Flashcards in Gas Diffusion, Transport, and Exchange Deck (30):

1

## Central Gas Law

###
PV=nRT

Pressure (mmHg) Volume (L) = Moles x gas constant x temp

2

## What constants are used for gas phase calculations?

###
BTPS

Body temp (37C or 310K), Ambient pressure, saturated with water vapor (47mmHg).

3

## What constants are used for gas dissolved in blood?

###
STPD

Standard Temp (0C or 273K), Standard Pressure (760mmHg), Dry gas

4

## How do pressure and volume of a gas relate?

### P1V1=P2V2. During inspiration, there's increased lung volume, which causes gas pressure to decrease.

5

## How to calculate partial pressure of a dry gas?

###
Px = Pb x F

Where Pb is barometric pressure and F is fractional concentration

6

## How to calculate partial pressure of humified gas?

###
Px = (Pb-PH2O) x F

PH2O at 37C is 47 mmHg

7

##
True or false?

The sum of partial pressures of all gases in a mixture is the total pressure of the mixture.

### True!

8

## What percent of atmospheric air at 760mmHg is Oxygen?

### 21%

9

## How does high altitude affect PO2 of inspired air?

### Decreases PO2 of inspired air due to low barometric pressure.

10

## Concentration of a free dissolved gas equation?

### Cx = Px x S. This applies to a dissolved gas that is free in solution.

11

##
True or false?

Only a dissolved gas, not a bound gas or chemically modified gas, contributes to its partial pressure.

### True

12

## Fick's Law of Simple Diffusion. Calculate rate of transfer.

###
Vx = (DAP)/ X

Diffusion coefficient, surface area, pressure gradient, divided by thickness.

13

## What factors affect diffusion coefficient?

### Molecular weight and solubility

14

## Difference in diffusion between O2 and CO2

### CO2 has a 20X higher D.

15

## How is N2 carried in blood?

### Exclusively in dissolved form.

16

## How is O2 carried in the blood?

### Mostly (98%) bound to hemoglobin. CO can also bind to hemoglobin.

17

## How is CO2 carried in the blood?

### Chemically modified to HCO3-.

18

## Diffusion limited gas exchange

### Amount of gas that is transported from alveoli to capillaries is limited by diffusion. This is true for CO, and transport of O2 in emphysema, fibrosis, and exercise.

19

## Perfusion limited gas exchange

### The amount of gas transported is based on the blood flow. This is true for O2, CO2. Occurs in the first 1/3 of capillary.

20

## Oxygen binding capacity

### 1 gram of Hba can bind 1.34 ml O2 when 100% saturated.

21

## Concentration of Hb in blood? How much O2 can it hold?

### 15 g/dL. Can hold 20.1 mL O2.

22

## How to calculate O2 bound to Hb

### Binding Capacity X % Saturation

23

## O2 delivery equation

### O2 Delivery = Cardiac Output x (Oxygenated Hb + Dissolved O2)

24

## What causes rightward shifts in the Hb-O2 curve.

### Increases in temp, Co2, [H], 2,3 DPG. Causes faster unloading into tissues.

25

## Why is Co dangerous?

### Because its affinity for Hb is 250x that of O2.

26

## Conversion of CO2L

### Dissolved CO2 in bloodstream. 93% is taken up into RBC's, 90% is converted to H2CO3 by carbonic anhydrase. H2CO3 dissociates into H+ and HCO3. H+ buffered, HCO3 pushed into plasma via exchange with Cl.

27

## Anion Exchange Protein (3 Band)

### Changes HCO3- with Cl- on RBCs.

28

## A-a gradient.

### The difference in PO2 of alveolar gas and arterial blood. Normally less than 12 mmHg.

29

## Calculate A-a gradient

### A-a = (PiO2 - PACO2/R) - PaO2

30