# Systems Phys

## 21 terms

### Define exchange as it pertains to the pulmonary system

Movement of gas across barrier

### Define transport as it pertains to the pulmonary system

Movement of gas through blood vessels

### What is the alveolar distance and how does it change during inspiration?

It is the distance between the endothelial lung lining and the pulmonary capillaries. It is lowest at the end of inspiration.

### When is the collective area of alveoli highest?

At the end of inspiration

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### How is the [O2] in blood solution counted? Which component affects PO2?

If it is bound to hemoglobin or diffused in the blood plasma solution. Only the blood in the solution affects PO2

### There is unidirectional, nonconcurrent diffusion across the alveoli barrier. T/F?

F. There is bi-directional simultaneous diffusion of gas across the barrier.

### How is the flow of a gas from one part of the barrier to another calculated?

Pressure *(Surface Area/thickness). This can be used for any gas

### How is net flow of gas across a barrier calculated?

(Flow from 1-->2) - (Flow from 2-->1)

### What is lung diffusion capacity and how is related to O2 exchange from the alveoli to the RBC? Which layer offers resistance to O2 diffusion into blood?

It is the summary of all 8 characterized layers of O2 to go into the cytoplasm of the RBC. The interstitial space offers resistance to O2 diffusion because of an intracellular matrix

### How does a change in physiological conditions affect the PO2 diffusion gradient?

The max. PO2 diffusion that can occur along the capillaries happens in 1/3 the length of the pulmonary distance. Under less physiological conditions, more diffusion occurs along a shorter length of the capillaries

### What is hemoglobin saturation?

The percent of hemoglobin molecules bound to oxygen

### What is the total oxygen-carrying capacity of blood and what does it measure? What is the max. O2-carrying capacity? What does this mean for hemoglobin saturation?

How much O2 100 mL of blood will hold and it incorporates O2 content + PO2 in solution. ~20%. This means that hemoglobin saturation will never be @ 100%

### What is hemoglobin (Hb)? How does it's conformation react to O2?

Hemoglobin is a tetramer of alpha and beta amino acid chains in a glomular arrangement. When O2 binds to Hb, it goes from a tensed, dome-like structure to a more planar structure. This conformational change increases the Hb's affinity for O2 exponentially. A fully saturated Hb molecule is completely planar.

### How is CO2 found in the pulmonary circulation?

As dissolved CO2, as bicarbonate ions and as carbamino compounds.

### Why is CO2 more soluble than O2?

Because CO2 has a greater solubility in the lipid membrane.

### Give the numerical breakdown of inhaled CO2 in the cytoplasmic solution of the pulmonary capillary.

11% of inhaled CO2 goes into cytoplasmic solution while the rest goes into the RBC.
1) 5% as bicarbonate
2) >1% as a carbamino compound

### Give the numerical breakdown of inhaled CO2 in the RBC.

1) 21% as carbamino compound
2) 64% as bicarbonate ions
3) 4% dissolved as gaseous CO2 in RBC plasma

### How does CO2 work to incr. [O2] in the capillary plasma?

Protons from the carbonic acid displace O2 from Hb (making reduced Hb); the O2 then goes into the capillary plasma

### Where can mixed venous blood be located? What is its composition as it relates to [CO2]?

Anywhere from R. atrium to the pulmonary arteries. 52% of CO2 in mixed venous blood is 48% CO2 arterial blood + 4% from tissues (the 4% is in the form of carbamino compounds, bicarbonate ions and dissolved CO2.