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 ________