Oxygen Transport and Hemoglobin Variants

Vocabulary practice flashcards covering hemoglobin structure, oxygen saturation, abnormal hemoglobin variants, and oxygen transport dynamics from the lecture.

Volume percent

An outdated unit of measure equivalent to milliliters of oxygen per deciliter of blood ($\text{mL/dL}$).

Heme group

The specific iron-containing site on a hemoglobin molecule where oxygen binds, with each hemoglobin molecule possessing $4$ binding spots.

Normal hemoglobin concentration

The typical concentration of hemoglobin in the blood, ranging from $12\text{ to }18\,\text{g/dL}$, with levels being slightly higher in men than in women.

Oxyhemoglobin

Hemoglobin that is chemically bound to oxygen, enabling blood to carry about $20\,\text{mL}$ of oxygen per deciliter at a normal $\text{PaO}_2$ of $100\,\text{mmHg}$ ($67$ times more than dissolved oxygen alone).

Carboxyhemoglobin

An altered hemoglobin compound formed when hemoglobin binds with high affinity to carbon monoxide instead of oxygen, commonly caused by automobile exhaust or house fires.

Methemoglobin

An ineffective hemoglobin molecule in which the iron has been oxidized into the ferric state, leaving it unable to release oxygen to tissues or bind with additional oxygen.

Co-oximetry

A diagnostic blood gas analysis using multiple wavelengths of light to detect and measure specific hemoglobin variants, such as methemoglobin and carboxyhemoglobin.

Methylene blue

An emergency intravenous ($\text{IV}$) treatment administered to symptomatic patients with methemoglobinemia to reverse the condition.

Sickle cell anemia

A recessive genetic disorder where red blood cells transform into fragile, $S$-shaped cells that rupture and clump together, causing thrombosis, severe pain, acute chest syndrome, and ischemia.

Fetal hemoglobin

A hemoglobin variant present during the $40$ weeks of gestation and up to $6$ months of age that exhibits a very high affinity for oxygen, enabling uptake from the placenta at a low $\text{PO}_2$ of $40\,\text{mmHg}$.

Arterial oxygen saturation ($\text{SaO}_2$)

The percentage of hemoglobin molecules fully saturated with oxygen in arterial blood, normally reaching $97.5\%$ at an arterial oxygen tension ($\text{PaO}_2$) of $100\,\text{mmHg}$.

Venous oxygen saturation ($\text{SvO}_2$)

The percentage of oxygen-saturated hemoglobin returning through the venous system after tissue extraction, normally measuring $75\%$ at a venous oxygen tension ($\text{PvO}_2$) of $40\,\text{mmHg}$.

Hypoxemia

A physiological condition defined strictly by an abnormally low oxygen tension or content within the arterial blood.

Hypoxia

A condition characterized by inadequate oxygen delivery to the body tissues, which can occur even with $100\%$ oxygen saturation if total hemoglobin concentration is severely low.