Heterotrophic Nutrition: Characteristics, Types and Examples

The Heterotrophic nutrition Is made by all living beings / organisms that require others to feed themselves because they are not able to produce food by themselves within their organism. The heterotrophic organisms consume organic elements of nature already constituted as foods and previously synthesized by other organisms.

On the contrary, in autotrophic nutrition the organism produces complex organic compounds (such as carbohydrates, fats and proteins) from simple substances present in its environment. They usually use light energy (photosynthesis) or inorganic chemical reactions (chemosynthesis).

Nutrition-heterotrofa

Autotrophic organisms do not need a living source of energy or organic carbon; Can decompose carbon dioxide to produce organic compounds to make biosynthesis and create a reserve of chemical energy.

Most autotrophs use water as a reducing agent, but some may use other hydrogen compounds, such as hydrogen sulfide. Some autotrophs, such as green plants and algae, are phototrophic, meaning that they convert the electromagnetic energy of sunlight into chemical energy in the form of reduced carbon.

What organisms / animals are heterotrophs?

This type of nutrition has human, animals, protozoa, bacteria, fungi and many microorganisms.

Heterotrophic beings are the most abundant on the planet. There is a predominance of the same and these are in the second, third and fourth link of the food chain, never in the first link since in this are the autotrophs.

As it is a type of nutrition, we must keep in mind that this process is carried out when the nutrients (in their most elemental phase) penetrate the consuming organism, that is, when assimilated by the cells that make up our organism.

Unlike heterotrophs, autotrophs have the ability to synthesize and feed on inorganic elements such as light, water, and carbon dioxide. This type of nutrition allows food to be transformed into its own cellular matter.

Types of Heterotrophic Nutrition

The four main types of heterotrophic nutrition are:

Holozoic nutrition

The word holozoic is composed of two words: holo = total and zoikos = animals and means"animals that eat all their food".

Complex foods reach a specialized digestive system and are divided into small pieces to be absorbed. It consists of 5 stages: ingestion, digestion, absorption, assimilation and ingestion. For example: the human being.

Saprophytic / saprotrophic nutrition

Organisms feed on dead organic remains from other organisms.

Parasitic nutrition

The organisms obtain food from other living organisms (the host), and the host receives no benefit from the parasite. When a parasite is present inside the host's body, it is known as an endoparasite (such as tapeworm).

Generally endoparasites attack and live in the intestine of an organism, while parasites such as mites and leeches attach to the exterior of the body of the guests. The latter are known as ectoparasites.

Symbiotic nutrition

Certain plants live in close association with other plants for long periods of time. For example: fungi and algae, rhizobium and legumes.

Difference between food and nutrition

Feeding : Through this process is taken from the outside world a series of substances necessary for nutrition.

Nutrition : It is the set of processes by means of which the organism transforms and incorporates substances that are necessary to cover its energetic and structural necessities.

Classification of heterotrophic beings

The heterotrophic organisms, not being able to create their own organic matter from the inorganic need to obtain matter and energy processed by other living beings that already have realized this process of transformation and this source can vary depending on the organism in question, and Can classify in:

  • Herbivores : Animals that mainly feed on herbs and plants (eg goats, sheep, rabbits, horses, etc.)
  • Carnivores : Those animals that they base feed on the meat of others to obtain their energy and nutritional requirements. It can be by predation or consumption of carrion (examples: lions, tigers, bears, sharks, etc.)
  • Commensalism : Obtaining some benefit (nutritive) while the other is not harmed or benefited (example of this form of biological interaction: crustaceans living near the sea sponges).
  • Parasitism : One participant (host) is in dependence on another (host) and gains a close relationship with him, which always implies damage to the host and can be considered as a particular case of predation ( Example: fleas and ticks that feed on the blood of dogs, tapeworms, etc.)
  • Mutualism : Through this biological interaction of individuals belonging to different species, both benefit from this process and even improve their biological fitness (eg pollinating insects).
  • Symbiosis : Involves a close and persistent relationship between organisms of different species and is called symbionts (example: lichens).
  • Saprophytes : Organisms that feed on waste left by other organisms and living beings (decomposing organic matter) and from these extracts the organic compounds needed to be nourished (example: saprophytes fungi).
  • Necrophagia : They feed on corpses or excrement.

Now, according to the energy source its subtypes would be:

  • Photoheterótrofos : Fix the energy of light and represent a very small group, only perform organic synthesis in the presence of light and oxygen-depleted media, when they lack this behave as heterotrophs.
  • Chemoheterotrophs : They use chemical energy extracted from inorganic or organic matter.

Nutrients

They are the chemicals that come from outside the cell and are necessary for the organism to perform its vital functions.

The main ones are the macronutrients and the most important of these are:

  • Proteins : Are considered as the raw material needed by the body for the construction and repair of body structures and functional units.

They are obtained mainly from foods of vegetable or animal origin such as meats, milk, cheese, eggs and Legumes Such as beans, lentils, etc.

  • Carbohydrates or carbohydrates : They are the main source of energy, it is the"fuel"necessary for the body to function and among some of these we can find: sugar, flour, cereals, bread, rice, corn, etc.
  • Lipids : They regulate the temperature of the body in isolation and it is the most dense nutrient of everything from the energetic point of view and also constitutes a great source of energy, it must be consumed with moderation in small quantities. It is necessary for cellular structures and for the construction of hormones.

Among some lipids we can find: oils, butter, cream, animal fat, etc.

  • Vitamins and minerals : Are part of micronutrients. They are needed in small quantities to meet the necessary quota required by the body, but that does not mean that they are not important, on the contrary, they are vital for the organism to function well.

For example: Vitamin A Causes night blindness in humans, etc.

Objectives of nutritional processes

Nutritional processes have three primary objectives:

  • Provide energy.
  • Provide materials for the synthesis, construction and renovation of organic structures.
  • Provide regulators (for chemical processes).

Cellular nutrition also includes 3 types of processes:

  • Incorporate ingested substances.
  • Metabolize nutrients.
  • Excrete debris.

Phases of heterotrophic nutrition

This type of nutrition can be divided into the following main stages:

  • Ingestion : After capturing the food, it is introduced to the digestive system from the external environment of the organism to the internal
  • Digestion : The matter ingested is not directly usable, therefore, by means of this process the food is transformed into simpler substances, small molecules or nutrients that can be absorbed by the organism and usable by the cells.
  • Absorption : In this stage the nutrients necessary for the proper functioning of the organism are absorbed and used and to be able to stay alive.
  • Excretion : Is the last stage of the digestive process. It is where non-usable substances are produced and defecated from the organism that can become toxic if they are not eliminated or expelled to the outside.

Forms of nutrition

There are a variety of forms of nutrition depending on the type of organism or being alive among some of them we can find that:

The unicellular organisms take from outside what they need to survive, the cell captures the food and proceeds to spread the digestive enzymes of its lysosomes on it. After this, the usable substances are absorbed into the cell and waste is excreted.

In the case of fungi, the process occurs by absorbing organic matter from the substrate on which they live. This organic matter they absorb can come from saprophytes, symbiosis with vegetables or also live parasitically on or inside other living things.

On the other hand, the animals, being multicellular organisms, have a little more complicated and go through a totally different process and with a clear cellular differentiation.

Each cell performs a specific function and they are grouped by having the same function forming tissues and these in turn form and are associated in organs that give rise to the apparatus or systems (digestive, circulatory, respiratory and excretory) that perform specific functions within the organism.

  • Digestive system : Is in charge of preparing the food ingested to be able to transform them into useful nutrients for the cells.
  • Respiratory system : It is in charge of taking the oxygen that the body needs for life and cellular respiration, then it expels it as carbon dioxide.
  • Excretory system : It has as a function to eliminate from the organism all those toxic substances resulting from digestion and that are produced by the cell in its functioning.
  • Circulatory system : Its job is to distribute nutrients and oxygen (taken up by other organisms) through all the cells of the body and carry waste and carbon dioxide to the corresponding organs.

Metabolism

It refers to the set of chemical and biological changes and reactions that take place in the cytoplasm in order to obtain energy for the cell and build its own cellular organic matter, in addition to which it can perform its normal activities as: reproduction, maintenance , Growth of their structures and respond to stimuli.

It is divided into two phases:

  • Anabolism : It is basically a phase of construction by means of which the biochemical energy coming from the catabolism and the small molecules that result from the digestion to be able to synthesize great organic molecules is used.
  • Catabolism : Stage of destruction, in this phase organic matter is oxidized by cellular respiration to achieve biochemical energy

References

  1. Arnaldo Polo, Yuby. "Difference between heterotrophic and autotrophic nutrition". Taken from scribd.com.
  2. García Garibay, Marciano; Quintero, Rodolfo & Agustín López. (1993). "Food Biotechnology"Editorial Limusa.


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