Physiology of Oxygen and Carbon Dioxide Transport

Vocabulary flashcards covering the key physiological concepts of oxygen and carbon dioxide transport, gas laws, haemoglobin structural dynamics, and the oxygen dissociation curve based on lecture material.

Haemoglobin

A protein inside red blood cells composed of $4$ globin chains ($2$ $\alpha$ chains and $2$ $\beta$ chains), each containing a haem group with an $\text{Fe}^{2+}$ ion that binds one $\text{O}_2$ molecule, allowing a single protein to transport up to $4$ $\text{O}_2$ molecules.

Dalton's Law

A physical law stating that the total atmospheric pressure exerted by a gas mixture is equal to the sum of the partial pressures of its individual gases ($P_{\text{atmos}} = P_1 + P_2 + P_3$).

Henry's Law

A physical law stating that the amount of dissolved gas in a liquid is directly proportional to its partial pressure above the liquid.

Fick's Law of Diffusion

A law stating that the rate of gas diffusion ($V'_{\text{gas}}$) across a membrane is directly proportional to the diffusion coefficient ($D$), surface area ($A$), and partial pressure gradient ($\Delta P$), and inversely proportional to membrane thickness ($T$) ($V'_{\text{gas}} = \frac{D \times A \times \Delta P}{T}$).

Positive Cooperativity

The structural phenomenon where the binding of one $\text{O}_2$ molecule to haemoglobin alters its shape, increasing the accessibility and affinity of the remaining haem groups for subsequent $\text{O}_2$ molecules.

T State

The tense, low oxygen-affinity conformation of haemoglobin that predominates in low $\text{PO}_2$ environments, such as metabolically active tissues, facilitating oxygen unloading.

R State

The relaxed, high oxygen-affinity conformation of haemoglobin that decisionally predominates in high $\text{PO}_2$ environments, such as lung capillaries, facilitating oxygen loading.

Carboxyhaemoglobin

The compound formed when carbon monoxide ($\text{CO}$) binds to haemoglobin with an affinity $200$ to $300$ times greater than oxygen, reducing oxygen-carrying capacity and shifting the oxygen dissociation curve to the left.

Bohr Effect

The physiological mechanism where elevated $\text{CO}_2$ and $\text{H}^+$ levels ($\downarrow \text{pH}$) decrease haemoglobin's affinity for oxygen, shifting the dissociation curve to the right and increasing $\text{O}_2$ unloading in tissues.

2,3-Bisphosphoglycerate (2,3-DPG)

An intermediate product of glycolysis that interacts with deoxygenated haemoglobin $\beta$ subunits, stabilizing the T state, decreasing oxygen affinity, and promoting oxygen release near peripheral tissues.

Type I Alveolar Cell

A squamous epithelial cell forming the thin structural wall of the alveolus, specialized for gas exchange across the capillary membrane.

Type II Alveolar Cell

A surfactant-secreting alveolar epithelial cell that helps reduce surface tension within the lungs.

Respiratory Acidosis

A acid-base condition characterized by reduced blood $\text{pH}$ resulting from the failure of the lungs to adequately excrete $\text{CO}_2$, seen in conditions like asthma, COPD, and opioid toxicity.

Respiratory Alkalosis

An acid-base condition marked by elevated blood $\text{pH}$ due to hyperventilation causing excessive loss of $\text{CO}_2$, seen in anxiety, fever, or pain.

Left Shift

A movement of the oxyhaemoglobin dissociation curve indicating increased oxygen affinity and reduced tissue delivery, caused by decreased temperature, decreased \text{[H^+]}, decreased $2,3\text{-DPG}$, or $\text{CO}$ presence.

Right Shift

A movement of the oxyhaemoglobin dissociation curve indicating reduced oxygen affinity and enhanced tissue unloading, caused by elevated temperature, increased \text{[H^+]} (acidosis), increased $\text{CO}_2$, or increased $2,3\text{-DPG}$.

Carbaminohaemoglobin

A complex formed when carbon dioxide ($\text{CO}_2$) binds directly to globin amino acid chains on haemoglobin, serving as one of three main methods of $\text{CO}_2$ blood transport.