pulmonary ventilation and circulation (midterm 3) Flashcards
what are the four functions of respiration
- Pulmonary ventilation - oxygenates blood and tissues and pulls out CO2
- Gas diffusion in the lung - the transport of oxygen and carbon dioxide between the alveoli and the blood
- Gas diffusion in the tissues - the transport of oxygen and carbon dioxide between the blood and tissues
- Regulation of ventilation - the control systems that regulate these mechanisms
where is the only place gas exchange occurs
alveolus
what does the anatomical dead space do
- Warm the air to body temperature
- Humidify the air to saturation
- Remove dust by nasal hairs of mucosal surfaces
what is the anatomical dead space and how big is it
the volume of lungs each breath has to fill to get to gas exchange - 150 mL - no gas exchange occurs here (water equilibrates in this space)
what are the two ways lungs can be expanded and contracted
- downward and upward movement of the diaphragm, changing chest cavity length
- elevation and depression of the ribs, changing chest cavity diameter
these work together to change volume
where does the lung float
in the thoracic cavity surrounded by pleuric fluid, which provides suction force that holds the lung to the thoracic wall
what is the charge of pleural pressure
slightly negative to keep the lungs open rest, and even more negative during inspiration
what are the mechanics of the lungs
lungs expand to let air in
-> muscle contraction during inhalation
-> muscle relaxation during expiration
=> there is elasticity of the lung
what is lung compliance defined as
the extent of lung volume increase due to an increase in transpulmonary pressure
the change in volume of the lung divided by the change in transpulmonary pressure
what do surfactants do
they can reduce water surface tension by ~ 90%
what are surfactant typically made of
amphiphilic molecules and type II alveolar epithelial cells
what is spirometry
the method by which the volume of air movement into and out of the lungs is recorded
what four volumes are measured by spirometry
- Tidal Volume (VT)- the volume of air
inspired or expired with each normal breath (typically 500 ml) - Inspiratory Reserve Volume (IRV) - the
extra volume of air that may be inspired in excess of the tidal volume (typically 3000 ml) - Expiratory Reserve Volume (ERV) - the
extra volume of air that may be expired in excess of the tidal volume (typically 1100 ml) - Residual Volume (RV) - the volume of air
remaining in the lungs after forceful expiration (typically 1200 ml)
what four values are calculated from spirometry
- Inspiratory Capacity (IC) - tidal volume plus inspiratory reserve volume
- Functional Residual Capacity (FRC) - expiratory reserve volume plus residual volume
- Vital Capacity (VC) - inspiratory reserve volume plus tidal volume plus expiratory reserve volume
- Total Lung Capacity (TLC) - vital capacity plus residual volume
what is the equation for VC, TLC, and FRC
VC = IRV + VT + ERV = IC + ERV
TLC = VC + RV = IC + FRC
FRC = ERV + RV
what is residual volume and how is it measured
air you don’t get rid of through breathing
measured using spirometry with air containing helium
how do you measure residual volume (specifics)
- breathe normally
- after expiration, breathe (Vr) in He
- measure Hei and Hef in spirometer
- He balance: Msi + Mli (=0) = Msf + Mlf
s = spirometer
L = lungs
M = mass
what are the equations to calculate residual volume
FRC = (CiHe / CfHe - 1)Vinspir
CiHe = initial [He] in spirometer
CfHe = final [He] in spirometer
Vinspir = initial volume of spirometer
=> RV = FRC - ERV
what is alveolar ventilation and what is the equation for it
the rate at which air reaches areas of gas exchange (Va) = RR (respiratory rate) x (Vt (tidal volume) - Vd)
how do you calculate anatomical dead space
= Vd
1. inspire pure O2
2. expire -> first pure O2, then mix of O2 + N2 from lung residual volume
Vd = (Vo2/(VN2 + Vo2))xVe
what does the pulomary artery have and how far does it extend
has deoxygenated blood and extends 5 cm beyond the apex of the right ventricle, then divides to supply blood to the lungs
what is the physiology of the pulmonary artery
walls are thin, branches are short, pulmonary vessels have larger diameters than those in the systemic system => pulmonary arteries have high compliance (small delta P = large delta V)
what is the difference between pressure pulses in ventricle/artery and aorta
pressure pulses in the right ventricle and pulmonary artery are significantly lower than those
observed in the aorta (left side of heart)
what occurs with pulmonary artery and right vent. pressure during systole
they are nearly equal because the valve is open
what occurs with pulmonary artery and right vent. pressure during diastole
During diastole, right ventricular pressure falls quickly, and pulmonary arterial pressure falls
slowly as blood moves through the pulmonary capillary bed
where does blood flow
to the regions of the lung where alveoli are more oxygenated
what is the normal level of O2 in the air of the alveoli and what happens when the concentration falls below this
73 mmHg
adjacent blood vessels constrict due to vasoconstrictors increasing and vasodilators decreasing
what happens to blood distribution due to hydrostatic pressure and what are the resulting values
there is a significant difference in BF to different areas of the lung
23 mmHg pressure difference between top and bottom of the lung
- 15 mmHg is above the heart, 8 mmHg is below the heart
what is lung height value
~ 30 cm
what happens when Palv > Pcap
capillary will collapse and BF will fall
what are the three zones of blood flow
- Zone 1: Palveolar > Pcap => No BF
- Zone 2: Palv < Pcap (only < durning systole => only blood flow during systeole => intermittent BF
- Zone 3: Palv < Pcap => constant BF
where does the lung have more hydrostatic pressure
@ bottom of lung
what zone flow does a healthy standing person have
zone 2 flow in top and zone 3 zone in bottom of lung
what zone flow does a person lying down have
zone 3
what zone flow does a person have during exercise
zone 3
