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The PNS includes motor neurons, mediating voluntary movement; the autonomic nervous system, comprising the sympathetic nervous system and the parasympathetic nervous system and regulating involuntary functions; and the enteric nervous system, a semi-independent part of the nervous system whose function is to control the gastrointestinal system.
Unlike the CNS, the PNS is not protected by the vertebral column and skull, or by the blood–brain barrier, which leaves it exposed to toxins. [3] The peripheral nervous system can be divided into the somatic nervous system and the visceral nervous system. Each of these have a sensory and a motor division.
The peripheral nervous system (PNS) is a collective term for the nervous system structures that do not lie within the CNS. [17] The large majority of the axon bundles called nerves are considered to belong to the PNS, even when the cell bodies of the neurons to which they belong reside within the brain or spinal cord.
These areas are formed as swellings known as the three primary brain vesicles. In the fifth week of development five secondary brain vesicles have formed. [70] The forebrain separates into two vesicles – an anterior telencephalon and a posterior diencephalon. The telencephalon gives rise to the cerebral cortex, basal ganglia, and related ...
Wound scars in the brain largely contain astrocytes. The extracellular matrix also provides support on the molecular level for the brain's cells, vehiculating substances to and from the blood vessels. At the organ level, the nervous system is composed of brain regions, such as the hippocampus in mammals or the mushroom bodies of the fruit fly. [11]
The somatic nervous system (SNS), also known as voluntary nervous system, is a part of the peripheral nervous system (PNS) that links brain and spinal cord to skeletal muscles under conscious control, as well as to sensory receptors in the skin. [1] [2] The other part complementary to the somatic nervous system is the autonomic nervous system ...
Nervous tissue, also called neural tissue, is the main tissue component of the nervous system.The nervous system regulates and controls body functions and activity. It consists of two parts: the central nervous system (CNS) comprising the brain and spinal cord, and the peripheral nervous system (PNS) comprising the branching peripheral nerves.
Nerves connect the spinal cord and brain to the rest of the body. All major bones, muscles, and nerves in the body are named, with the exception of anatomical variations such as sesamoid bones and accessory muscles. Blood vessels carry blood throughout the body, which moves because of the beating of the heart.