W3-L3: Lungs Flashcards
What is Henry’s Law?
Henry’s Law states that the amount of gas that dissolves in a liquid is directly proportional to the partial pressure of that gas above the liquid
2 factors govern the rate of the gas diffusion into a fluid:
- The pressure differential between the gas above the fluid and the gas dissolved in the fluid
- The solubility of the gas in the fluid
Henrys Law
- Pressure Differential and Gas Movement
The pressure difference between alveolar and pulmonary blood gases creates the driving force for gas diffusion across the pulmonary membrane
Henrys Law
- Solubility
If all gases had the same pressure differential, the solubility of each gas determines the number of molecules that move into or out of a fluid
Gases have different solubilities!
CO2: 57.03 mL/dL
O2: 2.26 mL/dL
N: 1.30 mL/dL
Can calculate the amount of gas dissolved in a fluid….
Quantity of gas (ml/dL) = solubility coefficient X (gas partial pressure / Total barometric pressure)
How does Gas exchange work?
- O2 travels from a high-low pressure as it dissolves and diffuses through alveolar membranes into blood
- CO2 exists under greater pressure in returning venous blood than in alveoli, causing net diffusion of CO2 from blood into lungs
- Blood spends approximately 0.75 s in the pulmonary capillary
check 132 notes
know the numbers on diagram
What Two factors impair gas transfer capacity at the
alveolar–capillary membrane?
- Buildup of a pollutant layer that “thickens” the alveolar membrane
- Reduction in alveolar surface area
- Each factor extends time before alveolar–capillary gas equilibrates
- For individuals with impaired lung function, the added demand for rapid gas exchange in exercise compromises aeration, negatively affecting performance
Transit Time
How does blood carry Oxygen?
The blood carries oxygen in 2 ways:
1. In physical solution dissolved in the fluid portion of blood
2. In loose combination with hemoglobin
How does the blood transport Oxygen in Physical Solution?
- Oxygen’s relative insolubility in water keeps its concentration low within body fluids
- 0.3 mL per 100 ml of blood (3mL per L of blood)
What are the functions of O2 transported in physical solution?
3
Functions of O2 transported in physical solution:
- Establishes PO2 of plasma and tissue fluids
- Helps to regulate breathing , particularly at altitude
- Determines O2 loading of hemoglobin in lungs and subsequent release in tissues
What is Hemoglobin?
iron-containing globular protein pigment
How does the blood carry oxygen in In loose combination with Hemoglobin?
- Carries 65-70 times more O2 than dissolved in plasma
- 197 ml of O2 per L
- Each of the four iron atoms in hemoglobin molecule can loosely bind one oxygen molecule:
Hb4 + 4O2 ——> Hb4O8 - Partial pressure of O2 dissolved in physical solution dictates oxygenation of hemoglobin to oxyhemoglobin
How much Hemoglobin do we have?
How much O2 can bind to 1g of Hb?
males have more
The Hemoglobin Molecule
How does Anemia Affect Oxygen Transport
- The bloodʼs O2 transport capacity changes slightly with normal variations in Hb content
- Iron deficiency anemia causes significant decreases in iron availability to decrease hemoglobin concentration, which reduces content of RBCs that reduce the bloodʼs O2- carrying capacity
- This effect diminishes a personʼs capacity to sustain even mild-intensity aerobic exercise
What is Cooperative binding?
Cooperative binding: The joining of O2 with Hb
- Binding of O2 molecule to the iron atom in one of the four globin chains progressively facilitates binding of subsequent molecules
What is Oxyhemoglobin dissociation curve?
Main Curve: Indicates how hemoglobin saturation varies with oxygen pressure.
Temperature: Lower temperatures increase hemoglobin’s affinity for oxygen; higher temperatures decrease it.
Acidity: Higher pH (less acidic) increases hemoglobin’s affinity for oxygen; lower pH (more acidic) decreases it.
What is the Oxyhemoglobin
Dissociation Curve?
(visual)
Percentage saturation of Hb (solid yellow line)
* Inset upper graph: Effect of temperature
- Inset lower graph: Effect of acidity
What is the Oxygen Transport Cascade?
(Visual)
Changing partial pressures as O 2 moves from ambient air at sea level (159 mm Hg) to the mitochondria of maximally active muscle tissue (2 to 3 mm Hg)
