Deep part of an organ. Fatty, whitish or yellowish substance that is found inside some bones of animals. Inner part of the roots and stems of the phanerogamic plants, consisting mainly of parenchymal tissue and surrounded by bundles of woody and sieving vessels. Principal substance of a non-material thing. The spinal cord is the portion of the central nervous system housed in the vertebral canal. It extends from the foramen magnum to the level where the first lumbar vertebra articulates with the second. It has gray matter in the center and white matter in the periphery.
In the gray matter they are distinguished. The anterior and posterior horns and the intermediate gray matter, traversed by the ependymal canal. The white matter is divided into three spinal cords: anterior, lateral and posterior, the cords in turn are made up of bundles, some sensitive and others motor. Sensory impulses reach the medulla through the posterior roots, and motor impulses depart from the medulla through the anterior roots. The integrative activity of the spinal cord corresponds to the spinal reflexes. There is also the bone marrow, which is found inside the bones and is of two types: the one that fills in the diaphyseal canal, of fatty constitution and yellowish color (fatty or yellow bone marrow) and the one that fills the spaces of the spongy bones (the short bones and the epiphyses of the long ones), which is red and is responsible for manufacturing the myeloid series of blood cells (red blood cells and leukocytes). The renal medulla is the inner part of the kidney that is pale in color and is distinguished in a cut in a cut of the outer part or cortex that has a red-brownish color.
It is made up of chronic- looking units called medullary pyramids, their number in the human kidney ranging between 12 and 18. It contains Heeln loops, collecting tubules, straight vessels and abundant intestinal tissue, receives 100% of the blood flow and its main function is the concentration and dilution of urine. Last but not least is the adrenal medulla that is found inside the adrenal gland, it is surrounded by the adrenal cortex and made up of cells derived from sympathicoblasts, which secrete adrenaline and noradrenaline, hormones that have sympathomimetric action (similar to sympathetic).
