Gas Transport Flashcards
1
Q
Gas homeostasis
A
- external respiration
- blood transport
- internal respiration
2
Q
External respiration
A
- respiratory gases pass between air and blood by diffusion in alveolar sacs
- thickness of respiratory membrane
- difference in partial pressure
- gas solubilities
- O2 arrives at equilibrium quickly
- CO2 takes more time (greater partial pressure gradient
3
Q
Internal respiration
A
- respiratory gases pass between the blood and interstitial fluid by diffusion in the true capillaries
- at rest, 25% of available O2 enters cells (during exercise, more is absorbed)
4
Q
Dalton’s Law
A
- pressure exerted by a specific gas in a mixture f gases is proportional to its representation in the mixture (by volume), the partial pressure of a gas
- total pressure = sum of all partial pressures exerted by each component
5
Q
Henry’s Law
A
- gases dissolve into liquid in proportion to their partial pressure
- partial pressure in gas phase and liquid phase are equal at equilibrium
6
Q
Gas solubility additional factors
A
- temperature: higher; less soluble
- solubility of the specific gas (CO2 20x more soluble than O2)
7
Q
Rate of diffusion of gases
A
Varies on:
- partial pressure of gases -altitude
- surface area of alveoli
- diffusion distance
- solubility and molecular weight
8
Q
O2 transport
A
- mostly done via bounding itself to hemoglobin containing Ge bearing protein (98%)
- smaller amount dissolved directly in the plasma(2%)
9
Q
Hemoglobin
A
- contains a heme group (polypeptide unit)
- O2 binding enhances further binding (cooperative binding)
- unloading enhances further unbinding
- increase affinity, increase saturation
- decrease affinity, decrease saturation
10
Q
Rate of loading and unloading O2 and factors
A
- PO2, less O2, slower rate
- blood pH, more acid, faster rate
- PCO2, more CO2, faster rate
- increased temp, faster rate
11
Q
CO2 transport
A
- mostly done by being dissolved in plasma as HCO3- (70%)
- smaller amount bound to hemoglobin (amino acids of protein) (20%)
- smallest amount dissolved in plasma as CO2 (10%)
12
Q
O2 dissociation curve
A
- almost fully saturated at 60 mmHg
- higher PO2, will bind with hemoglobin better
13
Q
2,3 bisphosphoglycerate (BPG)
A
- product of cell metabolism
- when bound, it stabilizes the deoxygenated confirmation of hemoglobin, facilitating O2 unloading to actively respiring Tissue
14
Q
Aging effects
A
-decreased lung elasticity
-decreased lung capacity
-decreased blood O2 levels
-decreased stimulating effects of CO2
-increased risk of respiratory tract infection
(Elderly are often hypoxic and exhibit sleep apnea)
