The kidneys are tucked up close to the liver toward the spine.
Modern times[ edit ] The variations in natural language definitions of what constitutes an organ, their degree of precision, and the variations in how they map to ontologies and taxonomies in information science for example, to count how many organs exist in a typical human body are topics explored by writer Carl Engelking of Discover magazine in as he analyzed the science journalism coverage of the evolving scientific understanding of the mesentery.
For example, the fact that the tissues of the mesentery are continuous was something that was simply not known for sure until it was demonstrated with microscopy.
However, one of the points made by an anatomist interviewed by Engelking is that, finality aside, much more could be done even now to represent existing human knowledge more clearly for computing purposes.
Origin and evolution[ edit ] Relationship of major animal lineages with indication of how long ago these animals shared a common ancestor.
On the left, important organs are shown, which allows us to determine how long ago these may have evolved. The organ level of organisation in animals can be first detected in flatworms and the more derived phyla.
The less-advanced taxa like PlacozoaSponges and Radiata do not show consolidation of their tissues into organs. Complex animals are composed of organs and many of these organs evolved a very long time ago.
For example, the liver evolved in the stem vertebrates more than million years ago, while the gut and brain are even more ancient, arising in the ancestor of vertebrates, insects, and worms more than million years ago. Given the ancient origin of most vertebrate organs, researchers have looked for model systems, where organs have evolved more recently, and ideally have evolved multiple times independently.
An outstanding model for this kind of research is the placentawhich has evolved more than times independently in vertebrates, has evolved relatively recently in some lineages, and exists in intermediate forms in extant taxa.Organs are then formed by the functional grouping together of multiple tissues.
The study of human and animal tissues is known as histology or, in connection with disease, histopathology. For plants, the discipline is called plant anatomy.
Tissues, and the microscopic units of tissues, the cells, are the building blocks of organs. Tissues include materials such as muscles, nerves and epithelia and connective .
Organs are structures made up of two or more tissues organized to carry out a particular function, and groups of organs with related functions make up the different organ systems. At each level of organization—cells, tissues, organs, and organ systems—structure is closely related to function.
Basic Anatomy - Tissues and Organs This Science quiz is called 'Basic Anatomy - Tissues and Organs' and it has been written by teachers to help you if you are studying the subject at middle school. Playing educational quizzes is a fabulous way to learn if you are in the 6th, 7th or 8th grade - aged 11 to The human body is everything that makes up, well, you.
The basic parts of the human body are the head, neck, torso, arms and legs. Our bodies consist of a number of biological systems that carry.
Basic Anatomy:Tissues, Organs, and Systems.
Ms. Ryder. There are many different types of cells in the human body. None of these cells would function well on their own, they are part of the larger organism that is called you.
Tissue. Cells group together to form tissues.