Chapter 8: The Respiratory System and Its Regulation

Vocabulary flashcards covering the anatomy, mechanics, gas exchange, transport, and regulation of the respiratory system from Chapter 8.

Pulmonary ventilation

The process of moving air into and out of the lungs, involving transport and exchange zones.

Pulmonary diffusion

External respiration involving gas exchange between the alveoli and pulmonary capillaries to replenish $O_2$ and remove $CO_2$.

Capillary diffusion

Internal respiration involving the exchange of gases between the blood and the body tissues.

Parietal pleura

The layer of the pleural sacs that lines the thoracic wall.

Visceral (pulmonary) pleura

The layer of the pleural sacs that lines the surface of the lungs.

Inspiration

An active process where the diaphragm flattens and external intercostals move the rib cage up and out to expand thoracic volume.

Boyle’s law

A gas law stating that at a constant temperature, pressure and volume are inversely proportional ($P \times V = \text{constant}$).

Expiration

Usually a passive process where inspiratory muscles relax and lung volume decreases, forcing air out; becomes active during forced breathing.

Respiratory pump

A mechanism where changes in intra-abdominal and intrathoracic pressure create a milking action that assists venous return and right atrial filling.

Spirometry

A diagnostic tool used to measure lung volumes, capacities, and flow rates.

Tidal volume

The amount of air entering and leaving the lungs with each normal breath.

Vital capacity (VC)

The greatest amount of air that can be expired after a maximal inspiration.

Residual volume (RV)

The amount of air remaining in the lungs after a maximal expiration.

Total lung capacity (TLC)

The sum of the vital capacity and the residual volume ($TLC = VC + RV$).

Functional residual capacity

The volume of air remaining in the lungs after a normal expiration.

Respiratory membrane

Also known as the alveolar-capillary membrane, it consists of the alveolar wall, capillary wall, and their basement membranes ($0.5$ to $40.0\text{ }μm$ thick).

Dalton’s law

Law stating that total air pressure is equal to the sum of the partial pressures of individual gases ($P_{\text{total}} = P_{N_2} + P_{O_2} + P_{CO_2}$).

Henry’s law

Law stating that gases dissolve in liquids in proportion to their partial pressures, depending on solubility and temperature.

Fick’s law

Law stating that the rate of diffusion is proportional to the surface area and the partial pressure gas gradient, and inversely proportional to tissue thickness.

$O_2$ diffusion capacity

The volume of $O_2$ diffused per minute per $mmHg$ of gradient; at rest it is approximately $21\text{ }mL\text{ }O_2/min/mmHg$.

Oxygen cascade

The dropping of partial pressures of oxygen at sea level from dry ambient air to the tissues and into the venous circulation.

Oxyhemoglobin

The form of hemoglobin when it is bound to oxygen ($O_2 + Hb$).

Bohr effect

The rightward shift of the $O_2-Hb$ dissociation curve caused by increased acidity (decreased pH), which promotes oxygen unloading at the muscles.

Carbonic anhydrase

The enzyme in red blood cells that catalyzes the reaction of $CO_2$ and $H_2O$ to form carbonic acid ($H_2CO_3$).

Chloride shift

The process where bicarbonate ion diffuses from red blood cells into the plasma.

Carbaminohemoglobin

Carbon dioxide bound to the protein (-globin) portion of hemoglobin, transporting 20\text{%} to 33\text{%} of $CO_2$.

(a-v)O2 difference

The difference in oxygen content between arterial and venous blood, reflecting the amount of oxygen extracted by the tissues.

Myoglobin

A protein in the muscle with a higher affinity for $O_2$ than hemoglobin, responsible for transporting oxygen to the mitochondria.

Central chemoreceptors

Receptors in the brain stem (medulla oblongata and pons) stimulated by increased $H^+$ in cerebrospinal fluid to increase breathing rate and depth.

Hering-Breuer reflex

A reflex triggered by mechanoreceptors in the pleurae and bronchioles that reduces breathing depth when the lungs are excessively stretched.