If we consider the levels of organization of life on our planet, then the first one, of course, will be molecular. On the contrary, the highest and the general - the biosphere. All the rest are intermediate. One of these is the organ, on which the formation of various structural parts of the body of all living things on Earth takes place. He is being studied by the science of biology. An organ is a part of the body. What they are with different types of creatures and what they are, we will consider below.
Biology: is an organ?
If you answer this question with a scientific definition, then we can say so. An organ is a combination of various cellular and tissue structures that resides in a living organism and performs a function.
At the same time, it does not matter at all which particular organism is involved, the main thing is that it be multicellular. Since for the simplest unicellular animals and plants, as well as for bacteria, the presence of any organs is uncharacteristic. The exception is cell structures or organelles.
The study of the concept and its essence is the science of biology. An organ is a living structure, which means part of the planet’s biomass. Therefore, the appropriate discipline should study it. True, there are several of them. A large biological family includes many different sections, sciences and more. Therefore, an organ can be studied at once by several of them. Most often these are disciplines such as:
- anatomy;
- physiology;
- biochemistry;
- histology;
- cytology;
- hygiene.
Thus, it becomes clear how biology defines the concept under consideration. An organ is a whole small system, which consists of numerous substances, molecules that unite into cells. The latter, in turn, form tissues that line the structure itself.
Moreover, there are no organs that exist independently of others as part of one being. All of them are closely interconnected, and those that perform similar functions form the so-called organ system. Therefore, most often, individual structures are considered as links of a single system within the body.
Organs of lower plant organisms
Plant organs naturally differ from those of other creatures. After all, this is generally a special kingdom of wildlife. In addition, not all plants are the same, therefore, their body parts are different.
So, there is a special department of lower plants. These include those that live under water, algae. Plant organs of this group are not expressed. They do not have a clear separation into the stem, leaves, and so on. The whole body is a thallus or thallus, and instead of roots there are special devices called rhizoids. They serve to fix in the substrate and attach to its surface.
The thallus itself can be very diverse in form and appearance. Sometimes it very much resembles strongly dissected leaves of higher plants. However, metamorphic division into organs is not observed anyway.
Thus, the body parts of the lower plants are:
Higher plants
This category includes all terrestrial species, whose body is clearly structured into separate parts. If we consider the classification of higher, we can distinguish several very voluminous classes. The most common and numerous of them are angiosperms.
The study of morphology, physiology and anatomy of plants engaged in botany - another section that includes the science of biology. The organs of flowering plants, in principle, repeat those of all other terrestrial, except for one significant difference - the presence of a flower as a generative organ.
Therefore, we consider all the organs that make up higher plants.
Generative organs
These, as already indicated, include the flower and all the structures included in it. Specifically, the following can be distinguished:
- pistils;
- stamens;
- receptacle;
- ovary;
- ovule;
- petals;
- pollen tube;
- pollen grains.
Together, these organs form a flower, in which fertilization occurs, the nucleation of the seed and the formation of the fetus around it.
In gymnosperms (conifers, ginkgs), the function of the generative organ is performed by the cone, in which the formation and development of the seed also occurs. In spore plants, this function is performed by sporangia, in which the smallest cells - spores ripen.
Vegetative organs
These include all that do not participate in reproduction. These are such structures:
- stem (in the case of trees and shrubs trunk);
- the root, which forms two systems - fibrous and pivotal in different species;
- leaves - the main organ for the implementation of the photosynthesis process.
These parts of the body are the vegetative organs of plants that live on land or on water, but not under its thickness. The structure and functioning of all these structures is studied by the science of biology. An organ is a whole small factory in which thousands of biochemical reactions take place. Therefore, consideration of their internal organization is extremely important for understanding the mechanisms of life of a particular type of plant.
Human organs
Separated from all other sciences is human biology. The organs of people are distinguished by a particularly complex organization, structure and functioning. Knowledge of the working mechanisms of each of them is important information for medicine that is used to maintain human health, to get rid and prevent various diseases.
There are many examples of the most diverse organs of the human body. For instance:
- heart;
- lungs;
- kidneys
- ovaries;
- intestines;
- leather;
- analyzers;
- stomach;
- spleen and others.
However, it is obvious that none of them can exist in isolation, only together. What is an organ system? Biology as a science gives the following definition of this concept. This is a combination of several parts of the body or organs that perform similar functions and have a much similar structure.
Biology, Grade 8: organ system
So, in the human body, eight main systems can be distinguished.
- Musculoskeletal, which includes bones and muscles.
- The coverslip. It consists of the outer and inner parts of the skin.
- Digestive It consists of such organs as the stomach, esophagus, larynx, oral cavity, tongue, spleen, liver, intestines, anus.
- Respiratory system. It includes the lungs, trachea, bronchi, alveoli and other structures.
- Excretory system. Organs: kidneys, ureters, bladder.
- Nervous system. Organs: brain and spinal cord and numerous branching nerves.
- Circulatory system: heart, blood vessels, aorta.
- Endocrine system: glands of internal and external secretion.
- Reproductive system: ovaries, uterus, external genitalia, testicles and others.
All these systems provide a coordinated and holistic work of the whole organism. And the bodies that compose them maintain this order from the inside.
Unusual senses in animals
Among these, there are several of the most interesting:
- Electric beak. Platypus.
- Echolocation. Dolphins and bats.
- Infrared vision. Snakes.
- Ultraviolet. Bees that distinguish more parts of the visible spectrum of light.
- The difference in polarization. Octopuses.
- External skeleton of high sensitivity. Spiders.
- Taste sensations. Fishes.
- Point matrix vision. Some marine life.