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The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events. [1] Nervous tissue first arose in wormlike organisms about 550 to 600 million years ago. In vertebrates, it consists of two main parts, the central nervous system (CNS) and the peripheral nervous ...
Each of these variables is controlled by one or more regulators or homeostatic mechanisms, which together maintain life. Homeostasis is brought about by a natural resistance to change when already in optimal conditions, [2] and equilibrium is maintained by many regulatory mechanisms; it is thought to be the central motivation for all organic ...
Autonomic nervous system, showing splanchnic nerves in middle, and the vagus nerve as "X" in blue. The heart and organs below in list to right are regarded as viscera. The autonomic nervous system has been classically divided into the sympathetic nervous system and parasympathetic nervous system only (i.e., exclusively motor).
The following diagram is provided as an overview of and topical guide to the human nervous system: Human nervous system. Human nervous system – the part of the human body that coordinates a person's voluntary and involuntary actions and transmits signals between different parts of the body. The human nervous system consists of two main parts ...
Since the time of Langley's unified proposal in the 1920s, these divisions have remained relatively constant; [9] [10] the parasympathetic nervous system is known to regulate unconscious activities of the body and maintain homeostasis, the sympathetic nervous system controls responses to external stimuli, but both are involuntary functions ...
The sympathetic nervous system regulates the "fight or flight" responses. The parasympathetic nervous system regulates the "rest and digest" responses. The enteric nervous system innervates the viscera (gastrointestinal tract, pancreas, and gall bladder). The somatic nervous system consists of peripheral nerve fibers that send sensory ...
Cerebral hyperaemia is a fundamental central nervous system mechanism of homeostasis that increases blood supply to neural tissue when necessary. [3] This mechanism controls oxygen and nutrient levels using vasodilation and vasoconstriction in a multidimensional process involving the many cells of the neurovascular unit, along with multiple ...
Neuroimmunology is a field combining neuroscience, the study of the nervous system, and immunology, the study of the immune system.Neuroimmunologists seek to better understand the interactions of these two complex systems during development, homeostasis, and response to injuries.