Gas Exchange Systems in Mammals, Fish, and Insects

A set of vocabulary flashcards covering the mechanisms, structures, and metrics of gas exchange in mammals, fish, and insects based on the provided lecture notes.

Surface area to volume ratio

A measurement that describes how much surface area an organism has relative to its size; multicellular organisms have a smaller ratio, requiring specialised gas exchange surfaces.

Efficient gas exchange surface features

Features include a large surface area (e.g. root hair cells), thin or short distance (e.g. alveoli), and a steep concentration gradient (e.g. gills).

Trachea

A wide tube supported by C-shaped cartilage to keep the passage open; it is lined with ciliated epithelium and goblet cells to carry air to the bronchi.

Ciliated epithelium cells

Lining within the trachea and bronchi that move mucus towards the throat to be swallowed, helping to prevent lung infections.

Goblet cells

Cells found in the trachea and bronchi that produce mucus.

Bronchi

Two narrower passages branching from the trachea, supported by rings of cartilage, that allow air to flow into the bronchioles.

Bronchioles

Narrower branches that lack cartilage and contain smooth muscle and elastic fibres, allowing them to contract and relax during ventilation.

Alveoli

Mini air sacs lined with epithelium cells that serve as the site of gas exchange; there are approximately $300$ million in each lung.

Inspiration

The process of breathing in where external intercostal muscles contract, the diaphragm flattens, and thorax volume increases to move air into the lungs.

Expiration

The process of breathing out where external intercostal muscles relax, the diaphragm domes upwards, and thorax volume decreases to move air out of the lungs.

Spirometer

A device used to measure lung volume by tracking a person's breath into an airtight chamber, creating a trace on a graph.

Vital capacity

The maximum volume of air that can be taken in or expelled from the lungs in one breath, identified as the maximum amplitude on a spirometer graph.

Tidal volume

The volume of air inhaled and exhaled during a single breath at rest, identified as the amplitude at rest on a spirometer graph.

Breathing rate

The number of breaths taken per minute, calculated by counting the number of peaks on a spirometer trace over one minute.

Gills

The gas transport system in fish, located within the body and supported by arches, consisting of gill filaments stacked in piles.

Lamellae

Structures at right angles to the gill filaments that increase surface area and facilitate the countercurrent exchange system.

Countercurrent exchange system

A mechanism where blood and water flow in opposite directions across the lamellae to maintain a steep concentration gradient.

Percentage of oxygen absorbed by fish

The countercurrent exchange system allows for $80\%$ of available oxygen to be absorbed.

Buccal cavity

The mouth area of a fish where volume and pressure changes enable water to flow in and reach the gas exchange surfaces.

Operculum

A structure in fish that pumps water over the lamellae to facilitate oxygen diffusion into the bloodstream.

Spiracles

Holes on an insect's body surface that can be opened or closed by a valve for gas or water exchange.

Tracheae (Insects)

Large tubes extending through all insect body tissues, supported by rings to prevent collapse.

Tracheoles

Smaller branches dividing off the tracheae in the insect's gas transport system.