Exam 3 Part 2 Flashcards
Pulmonary Ventilation
breathing air in & out of lungs
Gas Exchange (Diffusion)
movement of gases b/w lungs & blood
Gas Transport
transport of gases through blood
Pulmonary Ventilation: Atmospheric Pressure
pressure outside of body; 760 mm Hg
Pulmonary Ventilation: Intrapulmonary Pressure
pressure inside lungs
Pulmonary Ventilation: Intrapleural Pressure
pressure b/w pleurae
Boyle’s Law
P = 1/V
V increases, pressure decreases
V decreases, pressure increases
How pressure and volume changes affect ventilation during rest, inhalation, and exhalation (remember atmospheric, intrapleural, & intrapulmonary pressure) ‼️
- At Rest: no air movement, atmostpheric pressure is 760 mm Hg, intrapulmonary pressure (inside lungs) is 760 mm Hg, intrapleural pressure is 756 mm Hg (-4 atmospheric pressure)
- Inhalation: air going in = volume increases = pressure down, atmospheric pressure is 760 mm Hg, intrapulmonary pressure is 759 mm Hg, intrapleural pressure is 754 mm Hg (-6)
- Exhalation: air goes out = volume decrease, atmospheric pressure is 760 mm Hg, intrapulmonary pressure is 761 mm Hg, intrapleural pressure is 756 mm Hg (-4)
Mechanism of Ventilation
- Inhale (Quiet/Resting Inspiration): diaphragm flattens on contraction, contraction of external intercostal & accessory muscles elevate ribs, (forced inspiration) more accessory muscle used
- Exhale (Quiet/Resting Expiration):
diaphragm relax & dome-shaped, other muscles relax, lungs recoil *NO muscle contraction (forced expiration) internal intercostal & abdominal muscle contract
Factors Influencing Ventilation
- Airway Resistance: anything that impedes air flow thru/ respiratory tract (constriction & dilation)
- Alveolar Surface Tension: tension which tries to close alveoli & reduce surfactant (due to H2O collapsing alveoli, surfactant disrupt hydrogen bonding)
- Pulmonary Compliance: ability of lungs & chest wall to stretch & expand (ex. broken rib, no surfactant)
Pneumothorax
intrapleural pressue equal or higher than atmospheric pressue = collapsed lung
Restrictive Lung Diseases
decrease pulmonary compliance
ex. fibrosis (scar tissue in lung), neuromuscular disease (muscle can’t change in volume of chest)
Obstructive Heart Disease
increase airway resistance, trap oxygen-poor, CO2-rich air in alveoli
ex. COPD (emphysema, bronchitis) asthma
Dalton’s Law
each gas in a mixture exerts its own pressure, called its partial pressure (Pgas) relative to its abundance; the total pressure of a gas mixture is the sum of the partial pressures of all of its component gases
in a mixture of gases, every gas contributes its own pressure which is relation to its abundance
50% of mixture, partial pressure is 50% of total mixture
Pressure and diffusion laws regulate gas exchange
- Pulmonary gas exchange: exchange of gases
that happens in the lungs between alveoli and
blood - Tissue gas exchange: exchange of gases that
happens in tissues between blood in systemic
capillaries and body cells
*Gas exchange depends on the:
-Partial pressures of gases
-Gas solubility in water
!diffuse from higher pressure to lower pressure!
Oxygen Partial Pressure in Higher Altitudes
atmospheric pressure goes down, individual gas pressure goes down
At high altitudes: lower atm. P means lower PO2
Henry’s Law
higher partial pressure means more gas dissolved in solution; amount of dissolved gas also depends on solubility (CO2
has better solubility then O2)
*choose higher number, if same number, CO2 is better
5 factors that increase the efficiency of gas exchange‼️
- Difference in partial pressure (pressure gradient):
drives diffusion from higher to lower partial pressure.
The bigger the gradient, the faster the diffusion. - Distance for diffusion: smaller distance (thin
respiratory membrane) allows for faster diffusion.
Inflammation increases the distance for diffusion. - Lipid solubility of gasses: both O2 and CO2 have
good lipid solubility and so can cross membranes and
surfactant - Total surface area for diffusion: large surface area
provided by alveoli and pulmonary capillaries;
emphysema decreases the total surface area of alveoli. - Ventilation-perfusion matching: blood flow and air
flow are closely coordinated, so the greatest blood flow
goes to alveoli with highest oxygen content.
Describe the pulmonary gas exchange
label: pulmonary capillary
-blue= blood goes to atrial, PO2=40, PCO2=45
-red = venous , PO2=104, PCO2=40
-alveolus (circle), PO2=104, PCO2=40
O2 towards pulmonary capillary, CO2 towards alveolus
Describe the tissue gas exchange (including partial pressure values)
Systemic Capillary:
-Venous: PO2=100, PCO2=40
-Atrial: PO2-40, PCO2=45
Tissue Cells:
-PO2=40, PCO2=45
O2 towards tissue cells, CO2 towards systemic capillary
Oxygen Transport
Each hemoglobin can reversibly bind to 4 O2
Reverse binding
oxygen binds to the heme part of hemoglobin
Hemoglobin Loading
oxygen from alveoli binds to
hemoglobin in pulmonary capillaries; converts
deoxyhemoglobin to oxyhemoglobin
* Hb with 1–3 molecules of oxygen bound is
partially saturated while Hb with four
Hemoglobin Unloading
Hb in systemic capillaries
releases oxygen to cells of tissues
