Introduction:

One of the characteristics of living organisms is their ability to extract energy from food. While some organisms perform photosynthesis to create their own food, most other living creatures obtain their nourishment from the surrounding environment. Each animal has its own way of ingesting, breaking down food into simpler components, and eliminating waste. Humans gain energy by consuming meals, while livestock derive energy from the grasses they eat. Some marine organisms effortlessly absorb their nutrients from their habitat to acquire energy. The digestive process, including the large intestines, represents the initial step for animals that ingest their food in obtaining stored energy.

Article Sections:

1. Digestion:

2. Elimination:

3. Invertebrates:

4. Vertebrates:

5. What is Respiration?

6. Invertebrates:

7. Vertebrates:

8. What is Circulation?

9. Conclusion:

Digestion Process:

The process of digestion involves the ingestion of food and its breakdown into simple components and compounds that cells can utilize. When food is broken down into simple substances, it moves to cells in various parts of the body.

Elimination Process:

Following the process of digestion comes the elimination process. The body gets rid of waste, and these wastes have no value. They could lead to the poisoning of cells and tissues if they remain in the body.

Digestion and Elimination Processes in Invertebrates and Vertebrates:

1. Invertebrates:

   Invertebrates use various methods to digest food and get rid of waste. Sponges extract their food from suspended matter in water and filter it as it passes through holes in their bodies. In other types of invertebrates, such as cnidarians and flatworms, food enters a digestive cavity in the animal's body through a specialized opening. Specialized cells in this cavity digest the food and absorb nutrients, and then waste is eliminated through the same opening. In some other types of invertebrates, digestive organs consist of tubes, with one passing through the other. Earthworms, for example, have this type of digestive system, with two openings—one for ingesting food and the other for eliminating waste.

Vertebrates:

God, Almighty, created for the most complex animals more specialized digestive systems, and the structures of their digestive systems vary to deal with different foods. Rabbits, cows, and elephants, for example, feed on plants, so they have teeth capable of grinding plant food well. Their digestive systems also contain bacteria that aid in digesting plant tissues. In humans, digestion occurs in the mouth, stomach, and small intestine; the small intestine absorbs nutrients and transports them to the blood. Waste is eliminated from the body through the process of excretion, and the kidneys, lungs, liver, and skin work to rid the body of waste.

Respiration:

After the process of digestion, energy must be released from food molecules. In animals and other living creatures, the glucose resulting from the digestion of carbohydrates is a simple sugar. Respiration is the process of releasing the stored energy in glucose molecules. This process occurs in cells in the presence of oxygen. All living creatures, including plants, undergo respiration to obtain energy from food. The term "mechanical respiration" is also used to refer to the processes of inhalation and exhalation; inhalation supplies the body with the necessary oxygen to release energy from food, while exhalation helps the body eliminate waste, including carbon dioxide and water produced during cellular respiration. The lungs are part of the respiratory system, supplying the body with oxygen distributed to cells and expelling carbon dioxide.

Respiration in Invertebrates and Vertebrates.

1. Invertebrates:

Some invertebrates with soft bodies, such as flatworms, have a simple gas exchange process through diffusion. For oxygen to diffuse through living tissues, their surfaces must be moist. This is why many worms live in moist environments. Larger animals need specialized respiratory organs. Invertebrates like mollusks and crustaceans use gills rich in blood vessels, distributed near the surface of the body, for gas exchange. Most spiders have book lungs for gas exchange. Insects have highly branched tubes inside their bodies called tracheae, forming a network to deliver oxygen-rich air to every cell in the body.

2. Vertebrates:

Aquatic vertebrates, such as amphibians, initially live in water when young and transition to terrestrial life as they grow. Young amphibians exchange gases through gills and skin. Most adult amphibians use lungs and continue to use their skin for gas exchange. Three classes of vertebrates primarily use lungs for respiration: reptiles, birds, and mammals. Reptiles have scales covering their skin, so they rely on lungs for breathing. The same applies to birds and mammals. In humans, air enters through the mouth and nose into the pharynx, then to the larynx, trachea, and the branching airways that end in smaller and smaller air sacs called alveoli. Gas exchange occurs between the blood and the air entering the alveoli through their thin walls, regulated by the diaphragm during breathing.

Circulation:

The digestive and respiratory systems work together to sustain the lives of living creatures. Digestion provides glucose to cells, while respiration provides the oxygen needed to convert glucose into energy for cellular activities. Multicellular animals must be able to transport nutrients and oxygen to all their cells and eliminate waste. Circulation is the movement of vital substances, including oxygen, glucose, and waste, throughout the body. There are two types of circulatory systems in animals: open and closed. In open circulatory systems, as in arthropods and mollusks, the heart pumps blood directly to body tissues for direct exchange of substances with cells. In closed circulatory systems, as in vertebrates, blood is pumped through a network of blood vessels it cannot leave. Special valves in these systems regulate blood flow in one direction to prevent it from flowing in the wrong direction.

Conclusion:

1. Circulation, digestion, and respiration demonstrate a vital integration necessary for the lives of living creatures. These complex and harmonious processes reflect the wisdom of the Creator in designing living beings in ways that ensure their continuity.

2. Digestion, especially in the large intestine, analyzes and transforms food into usable substances for cells, while respiration provides the necessary oxygen to convert glucose into energy.

3. Circulatory systems, whether open as in some invertebrates or closed as in vertebrates, play a crucial role in distributing nutrients and oxygen to every cell in the body and in eliminating waste.

4. The digestive process in the large intestine, with its complex chemical reactions, stands out as a key efficiency in extracting essential nutrients for growth and maintenance. These intricate mechanisms highlight a delicate balance and integration in the design of life, showcasing the marvels of nature and the diversity of living organisms in this world.

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