Building
Schedule a nerve cell . Basic building block of the nervous system is the nerve tissue. It consists of interconnected nerve cells (neurons), whose cell body as Somata or Perikarya and their survival rates than nerve fibers (axons and dendrites) respectively.
At higher organisms, the nerve tissue from a network of neurons and glial cells many places to dock. The latter support the activity of nerve cells, without directly to the transmission of stimuli to be involved.
nervous system pictures building
Cephalopods and vertebrates nervous systems
Cephalopods and vertebrates
Especially highly centralized systems are the nerves of cephalopods and vertebrates. They are a great many functions of the nervous system and muscles of the centrally controlled. It therefore speaks of a central nervous system. This consists of the brain and the spinal cord.
The outside of the central nervous system underlying neural structures to be counted peripheral nervous system. The peripheral nervous system is divided into the somatic nervous system and the vegetative nervous system (including visceral or autonomous nervous system, consisting of sympathetic, and enteric nervous system Parasympathikus) broken. The vegetative nervous system is primarily concerned with controlling the activities of the outside of consciousness expiring body functions.
Arthropod nervous system
Arthropod
Schematic construction of a knitting head of nervous system
In the arthropod is already in the training of higher processing centers in the form of several nerve knots (ganglia). These ganglia are two nerves like knitting heads together, so we here of a knitting nervous talking head. For most of these animals is particularly great Oberschlundganglion trained. It already assumes the functions of a "brain", especially the processing of sensory stimuli. The ganglia of body segments often control the movements of the leg and wing muscles largely autonomous. The knitting head nerve systems (with the exception of the upper pharyngeal Gang Lions) below the digestive system. Therefore, one speaks also of abdominal Mark.
Evolution
Evolution
In the course of evolution and with the higher development of individual departments of the animal kingdom is a clear trend towards concentration and associated specialization of parts of the nervous system noted. While in primitive animals, yet some individual neurons fall special functions (eg pacemaker neurons, the clock for elementary body movements of worms pretend), to perform highly complex nervous systems of up to several billions of interconnected neurons in specific tasks.
In nervous systems with Zentralganglien the conduction of neurons in Afferenzen (from the sensors to the brain) and Efferenzen (from effectors to the brain, muscles, for example) are divided.
nervous
Nervous
Overview of the human nervous system
The term nervous system (Systema nervosum lat) is the totality of nerve cells in an organism and describes how they arranged and connected. It is an organ system of higher animals, which has the task to provide information on the environment and the organism record, process and reactions of the organism action to optimal to react to changes. The nervous realized one of the basic properties of life, the irritability (irritability).
Pain sensation
Pain is induced by mechanical damage of tissue cells.
•As a result of damage bradykinin like peptides are released.
•These peptides lead to the stimulation of IV type afferent fibers in the region
Pain sensation is transmitted to the brain by anterolateral pathway.
•The type IV afferents synapse on the neuron in lamina I and IV region of spinal gray matter.
•These second order neuron are inhibited by somatosensoric large afferent fibers.
•That is why the pain sense can be decreased by mechanical stimuli applied from same dermatomal region of pain.
Spinal Cord
•The spinal cord is the part of the central nervous system that is surrounded and protected by vertebral column.
•In cross section, the spinal cord is organized as a butterfly shaped mass of gray matter surrounded by white matter.
•Gray matter of spinal cord are designated as name or romen numeral.
•The neuron cell bodies are organized into three discrete areas of the gray matter: the dorsal horn, the intermediate zone, and the ventral horn
•The CNS is made up not only of the brain, but also the spinal cord.
•The spinal cord is a thick, hollow tube of nerves that runs down the back, through the spine.
•The ventral horn contains the motor neuron bodies for the somatic motor system.
•The white matter contains many sensory tracts ascending to the brain and motor neuron axon descending from the brain
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