Human biologyda:Humanbiologi Human biology is an academic field which focuses upon the study of human biology; it is closely related to medicine, primate biology, and a number of other fields. A human being is a multicellular eukaryote made up of an estimated 100,000 billion cells. As a species, humans are primates and the most notable difference is the more highly evolved brain. Even though humans are multicellular animals, many of the basic life processes of human cells are basically the same as in simple unicelluar eukaryotes such as yeast and even prokaryotes. One of the major differences betweens humans and yeast are that yeast are made of just one cell, and when it divides, the new cell is a new independent organism. A humans being is initially just one cell, a zygote, but unlike yeast, this cell doesn't divide into new independent organisms, rather it divides to form an embryo. The early embryo is made up of totipotent stem cells, these cells go on to differentiate. Differentiation is the process by which an unspecialized cell becomes specialized into one of the many cells that make up the body, such as a heart, liver, or muscle cell. During differentiation, certain genes are turned on, or become activated, while other genes are switched off, or inactivated. This process is intricately regulated. As a result, a differentiated cell will develop specific structures and perform certain functions. Differentiation can involve changes in numerous aspects of cell physiology; size, shape, polarity, metabolic activity, responsiveness to signals, and gene expression profiles can all change during differentiation. When developed, the human body is made up of many different types of cells, see list of distinct cell types in the adult human body. These cells makes up tissues, groups of cells that perform a similar function. E.g. muscle cells make up muscle tissue. Groups of tissues which perform some function makes up organs and groups of related organs makes up organ system. The human body is dependent on all the organ systems in order to survive and reproduce. Major organ systems of the human body:
The study of development from fertiziled cell to fully developed body is studied in developmental biology, the structure of the developed human body is studied in human anatomy and its function in human physiology. The human body can develop problems, and these are studied in medicine.
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