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Xochitecatl is located in a dominant position upon the summit of a 4 km-wide extinct volcano that forms a range of hills that rises approximately 200 meters above the floor of the Puebla-Tlaxcala Valley; the so-called Atlachino-Nativitas-Xochitecatl block, which is located in the centre of the valley.
It contains a sprawling palace with vibrantly colored murals painted in Maya style. The nearby site of Xochitecatl was a more public ceremonial complex associated with Cacaxtla. Cacaxtla and Xochitecatl prospered 650–900 CE, probably controlling important trade routes through the region with an enclave population of no more than 10,000 people.
HCN4 is the main isoform expressed in the sinoatrial node, but low levels of HCN1 and HCN2 have also been reported.The current through HCN channels, called the pacemaker current (I f), plays a key role in the generation and modulation of cardiac rhythmicity, [13] as they are responsible for the spontaneous depolarization in pacemaker action potentials in the heart.
The axons of the parvocellular neurosecretory neurons of the PVN project to the median eminence, a neurohemal organ at the base of the brain, where their neurosecretory nerve terminals release their hormones at the primary capillary plexus of the hypophyseal portal system. The median eminence contains fiber terminals from many hypothalamic ...
The central zone is composed of the glial cells, neuronal cell bodies and a high density of fenestrated capillaries. [8] Conversely, the rostral and caudal areas have a lower density of capillaries [8] and are mostly made of nerve fibers, with fewer neurons and glial cells seen in this area. Functionally, however, the SFO may be viewed in two ...
In chimpanzees and humans the neuropil provides a proxy measure of total connectivity within a local region because it is composed mostly of dendrites, axons, and synapses. [10] In insects the central complex plays an important role in higher-order brain function. The neuropil in Drosophila Ellipsoid is
The PPN within the MLR is composed of a diverse population of neurons containing the neurotransmitters gamma-amino-butyric acid (GABA), glutamate, and acetylcholine (ACh). [12] Results from animal and clinical studies suggest that cholinergic neurons in the PPN play a crucial role in modulating both the rhythm of locomotion and postural muscle ...
The M 2 muscarinic receptors are located in the heart and lungs. In the heart, they act to slow the heart rate down below the normal baseline sinus rhythm, by slowing the speed of depolarization. In humans, under resting conditions, vagal activity dominates over sympathetic activity.