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As per evidences, life originated on the planet Earth billions of years ago. Since then, new species have evolved from old ones. Simultaneously, many species had become extinct during the process of evolution. As of now, scientists have identified about 1.8 million species, which are classified into several groups based on the similarities and dissimilarities between the organisms. Among the many proposals of classification, the Carl Linnaeus system is the most accepted one. According to him, living things are classified into 5 kingdoms, based on the mode of nutrition and cellular organization.
5 Kingdoms of Living Things
In the past, all living things comprised of two categories, namely, the plants and animals. Organisms that remained stationary were categorized under plants. On the contrary, animals encompassed all living things that had the ability to move. In due course of time, scientists discovered more living organisms that could neither be included in plants nor animals. This was how the Linnaean system of taxonomic classification originated. Let’s discuss in brief each of the five kingdoms of living things.
Living things included in the kingdom Monera are minute and single-celled prokaryotes (organisms that lack membrane-bound nuclei). Members of this kingdom are bacteria, cyanobacteria or blue-green algae (BGA) and spirochetes. Some members of the same organism join together to form chains. Cyanobacteria is a type of organism, which is intermediate between algae (it possesses chlorophyll) and bacteria (it is a prokaryote). Their mode of nutrition is by absorbing food through the cell wall.
Protista includes single-celled eukaryotic organisms, which contain membrane-bound cell organelles. It includes organisms that are neither plants nor animals. In simpler terms, the living things classified under Protista are unusual and diverse forms, which cannot be grouped in any of the four remaining kingdoms. For example, the simplest organisms on Earth, amoeba (a protozoan) and giant sea kelp (an algae) belong to this kingdom. The members of Protista obtain nutrition by absorption, ingestion and photosynthesis. Read the rest of this entry »
Adipose tissue is a specialized connective tissue in the body which is the major storehouse of energy in the form of triglycerides deposition. Adipose is usually found in mammals as two different forms such as white and brown adipose tissues. Depending upon the species of mammals the amount and location of the tissue varies. Most of the fat tissues fall under the white category which is located in various organs and various parts in the body.
In human beings, this tissue is found at multiple locations; it is located beneath the skin as subcutaneous fat, surrounding internal organs as visceral fat, inside bones as bone marrow or yellow bone marrow and also in breast. Specific locations of such layers are referred to as adipocytes depots. These depots are a reservoir of adipose tissue that contains several cell types; the highest percentage of cells is adipocytes that contain fat droplets. Some other cells including fibroblasts, macrophages and endothelial cells are also a part of this tissue along with a number of tiny blood vessels. As the integument system includes the skin that accumulates in the deepest level of the subcutaneous layer, adipose tissue is formed beneath the skin and provides insulation to the body from heat and cold.
It acts as a protective padding around all vital organs in the body. Though its major function is to reserve lipids, it also acts as the main source of energy by synthesizing lipids to fulfill the needs of the individual. Obese persons are seen with more amount of adipose in their body. Excessive tissues are seen hanging downward from the abdomen and also known as a panniculus. Sometimes to remove such fats, surgeries are needed. The abdomen has a layer of adipocytes known as visceral and intra abdominal fat. The internal fat protects stomach, liver, intestines and kidneys by forming protective layers inside the body. Breast fat is also a type of white adipose tissue that helps in formation of milk during pregnancy with help of oxytocin hormone and helps the mother to nourish the infants. In human, excess fats are accumulated in the abdominal, hip and also in the thoracic regions.
In different mammals, adipocytes are also found; in mice they are found inside the abdominal layers and cavity forming several depots inside the body. Even around the uterus and ovaries, it forms a layer of fat filled mass providing protection. Brown adipose tissues are densely packed mitochondria and also found in various locations in mammals. As such tissues are good in vasuclarization, in hibernating animals they help in regulating body temperature through non-shivering thermogenesis.
You can learn more about adipose tissue functions, and get more articles and resources about adipose tissue by visiting Adipose Tissue
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