Nutrition function: what it is and processes

The nutrition function in living beings is different depending on whether the organism is animal or plant. Animals are organisms that present heterotrophic nutritionThis means that organisms are not able to generate their own food, but rather depend on other sources of energy to provide the organic carbon necessary for life. These carbon sources can be animals or plants. To incorporate these nutrients, animals have a digestive system that transforms matter into simpler substances that can be captured by cells. On the other hand, if the organism is complex, it is also necessary an apparatus that is in charge of the transport of the nutrients to the different parts that compose it, this is done by the circulatory system. In addition, to use nutrients, animal cells need oxygen from the outside, which provides them with the necessary energy for cellular processes necessary in nutrition to occur, therefore, They also have the intervention of a respiratory system. In the subsequent sections, the organs and devices involved in the nutrition function of animals are explained in more detail.

In this other post you can read more about heterotrophic organisms: what they are, characteristics and examples .

On the contrary to the heterotrophic nutrition seen in the previous section, the plants present autotrophic nutrition . This implies that they are capable of fixing inorganic carbon to make their own food, converting it into organic carbon, through photosynthesis. Although plants are capable of manufacturing their own nutrients, they also need external factors that intervene in the nutrition function, such as sunlight, water, mineral salts and CO2. Organs such as the root , stem and leaves intervene to perform the nutrition function in plants.. These help to capture the main elements essential for the survival of vegetables, such as nitrogen, phosphorus and potassium.

Learn more about Autotrophic Organisms: what they are, characteristics and examples by reading this other article.

Again, we can talk about the processes of this function, on the one hand, in animals and, on the other hand, in plants.

Processes of nutrition function in animals

In animal nutrition , the processes described below can be considered.

1. Ingestion of food: in this process, food is incorporated through the organs located in the oral cavity. Depending on the type of food that the animal ingests, the structures of the mouth will be specialized according to its characteristics, for example, if the organism feeds on microscopic particles, the structure present in the oral cavity will be filters, through the that will retain said particles.
2. Digestion: it is the process by which the macromolecules ingested at the beginning, are transformed into simpler molecules so that they can be assimilated by the cells of the organism. There are also different types of digestion: intracellular digestion (typical of unicellular organisms), extracellular digestion (present in higher organisms) and mixed digestion (combining intracellular and extracellular, present in metazoans).
3. Transport of food to the cells: when the transformation of food into assimilable substances has already taken place, these have to be transported throughout the body to reach each of the cells. It is done through the circulatory system.
4. Cell metabolism: it is a process that occurs within the cell and consists of the transformation of nutrients into energy or more complex molecules.
5. Excretion: lastly, those substances that have not been assimilated are expelled as waste to the outside.

Processes of nutrition function in plants

The processes that take place during nutrition in plants are very different from those of animals, since, as explained in the previous section, they are autotrophic organisms that make their own food.

1. First of all, they take water and minerals from the soil through the absorbent hairs of the root and CO2 through the stomata of the leaves. Next, the mixture formed by the water and the salts forms the raw sap that rises through the stem.
2. Photosynthesis occurs in the leaves , where thanks to the sunlight captured by chlorophyll, the raw sap and CO2 are transformed into processed sap, which serves as food for the plants. In this process, oxygen is also produced and released into the atmosphere.
3. Finally, the elaborated sap that has formed in the leaves has to be distributed throughout the body through tubes, different from those used by the raw sap that rises from the root and in the opposite direction in the first stage. In this way, the nutrients reach all parts of the plant, very important for those where photosynthesis does not occur, such as the stem.

Here you can read more about the Plant Nutrition Process .

In animals, depending on whether they are vertebrates or invertebrates, there are a great variety of types of structures involved in the function of nutrition. To carry out the function of nutrition, different systems are involved in the human body: the digestive system, the respiratory system, the circulatory system, the lymphatic system and the excretory system. The main characteristics of the devices involved , as well as which organs perform the nutrition function , are described below .

Digestive system

Responsible for digestion, in vertebrates, it is characterized by a hollow tube and is organized into three areas in which different organs intervene. The first area is the cephalic, where the oral cavity and pharynx meet, through communication with the respiratory system. The second of the areas, the trunk, is made up of the esophagus, stomach, and small and large intestine. Additionally, there are two glands that intervene in the digestive system secreting their contents to the small intestine through the same duct.

Respiratory apparatus

It is the one that takes care of providing oxygen and eliminating the CO2 generated in the different metabolic processes. It is made up of ducts such as the pharynx, trachea, main bronchi, bronchioles and alveolar lagoons through which air flows.

Circulatory system

Its function is to drive the blood throughout the body and thus, oxygen and nutrients reach all the cells that form it. The heart, arteries, veins, capillaries, and venules are the structures through which blood circulates in the circulatory system.

Lymphatic system

Closely linked to the circulatory system, the lymphatic system is where lymph circulates, a liquid formed for the most part by white blood cells and its function is, mainly, to transport protein substances to the blood. It is made up of the lymph nodes, lymph nodes, the thymus and the spleen.

Excretory system

It is responsible for the elimination of substances that cannot be assimilated by other devices. The urinary system is the main excretory system in animals, formed by the kidneys, ureters, bladder and urethra, through which the blood is filtered, being able to capture useful molecules back into the blood.