Resp Physiology 2 Flashcards
What does Boyle’s Law state?
At a constant temperature, pressure (P) and volume (V) are inversely proportional. P1V1 = P2V2.
What does Charles’ Law state?
At constant pressure, volume (V) is proportional to temperature (T). V1/T1 = V2/T2.
What does Dalton’s Law state?
The total pressure of a gas mixture is the sum of the partial pressures of its individual gases.
How does water vapor affect inspired gas?
Fully humidified air in the airways at 37°C exerts a vapor pressure of 6.3 kPa, diluting other gases.
What is the Alveolar Gas Equation?
PAO2 = FiO2 (PB - PH20) - (PaCO2/RQ)
PAO2 = Alveolar O2
FiO2 = Fraction of inspired O2
PB = Barometric pressure
PH2O = Water vapor pressure
PaCO2 = Arterial CO2
RQ = Respiratory Quotient (~0.8)
What does Henry’s Law state?
The amount of gas dissolved in a liquid is proportional to its partial pressure and solubility.
What does Graham’s Law state?
The rate of diffusion of a gas is inversely proportional to the square root of its molecular weight.
What factors influence gas diffusion across membranes?
Greater surface area and partial pressure difference (ΔP) increase diffusion; increased membrane thickness reduces it.
How is oxygen transported in the blood?
Oxygen is transported in two forms: bound to hemoglobin (Hb) and dissolved in plasma.
How much O₂ does hemoglobin (Hb) carry?
Each gram of Hb can carry 1.34 ml O₂, and at full saturation, ~200 ml O₂ per L of blood.
How much O₂ is dissolved in plasma?
Only ~3 ml O₂ per L of plasma at 13 kPa O₂, making Hb the primary O₂ carrier.
What factors shift the O₂-Hb curve to the right?
Decreased pH
increased CO₂
increased temperature
increased 2,3-DPG (Bohr effect).
What factors shift the O₂-Hb curve to the left?
Increased pH
decreased CO₂
decreased temperature
decreased 2,3-DPG
How do you calculate total oxygen content in blood?
CaO2 = (1.39xHbxSaO2x0.01) + (0.023xPaO2)
CaO2 = Arterial O2 content
1.34 = Max O2 carrying capacity of blood
Hb = Haemoglobin
SaO2 = Oxygen saturation
PaO2 = Arterial oxygen pressure
0.023 = solubility constant of oxygen
What is the Bohr Effect?
A decrease in pH or increase in CO₂ (PaCO₂) reduces Hb’s oxygen affinity, facilitating O₂ unloading in tissues.
What is the Haldane Effect?
Oxygenation of hemoglobin reduces its ability to bind CO₂, promoting CO₂ release in the lungs.
What are the three forms of CO₂ transport?
CO₂ is transported as bicarbonate (HCO₃⁻)
carbaminoheamoglobin compound bound to Hb
dissolved in plasma
How is CO₂ transported as bicarbonate (HCO₃⁻)?
CO₂ reacts with water to form carbonic acid (H₂CO₃), which dissociates into H⁺ and HCO₃⁻.
How is CO₂ transported as carbamino compounds?
CO₂ binds to proteins, mainly hemoglobin, forming carbaminohemoglobin.
How is CO₂ transported dissolved in plasma?
CO₂ is ~20 times more soluble than O₂, allowing a small but significant portion to be directly dissolved.
What is a V/Q mismatch?
An imbalance between alveolar ventilation (V) and perfusion (Q), leading to inefficient gas exchange.
What is a right-to-left shunt?
Blood bypasses ventilated alveoli, leading to hypoxia that does not improve with 100% O₂.
What is physiological dead space?
The sum of anatomical dead space (conducting airways) and alveolar dead space (ventilated but unperfused alveoli).
What do central chemoreceptors detect?
PaCO₂ and pH changes in cerebrospinal fluid.
What do peripheral chemoreceptors detect?
PaO₂, PaCO₂, and pH changes in blood.
Pulmonary Receptors – Stretch Receptors
Inhibit overinflation (Hering-Breuer reflex).
Pulmonary Receptors – Irritant Receptors
Respond to noxious stimuli, triggering bronchoconstriction and coughing.
Pulmonary Receptors – J-Receptors
Respond to pulmonary congestion, triggering rapid shallow breathing.
Pulmonary Receptors – Bronchial C-Fibers
React to inflammatory mediators, causing bronchoconstriction and mucus secretion.