Respiratory system 2: Pulmonary Ventilation Flashcards
External (pulmonary) respiration
The process of gas exchange between the alveoli of the lung and the blood in the pulmonary capillaries
Pulmonary respiration
The process of gas exchange between the air we breathe (atmosphere) and the alveoli of the lungs
Internal (pulmonary) respiration
The process of gas exchange between the systemic capillaries and the tissue cells
Boyle’s law
The pressure of a gas in a closed container is inversely proportional to the volume of the container
The most important muscle Invovled in inhalation/inspiration
Diaphragm (accounting 75% of contraction) and external intercostals (accounting 25% of contraction)
Quiet Inspiration/inhalation
Diaphragm descends 1 cm and ribs lifted by muscles
external intercostals elevate the ribs increasing the dimensions of the chest cavity
Inhalation of about 500ml of air
Forced inhalation
accessory muscles of inspiration (SCM, scalenes and pectoralis minor) are also used to lift chest upward as you gasp for air.
Diaphragm descends 4 cm
Intrathoracic pressure falls and 2-3 liters inhaled
Exhalation occurs when…
Alveolar (intrapulmonic) pressure is higher than atmospheric pressure.
Quiet expiration
Passive process with no muscle action
Elastic recoil and surface tension in alveoli pulls inward
Alveolar pressure increases and air is pushed out
Forced expiration
Exhalation becomes active during labored breathing and when air movement out of the lung is impeded. Internal intercostals depress ribs and abdominal muscles force diaphragm up.
Intrapleural pressure
is the pressure between the parietal and visceral layers of the lungs
Always subatomospheric
As diaphragm contracts and volume of Thracic cavity increases, volume of the pleural cavity also increases which causes intrapleural pressure to decreases even more
Helps keep parietal and visceral pleura stuck together when chest expands
Alveolar surface tension
Thin layer of fluid in alveoli causes inwardly directed force = surface tension
water molecules strongly attracted to each other causes alveoli to remain as small as possible
What does Type II alveolar cells produce?
Surfacant, detergent-like substance lowers alveolar surface tension. Insufficient in premature babies so that alveoli collapse at end of each exhalation
What is compliance of the lungs
Ease with which lungs and chest wall expand depends upon elasticity of lungs and surface tension
Some diseases reduce compliance
Which diseases reduce compliance of the lungs
Tuberculosis forms scar tissue
Pulmonary edema - fluid in lungs and reduced surfacant
Paralysis
Airway resistance
Resistance to airflow depends upon airway size
Increase size of chest - airways increase in diameter
contract smooth muscles in airways - decreases in diameter
Normal variation in breathing rate and depth is called
Eupnea
Breath holding is called
Apnea
Painful or difficult breathing is called
Dyspnea
Rapid breathing rate is called
Tachypnea
combinations of various patterns of intercostal and extracostal muscles, usually during need for increased ventilation as with exercise
Costal breathing
Usual mode of operation to move air by contracting and relaxing the diaphragm to change the lung volume
Diaphragmatic breathing
Used to express emotions and to clear air passageways
Modified respiratory movements
deep inspiration, closure of rima glottidis and strong expiration blasts air out of clear respiratory passages
Coughing
Spasmodic contraction of diaphragm and quick closure of rima glottidis produce sharp inspiratory sound
Hiccuping
an instrument that measures breathing volumes
Spirometer (respirometer)
The graph that charts the volumes called a spirogram
Total lung capacity (TLC)
Approx 6000 mls in guys, 4200 mls in females, this is a sum of all the air in the lung.
Tidal volume (TV)
the volume inhaled and exhaled under normal breaths
Functional residual capacity (FRC)
Expiratory reserve volume + Residual volume. The amount that always remains and the amount you can forcibly exhale after a normal exhale
2400 ml
Residual volume (RV)
The small amount of air that will always remain in your lungs, no matter how much you exhale 1200 ml
Expiratory reserve volume (ERV)
The amount of air you can force out after normal exhalation 1200 ml
Inspiratory reserve volume (IRV)
The additional air you can forcibly inhale after a normal inhalation 3100 ml
Inspiratory capacity (IC)
sum of tidal volume (normal inhale/exhale + Inspiratory Reserve volume, the max that you can forcibly inhale)
3600 ml
Vital capacity (VC)
Sum of Tidal volume + Inspiratory reserve volume + Expiratory reserve volume
Dalton’s law
The pressure of a gas exerts its own pressure as if no other gases are present.
PN2 + PO2+ PH2O+PCO2=Patm
What is approx % of each gas in Patm
- 6% N2
- 9% O2
- 04% CO2
- 06% other gases
Henry’s Law
The quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility
Nitrogen narcosis
N2 has low solubility at sea level but as total partial pressures increases (as in oxygen tank mixtures), a more than normal amount of N2 dissolves in plasma and tissues. They feel like they are “drunk”
Decompression sickness
when a scuba diver ascends too rapidly, the N2 comes out of solution and forms gas bubbles in nervous tissues. Symptoms include joint pain, dizziness, shortness of breath, fatigue or paralysis
Hyperbaric oxygenation
Hyperbaric chamber pressure is raised to 3 to 4 atmospheres so that tissues absorb more O2. Treatment for patients with anaerobic bacterial infections (tetanus and gangrene), heart disorders, carbon monoxide poisoning, cerebral edema, bone infections, gas embolisms and crush injuries. Anaerobic bacteria die in the presence of O2.
Rate of exchange depends on
Partial pressure
Surface area available for gas exchange
Diffusion distance
Molecular weight and solubility of the gas
what % of O2 gas is transported via haemoglobin
98.5% (oxyhemoglobin or Hb-O2)
how many % is dissolved in blood plasma
1.5%
How many % of O2 is unloaded to cells under normal resting conditions
25%
factors that affect the affinity of O2 to haemoglobin
- pH - the lower the pH (more acidic), the more H+ ions in solution, the less the affinity. Thus lowered blood plasma pH shits the curve to the RIGHT.
- Partial Pressure of CO2 - As PCO2 increases, the curve also shifts to the RIGHT b/c of increased H+ions in solution due to the reaction with carbonic anhydrase that forms H+ and HCO3-
- Temperature - as temperature increases, more O2 is released from Hb. (and vice versa for lowered body temp)
- BPG- (2,3 - bisphosphoglycerate)- compound produced by RBCs that decreases the affinity for O2 on Hb. Increase BPG, increase O2 release
- Fetal Hemoglobin (HB-F)-Fetal Hb finds to BPG with LESS affinity than maternal (Hb-A) thus binds O2 with MORE affinity
% of each carbon dioxide transport
7% blood blasma
23% attached to Hb to form Hb-CO2, Carbaminohemoglobin (Higher in tissue capillaries and lower in pulmonary capillaries)
70% is transported as bicarbonate ion (HCO3-)
Chloride shift
The conversion of CO2 to bicarbonate ions and the related chloride shift maintains the ionic balance between plasma and red blood cells
Heldane Effect
The lower the amount of Hb-O2 the higher the CO2 carrying capacity of the blood
Summary of gas exchange and transport in lungs and tissues
CO2 in blood causes O2 to split from hemoglobin
Similarly, the binding of O2 to hemoglobin causes a release of CO2 from blood
what is anatomical dead space/respiratory dead space
is the conducting airways with air that do not undergo respiratory exchange
volume of one breath
tidal (about 500 ml)
how much of tidal volume actually reach alveoli
350 ml. 150 ml (30%) remains in anatomical dead space
which volume in the lung can not be measured by a spirometer
residual
How does hight, gender and age of a person affect lung volumes
larger volume - taller younger and make
smaller female, shorter and elderly
what respiratory system structures are in the anatomical dead space
Nose, pharynx, larynx, bronchi, bronchioles, terminal bronchioles
vital capacity
inspiratory reserve volume 3100 and tidal volume 500 and expiratory reserve volume 1200 = 4800
volume of air/min that reaches the alveoli
alveolar ventilation rate (4200 ml/min)
Amount of air forcibly expired in 1 sec with maximal effort following maximal inhalation
FEV1
total volume of air taken in during one minute
minute volume of respiration (MVR) = 6000ml/min (tidal volume x 12 respirations per minute = 6000 ml/min)
to determine partial pressure of O2
multiply 760 by % of air that is O2 21% = 160 mm Hg
