Respirationn - fish, earthworm

Gills in aquatic animals : 

Gills in aquatic animals Outfoldings of the body surface suspended in water Sea stars Segmented worms or polychaetes Molluscs and crustaceans Fishes Young amphibians Total surface area is greater than the rest of the body

Slide 5: 

Earth's natural bodies of water have a low oxygen concentration--much lower than the level of oxygen in air at the earth's surface. Smaller organisms can obtain sufficient oxygen through the skin (e.g. flatworms), but larger organisms require special structures to collect enough oxygen to sustain life. This oxygen comes from molecules of oxygen gas (O2) dissolved in the water.

Slide 7: 

Aquatic respiration is the process whereby an aquatic animal obtains oxygen from water. Fish has specialised structures called the gills to carry out exchange of gases with water, the medium in which they live.

Slide 8: 

Fish have developed gills for respiration which have: large surface area which is needed for more oxygen to get in. high blood flow small/short diffusion distances contain 4 gill arches (Bony fishes), two gill arches (Cartilaginous fish) or 7 gill baskets (Lampreys) on each side of the fish's head each gill arch has 2 rows (hemibranchs) of gill filaments each gill filament has many lamellae

Slide 10: 

Gills – outgrowths to increase area in which gas passes over In fish, H2O enters mouth, passes over gills, & exits the operculum (gill cover) Countercurrent exchange Maximizes O2 and CO2 exchange

Slide 12: 

Bony fish use a type of countercurrent flow to maximize the intake of oxygen that diffuse through the gill. Countercurrent flow occurs when deoxygenated blood moves through the gill in one direction while oxygenated water moves through the gill in the opposite direction. This mechanism maintains the concentration gradient thus increasing the efficiency of the respiration process as well. Cartilaginous fish do not have a countercurrent flow system as they lack bones which are needed to have the opened out gill that bony fish have. The interesting thing in fish is a long bony cover for the gill that can be used for pushing water. Some fish pump water using the operculum. Without an operculum, other methods are required, such as ventilation. Some species of sharks use this system. When they swim, water flows into the mouth and across the gills. Because these sharks rely on this technique, they must keep swimming in order to respire.

Slide 15: 

The region between the buccal cavity (mouth) and the oesophagus is called the pharynx. In the pharyngeal region, the wall on either side shows slits which open to the exterior. These slits are called the gill slits. The gill slits are separated by a tissue called the gill arch or the branchial arch. There are four pairs of gill arches separating five pairs of gill slits. From each gill arch arise two rows of filaments, which are arranged in a V-shaped manner. The gill arch along with the filaments is called a gill. Gill Filaments

Slide 16: 

Each filament is made up of plate-like structures called lamellae, which have a rich supply of blood capillaries. Thus the barrier between the blood capillaries and the water is only few cells thick. The lamellae also serve to increase the surface area greatly. Along the gill arch run the blood vessels which give off branches into the filaments and the lamellae. The whole arrangement on either side is covered by a movable cover called the operculum (refer to the first diagram in this section). It consists of muscles and thin layers of bone. Gill Lamellae

Slide 17: 

Earthworm

Slide 20: 

Earthworm The respiratory surface for the earthworm is its SKIN Oxygen diffuses through the skin into CAPILLARIES, and the blood in the capillaries picks up the OXYGEN (hemoglobin) and transports it to body cells Damp soil helps to keep the earthworm’s skin MOIST If it’s too dry, the skin dries out and the earthworm SUFFOCATES If it’s too wet (rain), the skin cannot obtain adequate OXYGEN from the WATER

Slide 21: 

Earthworm has a segmented cylindrical body covered by a thin cuticle below which is the epidermis. This skin is always kept very moist by the secretion of mucus from the epidermis and body fluids from the excretory pores. It always lives in moist soil especially during the day. This prevents their skin from drying or desiccation. Pernapasan: Respiration is carried on at the surface of the body, oxygen being taken into, and carbon dioxide given off by, many blood capillaries in the skin. Waste products are extracted from the blood and coelomic fluid by seventeen pairs of nephridia which resemble those of the earthworm, but frequently lack the internal opening. Habitat: Hirudo, like most of the members of its family, lives in relatively shallow water in temperate or subtropical regions.

Slide 22: 

The epidermal layer has blood capillaries, which have looped out from the vascular system circulating the blood. These blood capillaries are so close to the skin that the gases can diffuse from the surroundings into and out of the blood through the skin and the capillary walls. The blood contains haemoglobin in solution which circulates the gases through the body.