Gas Exchange in Fish and Insects Review

Flashcards related to gas exchange in fish and insects

Saturation with Oxygen and No Countercurrent Flow

Percentage of saturation with oxygen in blood and water along the gill plate with NO countercurrent flow, equilibrium is reached and no more oxygen diffuses into the blood.

Saturation with Oxygen and Countercurrent Flow

Percentage of saturation with oxygen in blood and water along the gill plate with Countercurrent flow, diffusion happens along the full length of the lamellae, the blood absorbs more and more oxygen as it moves along.

Adaptations of Fish Gills

Thin epithelium/walls of lamellae, Large number of filaments and lamellae, Countercurrent flow system, Large number of capillaries around lamellae, Ventilation by operculum

Reasons Adaptations Increase Diffusion in Fish Gills

Shortens diffusion distance of gases from water to blood, Increases surface area for gas exchange, Maintains concentration gradient.

Ventilation in Fish

The fish takes water in through its buccal cavity which then flows through the pharynx and over the gill plates, leaving via the opercular openings on each side of the fish's head.

Ventilation Steps in Fish

1. mouth opens, operculum shuts
2. water enters cavity due to decreased pressure / increased volume
3. mouth closes, operculum opens
4. results in increased pressure/decreased volume
5. Increased pressure forces water out over gills

Gill Filaments

Attached to a bony gill arch, these create a large surface area for water to flow over. The gill filaments are covered in lots of tiny folds called lamella which further increase the surface area of the gills. The lamellae have lots of blood capillaries and a thin layer of cells.

Countercurrent Flow

Describes how the flow of water over the gill lamellae and the flow of blood within them are in opposite directions. Allows a diffusion gradient to be maintained all the way across the gill lamellae.

Gill

Located within the body of the fish, behind the head.

Gill Filaments

Make up the gills of a fish - they are stacked up in a pile.

Gill Lamellae

At a right angle to gill filaments, which increase the surface area of the gills.

Spiracle

Tiny pores that allow gases to enter and leave the tracheae (and water vapour to leave as well). They are opened and closed by a valve.

Tracheae

A large internal network of tubes in insects with supported rings to prevent them collapsing.

Tracheoles

These tubes extend from the tracheae and extend throughout all the body tissues of the insect to allow atmospheric air to be brought directly to respiring tissues.

Gas Exchange in Insects

Air enters the trachea through pores on the surface of the exoskeleton called spiracles. CO2 and O2 will diffuse in/out of the spiracles down their concentration gradient. The ends of tracheoles are filled with fluid, primarily consisting of water.