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Nucleus Raphe Pallidus
The nucleus raphe pallidus receives afferent connections from the periaqueductal gray, the Paraventricular nucleus of hypothalamus, central nucleus of the amygdala, lateral hypothalamic area, and parvocellular reticular nucleus. Also, the nucleus raphe pallidus receives afferents from the medial preoptic area, median preoptic nucleus and lateral paragigantocellular reticular nuclei. The nucleus raphe pallidus has recently been shown to be involved in the activation of a fever as an immunoreaction. It has been implied that the preoptic area is constantly inhibiting the raphe pallidus, especially the rostral portion, with GABA. When the preoptic area receives immune signals from the body, the inhibition stops and the rostral portion of the nucleus raphe pallidus excites the intermediolateral cell column, which induces a fever. The nucleus raphe pallidus has also been known to mediate the tachycardia response, an extremely high heart rate known to be incited by emotional or psych ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periaqueductal Gray
The periaqueductal gray (PAG, also known as the central gray) is a brain region that plays a critical role in autonomic function, motivated behavior and behavioural responses to threatening stimuli. PAG is also the primary control center for descending pain modulation. It has enkephalin-producing cells that suppress pain. The periaqueductal gray is the gray matter located around the cerebral aqueduct within the tegmentum of the midbrain. It projects to the nucleus raphe magnus, and also contains descending autonomic tracts. The ascending pain and temperature fibers of the spinothalamic tract send information to the PAG via the spinomesencephalic tract (so-named because the fibers originate in the spine and terminate in the PAG, in the mesencephalon or midbrain). This region has been used as the target for brain-stimulating implants in patients with chronic pain. Role in analgesia Stimulation of the periaqueductal gray matter of the midbrain activates enkephalin-releasing ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraventricular Nucleus Of Hypothalamus
The paraventricular nucleus (PVN, PVA, or PVH) is a nucleus in the hypothalamus. Anatomically, it is adjacent to the third ventricle and many of its neurons project to the posterior pituitary. These projecting neurons secrete oxytocin and a smaller amount of vasopressin, otherwise the nucleus also secretes corticotropin-releasing hormone (CRH) and thyrotropin-releasing hormone (TRH). CRH and TRH are secreted into the hypophyseal portal system and act on different targets neurons in the anterior pituitary. PVN is thought to mediate many diverse functions through these different hormones, including osmoregulation, appetite, and the response of the body to stress. Location The paraventricular nucleus lies adjacent to the third ventricle. It lies within the periventricular zone and is not to be confused with the periventricular nucleus, which occupies a more medial position, beneath the third ventricle. The PVN is highly vascularised and is protected by the blood–brain barrier, althou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amygdala
The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex vertebrates, including humans. Shown to perform a primary role in the processing of memory, decision making, and emotional responses (including fear, anxiety, and aggression), the amygdalae are considered part of the limbic system. The term "amygdala" was first introduced by Karl Friedrich Burdach in 1822. Structure The regions described as amygdala nuclei encompass several structures of the cerebrum with distinct connectional and functional characteristics in humans and other animals. Among these nuclei are the basolateral complex, the cortical nucleus, the medial nucleus, the central nucleus, and the intercalated cell clusters. The basolateral complex can be further subdivided into the lateral, the basal, and the accessory basal nucle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parvocellular Reticular Nucleus
The parvocellular reticular nucleus is part of the brain located dorsolateral to the caudal pontine reticular nucleus. The dorsal portion of the reticular nucleus has been shown to innervate the mesencephalic trigeminal nucleus and its surrounding area. Also, it projects to the facial nucleus, hypoglossal nucleus and parabrachial area along with parts of the caudal parvocellular reticular formation.Ter Horst, GJ et al. Projections from the rostral parvocellular reticular formation to pontine and medullary nuclei in the rat: involvement in autonomic regulation and orofacial motor control. Neuroscience. 1991;40(3):735-58. This nucleus is also involved in expiration with a part of the gigantocellular nucleus The gigantocellular reticular nucleus (Gi) is a subregion of the medullary reticular formation. As the name indicates, it consists mainly of so-called giant neuronal cells. This nucleus has been known to innervate the caudal hypoglossal nucleus, .... References Medull ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medial Preoptic Area
The preoptic area is a region of the hypothalamus. MeSH classifies it as part of the anterior hypothalamus. TA lists four nuclei in this region, (medial, median, lateral, and periventricular). Functions The preoptic area is responsible for thermoregulation and receives nervous stimulation from thermoreceptors in the skin, mucous membranes, and hypothalamus itself. Nuclei Median preoptic nucleus The median preoptic nucleus is located along the midline in a position significantly dorsal to the other three preoptic nuclei, at least in the crab-eating macaque brain. It wraps around the top (dorsal), front, and bottom (ventral) surfaces of the anterior commissure. The median preoptic nucleus generates thirst. Drinking decreases noradrenaline release in the median preoptic nucleus. Medial preoptic nucleus The medial preoptic nucleus is bounded laterally by the lateral preoptic nucleus, and medially by the preoptic periventricular nucleus. It releases gonadotropin-releasing hormon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preoptic Area
The preoptic area is a region of the hypothalamus. MeSH classifies it as part of the anterior hypothalamus. TA lists four nuclei in this region, (medial, median, lateral, and periventricular). Functions The preoptic area is responsible for thermoregulation and receives nervous stimulation from thermoreceptors in the skin, mucous membranes, and hypothalamus itself. Nuclei Median preoptic nucleus The median preoptic nucleus is located along the midline in a position significantly dorsal to the other three preoptic nuclei, at least in the crab-eating macaque brain. It wraps around the top (dorsal), front, and bottom (ventral) surfaces of the anterior commissure. The median preoptic nucleus generates thirst. Drinking decreases noradrenaline release in the median preoptic nucleus. Medial preoptic nucleus The medial preoptic nucleus is bounded laterally by the lateral preoptic nucleus, and medially by the preoptic periventricular nucleus. It releases gonadotropin-releasing hormon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tachycardia
Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal (such as with exercise) or abnormal (such as with electrical problems within the heart). Complications Tachycardia can lead to fainting. When the rate of blood flow becomes too rapid, or fast blood flow passes on damaged endothelium, it increases the friction within vessels resulting in turbulence and other disturbances. According to the Virchow's triad, this is one of the three conditions that can lead to thrombosis (i.e., blood clots within vessels). Causes Some causes of tachycardia include: * Adrenergic storm * Anaemia * Anxiety * Atrial fibrillation * Atrial flutter * Atrial tachycardia * Atrioventricular reentrant tachycardia * AV nodal reentrant tachycardia * Brugada syndrome * Circulatory shock and its various causes ( obstr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agonist
An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the agonist, while an inverse agonist causes an action opposite to that of the agonist. Etymology From the Greek αγωνιστής (agōnistēs), contestant; champion; rival < αγων (agōn), contest, combat; exertion, struggle < αγω (agō), I lead, lead towards, conduct; drive Types of agonists can be activated by either endogenous agonists (such as |
