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The brain is small and simple in some species, such as nematode worms; in other species, such as vertebrates, it is a large and very complex organ. [4] Some types of worms, such as leeches , also have an enlarged ganglion at the back end of the nerve cord, known as a "tail brain".
The occipital bone found in the rear of the skull is thicker to limit fractures caused by blows to the back of the head. The eight bones are blended together to form the cranial cavity. The pituitary gland is also found in the make up of the cranial cavity. It plays a major role in the body, creating and secreting many bodily hormones.
The brain consumes up to 20% of the energy used by the human body, more than any other organ. [131] In humans, blood glucose is the primary source of energy for most cells and is critical for normal function in a number of tissues, including the brain. [ 132 ]
A bone is a rigid organ [1] that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, and enable mobility.
Proprioception – sense of the relative position of the parts of the body; Nociception – signals pain in response to nerve-damage or damage to tissue; Equilibrioception – sense of body movement, direction, acceleration, and balance Vestibular nerve (part of cranial nerve 8) – the main equilibrioception-related cranial nerve
This article contains a list of organs in the human body. It is widely believed that there are 79 organs (this number goes up if you count each bone and muscle as an organ on their own, which is becoming a more common practice [1] [2]); however, there is no universal standard definition of what constitutes an organ, and some tissue groups' status as one is debated. [3]
The bone mass in the skeleton makes up about 14% of the total body weight (ca. 10–11 kg for an average person) and reaches maximum mass between the ages of 25 and 30. [2] The human skeleton can be divided into the axial skeleton and the appendicular skeleton .
In osteology, the osteon or haversian system (/ h ə ˈ v ɜːr. ʒ ən /; named for Clopton Havers) is the fundamental functional unit of much compact bone. Osteons are roughly cylindrical structures that are typically between 0.25 mm and 0.35 mm in diameter . [ 1 ]