Gas Exchange in Animals

Flashcards covering gas exchange mechanisms, respiratory surfaces, ventilation methods, and respiratory pigments in various animals based on lecture notes.

Gas exchange

The movement of $O_2$ and $CO_2$ between an animal and its environment.

Respiratory Medium

The source of oxygen, which is typically air or water.

Respiratory Surface

The epithelium where gas exchange with the respiratory medium takes place; it must remain moist.

Ventilation

The flow of the respiratory medium across the respiratory surface.

Cutaneous respiration

Gas exchange occurring across the skin, seen in annelids and amphibians, requiring a moist surface and a dense capillary network.

Gills

Outfoldings (evagination) of the body surface used as respiratory surfaces in larger aquatic animals.

Tracheal systems

A branching system of tubes used for gas exchange in terrestrial insects and their relatives.

Lungs

Invaginations of the body surface restricted to one location, such as the booklungs in spiders, mantle lungs of snails, and vertebrate lungs.

Countercurrent exchange

A mechanism in fish gills where blood and water move in opposite directions, allowing the blood to gain almost $100\%$ of the available $O_2$.

Ram ventilation

A method of gill ventilation where an animal swims with its mouth open.

Spiracles

Openings at the body surface of insects through which air enters the tracheal system.

Alveoli

Air sacs that serve as the respiratory surface in mammalian lungs; there are approximately $300$ million in humans.

Epiglottis

A structure that closes off the larynx during swallowing to protect the airway.

Pleura

A double-layered membrane with slippery fluid that separates the lungs from the wall of the thoracic cavity.

Surfactant

A lipoprotein coating on the alveoli that prevents them from collapsing.

Positive pressure breathing

A ventilation method where air is forced or "swallowed" into the lungs, used by animals like frogs.

Negative pressure breathing

A ventilation method used by mammals where the contraction of the diaphragm and rib muscles expands the thoracic cavity to pull air in.

Tidal volume

The amount of air inhaled or exhaled during normal breathing, which is approximately $500\,ml$.

Vital capacity

The maximum volume of air that can be inhaled/exhaled; approximately $3400\,ml$ for females and $4800\,ml$ for males.

Residual volume

The air remaining in the lungs after a forced exhalation.

Parabronchi

Gas-exchanging tubes in the avian (bird) respiratory system that facilitate one-way airflow.

Hemocyanin

A blue, copper-containing ($Cu$) respiratory pigment found in the fluid of arthropods and molluscs.

Hemoglobin

An iron-containing ($Fe$) respiratory pigment found in vertebrate red blood cells ($RBC$) that consists of four subunits.

Bicarbonate ions

The form in which $70\%$ of $CO_2$ is transported in the plasma.