O2 Transport + Hemoglobin

CaO2, plasma, Hb

Factors influence arterial O2 content (__)

(1) Amount of O2 dissolved in __  

(2) Amount of O2 bound to __

250 ml/min

Resting tissue O2 consumption for maintaining baseline metabolism  =

O2, capillaries, tissues

Carbon monoxide poisoning is primarily a problem of:

• Transport of __ (gas) between pulmonary __ and capillary beds in other __

Rate

__ is volume of O2 delivered to systemic vascular beds per time unit

• O2 Delivery to specific tissue = tissue blood flow x arterial O2 content

cardiac output x CaO2

Systematic O2 delivery formula =

Humidification, alveoli, A-a

Oxygen cascade

1. Dry air → __

2. Airways → Mixing with gas already in the __

3. Alveoli → _-_ gradient

4. Capillaries

PO2, PIO2, PAO2, tissue O2

Oxygen cascade to math equivalents

1. Dry air = __ of dry air

2. Airways = __ (accounting water pressure)

3. Alveoli = __

4. Capillaries = linked to __ __ consumption

Inspired, alveolar, arterial, arterial Hb

Each level of O2 cascade influences levels downstream

• 1. __ PO2

  • Affected by altitude/barometric pressure, supplemental O2

• 2. __ PO2

  • Affected by lung compliance, airway resistance, alveolar ventilation + perfusion

• 3. __ PO2

  • Affected by surface area, membrane thickness (i.e. fibrosis, pulmonary edema)

• 4. __ __O2

  • Hb levels and binding sites (i.e. anemia, CO)

partial pressure x solubility

Concentration of gas in solution formula =

0.003 mL O2

Solubility of O2 in water at 37 C = __ __ __ / 100 mL

PO2, 0.003, 1.34, Hb, saturation

Blood O2 content = (__ x __) + (__ x __ concentration x % __)

1.34, 15

Each gram of Hb carries __ ml O2

• Hb average in adults = __ g/dL

Diffusion, fibrosis, alveoli

PO2 doesn’t always fully equilibrate between alveoli and pulmonary capillaries

• __ diffusion rates from disease (i.e. pulmonary __) mean blood flows past__ faster than gases can equilibrate

28, saturated

At PO2 of __ mm Hg, Hb binding sites are 50% __

4, Fe2+, 4, constant

Hemoglobin

• Hemoglobin has _ heme groups

• Each heme group with __ atom binding to one molecule of O2

• _ O2 molecules max per hemoglobin but 8 oxygen atoms max per hemoglobin

• In blood there is __ movement of dissolved O2 onto abundant hemoglobin and back to dissolved

Relaxed, strong

Hemoglobin Binding

• __ State involves high O2 levels → __ HB-O2 affinity → HB holds O2 tightly

  • Hands are open to receive more O2

Tense, weak

Hemoglobin Binding

• __ State involves Low O2 levels → __ HB-O2 affinity → HB holds O2 loosely

  • Fist squeezes tight to force O2 out

Binding, unloading

• Higher PaO2 promotes more__ (relaxed state)

• Lower PaO2 promotes __ (tense state)

Hb-O2 dissociation curve, net

• __ __ __ is a sigmoid shape indicating changing O2 affinity of Hb

• Represents __ saturation, not saturation of individual Hb molecule

Rightward, increase, increase, decrease, increase

• Decreasing Hb affinity for O2 = __ shift to curve

  • By __ temperature, __ PCO2, __ pH, __ 2,3-BPG

Leftward, decrease, decrease, increase, decrease

• Increasing Hb affinity for O2 = __ shift to curve

  • By __ temperature, __ PCO2, __ pH, __ 2,3-BPG

Leftward, maternal

Fetal hemoglobin has a __ shift to the Hb curve, because…

• Allows O2 to unload from the __ bloodstream to fetal bloodstream

Pulse Oximetry

Measures ratios of light wavelengths absorbed by tissue

Oxyhemoglobin / total Hb x 100

Percent Hb saturation formula =

CO2, PaO2

Why is initial response to disturbance mediated by central chemoreceptors rather than peripheral PaO2 chemoreceptors?

• Small changes in __ can deviate from central chemoreceptor set point and lead to changes in respiratory rate

• Dramatic change in __ necessary to reach error detection and change respiratory rate

(PaO2 vs CO2)