Respiratory Physiology and Gas Exchange

Flashcards covering the mechanisms of gas exchange, hemoglobin oxygen affinity, brain centers for respiratory control, and the physiological drivers of breathing in healthy vs. COPD patients.

Alveoli

The fine air sacs in the walls of the lungs where oxygen from the air dissolves into a solution in the plasma within the capillaries.

Alkalosis

A condition characterized by a high $pH$ level, often caused by low $CO_2$; in this environment, oxygen attaches almost irreversibly to the hemoglobin molecule.

Acidosis

A condition characterized by a low $pH$ level, often caused by high $CO_2$; in this environment, oxygen is easily released from hemoglobin.

Hemoglobin

A special oxygen-binding protein found in red blood cells that helps transport oxygen throughout the body.

Heme

An iron-containing pigment within hemoglobin, consisting of four molecules per hemoglobin molecule, which binds oxygen loosely and reversibly.

Oxyhemoglobin

Hemoglobin that is fully saturated with oxygen, appearing bright red in color.

Deoxyhemoglobin

Hemoglobin that is not saturated with oxygen, appearing purplish blue in color.

Partial pressure of oxygen

A value representing the level of dissolved oxygen in the plasma.

Oxygen dissociation curve

A graph demonstrating the relationship between oxygen carried in combination with hemoglobin ($O_2$ saturation) and the partial pressure of oxygen in the arterial blood.

Bohr effect

The mechanism where shifts in $pH$ and $CO_2$ levels determine whether oxygen binds tightly to or releases from hemoglobin; it is illustrated by shifts in the oxygen dissociation curve.

Left shift

A shift on the oxygen dissociation curve caused by alkalosis (high $pH$) that reduces the amount of oxygen released from hemoglobin.

Right shift

A shift on the oxygen dissociation curve caused by acidosis (low $pH$) that makes it easier for oxygen to release from hemoglobin.

Medulla oblongata

The part of the brainstem that monitors and controls basic life support functions, including the real-time regulation of breathing.

Pons

The part of the brainstem located higher than the medulla that contains backup respiratory centers, including the amnestic and pneumataxic centers.

Hering-Breuer reflex

A reflex triggered by stretch receptors in the lung tissue that sends information to the medulla to prevent the over-inflation of the lungs.

Carotid sinus

The bifurcation where the internal and external carotid arteries branch, containing chemoreceptors that measure the chemistry of blood going to the brain.

Arch of the aorta

A location containing chemoreceptors that measure the chemistry of the blood being sent to the rest of the body.

Chemoreceptors

Receptors that monitor blood chemistry by measuring levels of oxygen, $CO_2$, and hydrogen ions (which represent $pH$).

$CO_2$ retainers

Significant COPD patients whose $CO_2$ levels are chronically high, making $CO_2$ an ineffective measure for directing ventilation.

Hypoxic drive

A respiratory drive found in significant COPD patients where the brain monitors low $O_2$ levels as the stimulus to breathe instead of high $CO_2$ levels.

PlethWave

A wave monitor with a characteristic notch used to verify that the $SpO_2$ reading is correct.