after a maximum expiration. the average volume is about _____ mL
minute ventilation
total air flows in and out of respiratory system in a minute; calculated by multiplying the tidal volume by the respiration rate (# of breathes per minute)
spirometry
used to test for respiratory disorders; diseases that can be diagnosed fall into two categories: obstructive pulmonary diseases and restrictive pulmonary diseases
intra-alveolar pressure
varies with ventilation. during inspiration it is less than atmospheric pressure. during expiration it is greater than atmospheric pressure. At rest it is equal to atmospheric pressure. when it is equal to atmospheric pressure it is considered to be at 0 mmHg.
pressure gradients
ventilation results from bulk flow of air as the result of this created between alveoli and atmospheric pressure
total lung capacity
volume of air in the lungs at the end of a max inspiration; sum of all of the lung volumes (tidal volume + inspiratory reserve volume + expiratory reserve volume + residual volume); ~5700 ml
functional residual capacity
volume of air remaining in the lungs at the end of a tidal expiration; sum of expiratory reserve volume and residual volume; ~2200 ml
tidal volume; 500 mL
volume of air that moves into and out of the lungs in one unforced breath. the average volume is about ______ mL
radius decreases and resistance increases
when bronchioles contract (bronchoconstriction)the radius of the bronchioles _______ and the resistance ________
radius increases and resistance decreases
when bronchioles relax (bronchodilation) the radius ______ and resistance ________
