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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 ...
The human brain is the central organ of the human nervous system, and with the spinal cord, comprises the central nervous system. It consists of the cerebrum, the brainstem and the cerebellum. The brain controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sensory nervous ...
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 ...
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 ...
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 ...
Two proteins are involved in this accumulation of amyloid beta: serum response factor or SRF and myocardin. [9] Together, these 2 proteins determine whether smooth muscle of blood vessels contract. SRF and myocardin are more active in the brains of people with Alzheimer's disease.
The sympathetic nervous system is responsible for setting off the fight-or response. [3] The parasympathetic nervous system is responsible for the body's rest and digestion response. [3] In many cases, both of these systems have "opposite" actions where one system activates a physiological response and the other inhibits it.
Neural top–down control of physiology concerns the direct regulation by the brain of physiological functions (in addition to smooth muscle and glandular ones). Cellular functions include the immune system’s production of T-lymphocytes and antibodies, and nonimmune related homeostatic functions such as liver gluconeogenesis, sodium reabsorption, osmoregulation, and brown adipose tissue ...