part 2

Oxygen and carbon dioxide diffusion takes place between blood and respiration surfaces.

Gas exchange takes place between blood and body cells.

It is the breaking down of glucose in cells to produce energy. Oxygen and carbon dioxide are released at the end.

is the exchange of gases between an organism and its environment (taking in oxygen and releasing CO2 ).

1. Body surface 2. Gills 3. Trachea 4. Lungs 5. Skin

Trachea are systems of pipes. Branches of these pipes penetrate all tissue to facilitate the diffusion of gases into all regions of the body.

Mollusks, echinoderms, crustaceans, fish and amphibians respire through gills.

Adult amphibians, reptiles, birds and mammals respire through lungs.

The most important feature of gills is that they absorb oxygen dissolved in water.

There are three types of respiration in invertebrates: 1. Cutaneous respiration 2. Gill respiration 3. Tracheal respiration

1. Unicellular organisms provide gas exchange by simple diffusion through the cell membrane. 2. Invertebrates, like hydra and planaria, use different methods to provide gas exchange. Their wide body surface provides enough area to take enough oxygen. 3. More developed invertebrates, like earthworms, provide gas exchange through their body surface and oxygen is transported to cells by circulatory system.

Hydra and planaria provide gas exchange by diffusion through their wide body surface and body extensions.

Are the respiratory organs of aquatic organisms. They’re formed from the projections of epithelium and are closely associated with the circulatory system.

Starfish and sea worms have gill respiration.

1. The branches of trachea penetrate all tissues to facilitate the diffusion of gases into all regions of the body. 2. Each trachea opens into the exterior of the body by a series of spiracles, with one pair in each body segment. 3. In the tracheal system, gas exchange occurs at the tracheoles by simple diffusion. 4. Oxygen is transmitted from the spiracles to the tracheae, then through the tracheoles and finally into the tissue. 5. Carbon dioxide follows the same pathway but in the opposite direction.

1. Some kinds of vertebrates like amphibia and Some fishes use their skin for gas exchange. For example, eels provide 60% of gas exchange by its skin which is rich in blood capillaries. 2. Cutaneous respiration has a big role for amphibia during hibernation.

Thickness of skin, being rich in blood vessels and the presence of mucous glands are advantages of cutaneous respiration in amphibia.

Because of its advantages, which include: 1. Thickness of the skin. 2. Being rich in blood vessels. 3. The presence of mucous glands.

Because they don’t have gills or lungs.

Extract dissolved oxygen from water and excretes carbon dioxide

Gills are composed of comb-like filaments, the gill lamellae, which help increase their surface for oxygen exchange.

Help increase the surface of gills for oxygen exchange

When a fish breathes, it draws in a mouthful of water at regular intervals. Then, it draws the sides of its throat together, forcing the water through the gill openings, so the water passes through the gills to the outside.

: هو السديلة العظمية التي تحمي الخياشيم من الأذى. يفتح ويغلق ليسمح للماء بالمرور عبر الخياشيم.

1. The lungs of amphibia are similar to small sacs as there are no folds on their surface. 2. Since the lungs are unfolded, no alveoli is present. 3. In contrast to other vertebrates, the lungs in amphibia are attached directly to the pharynx and there's no trachea.

1. There are five air sacs attached to the lung. These sacs use much of the body cavity to be filled with air. They penetrate the bones and connective tissue under the skin, an aspect that is closely related to the flying ability of birds. 2. Trachea is divided into two bronchi. Then, bronchi are divided into bronchioles which are connected to the bones via capillaries and air sacs. 3. Air enters the respiratory system through the nostrils and flows into the lungs and then to the air sacs. Air sacs increase the oxygen storage capacity of birds. 4. The oxygen taken by the lungs passes into the blood and is carried to the body cells.

Because it includes air capillaries surrounded by a network of blood capillaries.