O2 Transport [1]

the process whereby gas molecules move from an area of high partial pressure to an area of low partial pressure.

diffusion

The relationship between Hb saturation and PO2 is not linear4 ; instead, it forms what curve

S-shaped curve

this part of the curve represents the normal operating range for arterial blood

upper flatter part

in this part of the curve, major changes in PaO2 have little effect on SaO2, indicating a strong affinity of Hb for O2.

flatter upper part

With a normal PaO2 of 100 mm Hg, SaO2 is approximately

97%

true or false: If a disease process results in a substantial reduction in PaO2 to 65 mm Hg, SaO2 would not drop as drastically and will be approximately 90% in the curve

true

in this drop of PO2, the curve steepens dramatically and the SaO2 drops significantly.

<60 mmHg

with PO2 less than 60 mm Hg, a small decrease in PO2 causes a large decrease in SaO2, indicating what affinity

less affinity

states that the total O2 uptake by the peripheral tissues is equal to the product of the blood flow to the peripheral tissues and the arterial-to-venous O2 content difference

fick equation

Fick’s equation

whole-body O2 consumption

CaO2

arterial O2 content

mixed venous O2 content

factors affecting O2 loading & unloading [3]

blood pH

body temperature

erythrocyte conc.

impact of changes in blood pH on Hb’s affinity for O2 is called

bohr effect

this Hb is less soluble than normal Hb, which causes it to become susceptible to polymerization and precipitation when deoxygenated.

sickle cell Hb

Certain events such as dehydration, hypoxia, and acidosis cause HbS to crystallize and the RBCs to become hardened and curved ; what Hb

sickle cell

this is an abnormal form of the molecule in which the iron in the heme-complex (Fe2+ ) loses an electron and is oxidized to its ferric state (Fe3+ ).

methemoglobin

In the ferric state, the iron ion cannot combine with O2. This is called

methemoglobinemia

this is the chemical combination of Hb with CO.

carboxyhemoglobin

The affinity of Hb for CO is more than how many times greater than it is for O2.

>200x

. The combination of CO with Hb shifts the HbO2 curve to?

left

Fick’s first law of diffusion law for determining the rate of gaseous diffusion across biologic membranes. [equation]

cross-sectional area available for diffusion

A

diffusion coefficient of the gas

D

thickness of the membrane

T

partial pressure gradient across the membrane

P1-P2

rewritten fick’s first law of diffusion

a measure of the proportion of available Hb that is carrying O2

saturation

this is computed as the ratio of HbO2 (content) to total Hb (capacity).

saturation

this Hb is for fetal life

fetal Hb

up to how long does fetal Hb exist

fetal life up to 1 yr

true or false: HbF has a greater affinity for O2 than normal adult Hb, manifested by a leftward shift of the HbO2 curve

true

what effect: Deoxygenation of the blood increases its ability to carry carbon dioxide

haldane

this is O2 delivery to tissues

DO2

O2 delivery to tissues formula

DO2 = CaO2 x CO

Expected PaO2 in older adults formula

100 - (0.323 x age in years)

this can still occur when the arterial O2 Content (CaO2) is normal but blood flow is reduced

hypoxia

this is Local Reductions in perfusion

ischemia

cyanide poisoning is under

dysoxia

in this, cellular uptake of O2 is decreased

cyanide poisoning

this disrupts the intracellular cytochrome oxidase system, preventing cellular use of O2

cyanide

A decrease in alveolar ventilation occurs when [3]

inadequate minute volume

increased dead space ventilation / min

V/Q imbalance