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