Ventilatory Stroke Volume in Respiration

Gills

Counter current exchange of water and blood along the lamellae

Unidirectional flow of water

<p>Numerous minute lamellae</p> Signup and view all the answers

<p>Bidirectional (tidal) movement of air</p> Signup and view all the answers

<p>The close lamellar spacing and thin epithelia in the gills of active, fast-growing fish decrease the distance across which oxygen in the water must diffuse to enter the blood. This increases the rate of diffusion, allowing these fish to meet their increased demand for oxygen from the water.</p> Signup and view all the answers

<p>In most bony fishes, gill ventilation is accomplished by the synchronous expansion and contraction of the buccal and opercular cavities, providing a nearly continuous unidirectional flow of water over the gill surfaces. Fish can vary the ventilation volume to influence the rate of gas exchange at the gills, increasing the ventilation volume to maintain the gas exchange rate in hypoxic water.</p> Signup and view all the answers

<p>Fish can influence their gas exchange rate at the gills by varying both the ventilatory frequency (number of buccal and opercular strokes per minute) and the ventilation volume. Increasing either the frequency or the volume of ventilation will increase the rate of water flow over the gill surfaces, thereby enhancing the gas exchange rate.</p> Signup and view all the answers

<p>Fishes that are highly active and fast-growing typically have larger gill surface areas and extra-thin gill epithelial layers. These adaptations decrease the distance across which oxygen in the water must diffuse to enter the blood, thereby increasing the rate of oxygen diffusion and allowing the fish to meet their increased metabolic demand for oxygen.</p> Signup and view all the answers

<p>Ram gill ventilation is a passive ventilation mechanism used by at least one species from each of eight teleostean families, where the fish ceases branchial (gill) movements and instead relies on the forward motion of the fish to force water over the gill surfaces. This is in contrast to the more common active gill ventilation mechanism in bony fishes, where the synchronous expansion and contraction of the buccal and opercular cavities creates a unidirectional flow of water over the gills.</p> Signup and view all the answers

<p>The respiratory adaptations of fish gills, such as the close lamellar spacing, thin epithelial layers, and active ventilation mechanisms, are specifically tailored to facilitate efficient gas exchange with the surrounding water. In contrast, terrestrial vertebrates have evolved respiratory systems adapted for gas exchange with the air, typically involving lungs, a diaphragm, and a more complex circulatory system to transport gases throughout the body.</p> Signup and view all the answers

<p>Larval stages of fishes like the swamp eel (Monopterus albus) use their skin almost exclusively for respiration.</p> Signup and view all the answers

<p>Some fish species have evolved behavioral means and corresponding respiratory structures to cope with hypoxic waters, such as swimming to the surface to inspire oxygen-rich water (aquatic surface respiration).</p> Signup and view all the answers

<p>In some air-breathing fishes, the well-vascularized skin allows for diffusion of gases, enabling them to use the atmosphere for respiration. The percent of gas exchanged across the skin can range from 10-94% in different species.</p> Signup and view all the answers

<p>Electric eels have a well-vascularized area in their buccal cavity (mouth), where most of their required oxygen is taken up from air.</p> Signup and view all the answers

<p>These tropical catfish genera have parts of their guts specialized for oxygen uptake by actually swallowing air. However, the elimination of respiratory carbon dioxide occurs primarily at the gills, as the gut is not closely associated with the external environment.</p> Signup and view all the answers

<p>Lungfishes are adapted to extensive drought conditions that may completely dry up their environments. They breathe air through a small vent to the atmosphere, allowing them to survive extensive dry periods in the mud of dried-up lakes and rivers.</p> Signup and view all the answers