Wk1 Transport of Gases

Hypoxia indicates _____ while hypoxemia is just _____

tissue hypoxia, low O₂ in the blood

Term for % Hemoglobin that has oxygen bound

Saturation

When blood PO₂ increases, the reaction is driven to the right _____

Increasing % hemoglobin saturation

WHen blood PO₂ decreases, the reaction is driven to the left and ____

Oxygen is released from Hb decreasing % Hemoglobin saturation

Only _____ contributes to the partial pressure of oxygen, so this is important to consider when Oxygen combines with hemoglobin to be oxyhemoglobin

Dissolved oxygen

In 100ml blood there is ____ of oxygen, while only 0.3 is ____

20ml (oxyhemoglobin), dissolved oxygen

What is meant by cooperativity in O₂ binding and releasing?

As more O₂ binds, O₂ affinity increases. A more O₂ is released, O₂ affinity decreases. This makes a sigmoidal curve

In the Oxyhemoglobin Dissociation curve, the plateau of the curve is where _____ in the pulmonary capillaries

Hb is almost fully saturated

In the Oxyhemoglobin Dissociation curve, the step portion of the curve is where _____ in the systemic capillaries

Hb unloading increases in response to a small local decline in blood PO₂

A left shift to the Oxyhemoglobin Dissociation curve causes ______

Increased Hb affinity

A right shift to the Oxyhemoglobin Dissociation curve causes _____

Reduced Hb affinity

How do these factors shift the HbO₂ DissociationCurve?

• Increased Temperature

• Increased CO₂

• Increased 2,3-BPG

• Decreased pH


Right shift- promotes oxygen unloading in tissues

How do these factors shift the HbO₂ Dissociation curve?

• Decreased temperature

• Decreased CO₂

• Decreased 2,3-BPG

• Increased pH


Left shift- favors loading of oxygen

What is the effect of Polycythemia on the HbO₂ Dissociation curve?

Shifts the curve upward b/c arterial O₂ content increases

What is the effect of Anemia on the HbO₂ Dissociation curve?

Shifts the curve downward b/c arterial O₂ content decreases

How would a higher altitude affect the HbO₂ Dissociation curve?

Shifts to right

____ binds Hb at O₂ binding sites with 250x time affinity of O₂ and can displace O₂ from Hb lungs and makes it harder to release O2 in tissues

Carbon Monoxide

What is the affect of Methemoglobinemia due to oxidation of heme iron from Fe²⁺ to Fe³⁺?

Oxidized heme sites cannot bind O₂

In diffusion limited Gas exchange, diffusion will continue as long as ____

The partial pressure gradient for the gas is maintained

In perfusion limited gas exchange, the partial pressure gradient is NOT maintained, so the only way to increases amount of gas transported is to _____

Increase blood flow

_____ is always PERFUSIOn limited, where partial pressure has ____

N₂O, euquilibrated with alveolar pressure

_____ is always DIFFUSION limited, where P_co ____ equilibrium with alveolar pressure

CO, does not

____ +____ are usually perfusion limited but pathology, exercise, or altitude can make them diffusion limited

CO₂ + O₂

When would O₂ transport become diffusion limited?

Under fibrosis or strenuous exercise

In the Bohr Effect, increased CO₂ or Lower pH ___ Hb affinity for O₂ promoting ____

Reduces, oxygen unloading

Removing O₂ from Hb increases the ability of Hb to pick up CO₂, which is known as the ____

Haldane Effect