|
Algedonic Signal
An algedonic signal is a pre-emptive message concerning pleasure or pain. An arousal mechanism can generate an algedonic signal, and thus provide an important survival mechanism to a living organism by alerting it to a threat. An example of the disastrous consequences of such a system not being in place is that of a moth attracted by the light of an open flame without recognising the danger of fire. In the human nervous system a variety of algedonic signals are brought together in the midbrain reticular formation from across the whole body. A source of pain, such as touching a burning surface or treading on broken glass, creates such an algedonic signal which interrupts consciousness and provokes a reflex action In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus. Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs .... References {{reflist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Nervous System
In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events. 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 system (PNS). The CNS consists of the brain and spinal cord. The PNS consists mainly of nerves, which are enclosed bundles of the long fibers or axons, that connect the CNS to every other part of the body. Nerves that transmit signals from the brain are called motor nerves or '' efferent'' nerves, while those nerves that transmit information from the body to the CNS are called sensory nerves or '' afferent''. Spinal nerves are mixed nerves that serve both fu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Midbrain Reticular Formation
The midbrain reticular formation (MRF), also known as reticular formation of midbrain, mesencephalic reticular formation, tegmental reticular formation, and formatio reticularis (tegmenti) mesencephali, is a structure in the midbrain consisting of the dorsal tegmental nucleus, ventral tegmental nucleus, and cuneiform nucleus. These are also known as the tegmental nuclei.NeuroNamestegmental nuclei BrainInfo. Accessed January 25, 2011. The dorsal and ventral tegmental nuclei receive connections from the mammillo-tegmental ''bundle of Gudden'', a branch of the mammillothalamic tract. The bundle of Gudden might be identical to the hypothalamotegmental tract. Along with the oral pontine reticular nucleus, the midbrain reticular formation projects to the gigantocellular reticular nucleus. The midbrain reticular formation is the point at which the different algedonic signals come together, ensuring that the organism is aware of potential threats. See also *Hypothalamotegmental tract ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflex Action
In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus. Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs via neural pathways in the nervous system called reflex arcs. A stimulus initiates a neural signal, which is carried to a synapse. The signal is then transferred across the synapse to a motor neuron which evokes a target response. These neural signals do not always travel to the brain, so many reflexes are an automatic response to a stimulus that does not receive or need conscious thought. Many reflexes are fine-tuned to increase organism survival and self-defense. This is observed in reflexes such as the startle reflex, which provides an automatic response to an unexpected stimuli, and the feline righting reflex, which reorients a cat's body when falling to ensure safe landing. The simplest type of reflex, a short-latency reflex, has a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
